Android Coding

Touch to move Bitmap inside a custom View

2012-03-19T14:57:00.002-07:00

Refer to the article Detect Touch Event, test on Custom View. Modify to add a Bitmap in the custom view, if user touch the View over the bitmap, it will be moved accordingly.

package com.TestSingleTouch;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;

public class TestSingleTouch extends Activity {
 
 
 public class TouchView extends View {
  
  private Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
  private float x, y;
  boolean touching = false;
  
  Bitmap bm = BitmapFactory.decodeResource(
      getResources(),
      R.drawable.ic_launcher);
  int bm_x = 0;
  int bm_y = 0;
  int bm_w = bm.getWidth();
  int bm_h = bm.getHeight();
  int bm_offsetx;
  int bm_offsety;
  boolean dm_touched = false;
  
  
  public TouchView(Context context) {
   
   super(context);
   // TODO Auto-generated constructor stub 
   
  }
  
  @Override
  protected void onDraw(Canvas canvas) {
   // TODO Auto-generated method stub
   paint.setStyle(Paint.Style.STROKE);
   paint.setStrokeWidth(1);
   paint.setColor(Color.WHITE);
   
   if(touching){
    canvas.drawRect(x, y, x+bm_w, y+bm_h, paint);
   }
   
   canvas.drawBitmap(bm, bm_x, bm_y, paint);
  }
  
  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
   // TODO Auto-generated method stub
   setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec),
     MeasureSpec.getSize(heightMeasureSpec)); 
  }
  
  @Override
  
  public boolean onTouchEvent(MotionEvent event) {
   // TODO Auto-generated method stub
   int action = event.getAction();
   switch(action){
   case MotionEvent.ACTION_MOVE:
    x = event.getX();
    y = event.getY();
    touching = true;

    if(dm_touched){
     bm_x = (int)x - bm_offsetx;
     bm_y = (int)y - bm_offsety;
    }
    
    break; 
   case MotionEvent.ACTION_DOWN:
    x = event.getX();
    y = event.getY();
    touching = true;
    
    //check if bm touched
    if((x > bm_x)
     && (x < bm_x+bm_w)
     && (y > bm_y)
     && (y < bm_y+bm_h)){
     bm_offsetx = (int)x - bm_x;
     bm_offsety = (int)y - bm_y;
     dm_touched = true;
    }
    
    break; 
   case MotionEvent.ACTION_UP:
   default:
    dm_touched = false;
    touching = false; 
   }

   invalidate();
   return true; 
  } 
 }
 
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(new TouchView(this)); 
  
 }
}

Implement Horizontal ListView using android.widget.Gallery, with custom BaseAdapter.

2012-03-15T21:13:00.001-07:00

Refer to the article Implement a photo bar using android.widget.Gallery, with custom BaseAdapter, and custom object. It can be modify to implement a Horizontal ListView, like this:

Modify the main java code to implement our custom BaseAdapter for Gallery.

package com.AnHorizontalListView;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.TextView;
import android.widget.Toast;

public class AnHorizontalListViewActivity extends Activity {
 
 Gallery myHorizontalListView;
 MyAdapter myAdapter;
 
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      myHorizontalListView = (Gallery)findViewById(R.id.horizontallistview);
    
      myAdapter = new MyAdapter(this);
      myHorizontalListView.setAdapter(myAdapter);
    
      myHorizontalListView.setOnItemClickListener(new OnItemClickListener(){

   @Override
   public void onItemClick(AdapterView<?> parent, View view, int position,
     long id) {
    Toast.makeText(
      AnHorizontalListViewActivity.this,
      parent.getItemAtPosition(position).toString() + " Clicked",
      Toast.LENGTH_LONG)
      .show();
    
   }});
    
  }

  public class MyAdapter extends BaseAdapter {
   
   Context context;
   
   String[] itemsArray = {
     "SUN","MON", "TUS", "WED", "THU", "FRI", "SAT"};
   
   MyAdapter(Context c){
    context = c;
   }

  @Override
  public int getCount() {
   // TODO Auto-generated method stub
   return itemsArray.length;
  }

  @Override
  public Object getItem(int position) {
   // TODO Auto-generated method stub
   return itemsArray[position];
  }

  @Override
  public long getItemId(int position) {
   // TODO Auto-generated method stub
   return position;
  }

  @Override
  public View getView(int position, View convertView, ViewGroup parent) {
   // TODO Auto-generated method stub
   
   View rowView = LayoutInflater
     .from(parent.getContext())
     .inflate(R.layout.row, null);
   TextView listTextView = (TextView)rowView.findViewById(R.id.itemtext);
   listTextView.setText(itemsArray[position]);
   
   return rowView;
  }
  
  
  }
}

Create /res/layout/row.xml to define the layout of individual items in Gallery.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical" >

  <TextView
      android:id="@+id/itemtext"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_margin="20dp"
      android:textColor="@android:color/white"
      android:textStyle="bold"
      android:textSize="30sp"/>

</LinearLayout>

Main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical" >

  <TextView
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:text="@string/hello" />
  <Gallery
      android:id="@+id/horizontallistview"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content" />

</LinearLayout>

Dual VideoView to play 3gp from YouTube

2012-03-15T06:36:00.003-07:00

It's a simple example to include two VideoView in layout to play differnece 3gp from YouTube at the same time.

Reference: A simple example using VideoView to play 3gp from YouTube.

Main Layout:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />
    <LinearLayout
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="match_parent">
        <VideoView
            android:id="@+id/myvideoview"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content" />
        <VideoView
            android:id="@+id/myvideoview2"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content" />
    </LinearLayout>
</LinearLayout>

Main Code:

package com.AnVideoView;

import android.app.Activity;
import android.net.Uri;
import android.os.Bundle;
import android.widget.MediaController;
import android.widget.VideoView;

public class AnVideoView extends Activity {
 
 String SrcPath = "rtsp://v5.cache1.c.youtube.com/CjYLENy73wIaLQnhycnrJQ8qmRMYESARFEIJbXYtZ29vZ2xlSARSBXdhdGNoYPj_hYjnq6uUTQw=/0/0/0/video.3gp";
 String SrcPath2 = "rtsp://v2.cache7.c.youtube.com/CjYLENy73wIaLQk4RDShYkdS1BMYJCAkFEIJbXYtZ29vZ2xlSARSBXdhdGNoYKjR78WV1ZH5Tgw=/0/0/0/video.3gp";
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        VideoView myVideoView = (VideoView)findViewById(R.id.myvideoview);
        myVideoView.setVideoURI(Uri.parse(SrcPath));
        myVideoView.setMediaController(new MediaController(this));
        myVideoView.requestFocus();
        myVideoView.start();
        
        VideoView myVideoView2 = (VideoView)findViewById(R.id.myvideoview2);
        myVideoView2.setVideoURI(Uri.parse(SrcPath2));
        myVideoView2.setMediaController(new MediaController(this));
        myVideoView2.requestFocus();
        myVideoView2.start();
    }
}

Create our Android Compass

2012-03-12T15:01:00.003-07:00

Base on last post "Detect Orientation using Accelerometer and Magnetic Field sensors", a Android compass is implemented here. In the implementation, the final result (base on Accelerometer and Magnetic Field sensors) is show in RED, point to the north.

