Thoughts of "Sudar Nimalan"

JNI Error: Local reference table overflow

2015-07-17T22:15:00.000-07:00

If you are working on JNI, you may have faced issue:

"Local reference table overflow 512 entries"

Say you have following code, you will immediately get this issue.

void methodOne()
{
for(int i = 0 ; i < 1000 ; i++)
{
jobject localReferenceOne = ...;
methodTwo(localReferenceOne);
}
}

void methodTwo(jobject parameter)
{
jobejct localReferenceTwo = ...;
}

First You should delete all local reference once you are done with that.

void methodOne()
{
for(int i = 0 ; i < 1000 ; i++)
{
jobject localReferenceOne = ...;
methodTwo(localReferenceOne);
env->DeleteLocalRef(localReferenceOne);
}
}

void methodTwo(jobject parameter)
{
jobejct localReferenceTwo = ...;
...
env->DeleteLocalRef(localReferenceOne);
}

But you will still faces the issue. This is because parameter also local reference. You cannot delete the parameter using DeleteLocalRef. To delete parameter local reference you need to call PushLocalFrame and PopLocalFrame before and after method call.

void methodOne()
{
for(int i = 0 ; i < 1000 ; i++)
{
env->PushLocalFrame(0);
jobject localReferenceOne = ...;
methodTwo(localReferenceOne);
env->DeleteLocalRef(localReferenceOne);
env->PopLocalFrame(0);
}
}

void methodTwo(jobject parameter)
{
jobejct localReferenceTwo = ...;
...
env->DeleteLocalRef(localReferenceOne);
}

Android JNI Call back

2014-04-15T01:00:00.000-07:00

In the above images shows all possible scenarios of Android JNI calls and its call backs.

Android UI mostly implemented in Java, then if needed there will be C++ implementation to perform low level operations. In this case JNI is used.

1. Java to C++ calls :
First UI will need to make some call to C++, for example start engine etc.

In Java:
1.1. Need to write a native method:
package demo;
class Service{
public static native doSomething();
}
1.2. Call this method to invoke/access the low level.
....
//Somewhere
Service.doSomething();
....

In C++:
1.2. Need to write the implementation for above native method:
JNIEXPORT jint JNICALL Java_demo_Service_doSomeThing(JNIEnv * env, jobject ){
..............
..............
}

2. C++ to Java Call
There may be some cases C++ Implementation may need to call back UI, for example inform the progress update.
This can happen from the same thread which the initial called made from Java or C++ may have created a new thread and may call from there.

In Java: Write a Observer to receive those call backs.
package demo;
class Service{
public static void onCallBack(){
............
//add implementation to handle call back
...............
}
}

Any callback from C++ to Java need to be implemented using given JNI refection APIs.

jclass jcls = env->FindClass("dem/Service");
jmethodID mid = env->GetStaticMethodID(jcls,"onCallBack","....");
env->CallStaticVoidMethod(jcls,mid);

This will perform what we want, but we will need some more extra implementation to make it work in caseof concurrent access from c++.

2.1 Calling from same thread.
In this case, the above listing will work without any issue. We can use the same JNIEnv which passed in Java_demo_Service_doSomeThing call above 1.2

2.2 Calling from other thread
In this case we cannot use the above env passed with Java_demo_Service_doSomeThing as it is invalid in other threads.
So We have to create a new JNIEnv using JavaVM, which is passed in JNI_OnLoad.
So,
2.2.1 Write a JNI_OnLoad in your native c++ code:

static JavaVM * s_Jvm;

JNIEXPORT jint JNI_OnLoad(JavaVM* vm, void* reserved)
{
s_Jvm = vm;//Keep for future use.
return JNI_VERSION_1_6;

}

2.2.2 Attach Current Thread to create JNIEnv:
JNIEnv * env;
s_Jvm->AttachCurrentThread(&env,NULL);

2.2.3 If you try FindClass with this JNIEnv it will return NULL in Android since uses special Class Loader in Java and in New thread which created in C++ will use the

jclass jcls = env->FindClass("dem/Service");

2.2.4 So this should be done inside OnLoad method : (code are in bold) and assign to global reference to use in future.

jclass s_jcls;

JNIEXPORT jint JNI_OnLoad(JavaVM* vm, void* reserved)
{
s_Jvm = vm;//Keep for future use.
s_jcls = env->NewGlobalRef(env->FindClass("dem/Service"));
return JNI_VERSION_1_6;

}

2.2.5 Now you can use this s_jcls to make any call backs

GetStaticMethodID

CallStaticObjectMethod

etc...