Create a custom View, Compass, extends View. The method update() is called from onSensorChanged() of main activity, with the updated direction.

package com.AndroidDetOrientation;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

public class Compass extends View {

 private float direction;
 
 public Compass(Context context) {
  super(context);
  // TODO Auto-generated constructor stub
 }

 public Compass(Context context, AttributeSet attrs) {
  super(context, attrs);
  // TODO Auto-generated constructor stub
 }

 public Compass(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  // TODO Auto-generated constructor stub
 }

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  setMeasuredDimension(
    MeasureSpec.getSize(widthMeasureSpec),
    MeasureSpec.getSize(heightMeasureSpec));
 }

 @Override
 protected void onDraw(Canvas canvas) {
  
  int w = getMeasuredWidth();
  int h = getMeasuredHeight();
  int r;
  if(w > h){
   r = h/2;
  }else{
   r = w/2;
  }
  
  Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
  paint.setStyle(Paint.Style.STROKE);
  paint.setStrokeWidth(5);
  paint.setColor(Color.WHITE);
  
  canvas.drawCircle(w/2, h/2, r, paint);
  
  paint.setColor(Color.RED);
  canvas.drawLine(
    w/2,
    h/2,
    (float)(w/2 + r * Math.sin(-direction)),
    (float)(h/2 - r * Math.cos(-direction)),
    paint);

 }
 
 public void update(float dir){
  direction = dir;
  invalidate();
 }
 
}

Modify main activity, AndroidDetOrientationActivity, to update Compass.

package com.AndroidDetOrientation;

import android.app.Activity;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.widget.TextView;

public class AndroidDetOrientationActivity extends Activity
 implements SensorEventListener{
 
 SensorManager sensorManager;
 private Sensor sensorAccelerometer;
 private Sensor sensorMagneticField;
 
 private float[] valuesAccelerometer;
 private float[] valuesMagneticField;
 
 private float[] matrixR;
 private float[] matrixI;
 private float[] matrixValues;
 
 TextView readingAzimuth, readingPitch, readingRoll;
 Compass myCompass;
 
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      readingAzimuth = (TextView)findViewById(R.id.azimuth);
      readingPitch = (TextView)findViewById(R.id.pitch);
      readingRoll = (TextView)findViewById(R.id.roll);
    
      myCompass = (Compass)findViewById(R.id.mycompass);
    
      sensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
      sensorAccelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
   sensorMagneticField = sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
    
   valuesAccelerometer = new float[3];
   valuesMagneticField = new float[3];

   matrixR = new float[9];
   matrixI = new float[9];
   matrixValues = new float[3];
  }

 @Override
 protected void onResume() {

  sensorManager.registerListener(this,
    sensorAccelerometer,
    SensorManager.SENSOR_DELAY_NORMAL);
  sensorManager.registerListener(this,
    sensorMagneticField,
    SensorManager.SENSOR_DELAY_NORMAL);
  super.onResume();
 }

 @Override
 protected void onPause() {

  sensorManager.unregisterListener(this,
    sensorAccelerometer);
  sensorManager.unregisterListener(this,
    sensorMagneticField);
  super.onPause();
 }

 @Override
 public void onAccuracyChanged(Sensor arg0, int arg1) {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void onSensorChanged(SensorEvent event) {
  // TODO Auto-generated method stub
  
  switch(event.sensor.getType()){
  case Sensor.TYPE_ACCELEROMETER:
   for(int i =0; i < 3; i++){
    valuesAccelerometer[i] = event.values[i];
   }
   break;
  case Sensor.TYPE_MAGNETIC_FIELD:
   for(int i =0; i < 3; i++){
    valuesMagneticField[i] = event.values[i];
   }
   break;
  }
  
  boolean success = SensorManager.getRotationMatrix(
       matrixR,
       matrixI,
       valuesAccelerometer,
       valuesMagneticField);
  
  if(success){
   SensorManager.getOrientation(matrixR, matrixValues);
   
   double azimuth = Math.toDegrees(matrixValues[0]);
   double pitch = Math.toDegrees(matrixValues[1]);
   double roll = Math.toDegrees(matrixValues[2]);
   
   readingAzimuth.setText("Azimuth: " + String.valueOf(azimuth));
   readingPitch.setText("Pitch: " + String.valueOf(pitch));
   readingRoll.setText("Roll: " + String.valueOf(roll));
   
   myCompass.update(matrixValues[0]);
  }
  
 }
}

Modify main.xml to add a View of Compass.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical" >

  <TextView
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:text="@string/hello" />
  <TextView
      android:id="@+id/azimuth"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"/>
  <TextView
      android:id="@+id/pitch"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"/>
  <TextView
      android:id="@+id/roll"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"/>
  <view
      class="com.AndroidDetOrientation.Compass"
      android:id="@+id/mycompass"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"/>

</LinearLayout>

Detect Orientation using Accelerometer and Magnetic Field sensors

2012-03-11T16:44:00.004-07:00

The post Detect Android device rotation, using Accelerometer sensor base on accelerometer only. It is another method to obtain it using both Accelerometer and Magnetic Field sensors together.

Example:

package com.AndroidDetOrientation;

import android.app.Activity;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.widget.TextView;

public class AndroidDetOrientationActivity extends Activity 
 implements SensorEventListener{
 
 SensorManager sensorManager;
 private Sensor sensorAccelerometer;
 private Sensor sensorMagneticField;
 
 private float[] valuesAccelerometer;
 private float[] valuesMagneticField;
 
 private float[] matrixR;
 private float[] matrixI;
 private float[] matrixValues;
 
 TextView readingAzimuth, readingPitch, readingRoll;
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        readingAzimuth = (TextView)findViewById(R.id.azimuth);
        readingPitch = (TextView)findViewById(R.id.pitch);
        readingRoll = (TextView)findViewById(R.id.roll);
        
        sensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
        sensorAccelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
     sensorMagneticField = sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
        
     valuesAccelerometer = new float[3];
     valuesMagneticField = new float[3];
     
     matrixR = new float[9];
     matrixI = new float[9];
     matrixValues = new float[3];
    }
    
 @Override
 protected void onResume() {

  sensorManager.registerListener(this, 
    sensorAccelerometer, 
    SensorManager.SENSOR_DELAY_NORMAL);
  sensorManager.registerListener(this, 
    sensorMagneticField, 
    SensorManager.SENSOR_DELAY_NORMAL);
  super.onResume();
 }

 @Override
 protected void onPause() {

  sensorManager.unregisterListener(this, 
    sensorAccelerometer);
  sensorManager.unregisterListener(this, 
    sensorMagneticField);
  super.onPause();
 }

 @Override
 public void onAccuracyChanged(Sensor arg0, int arg1) {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void onSensorChanged(SensorEvent event) {
  // TODO Auto-generated method stub
  
  switch(event.sensor.getType()){
  case Sensor.TYPE_ACCELEROMETER:
   for(int i =0; i < 3; i++){
    valuesAccelerometer[i] = event.values[i];
   }
   break;
  case Sensor.TYPE_MAGNETIC_FIELD:
   for(int i =0; i < 3; i++){
    valuesMagneticField[i] = event.values[i];
   }
   break;
  }
  
  boolean success = SensorManager.getRotationMatrix(
       matrixR, 
       matrixI, 
       valuesAccelerometer, 
       valuesMagneticField);
  
  if(success){
   SensorManager.getOrientation(matrixR, matrixValues);
   
   double azimuth = Math.toDegrees(matrixValues[0]);
   double pitch = Math.toDegrees(matrixValues[1]);
   double roll = Math.toDegrees(matrixValues[2]);
   
   readingAzimuth.setText("Azimuth: " + String.valueOf(azimuth));
   readingPitch.setText("Pitch: " + String.valueOf(pitch));
   readingRoll.setText("Roll: " + String.valueOf(roll));
  }
  
 }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />
    <TextView
        android:id="@+id/azimuth" 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
    <TextView
        android:id="@+id/pitch" 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
    <TextView
        android:id="@+id/roll" 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>

Next
- Create our Android Compass

SurfaceView Game step-by-step: react device movement/orientation using accelerometer

2012-03-07T05:52:00.002-08:00

With the help of accelerometer on Android device(Get detail info of Accelerometer), we can react device movement/orientation for our SurfaceView Game(Implement onTouchEvent() to handle user touch on SurfaceView). After finished, the the Sprite will move once user move the device.

Implement new class - MyAccelerometer.java.

package com.MyGame;

import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;

public class MyAccelerometer implements SensorEventListener{

 private SensorManager sensorManager;
 private Sensor sensorAccelerometer;
 private MyGameActivity parent;
 
 private float maximumRange;
 
 public MyAccelerometer(Context c) {
  parent = (MyGameActivity)c;
 }
 
 void registerListener(){
  sensorManager = (SensorManager)parent.getSystemService(Context.SENSOR_SERVICE);
      sensorAccelerometer = sensorManager.getDefaultSensor(
        Sensor.TYPE_ACCELEROMETER);
    
      maximumRange = sensorAccelerometer.getMaximumRange();
    
  sensorManager.registerListener(this,
    sensorAccelerometer,
    SensorManager.SENSOR_DELAY_NORMAL);
 }
 
 void unregisterListener(){
  sensorManager.unregisterListener(this);
 }

 @Override
 public void onAccuracyChanged(Sensor sensor, int accuracy) {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void onSensorChanged(SensorEvent event) {
  // TODO Auto-generated method stub
  /*
   * event.values[0]: azimuth, rotation around the Z axis.
   * event.values[1]: pitch, rotation around the X axis.
   * event.values[2]: roll, rotation around the Y axis.
   */
  
  float valueAzimuth = event.values[0];
  float valuePitch = event.values[1];
  
  parent.updateAccelerometer(
    valueAzimuth/maximumRange, -valuePitch/maximumRange);
  
 }

}

Modify MyGameActivity.java to instance MyAccelerometer object in onCreate(), init it in onResume(), unregisterListener it in onPause(), and also implement updateAccelerometer().

package com.MyGame;

import android.app.Activity;
import android.graphics.PixelFormat;
import android.os.Bundle;

public class MyGameActivity extends Activity {
 
 MyGameSurfaceView myGameSurfaceView1;
 MyForeground myForeground;
 
 MyAccelerometer myAccelerometer;
 
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      myGameSurfaceView1 = (MyGameSurfaceView)findViewById(R.id.myview1);
      myForeground = (MyForeground)findViewById(R.id.myforeground);
    
      //Set myForeground using transparent background
      myForeground.setZOrderOnTop(true);
      myForeground.getHolder().setFormat(PixelFormat.TRANSPARENT);
    
      myAccelerometer = new MyAccelerometer(this);
    
  }

 @Override
 protected void onResume() {
  // TODO Auto-generated method stub
  super.onResume();
  myGameSurfaceView1.MyGameSurfaceView_OnResume();
  myForeground.MyGameSurfaceView_OnResume();
  
  myAccelerometer.registerListener();

 }

 @Override
 protected void onPause() {
  // TODO Auto-generated method stub
  super.onPause();
  myGameSurfaceView1.MyGameSurfaceView_OnPause();
  myForeground.MyGameSurfaceView_OnPause();
  
  myAccelerometer.unregisterListener();
 }
 
 void updateAccelerometer(float tx, float ty){
  int w = myForeground.getWidth();
  int h = myForeground.getHeight();
  
  float x = ((w/2) * tx) + (w/2);
  float y = ((h/2) * ty) + (h/2);
  myForeground.updateAccelerometer(x, y);
 }

}

Update MyForeground.java.

package com.MyGame;

import android.content.Context;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.PorterDuff.Mode;
import android.util.AttributeSet;

public class MyForeground extends MyGameSurfaceView {
 
 Sprite mySprite;

 public MyForeground(Context context) {
  super(context);
  init();
 }

 public MyForeground(Context context, AttributeSet attrs) {
  super(context, attrs);
  init();
 }

 public MyForeground(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  init();
 }
 
 private void init(){
  mySprite = new Sprite(
    BitmapFactory.decodeResource(getResources(), R.drawable.icon_me),
    100, 100);
 }

 @Override
 protected void onDraw(Canvas canvas) {
  //Clear Canvas with transparent background
  canvas.drawColor(Color.TRANSPARENT, Mode.CLEAR);
  
  mySprite.draw(canvas);
 }

 @Override
 public void updateStates() {
  // TODO Auto-generated method stub
  mySprite.update();
 }
 
 void updateAccelerometer(float tx, float ty){
  mySprite.setX((int)tx);
  mySprite.setY((int)ty);
 }

}

Update Sprite.java to remove un-used code.

package com.MyGame;

import android.graphics.Bitmap;
import android.graphics.Canvas;

public class Sprite {
 private Bitmap bitmap;
 private int x;
 private int y;
 float bitmap_halfWidth, bitmap_halfHeight;
 
 public Sprite(Bitmap bm, int tx, int ty){
  bitmap = bm;
  x = tx;
  y = ty;
  bitmap_halfWidth = bitmap.getWidth()/2;
  bitmap_halfHeight = bitmap.getHeight()/2;  
 }
 
 public void setX(int tx){
  x = tx;
 }
 
 public void setY(int ty){
  y = ty;
 }
 
 public int getX(){
  return x;
 }
 
 public int getY(){
  return y;
 }
 
 public void draw(Canvas canvas){
  canvas.drawBitmap(bitmap, x-bitmap_halfWidth, y-bitmap_halfHeight, null);
 }
 
 public void update(){

 }

}

The code can be download here: https://sites.google.com/site/helloandroidingcoding/download/MyGame_20120307.zip?attredirects=0&d=1

Get detail info of Accelerometer

2012-03-05T09:55:00.002-08:00

package com.exercise.AndroidAccelerometer;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;

public class AndroidAccelerometerActivity extends Activity 
 implements SensorEventListener{
 
 private SensorManager sensorManager;
 private Sensor sensorAccelerometer;
 
 TextView readingAzimuth, readingPitch, readingRoll;
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        sensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
        sensorAccelerometer = sensorManager.getDefaultSensor(
          Sensor.TYPE_ACCELEROMETER);
        
        readingAzimuth = (TextView)findViewById(R.id.azimuth);
        readingPitch = (TextView)findViewById(R.id.pitch);
        readingRoll = (TextView)findViewById(R.id.roll);
        TextView info = (TextView)findViewById(R.id.info);
          
        String stringInfo = "\n"
        + "Name: " + sensorAccelerometer.getName() + "\n"
        + "Type: " + sensorAccelerometer.getType() + "\n"
        + "Vendor: " + sensorAccelerometer.getVendor() + "\n"
        + "Version: " + sensorAccelerometer.getVersion() + "\n"
        + "Class: " + sensorAccelerometer.getClass() + "\n"
        + "Resolution: " + sensorAccelerometer.getResolution() + "\n"
        + "MaximumRange: " + sensorAccelerometer.getMaximumRange() + "\n"
        + "Power: " + sensorAccelerometer.getPower() + "\n";
        
        info.setText(stringInfo);
        
    }

 @Override
 protected void onPause() {
  super.onPause();
  sensorManager.unregisterListener(this);
 }

 @Override
 protected void onResume() {
  super.onResume();
  sensorManager.registerListener(this, 
    sensorAccelerometer, 
    SensorManager.SENSOR_DELAY_NORMAL);
 }

 @Override
 public void onAccuracyChanged(Sensor arg0, int arg1) {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void onSensorChanged(SensorEvent event) {

  /*
   * event.values[0]: azimuth, rotation around the Z axis.
   * event.values[1]: pitch, rotation around the X axis.
   * event.values[2]: roll, rotation around the Y axis.
   */
  
  float valueAzimuth = event.values[0];
  float valuePitch = event.values[1];
  float valueRoll = event.values[2];
  
  readingAzimuth.setText("Azimuth: " + String.valueOf(valueAzimuth));
        readingPitch.setText("Pitch: " + String.valueOf(valuePitch));
        readingRoll.setText("Roll: " + String.valueOf(valueRoll));

  
 }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />
    <TextView
        android:id="@+id/info" 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
    <TextView
        android:id="@+id/azimuth" 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
    <TextView
        android:id="@+id/pitch" 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
    <TextView
        android:id="@+id/roll" 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>

Detect Android device rotation, using Accelerometer sensor

2012-02-27T09:24:00.003-08:00

package com.AndroidRotation;

import android.app.Activity;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.widget.TextView;

public class AndroidRotationActivity extends Activity implements SensorEventListener{
 
 private SensorManager manager;
 private Sensor sensor;
 