Visio: Adding New Connection Points to Shape

2014-01-25T07:31:00.001-08:00

Step 1: Click on the X icon next to connection icon

Step 2: Press Ctrl and click on the Shape where you want the new connection point.

Eclipse, Ant, CVS with Windows 7

2013-10-08T00:55:00.001-07:00

I got a new machine with Windows 7, and started to setup my build environment.

We have an ant script to update from CVS and tag and etc...

Simply adding following ant task I could do this.

<target name="cvs_update">
<cvs command="update -dP">
</cvs>
</target>
<target name="cvs_tag">
<cvs command="tag ABC_${build_time}">
</cvs>
</target>

But, we should install WinCVS/CVSNT to run this task.

In Windows 7 I got a first issue, ant couldn't find the cvs.exe even if the cvs.exe in PATH variable. And if you check the in command prompt by type cvs it will run. But in Eclipse when you run above ant task it will keep saying application cvs not found.

[cvs] Caught exception: Cannot run program "cvs": CreateProcess error=2, The system cannot find the file specified

Only solution I found is:
uninstall and install CVSNT into a folder, which name doesn't have any spaces (Example Program_Files_(x86))

The 2nd I faced in login

[cvs] cvs update: Empty password used - try 'cvs login' with a real password [cvs]

The only solution I found is:
Run CVSNT Password Agent.

Eclipse, Java : Inserting Single line "if block"

2013-05-18T04:41:00.001-07:00

If we run our program after completing coding, those will not as excepted mostly, or at-least in testing we will find places where we have missed some null check or etc. So we may have to add a if condition to check and to avoid those Exceptions. Mostly those will be a single line "if blocks".

I am talking about cases like below. Say you have following line:

myObject.myMethod();

Here we got a NullPointerException because myObject is null, I wanted added a null check before this:

if(myObject!=null)
myObject.myMethod();

This is correct, but I mostly don't like this, for future coding and because of the readability, I prefer to add a block as follows. Sometime reader will think that, all the statements which following the above statement also inside the if condition.

if(myObject!=null){
myObject.myMethod();
}

It was hard for me always, because I had to write if block and copy paste the statement inside. But i found a method to do in Eclipse without doing copy paste.

Just go infront of the statement and start typing your if condition and write up to { and press enter key, then you will get what you want.

if(myObject!=null){|myObject.myMethod(); <-- font="">Keep the curser at the | position and press enter.

Okey now you try and let me know your comments.

Part 2:Useful Eclipse Templates for Android Development

2013-01-30T01:22:00.000-08:00

Part 1:Useful Eclipse Templates for Android Development

Weak Reference for Views in Activity.

Inside onCreate of each Android Activity we used to setContentView with layout xml. Then to access each view from the activity we use:

View view = findViewById(R.id..........);

to avoid calling findViewById multiple time, call this only in onCreate and keep this view as member variable inside activity.

View mView

.....

mView = findViewById(R.id..........);

Then, question is why we need to overload the onCreate method, we call findViewById only when needed and keep as member variable. So introduce following get method.

View getView(){
if(mView==null){
mView = findViewById(R.id..........);
}
return mView;
}

But in some cases, to avoid memory leakage issues, we need to remove all view from content view and need to null all these references in activity. But rather find each reference and assign to null, if we make a weak reference then it should all clear as we remove view from activity. For Example:

private WeakReference mView;
public View getView() {
if(!(mView!=null && mView.get()!=null)){
mView = new WeakReference((View) findViewById(R.id.....));
}
return mFrameAddStyleView.get();
}
Now, Let see how to write a Eclipse template to auto generate this:

Eclipse - > Windows -> Preferences -> Java -> Editor -> Templates -> New ...
Name:- wfind
Pattern:-
private WeakReference<${type}> m${new_name};
public ${type} get${new_name}() {
if(!(m${new_name}!=null && m${new_name}.get()!=null)){
m${new_name} = new WeakReference<${type}>((${type}) findViewById(R.id.${cursor}));
}
return m${new_name}.get();}

Now go to your activity class and type wfind and press Ctrl+Space you will get what you want.