 TextView azimuth, pitch, roll;
 
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
    
      manager = (SensorManager)getSystemService(SENSOR_SERVICE);
      sensor = manager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    
      azimuth = (TextView)findViewById(R.id.azimuth);
      pitch = (TextView)findViewById(R.id.pitch);
      roll = (TextView)findViewById(R.id.roll);
  }

 @Override
 protected void onPause() {
  super.onPause();
  manager.unregisterListener(this);
 }

 @Override
 protected void onResume() {
  super.onResume();
  manager.registerListener(this, sensor, SensorManager.SENSOR_DELAY_NORMAL);
 }

 @Override
 public void onAccuracyChanged(Sensor arg0, int arg1) {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void onSensorChanged(SensorEvent arg0) {
  
  azimuth.setText("Azimuth: " + String.valueOf(arg0.values[0]));
      pitch.setText("Pitch: " + String.valueOf(arg0.values[1]));
      roll.setText("Roll: " + String.valueOf(arg0.values[2]));
  
 }
}

Next:
- Get detail info of Accelerometer

Related:
- Detect Orientation using Accelerometer and Magnetic Field sensors

Implement onTouchEvent() to handle user touch on SurfaceView

2012-02-15T15:14:00.001-08:00

Modify from last article Sprite auto-run, implement onTouchEvent() to handle user touch on SurfaceView. When user touch on the screen(SurfaceView), it will call setX(x) and setY(y) of mySprite object to update its position.

package com.MyGame;

import android.content.Context;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.PorterDuff.Mode;
import android.util.AttributeSet;
import android.view.MotionEvent;

public class MyForeground extends MyGameSurfaceView {
 
 Sprite mySprite;

 public MyForeground(Context context) {
  super(context);
  init();
 }

 public MyForeground(Context context, AttributeSet attrs) {
  super(context, attrs);
  init();
 }

 public MyForeground(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  init();
 }
 
 private void init(){
  mySprite = new Sprite(
    BitmapFactory.decodeResource(getResources(), R.drawable.icon_me),
    100, 100);
 }

 @Override
 protected void onDraw(Canvas canvas) {
  //Clear Canvas with transparent background
  canvas.drawColor(Color.TRANSPARENT, Mode.CLEAR);
  
  mySprite.draw(canvas);
 }

 @Override
 public void updateStates() {
  // TODO Auto-generated method stub
  mySprite.update();
 }

 @Override
 public boolean onTouchEvent(MotionEvent event) {
  int x = (int) event.getX();
  int y = (int) event.getY();
  
  int action = event.getAction();
  switch(action){
  case MotionEvent.ACTION_DOWN:
   mySprite.setX(x);
   mySprite.setY(y);
   break;
  case MotionEvent.ACTION_MOVE:
   break;
  case MotionEvent.ACTION_UP:
   break;
  case MotionEvent.ACTION_CANCEL:
   break;
  case MotionEvent.ACTION_OUTSIDE:
   break;
  default: 
  }
  
  return true;
  
 }

}

Next:
- React device movement/orientation using accelerometer

Sprite auto-run

2012-02-12T08:33:00.001-08:00

In last article Introduce Sprite without movement. In this article, we are going to make it self move.

Modify Sprite.java to make it self random move inside the canvas.

package com.MyGame;
import java.util.Random;

import android.graphics.Bitmap;
import android.graphics.Canvas;

public class Sprite {
 private Bitmap bitmap;
 private int x;
 private int y;
 float bitmap_halfWidth, bitmap_halfHeight;
 
 Random random = new Random();
 private int dirX;
 private int dirY;
 private int moveX;
 private int moveY;
 
 final int MAX = 99;
 
 public Sprite(Bitmap bm, int tx, int ty){
  bitmap = bm;
  x = tx;
  y = ty;
  bitmap_halfWidth = bitmap.getWidth()/2;
  bitmap_halfHeight = bitmap.getHeight()/2;

  if(random.nextBoolean()){
   dirX = 1;
  }else{
   dirX = -1;
  }
  
  if(random.nextBoolean()){
   dirY = 1;
  }else{
   dirY = -1;
  }
  
  moveX = random.nextInt(MAX) + 1;
  moveY = random.nextInt(MAX) + 1;
  
 }
 
 public void setX(int tx){
  x = tx;
 }
 
 public void setY(int ty){
  y = ty;
 }
 
 public int getX(){
  return x;
 }
 
 public int getY(){
  return y;
 }
 
 public void draw(Canvas canvas){
  
  if(x < 0){
   x = 0;
   dirX *= -1;
   moveX = random.nextInt(MAX) + 1;
  }else if(x >= canvas.getWidth()){
   x = canvas.getWidth();
   dirX *= -1;
   moveX = random.nextInt(MAX) + 1;
  }
  
  if(y < 0){
   y = 0;
   dirY *= -1;
   moveY = random.nextInt(MAX) + 1;
  }else if(y >= canvas.getHeight()){
   y = canvas.getHeight();
   dirY *= -1;
   moveY = random.nextInt(MAX) + 1;
  }
  
  
  canvas.drawBitmap(bitmap, x-bitmap_halfWidth, y-bitmap_halfHeight, null);
 }
 
 public void update(){
  x += (dirX * moveX);
  y += (dirY * moveY);
 }

}

Modify MyForeground.java to override updateStates(), call mySprite.update() indirectly. Also note the method onDraw(); because SurfaceView will not remove the old Sprite, so we have to clear the canvas before draw the new Sprite. TO clear canvas with TRANSPARENT background, we can call the method canvas.drawColor(Color.TRANSPARENT, Mode.CLEAR).

package com.MyGame;

import android.content.Context;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.PorterDuff.Mode;
import android.util.AttributeSet;

public class MyForeground extends MyGameSurfaceView {
 
 Sprite mySprite;

 public MyForeground(Context context) {
  super(context);
  init();
 }

 public MyForeground(Context context, AttributeSet attrs) {
  super(context, attrs);
  init();
 }

 public MyForeground(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  init();
 }
 
 private void init(){
  mySprite = new Sprite(
    BitmapFactory.decodeResource(getResources(), R.drawable.icon_me),
    100, 100);
 }

 @Override
 protected void onDraw(Canvas canvas) {
  //Clear Canvas with transparent background
  canvas.drawColor(Color.TRANSPARENT, Mode.CLEAR);
  
  mySprite.draw(canvas);
 }

 @Override
 public void updateStates() {
  // TODO Auto-generated method stub
  mySprite.update();
 }

}

Next:
- Implement onTouchEvent() to handle user touch on SurfaceView

Introduce Sprite

2012-02-09T13:02:00.001-08:00

Base on last post Create transparent foreground SurfaceView, the object on foreground was draw as a bitmap. We are going to implement a Sprite class here. Sprite object keep it's own status such as location(x, y) and bitmap, and also draw itself on canvas.

Add class Sprite.java

package com.MyGame;

import android.graphics.Bitmap;
import android.graphics.Canvas;

public class Sprite {
private Bitmap bitmap;
private int x;
private int y;
float bitmap_halfWidth, bitmap_halfHeight;

public Sprite(Bitmap bm, int tx, int ty){
 bitmap = bm;
 x = tx;
 y = ty;
 bitmap_halfWidth = bitmap.getWidth()/2;
 bitmap_halfHeight = bitmap.getHeight()/2;
}

public void setX(int tx){
 x = tx;
}

public void setY(int ty){
 y = ty;
}

public int getX(){
 return x;
}

public int getY(){
 return y;
}

public void draw(Canvas canvas){
 canvas.drawBitmap(bitmap, x-bitmap_halfWidth, y-bitmap_halfHeight, null);
}

}

Modify MyForeground.java

package com.MyGame;

import android.content.Context;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.util.AttributeSet;

public class MyForeground extends MyGameSurfaceView {

Sprite mySprite;

public MyForeground(Context context) {
 super(context);
 init();
}

public MyForeground(Context context, AttributeSet attrs) {
 super(context, attrs);
 init();
}

public MyForeground(Context context, AttributeSet attrs, int defStyle) {
 super(context, attrs, defStyle);
 init();
}

private void init(){
 mySprite = new Sprite(
   BitmapFactory.decodeResource(getResources(), R.drawable.icon_me),
   100, 100);
}

@Override
protected void onDraw(Canvas canvas) {
 mySprite.draw(canvas);
}

}

Next:
- Sprite auto-run

Create transparent foreground SurfaceView

2012-01-28T11:08:00.000-08:00

Start reading here: Create a SurfaceView Game step-by-step

In previoud posts, we have created a custom SurfaceView(MyGameSurfaceView.java) with background thread. Now we are going to create another MyForeground class by extending our MyGameSurfaceView, with overriding code. Base on the existing MyGameSurfaceView class, it's easy to implement the new MyForeground class.

- Create a new class: Right click to select our package (com.MyGame) in Package Explorer, select File -> New -> Class in Eclipse Menu.

- Enter class name, MyForeground, in Name field. And click Browse...

- Type MyGameSurfaceView in Choose a type box, and select MyGameSurfaceView - com.MyGame, click OK.

- Scroll down in New Java Class dialog, click to check Constructors from superclass. Click Finish.

- Now, we have a new class MyForeground.java under com.MyGame.

- Modify MyForeground.java to override onDraw(Canvas canvas). We are going to draw each pixel on foreground, so we need not to handle the "Flickering problems". For now, we simple draw a icon on a fixed location on foreground.

package com.MyGame;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.util.AttributeSet;

public class MyForeground extends MyGameSurfaceView {

public MyForeground(Context context) {
 super(context);
 // TODO Auto-generated constructor stub
}

public MyForeground(Context context, AttributeSet attrs) {
 super(context, attrs);
 // TODO Auto-generated constructor stub
}

public MyForeground(Context context, AttributeSet attrs, int defStyle) {
 super(context, attrs, defStyle);
 // TODO Auto-generated constructor stub
}

@Override
protected void onDraw(Canvas canvas) {
 Bitmap me = BitmapFactory.decodeResource(getResources(), R.drawable.icon_me);
 int loc_x = canvas.getWidth()/2;
 int loc_y = canvas.getHeight()/2;
 canvas.drawBitmap(me, loc_x, loc_y, null);
}

}

- Modify main.xml to add a new MyForeground, overlape with original MyGameSurfaceView inside a FrameLayout.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical" >

  <TextView
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:text="@string/hello" />
  <FrameLayout
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      >
  <com.MyGame.MyGameSurfaceView
      android:id="@+id/myview1"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent" />
  <com.MyGame.MyForeground
      android:id="@+id/myforeground"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent" />
  </FrameLayout>
</LinearLayout>

- Modify MyGameActivity.java to handle MyForeground. Please note that in order to make the MyForeground transparency, we have to add the code:
myForeground.setZOrderOnTop(true);
myForeground.getHolder().setFormat(PixelFormat.TRANSPARENT);

package com.MyGame;

import android.app.Activity;
import android.graphics.PixelFormat;
import android.os.Bundle;

public class MyGameActivity extends Activity {

MyGameSurfaceView myGameSurfaceView1;
MyForeground myForeground;

  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      myGameSurfaceView1 = (MyGameSurfaceView)findViewById(R.id.myview1);
      myForeground = (MyForeground)findViewById(R.id.myforeground);
    
      //Set myForeground using transparent background
      myForeground.setZOrderOnTop(true);
      myForeground.getHolder().setFormat(PixelFormat.TRANSPARENT);
    
  }

@Override
protected void onResume() {
 // TODO Auto-generated method stub
 super.onResume();
 myGameSurfaceView1.MyGameSurfaceView_OnResume();
 myForeground.MyGameSurfaceView_OnResume();

}

@Override
protected void onPause() {
 // TODO Auto-generated method stub
 super.onPause();
 myGameSurfaceView1.MyGameSurfaceView_OnPause();
 myForeground.MyGameSurfaceView_OnPause();
}

}

Flickering problems due to double buffer of SurfaceView

2012-01-25T13:21:00.000-08:00

If you try the code in last post Link SurfaceView and Background Thread work together, you can note that the screen seem to flicker between two bitmap! It's due to double buffer of Android's SurfaceView: When you draw on Buffer A, Buffer B is being displayed; then you draw on Buffer B, Buffer A is being displayed. Such that you draw random points on Buffer A and B alternatively, not a single bitmap. This feature can solve some problem of display performance - but not in our case.

In order to solve the problem, you can:
- Draw each pixel on each buffer (It's not practical in our case), OR
- Draw on a single bitmap, then draw the bitmap on canvas.

Here is how to solve the double buffer problem using the second approach:

Modify the SurfaceView - MyGameSurfaceView.java

In surfaceCreated(), create a bitmap(myCanvasBitmap) accroading to the dimension of the SurfaceView. (Please note that not in MyGameSurfaceView_OnResume() - because the SurfaceView may be not yet ready when MyGameSurfaceView_OnResume() is called.) Create a new canvas(myCanvas). Then specify the bitmap(myCanvasBitmap) for the canvas(myCanvas) to draw into, by calling myCanvas.setBitmap(myCanvasBitmap) - Everything draw on myCanvas will draw on myCanvasBitmap.

In onDraw(), we draw on myCanvas, NOT canvas from the method argument. So everything will be draw on myCanvasBitmap. Then, draw the bitmap on canvas (from the method argument) using identity matrix, by calling canvas.drawBitmap(myCanvasBitmap, identityMatrix, null).

Such that, all we draw are draw on a single bitmap; to make both buffer consistance.

MyGameSurfaceView.java

package com.MyGame;

import java.util.Random;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class MyGameSurfaceView extends SurfaceView implements SurfaceHolder.Callback{

SurfaceHolder surfaceHolder;

MyGameThread myGameThread = null;

int myCanvas_w, myCanvas_h;
Bitmap myCanvasBitmap = null;
Canvas myCanvas = null;
Matrix identityMatrix;

private Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
 Random random;

public MyGameSurfaceView(Context context) {
super(context);
// TODO Auto-generated constructor stub
}

public MyGameSurfaceView(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
}

public MyGameSurfaceView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
// TODO Auto-generated method stub

}

@Override
public void surfaceCreated(SurfaceHolder holder) {

myCanvas_w = getWidth();
myCanvas_h = getHeight();
myCanvasBitmap = Bitmap.createBitmap(myCanvas_w, myCanvas_h, Bitmap.Config.ARGB_8888);
myCanvas = new Canvas();
myCanvas.setBitmap(myCanvasBitmap);

identityMatrix = new Matrix();
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub

}

public void MyGameSurfaceView_OnResume(){

random = new Random();
surfaceHolder = getHolder();
getHolder().addCallback(this);

//Create and start background Thread
myGameThread = new MyGameThread(this, 200);
myGameThread.setRunning(true);
myGameThread.start();

}

public void MyGameSurfaceView_OnPause(){
//Kill the background Thread
boolean retry = true;
myGameThread.setRunning(false);

while(retry){
 try {
  myGameThread.join();
  retry = false;
 } catch (InterruptedException e) {
  e.printStackTrace();
 }
}
}

@Override
protected void onDraw(Canvas canvas) {

paint.setStyle(Paint.Style.STROKE);
     paint.setStrokeWidth(3);
  
     //int w = myCanvas.getWidth();
     //int h = myCanvas.getHeight();
     int x = random.nextInt(myCanvas_w-1);
     int y = random.nextInt(myCanvas_h-1);
     int r = random.nextInt(255);
     int g = random.nextInt(255);
     int b = random.nextInt(255);

     paint.setColor(0xff000000 + (r << 16) + (g << 8) + b);
     myCanvas.drawPoint(x, y, paint);
  
     canvas.drawBitmap(myCanvasBitmap, identityMatrix, null);

}

public void updateStates(){
//Dummy method() to handle the States
}

public void updateSurfaceView(){
//The function run in background thread, not ui thread.