Android: UI Automator Viewer (uiautomatorviewer) - issue in landscape screen

2012-11-15T21:20:00.002-08:00

If you are ttrying to use UI Testing tools introduced in Android SDK Tools, Revision 21 you will see a port-tailed image in uiautomatorviewer capture for landscape activities.
Hover over selection and uix file will perform properly, but only issue will be the image will not be aligned properly.
I found a possible workaround, just close the file (note down the location) and got the folder, you will see a image, please rotate accordingly.
Then come back and reopen the uix, it will ask for the screen slot, just show the rotated screen.

Java: Random Unique Indexes

2012-10-02T18:18:00.000-07:00

Say you have a list of items, you want to pick item from the list in random order, but need to avoid duplicate items until you get all items from the list.
assume below list of colors
0. Red
1. Blue
2. Yellow
3. Green

You may have to display as Blue, Red, Yellow and Green, here you see we have random items but not duplicated.

Here I write a Java Utilities for that purpose. Here we have to generate random numbers with in the limit but we have to ignore already generated values when try next time.

So, First create a list of indexes.

[0]->0
[1]->1
[2]->2
[3]->3

mIndexes = new int[size];
for(int i = 0 ; i < mIndexes.length;i++){
mIndexes[i] = i;
}
First you have to create a random number within the size so,
mNextMaxIndex = size;

Let see how to generate random index with no duplicate.
Generate a random index with the size limit.
int index = mRandom.nextInt(mNextMaxIndex);
Value from the index will be the result.
int result = mIndexes[index];
now swap this value to end of the effect list and reduce the limit by one.

mNextMaxIndex--;
mIndexes[index] = mIndexes[mNextMaxIndex];
mIndexes[mNextMaxIndex] = result;

Say you got 2 then result will be 2 and our new list will be

[0]->0
[1]->1
[2]->3
[3]->2
and mNextMaxIndex will be 3.
Now for the next index, generate a random number within 3 and do the same steps again.
But finally if we reach the start we have to reset back start from the end.

if(mNextMaxIndex<1 font="font">
mNextMaxIndex = mIndexes.length;
}

I have the source code here, it have a main method to test his also i see a

Android: Issue In loading MP3 files, which Saved by Same Application

2012-09-20T19:30:00.000-07:00

We had to list down and play some bundled MP3 files from our android application. We added a zip file with proper folder structure inside assert. Application will extract that into /data/data/{package name}/files/ folder on loading and make use of this.
In this both Media Metadata Retriever or Media Player API didn't work if we use direct file-name or URI.
First I was thinking the issue in permission of the written file, I manage to write files with the permission -rw-rw-rw but that was not enough. Issue was with owner. Those written files owner and group as same as the application not root or etc.
I couldn't find a API to change the owner of a file.But lucky, Media Metadata Retriever and Media Player API could accept File Descriptor, So We had to use FileInputStream to get The File Descriptor and pass it to tose APIs.

Android: Layout Transition CHANGING animation for API level 11-15

2012-08-22T08:50:00.000-07:00

In android, Layout Transition is introduced from API level 11. By enabling layout transition application can get predefine platform animations for following changes.

1. APPEARING - animation that runs on those items that are appearing in the container.
2. CHANGE_APPEARING - animation that runs on those items that are changing due to a new item appearing in the container.
3. CHANGE_DISAPPEARING - animation that runs on those items that are changing due to an item disappearing from the container.
4. DISAPPEARING - animation that runs on those items that are disappearing from the container.

These are fast, tested, easy to incorporate with our applications.

CHANGING animation was not added to API at that time, but it has been added now in API level 16.

CHANGING - animation that runs on those items that are changing due to a layout change not caused by items being added to or removed from the container.

So incase if we want to support devices in API level 11, it is good to have some work around, and it should be able to get platform animation in other decides more than API level 16.

I am trying to make a utility for this to simply incorporate this and here I have two options.

1. Simple One time registration/setup, but this will not support scroll changes or any other property changes. only support left, top, right and bottom.

First we register on layout change listener for both layout and its children. So as soon as there is a layout change in these views the callback will be called.

private static void setupChangeAnimationOneTime(final View view) {
...
final View.OnLayoutChangeListener onLayoutChangeListener = new View.OnLayoutChangeListener() {
@Override
public void onLayoutChange(View v, int left, int top, int right,
int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
...

}
};
view.addOnLayoutChangeListener(onLayoutChangeListener);
...
}

Here, create a object animator, with old and new values.