Canvas canvas = null;

try{
 canvas = surfaceHolder.lockCanvas();

 synchronized (surfaceHolder) {
  updateStates();
  onDraw(canvas);
 }
}finally{
 if(canvas != null){
  surfaceHolder.unlockCanvasAndPost(canvas);
 }
}
}

}

next:
- Create transparent foreground SurfaceView

Link SurfaceView and Background Thread work together

2012-01-24T13:28:00.001-08:00

In previous posts "Create SurfaceView for our game" and "Implement background thread for our game", we have created DUMMY MyGameSurfaceView and MyGameThread classes, without any function, and without any interaction. In this step, we are going to modify the Java code to make them work together.

Modify main.xml to include MyGameSurfaceView in the layout.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:orientation="vertical" >

 <TextView
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:text="@string/hello" />
 <com.MyGame.MyGameSurfaceView
     android:id="@+id/myview1"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent" />
</LinearLayout>

Modify the main activity (MyGameActivity), call myGameSurfaceView1.MyGameSurfaceView_OnResume() in onResume() and call myGameSurfaceView1.MyGameSurfaceView_OnPause() in onPause(); to start and stop the background thread.

package com.MyGame;

import android.app.Activity;
import android.os.Bundle;

public class MyGameActivity extends Activity {
 
 MyGameSurfaceView myGameSurfaceView1;
 
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.main);
     myGameSurfaceView1 = (MyGameSurfaceView)findViewById(R.id.myview1);
  
 }

 @Override
 protected void onResume() {
  // TODO Auto-generated method stub
  super.onResume();
  myGameSurfaceView1.MyGameSurfaceView_OnResume();
 }

 @Override
 protected void onPause() {
  // TODO Auto-generated method stub
  super.onPause();
  myGameSurfaceView1.MyGameSurfaceView_OnPause();
 }

}

Modify MyGameThread.java. It's a classic structure of backgraound thread. One thing have to note is the statement parent.updateSurfaceView() in run(), it will call back the function updateSurfaceView() in it's parent object.

package com.MyGame;

public class MyGameThread extends Thread {
 
 volatile boolean running = false;
 
 MyGameSurfaceView parent;
 long sleepTime;
 
 MyGameThread(MyGameSurfaceView sv, long st){
  super();
  parent = sv;
  sleepTime = st;
 }
 
 public void setRunning(boolean r){
  running = r;
 }
 
 @Override
 public void run() {
  // TODO Auto-generated method stub
  while(running){

   try {
    sleep(sleepTime);
    parent.updateSurfaceView();
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }

  }
 }

}

Modify MyGameSurfaceView.java. It's the main part in the code. updateSurfaceView() is a call back function from background thread (MyGameThread.java) in pre-defined duration reached. In-directly, it call updateStates() and onDraw(canvas) to update states (not yet implemented) and draw something on screen (some random drawing is implemented). Please note that updateSurfaceView() is called from background thread, that means it run in background thread, not in UI thread. That's why we need something like surfaceHolder.lockCanvas(), surfaceHolder.unlockCanvasAndPost(canvas) and synchronized (surfaceHolder).

package com.MyGame;

import java.util.Random;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class MyGameSurfaceView extends SurfaceView implements SurfaceHolder.Callback{
 
 SurfaceHolder surfaceHolder;
 
 MyGameThread myGameThread = null;
 
 private Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
 Random random;

 public MyGameSurfaceView(Context context) {
  super(context);
  // TODO Auto-generated constructor stub
 }

 public MyGameSurfaceView(Context context, AttributeSet attrs) {
  super(context, attrs);
  // TODO Auto-generated constructor stub
 }

 public MyGameSurfaceView(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  // TODO Auto-generated constructor stub
 }

 @Override
 public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void surfaceCreated(SurfaceHolder holder) {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void surfaceDestroyed(SurfaceHolder holder) {
  // TODO Auto-generated method stub
  
 }
 
 public void MyGameSurfaceView_OnResume(){
  
  random = new Random();
  surfaceHolder = getHolder();
  getHolder().addCallback(this);
  
  //Create and start background Thread
  myGameThread = new MyGameThread(this, 500);
  myGameThread.setRunning(true);
  myGameThread.start();
  
 }
 
 public void MyGameSurfaceView_OnPause(){
  //Kill the background Thread
  boolean retry = true;
  myGameThread.setRunning(false);
  
  while(retry){
   try {
    myGameThread.join();
    retry = false; 
   } catch (InterruptedException e) {
    e.printStackTrace(); 
   } 
  }
 }
 
 @Override
 protected void onDraw(Canvas canvas) {
  paint.setStyle(Paint.Style.STROKE);
     paint.setStrokeWidth(3);
      
     int w = canvas.getWidth();
     int h = canvas.getHeight();
     int x = random.nextInt(w-1);
     int y = random.nextInt(h-1);
     int r = random.nextInt(255);
     int g = random.nextInt(255);
     int b = random.nextInt(255);
  
     paint.setColor(0xff000000 + (r << 16) + (g << 8) + b);
     canvas.drawPoint(x, y, paint);
 }

 public void updateStates(){
  //Dummy method() to handle the States
 }

 public void updateSurfaceView(){
  //The function run in background thread, not ui thread.
  
  Canvas canvas = null;
   
  try{
   canvas = surfaceHolder.lockCanvas();

   synchronized (surfaceHolder) {
    updateStates();
    onDraw(canvas);
   }
  }finally{
   if(canvas != null){
    surfaceHolder.unlockCanvasAndPost(canvas);
   }
  } 
 }

}

The idea is:

The main.xml layout define MyGameSurfaceView.
MyGameSurfaceView start background thread.
When background thread reach the pre-defined duration, it call back updateSurfaceView() function of
MyGameSurfaceView to do and draw something.

Next:
- Flickering problems due to double buffer of SurfaceView

Implement background thread for our game

2012-01-21T12:59:00.001-08:00

Start reading here: Create a SurfaceView Game step-by-step

- Click to select our package (com.MyGame) in Package Explorer. Then click File of Eclipse, -> New -> Class

- Enter "MyGameThread" in the Name field, then click Browse... to select Superclass.

- Enter Thread in the search box to choice Thread - java.lang, then click OK.

- Then click Finish in the New Java Class dialog.

- In the Edit Windows (with MyGameThread.java), right click on any blank space, select Source -> Override/Implement Methods...

- Type "run" on In Override/Implement Methods dialog, it will search the matched method for you: the run() will be listed. Click to select run(), and click Ok.

- It's the basic of our Thread. We will add/modify more methods later.

Create SurfaceView for our game

2012-01-15T07:57:00.001-08:00

Start reading here: Create a SurfaceView Game step-by-step

In this step, we are going to create our dummy SurfaceView:

- Click to select our package (com.MyGame) in Package Explorer. Then click File of Eclipse, -> New -> Class

- Enter "MyGameSurfaceView" in the Name field, then click Browse... to select Superclass.

- Enter SurfaceView in the search box to choice SurfaceView - android.view, then click OK.

- Then click Finish in the New Java Class dialog.

- A new class of MyGameSurfaceView.java extends SurfaceView will be generated for you. But, you will be prompted with error of undefined default constructor. Move mouse over the word with error, MyGameSurfaceView. A hints box will open for you, click to Add constructor 'MyGameSurfaceView(Context)'.

- Modify the code of MyGameSurfaceView class declaration from:

public class MyGameSurfaceView extends SurfaceView

to:

public class MyGameSurfaceView extends SurfaceView implements SurfaceHolder.Callback

- You will be prompt for error again: SurfaceHolder cannot be resolved! Move mouse over the word with error, SurfaceHolder. And select Import 'SurfaceHolder'(android.view).

- MyGameSurfaceView will be prompt with error again: The type MyGameSurfaceView must implement the inherited abstract method SurfaceHolder.Callback.surfaceDestroyed(SurfaceHolder). Move mouse over the word with error, MyGameSurfaceView, select Add unimplemented methods.

- Now three Auto-generated method will be added:
surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3)
surfaceCreated(SurfaceHolder arg0)
surfaceDestroyed(SurfaceHolder arg0)

- In order to make our code more human readable, modify arg(s) with meaningful words:

package com.MyGame;

import android.content.Context;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class MyGameSurfaceView extends SurfaceView implements SurfaceHolder.Callback{

public MyGameSurfaceView(Context context) {
super(context);
// TODO Auto-generated constructor stub
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
// TODO Auto-generated method stub

}

@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub

}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub

}

}

- Save it in this moment.

Create a SurfaceView Game step-by-step

2012-01-11T23:52:00.002-08:00

In the coming posts, I will TRY to create a basic game, a VERY BASIC GAME: base on SurfaceView implements SurfaceHolder, display something as Sprites, running in backgroud Thread.

New a project MyGame of package com.MyGame, target Android 2.2, API Level 8.

Prepare my character

Creating graph is my weakest. As a example, I decide to copy my character from Android build-in icon.
- Create a /res/drawable folder.

- Open a file explorer and browse to any Android build-in platform drawable folder (ex. /android-sdks/platforms/android-8/data/res/drawable-mdpi/), drag any icon you want to /res/drawable folder under your project.

- Select Copy files in the coming File Operation dialog.

- Rename the drawable to icon_me.png: Click to select the copied icon, click File from Eclipse menu, and Rename...

In the coming posts, I will show more in step-by-step.

Create SurfaceView for our game

Implement background thread for our game

Link SurfaceView and Background Thread work together

Flickering problems due to double buffer of SurfaceView

Create transparent foreground SurfaceView

Introduce Sprite

Sprite auto-run

Implement onTouchEvent() to handle user touch on SurfaceView

React device movement/orientation using accelerometer

Create custom Theme inheriting properties from build-in Theme

2012-01-03T10:25:00.001-08:00

Refer from the previous posts:
- Create style using Android Resources Tools
- Create style inheriting properties from another style
- Apply style on whole application/activity as theme
- Using Android build-in theme

We can create our custom Theme, by inheriting properties from build-in Theme.

Create(or modify from previous post) /res/values/mystyle.xml, create our custom style (MyStyle) from build-in "@android:style/Theme.Dialog".

<?xml version="1.0" encoding="utf-8"?>
<resources>
   <style name="MyStyle"
       parent="@android:style/Theme.Dialog">
       <item name="android:layout_width">wrap_content</item>
       <item name="android:layout_height">wrap_content</item>
       <item name="android:textColor">#AAA</item>
       <item name="android:textSize">18dip</item>
       <item name="android:background">#222</item>
       <item name="android:padding">5dip</item>
   </style>
   <style name="MyStyle.GreenBold">
       <item name="android:textColor">#00FF00</item>
       <item name="android:textStyle">bold</item>
   </style>
</resources>

Modify AndroidManifest.xml using theme of our custom style, "@style/MyStyle.GreenBold".

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.AndroidStyle"
   android:versionCode="1"
   android:versionName="1.0" >

   <uses-sdk android:minSdkVersion="8" />

   <application
       android:icon="@drawable/ic_launcher"
       android:label="@string/app_name"
       android:theme="@style/MyStyle.GreenBold" >
       <activity
           android:name=".AndroidStyleActivity"
           android:label="@string/app_name" >
           <intent-filter>
               <action android:name="android.intent.action.MAIN" />

               <category android:name="android.intent.category.LAUNCHER" />
           </intent-filter>
       </activity>
   </application>

</manifest>

Main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:orientation="vertical" >

   <TextView
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       android:text="@string/hello" />
   <TextView
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       android:text="using Style inherit from Android's build-in theme" />
  
</LinearLayout>

Using Android build-in theme

2012-01-02T13:06:00.001-08:00

We can apply Android build-in theme on our app. It's a example using Theme.Dialog.

Modify AndroidManifest.xml using android:theme="@android:style/Theme.Dialog".

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.AndroidStyle"
   android:versionCode="1"
   android:versionName="1.0" >

   <uses-sdk android:minSdkVersion="8" />

   <application
       android:icon="@drawable/ic_launcher"
       android:label="@string/app_name"
       android:theme="@android:style/Theme.Dialog" >
       <activity
           android:name=".AndroidStyleActivity"
           android:label="@string/app_name" >
           <intent-filter>
               <action android:name="android.intent.action.MAIN" />

               <category android:name="android.intent.category.LAUNCHER" />
           </intent-filter>
       </activity>
   </application>

</manifest>

Modify main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:orientation="vertical" >

   <TextView
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       android:text="@string/hello" />
   <TextView
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       android:text="using Android's Theme.Dialog" />
  
</LinearLayout>

Apply style on whole application/activity as theme

2012-01-01T19:33:00.001-08:00

The custome style create in last posts Create style using Android Resources Tools and Create style inheriting properties from another style can be apply on whole application/activity as theme.

Modify AndroidManifest.xml to add android:theme="@style/MyStyle.GreenBold" property inside <application> to apply the style as theme on whole application, or inside <activity> to apply on individual activity only.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
 package="com.AndroidStyle"
 android:versionCode="1"
 android:versionName="1.0" >

 <uses-sdk android:minSdkVersion="8" />

 <application
     android:icon="@drawable/ic_launcher"
     android:label="@string/app_name"
     android:theme="@style/MyStyle.GreenBold" >
     <activity
         android:name=".AndroidStyleActivity"
         android:label="@string/app_name" >
         <intent-filter>
             <action android:name="android.intent.action.MAIN" />

             <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
     </activity>
 </application>

</manifest>

Modify main.xml, change TextView using application/activity theme.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:orientation="vertical" >

 <TextView
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:text="@string/hello" />
 <TextView
     android:layout_width="fill_parent"
     android:text="Default, using style of MyStyle.GreenBold defined in AndroidManifest.xml" />

</LinearLayout>

Related:
- Using Android build-in theme

Create style inheriting properties from another style

2012-01-01T09:16:00.001-08:00

Refer to the style of last post Create style using Android Resources Tools, we can create a new style(MyStyle.GreenBold) inheriting properties from another existing style (MyStyle).

Modify /res/values/strings.xml, add a new style "MyStyle.GreenBold" inherit properties from "MyStyle", change and add properties of "android:textColor" and "android:textStyle".

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="MyStyle">
        <item name="android:layout_width">wrap_content</item>
        <item name="android:layout_height">wrap_content</item>
        <item name="android:textColor">#AAA</item>
        <item name="android:textSize">18dip</item>
        <item name="android:background">#222</item>
        <item name="android:padding">5dip</item>
    </style>
    <style name="MyStyle.GreenBold">
        <item name="android:textColor">#00FF00</item>
        <item name="android:textStyle">bold</item>
    </style>
</resources>

Modify main.xml adding TextView using new style of "MyStyle.GreenBold".

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />
    <TextView
        style="@style/MyStyle"
        android:layout_width="fill_parent"
        android:text="it's text using style" />
    <TextView
        style="@style/MyStyle.GreenBold"
        android:layout_width="fill_parent"
        android:text="it's text using style of MyStyle.GreenBold" />
</LinearLayout>

next:
- Apply style on whole application/activity as theme

Create style using Android Resources Tools

2011-12-28T06:57:00.001-08:00

- Start Eclipse, create a new Android project.

- Right click /res/values/ in Package Explorer, click New -> Other....

- Expand Android, and select Android XML Values File, click Next.

- Enter file name, mystyle.xml.

- Click Finish.

- The generated file will be opened in Resources mode. Click the tab with file name, mystyle.xml, to view in edit mode. The wizard should have create a root of <resources> for you.

- Switch back to Resources mode by clicking on Resources tab.

- Click on the Add button.

- Select Style/Theme, and click OK.

- Enter "MyStyle" in the name field.