PropertyValuesHolder pvhLeft = PropertyValuesHolder.ofInt("left", oldLeft, left);
PropertyValuesHolder pvhTop = PropertyValuesHolder.ofInt("top", oldTop, top);
PropertyValuesHolder pvhRight = PropertyValuesHolder.ofInt("right", oldRight, right);
PropertyValuesHolder pvhBottom = PropertyValuesHolder.ofInt("bottom", oldBottom, bottom);
ObjectAnimator changeAnimator = ObjectAnimator.ofPropertyValuesHolder((Object)view,
pvhLeft, pvhTop, pvhRight, pvhBottom);
changeAnimator.setDuration(600);

Start the animator.

changeAnimator.start();

In this option, we don't know other property of the view. so we cannot animate them.

2. Advanced approach, setup in each layout changes, for this the root layout needed to be a custom layout, where the onlayout method should be overridden or need to find a proper action where the layout change is happened (example onClick etc).

First create an animator with properties you wanted animate. Use null for target object and some arbitrary values, which will be changed in setup.

public static ObjectAnimator getDefaultChangeAnimator(){
if(sDefaultChangeAnimator==null){
PropertyValuesHolder pvhLeft = PropertyValuesHolder.ofInt("left", 0, 1);
PropertyValuesHolder pvhTop = PropertyValuesHolder.ofInt("top", 0, 1);
PropertyValuesHolder pvhRight = PropertyValuesHolder.ofInt("right", 0, 1);
PropertyValuesHolder pvhBottom = PropertyValuesHolder.ofInt("bottom", 0, 1);
PropertyValuesHolder pvhScrollX = PropertyValuesHolder.ofInt("scrollX", 0, 1);
PropertyValuesHolder pvhScrollY = PropertyValuesHolder.ofInt("scrollY", 0, 1);
sDefaultChangeAnimator = ObjectAnimator.ofPropertyValuesHolder((Object)null,
pvhLeft, pvhTop, pvhRight, pvhBottom, pvhScrollX, pvhScrollY);
sDefaultChangeAnimator.setDuration(600);
}
return sDefaultChangeAnimator;
}

Now the animator has to be setup just before the layout change of the layout and it's children. First start state will be setup and layout change listener wil be registered.

private static void setupChangeAnimation(final View view) {
…
changeAnimator.setTarget(view);
…
changeAnimator.setupStartValues();
final View.OnLayoutChangeListener onLayoutChangeListener = new View.OnLayoutChangeListener() {
@Override
public void onLayoutChange(View v, int left, int top, int right,
int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
...
changeAnimator.setupEndValues();
changeAnimator.start();
…
};
changeAnimator.addListener(animatorListener);
view.addOnLayoutChangeListener(onLayoutChangeListener);
...
}

after layout change, inside the on layout change callback the end state of the animator will be setup and start immediately.

Here we need to make sure setupChangeAnimation called just before the layout change. For this we have two possible place,
1. inside the onlayout call of animation enabled layout.
2. posible action code that make layout changes. (example onClick())

public class DemoLinearLayout extends LinearLayout {
...
protected void onLayout(boolean changed, int l, int t, int r, int b) {
LayoutTransitionUtil.checkAndSetupChangeAnimationForAllChild(this);
super.onLayout(changed, l, t, r, b);
}
}

@Override
public void onClick(View view) {
...
LayoutTransitionUtil.setupChangeAnimation((ViewGroup)findViewById(R.id.frm_linear_04));
}

Here I am uploading the sample source code for reference.

Android: Relative Layout with weighted size

2012-08-16T00:39:00.001-07:00

Android applications should support multiple screens, So absolute values cannot be used in layouts. Mostly Relative Layout or Liner Layout is used in UI arrangements, In Relative Layout, views can be arranged relatively. for example one button can be arranged below to another etc. But, only in Liner Layout, views' size can be specified with weight. i.e width of a view can be 70% of it parent width etc. This feature is very useful in supporting multiple screens. Since it applies weight in vertically or horizontally at a time normally Liner Layout need to be nested. This may reduce the performance.

So, It is better introducing weight attributes for Relative Layout and will improve application performance. If this can be done in Android API level it is easy since already an implementation is there for Relative Layout. I see this is an enhancement for Relative Layout and no need to introduce another Layout, otherwise same code will be duplicated.

Lets' try this with an example, Say If you want to create a layout as below:

The expectation is as below: setting layout_width=0dip and introducing layout_width_weight and set required value.