- Click on Add button.

- Select Item and click OK.

- Enter "android:layout_width" in Name field, and "wrap_content" in Value field.

- Click on mystyle.xml tab to view in edit mode. The wizard have already filled in the item.

- Repeat to fill in others.

<?xml version="1.0" encoding="utf-8"?>
<resources>
   <style name="MyStyle">
       <item name="android:layout_width">wrap_content</item>
       <item name="android:layout_height">wrap_content</item>
       <item name="android:textColor">#AAA</item>
       <item name="android:textSize">18dip</item>
       <item name="android:background">#222</item>
       <item name="android:padding">5dip</item>
   </style>

</resources>

- Save It.

- Modify main.xml to add a TextView using MyStyle.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:orientation="vertical" >

   <TextView
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       android:text="@string/hello" />
   <TextView
       style="@style/MyStyle"
       android:layout_width="fill_parent"
       android:text="it's text using style" />
  
</LinearLayout>

- Finished!

next:
- Create style inheriting properties from another style
- Apply style on whole application/activity as theme

Create your own London 2012 App

2011-12-19T06:01:00.004-08:00

London 2012 Olympic is coming! Official site of the London 2012 Olympic (http://www.london2012.com/) have a very nice designed mobile version. You will be redirected to mobile version if you browse http://www.london2012.com/ using mobile device.

So, you can easily create your own London 2012 App for Android by embedding WebView.

Modify main.xml to embed a WebView.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:orientation="vertical" >
<RelativeLayout
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical" >
  <TextView
      android:id="@+id/myblog"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:text="@string/my_blog"
 android:padding="5dp"
 android:autoLink="web"
 android:gravity="center_horizontal"
      android:layout_alignParentBottom="true"/>
  <WebView
      android:id="@+id/webview"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      android:layout_alignParentTop="true"
      android:layout_above="@id/myblog"/>
</RelativeLayout>
</LinearLayout>

Modify /res/values/strings.xml to add String of "my_blog", to advertise me:)

<?xml version="1.0" encoding="utf-8"?>
<resources>

 <string name="hello">Hello World, MyLondon2012Activity!</string>
 <string name="app_name">MyLondon2012</string>
<string name="my_blog">http://android-coding.blogspot.com/</string>
</resources>

Modify main activity to handle WebView.

package android.coding.myLondon2012;

import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.webkit.WebChromeClient;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MyLondon2012Activity extends Activity {

WebView webView;
final String London2012_URL = "http://www.london2012.com/";

 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     getWindow().requestFeature(Window.FEATURE_PROGRESS);
     setContentView(R.layout.main);
     webView = (WebView)findViewById(R.id.webview);
     webView.getSettings().setJavaScriptEnabled(true);
     webView.setWebViewClient(new MyWebViewClient());
     webView.loadUrl(London2012_URL);
  
     final Activity activity = this;
     webView.setWebChromeClient(new WebChromeClient() {
    
      public void onProgressChanged(WebView view, int progress) {
       // Activities and WebViews measure progress with different scales.
       // The progress meter will automatically disappear when we reach 100%
       activity.setProgress(progress * 100);
      }});
 }

public class MyWebViewClient extends WebViewClient {

@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
 view.loadUrl(url);
         return true;
}

}
}

Save the icon in /res/drawable/london2012.png

Modify AndroidManifest.xml to enable "android.permission.INTERNET".

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
 package="android.coding.myLondon2012"
 android:versionCode="1"
 android:versionName="1.0" >

 <uses-sdk android:minSdkVersion="8" />
 <uses-permission android:name="android.permission.INTERNET"/>

 <application
     android:icon="@drawable/london2012"
     android:label="@string/app_name" >
     <activity
         android:name=".MyLondon2012Activity"
         android:label="@string/app_name" >
         <intent-filter>
             <action android:name="android.intent.action.MAIN" />

             <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
     </activity>
 </application>

</manifest>

Download Eclipse project of myLondon2012: http://goo.gl/tg18O
Download Installable APK Android package of myLondon2012: http://goo.gl/28tnz

Related Post:
- android.webkit.WebView
- More on WebView, override url loading
- Enable JavaScript and built-in zoom control of WebView
- Display Progress Bar on WebView when loading
- Handle the Back button in WebView, to back in history

Copy part of Bitmap

2011-12-14T10:22:00.001-08:00

Last post Copy bitmap using getPixels() and setPixels() show how to copy a whole Bitmap using getPixels() and setPixels(). It can be used to copy part of a Bitmap.

package com.AndroidCopyBitmap;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.os.Bundle;
import android.widget.ImageView;

public class AndroidCopyBitmapActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        ImageView image1 = (ImageView)findViewById(R.id.image1);
        ImageView image2 = (ImageView)findViewById(R.id.image2);
        
        Bitmap oldBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
        
        int orgWidth = oldBitmap.getWidth();
        int orgHeight = oldBitmap.getHeight();
        
        int firstx, firsty;
        int halfWidth = orgWidth/2;
        int halfHeight = orgHeight/2;
        
        //Create a same size Bitmap
        Bitmap newBitmap = Bitmap.createBitmap(orgWidth, orgHeight, Bitmap.Config.ARGB_8888);
        //Create a pixel of 1/4 size, to copy part of the bitmap
        int[] pixels = new int[halfWidth * halfHeight];
        
        //Copy Upper-Left part to Bottom-Right
        oldBitmap.getPixels(pixels, 0, halfWidth, 0, 0, halfWidth, halfHeight);
        newBitmap.setPixels(pixels, 0, halfWidth, halfWidth, halfHeight, halfWidth, halfHeight);
         
        //Copy Bottom-Right to Upper-Left part
        oldBitmap.getPixels(pixels, 0, halfWidth, halfWidth, halfHeight, halfWidth, halfHeight);
        newBitmap.setPixels(pixels, 0, halfWidth, 0, 0, halfWidth, halfHeight);
        
        //Copy Bottom-Left part to Upper-Right
        oldBitmap.getPixels(pixels, 0, halfWidth, 0, halfHeight, halfWidth, halfHeight);
        newBitmap.setPixels(pixels, 0, halfWidth, halfWidth, 0, halfWidth, halfHeight);
         
        //Copy Upper-Right to Bottom-Left part
        oldBitmap.getPixels(pixels, 0, halfWidth, halfWidth, 0, halfWidth, halfHeight);
        newBitmap.setPixels(pixels, 0, halfWidth, 0, halfHeight, halfWidth, halfHeight);
         
        image1.setImageBitmap(oldBitmap);
        image2.setImageBitmap(newBitmap);
    }
}

Copy bitmap using getPixels() and setPixels()

2011-12-13T00:25:00.001-08:00

Example of copy bitmap using Bitmap.getPixels() and Bitmap.setPixels().

package com.AndroidCopyBitmap;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.os.Bundle;
import android.widget.ImageView;

public class AndroidCopyBitmapActivity extends Activity {
   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);
       ImageView image1 = (ImageView)findViewById(R.id.image1);
       ImageView image2 = (ImageView)findViewById(R.id.image2);
      
       Bitmap oldBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
      
       int orgWidth = oldBitmap.getWidth();
       int orgHeight = oldBitmap.getHeight();
       
       Bitmap newBitmap = Bitmap.createBitmap(orgWidth, orgHeight, Bitmap.Config.ARGB_8888);
       int[] pixels = new int[orgWidth * orgHeight];
       oldBitmap.getPixels(pixels, 0, orgWidth, 0, 0, orgWidth, orgHeight);
       newBitmap.setPixels(pixels, 0, orgWidth, 0, 0, orgWidth, orgHeight);
       
       image1.setImageBitmap(oldBitmap);
       image2.setImageBitmap(newBitmap);
   }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:orientation="vertical" >

   <TextView
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       android:text="@string/hello" />
   <ImageView
       android:id="@+id/image1"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content" />
   <ImageView
       android:id="@+id/image2"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content" />

</LinearLayout>

next:
- Copy part of Bitmap