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

<Button
android:id="@+id/button01"
android:layout_width="0dip"
android:layout_width_weight="0.2500"
android:layout_height="0dip"
android:layout_height_weight="0.1666"
android:text="Button01" />

<Button
android:id="@+id/button02"
android:layout_width="0dip"
android:layout_width_weight="0.2500"
android:layout_height="0dip"
android:layout_height_weight="0.1666"
android:layout_below="@+id/button01"
android:text="Button02" />

<Button
android:id="@+id/button03"
android:layout_width="0dip"
android:layout_width_weight="0.2500"
android:layout_height="0dip"
android:layout_height_weight="0.1666"
android:layout_below="@+id/button02"
android:text="Button03" />

<Button
android:id="@+id/button04"
android:layout_width="0dip"
android:layout_width_weight="0.5000"
android:layout_height="0dip"
android:layout_height_weight="0.5000"
android:layout_centerInParent="true"
android:text="Button04" />

<Button
android:id="@+id/button05"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_alignParentRight="true"
android:layout_below="@id/button04"
android:text="Button05" />

</RelativeLayout>

I checked for necessary changes in Relative Layout source code and found that,

1. Both fields for holding weight values need to be added in RelativeLayout.LayoutParams class and loading this values into it.
2. new Parameter need to be added to RelativeLayout.getChildMeasureSpec method inorder to pass the value from RelativeLayout.measureChild and RelativeLayout.measureChildHorizontal methods.
3. Add extra condition if child size equals to zero then make use of the weight value inside RelativeLayout.getChildMeasureSpec to calculate the size.

private int getChildMeasureSpec(..., float weight){
...
if (childSize == 0) {
childSpecMode = MeasureSpec.EXACTLY;
childSpecSize = (int)(mySize*weight);
}else if(chileSize>0){
....
}
...
}

But before going for a Android API level change, It is better to try out. It is impossible since it a private method, it cannot be overridden.

But this methods are called only in onMeasure, So I created a new layout by extending Relative Layout and copy source from Android API for those 4 methods(onMeasure, measureChild, measureChildHorizontal and getChildMeasureSpec), and since these methods use some private/hide methods/field from RelativeLayout and other Android API, I used Java Reflection to access them.

Now, Since weight attributes also not added into API using those in XML also impossible. But lucky I found that negative values also can be set to layout_width and layout_height and only -1,-2 has used. So I try to use the negative values to indicate those weight values and modify the condition in getChildMeasureSpec according to that.

I found more that, if we set negative px value then childSize will be one less than the value set in XML. Since childSize is integer number and get more precision I go for 10,000 scaled weighted values.

So the layout xml will be like this.

<?xml version="1.0" encoding="utf-8"?>
<demo.widget.WeightedSizeRelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<Button
android:id="@+id/button01"
android:layout_width="-2501px"
android:layout_height="-1667px"
android:text="Button01" />

<Button
android:id="@+id/button02"
android:layout_width="-2501px"
android:layout_height="-1667px"
android:layout_below="@+id/button01"
android:text="Button02" />

<Button
android:id="@+id/button03"
android:layout_width="-2501px"
android:layout_height="-1667px"
android:layout_below="@+id/button02"
android:text="Button03" />

<Button
android:id="@+id/button04"
android:layout_width="-5001px"
android:layout_height="-5001px"
android:layout_centerInParent="true"
android:text="Button04" />

<Button
android:id="@+id/button05"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_alignParentRight="true"
android:layout_below="@id/button04"
android:text="Button05" />

</demo.widget.WeightedSizeRelativeLayout>

and the necessary changes for getChildMeasureSpec method is this:

private int getChildMeasureSpec(...){
........

if (childSize < -2 ) {
// Child wanted an exact size. Give as much as possible
childSpecMode = MeasureSpec.EXACTLY;

childSpecSize = (int) (mySize*(-1.0f*childSize/10000));

}else if (childSize >= 0) {
.........

}

I have uploaded both Java and demo xml here.

Let test this and hope necessary implementation for adding weight attribute into Relative Layout Parameter will be added.

Android: Drawing both side clipped Progress Bar

2012-07-22T03:54:00.001-07:00

In most of the android application we can see some kind of progress bar with rounded corners as show below. Mostly in media players this used to indicate the curent duration and/or percentage of buffed content etc. These a mostly one side clipped. Let check how we can draw a both side clipped progress bar.

Android API provide a build in progress bar, application developer can make use of this in their development. For that they manly use ClipDrawable. In android, In case of these kind of stretchable background we can use nine-patch drawable those will be stretched in runtime and reduce both memory usage of application.

Assume you have created a nine-patch and added into res folder.

// Lets load the drawable and get it minimum height,
// here I am going to stretch horizontally so i get height.
Drawable drawable = getResources().getDrawable(R.drawable.progress);
int height = drawable.getMinimumHeight();
// If you check, you can identify that the drawable will be NinePatchDrawable.

// First lets examine how this nine patch getting drawn.
// set the boundary and pass the canvas to be drawn.
drawable.setBounds(0, 0, getWidth(), height);
drawable.draw(canvas);
//this will draw the 0-100% progress bar.

//Now let us try a clipped progress bar.

//Create a clip drawable with above nine-patch, Gravity.LEFT , ClipDrawable.HORIZONTAL
ClipDrawable clipDrawable1 = new ClipDrawable(drawable, Gravity.LEFT, ClipDrawable.HORIZONTAL);

//Set the level 9000, this will draw the 90% of the left part.
clipDrawable1.setLevel(9000);
clipDrawable1.setBounds(0, height, getWidth(), 2*height);
clipDrawable1.draw(canvas);
//this will draw 0-90%

//Lets create another ClipDrawable which will draw 80% of right part.
ClipDrawable clipDrawable2 = new ClipDrawable(clipDrawable1, Gravity.RIGHT, ClipDrawable.HORIZONTAL);
clipDrawable2.setLevel(8000);
clipDrawable2.setBounds(0, 2*height, getWidth(), 3*height);
clipDrawable2.draw(canvas);
//This draws 20%-80%
//But we expected this should draw 20%-90% progress bar.
//But issue is above clipDrawable2.setLevel(8000) set level of both Drawable.

//So set level of clipDrawable1 again and draw.
clipDrawable1.setLevel(9000);
clipDrawable2.setBounds(0, 3*height, getWidth(), 4*height);
clipDrawable2.draw(canvas);
//This will draw 20%-90% drawable.

Take, we can draw both sided progress bar using clip drawable one inside another, but set Level method will set all children's level, so after setting parent level we have to set chid levels in that order.

Android: Understating Text Drawing

2012-06-29T00:11:00.001-07:00

When it comes to draw text inside our custom view, it is difficult to position text vertically in correct place if we use canvas.drawText(..,x,y..) , because it will not start to draw from the give y coordinate rather it will position the text base line in the give y coordinate.

First look at this following image:

In the first view (view 01) text and a red line are drawn in the middle vertically.
TEXT_PAINT.setColor(Color.WHITE);

//Drawing the text at middle of the view

canvas.drawText(LONG_STRING, 0, getHeight()/2, TEXT_PAINT);

TEXT_PAINT.setColor(Color.RED);

//Here we draw the middle line

canvas.drawLine(0, getHeight()/2, getWidth(), getHeight()/2, TEXT_PAINT);

If you think that, the text is drawn on top of the line, then simply if we find an API to get the height of the text then we can align use that value.
Rect rect = new Rect();

TEXT_PAINT.setColor(Color.BLUE);

TEXT_PAINT.getTextBounds(LONG_STRING, 0, LONG_STRING.length(), rect);

//Measure the height and draw line on top of text

canvas.drawLine(0, getHeight()/2-rect.height(), getWidth(), getHeight()/2-rect.height(), TEXT_PAINT);

But that is not the case, you see, some part of 'y' from 'Please try this is...' is drawn down of the middle line. So we want to know how actually text are drawn and actual center of the text.

To understand this I used StaticLayout in the second view (view 02).
TEXT_PAINT.setColor(Color.WHITE);

//Create a static layout to draw

StaticLayout staticLayout = new StaticLayout(

LONG_STRING, 0, LONG_STRING.length(),

TEXT_PAINT,

getWidth(),android.text.Layout.Alignment.ALIGN_CENTER ,

1.0f, 1.0f, false);

staticLayout.draw(canvas);

It provides necessary API to get top, bottom and base line of the text. In the second view you can see those lines.
for(int i = 0 ; i < staticLayout.getLineCount();i++){

TEXT_PAINT.setColor(Color.BLUE);

canvas.drawLine(0, staticLayout.getLineTop(i), getWidth(), staticLayout.getLineTop(i), TEXT_PAINT);

TEXT_PAINT.setColor(0x7FFFFFFF&Color.YELLOW);

canvas.drawRect(staticLayout.getLineLeft(i), staticLayout.getLineTop(i), staticLayout.getLineRight(i), staticLayout.getLineBottom(i), TEXT_PAINT);

TEXT_PAINT.setColor(Color.RED);

canvas.drawLine(0, staticLayout.getLineBaseline(i), getWidth(), staticLayout.getLineBaseline(i), TEXT_PAINT);

TEXT_PAINT.setColor(Color.MAGENTA);

canvas.drawLine(0, staticLayout.getLineBottom(i), getWidth(), staticLayout.getLineBottom(i), TEXT_PAINT);

}

Now let use this values to draw text in proper place as shown in view 03.
canvas.drawText(LONG_STRING, 0, getHeight()/2+(staticLayout.getLineBaseline(0)-staticLayout.getLineBottom(0)/2), TEXT_PAINT);

I have uploaded sample source code here:
Thanks

Android: Play video on Top of GLSurfaceView

2012-06-27T03:51:00.000-07:00

i modified the GLSurfaceViewActivity from ApiDemo to check to see where can play Video on top of GLSurfaceView.

public class GLSurfaceViewActivity extends Activity implements OnClickListener, OnCompletionListener, OnTouchListener {

@SuppressWarnings("unused")
private static final String TAG = "com.example.android.apis.graphics.GLSurfaceViewActivity";

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

// Create our Preview view and set it as the content of our
// Activity
mGLSurfaceView = new GLSurfaceView(this);
mGLSurfaceView.setOnTouchListener(this);
mGLSurfaceView.setRenderer(new CubeRenderer(false));
FrameLayout frameLayout = new FrameLayout(this);
frameLayout.addView(mGLSurfaceView, new FrameLayout.LayoutParams(FrameLayout.LayoutParams.FILL_PARENT,FrameLayout.LayoutParams.FILL_PARENT));

mVideoView = new VideoView(this);
mVideoView.setVisibility(View.INVISIBLE);
mVideoView.setOnCompletionListener(this);
frameLayout.addView(mVideoView, new FrameLayout.LayoutParams(FrameLayout.LayoutParams.FILL_PARENT,FrameLayout.LayoutParams.FILL_PARENT));

mCheckBox = new CheckBox(this);
mCheckBox.setText("Load Video");
mCheckBox.setOnClickListener(this);
frameLayout.addView(mCheckBox, new FrameLayout.LayoutParams(FrameLayout.LayoutParams.WRAP_CONTENT,FrameLayout.LayoutParams.WRAP_CONTENT,Gravity.CENTER));
setContentView(frameLayout);
}

@Override
protected void onResume() {
// Ideally a game should implement onResume() and onPause()
// to take appropriate action when the activity looses focus
super.onResume();
mGLSurfaceView.onResume();
}

@Override
protected void onPause() {
// Ideally a game should implement onResume() and onPause()
// to take appropriate action when the activity looses focus
super.onPause();
mGLSurfaceView.onPause();
}

private GLSurfaceView mGLSurfaceView;
private VideoView mVideoView;
private CheckBox mCheckBox;

@Override
public void onClick(View arg0) {
if(mCheckBox.isChecked()){
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("video/*");
startActivityForResult(Intent.createChooser(intent, "Chose a Video"), 10);
}else{
mVideoView.setVisibility(View.VISIBLE);
mVideoView.start();
mCheckBox.setChecked(true);
}

}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if(data!=null && data.getData()!=null){
mCheckBox.setText("Play Video");
mVideoView.setVideoURI(data.getData());
mVideoView.setVisibility(View.VISIBLE);
mVideoView.start();
}else{
mCheckBox.setChecked(false);
}
super.onActivityResult(requestCode, resultCode, data);
}

@Override
public void onCompletion(MediaPlayer arg0) {
mVideoView.setVisibility(View.INVISIBLE);

}

@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
mVideoView.setTranslationX(motionEvent.getX());
mVideoView.setTranslationY(motionEvent.getY());
return true;
}
}

Logging Caller Method Info in Java

2012-06-26T23:59:00.001-07:00

In our application, one method maybe called from multiple locations. While debugging application we may need to log it caller caller method information in those case following line will be use full.
Here from the current thread, I get called Stack and print that for us.

private static void someMethod() {
System.out.println(Thread.currentThread().getStackTrace()[0]);
System.out.println(Thread.currentThread().getStackTrace()[1]);
System.out.println(Thread.currentThread().getStackTrace()[2]);
}

java.lang.Thread.getStackTrace(Thread.java:1479)
demo.TestThread.someMethod(TestThread.java:14)
demo.TestThread.main(TestThread.java:9)

What we want from this output is "demo.TestThread.main(TestThread.java:9)" So you use in your java application.

System.out.println(Thread.currentThread().getStackTrace()[2]);

Okey for Android Application I try followings:

public void onCreate(Bundle savedInstanceState) {
..................

Log.i(TAG, "::onCreate:" +Thread.currentThread().getStackTrace()[0]);
Log.i(TAG, "::onCreate:" +Thread.currentThread().getStackTrace()[1]);
Log.i(TAG, "::onCreate:" +Thread.currentThread().getStackTrace()[2]);
Log.i(TAG, "::onCreate:" +Thread.currentThread().getStackTrace()[3]);

............
}

onCreate:dalvik.system.VMStack.getThreadStackTrace(Native Method)
onCreate:java.lang.Thread.getStackTrace(Thread.java:591)
onCreate:demo.multi.line.text.DemoMultiLineTextActivity.onCreate(DemoMultiLineTextActivity.java:58)
onCreate:android.app.Activity.performCreate(Activity.java:4518)

What we want from this output is "onCreate:android.app.Activity.performCreate(Activity.java:4518)" So you use in your Android application:

Log.i(TAG, "::onCreate:" +Thread.currentThread().getStackTrace()[3]);

Android: Bigger Image for any of the Image inside Grid View

2012-06-22T09:13:00.001-07:00

As and extension for my earlier post, I have created the project to apply for any of the image in the grid and it will support for any number of columns and the bigger image and can take any number of column with.

I have uploaded the source code here: http://dl.dropbox.com/u/7717254/DemoGridView_02.zip

But if you have bigger image column size if greater than half of the grid column size it has some bug, and need to fix that first.

Android: Bigger image for first item of the gridview

2012-06-20T04:58:00.000-07:00

Say you want layout like below:

I start to implement with following XML , activity, adapter:

<?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" >

<GridView
android:id="@+id/gridView1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:numColumns="5" >
</GridView>

</LinearLayout>

package demo.grid.view;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.ImageView.ScaleType;

public class DemoGridViewActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
GridView gridView = (GridView)findViewById(R.id.gridView1);
gridView.setAdapter(new GridViewAdaptor());
}

class GridViewAdaptor extends BaseAdapter{

@Override
public int getCount() {
return 50;
}

@Override
public Object getItem(int arg0) {
return arg0;
}

@Override
public long getItemId(int arg0) {
return arg0;
}

@Override
public View getView(int arg0, View arg1, ViewGroup arg2) {
ImageView imageView;
if(arg1==null){
imageView = new ImageView(DemoGridViewActivity.this){
@Override
protected void onMeasure(int widthMeasureSpec,
int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension(getMeasuredWidth(), getMeasuredWidth());
}
};
}else{
imageView = (ImageView) arg1;
}

imageView.setLayoutParams(new GridView.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT));
imageView.setBackgroundColor(Color.BLUE);
imageView.setScaleType(ScaleType.FIT_XY);
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
switch(arg0){
case 0:
imageView.setImageBitmap(Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth()/2, bitmap.getHeight()/2));
imageView.setBackgroundColor(Color.RED);
return imageView;
case 1:
imageView.setImageBitmap(Bitmap.createBitmap(bitmap, bitmap.getWidth()/2, 0, bitmap.getWidth()/2, bitmap.getHeight()/2));
imageView.setBackgroundColor(Color.GREEN);
return imageView;
case 5:
imageView.setImageBitmap(Bitmap.createBitmap(bitmap, 0, bitmap.getHeight()/2, bitmap.getWidth()/2, bitmap.getHeight()/2));
imageView.setBackgroundColor(Color.YELLOW);
return imageView;
case 6:
imageView.setImageBitmap(Bitmap.createBitmap(bitmap, bitmap.getWidth()/2, bitmap.getHeight()/2, bitmap.getWidth()/2, bitmap.getHeight()/2));
imageView.setBackgroundColor(Color.MAGENTA);
return imageView;
default:
imageView.setImageResource(R.drawable.ic_launcher);
return imageView;
}
}

}
}

Now this issue is how to work with a list of object and translate it into this grid view. Following translation needed to be done for adapter:

@Override
public int getCount() {
return integers.size()+3;
}

switch(arg0){
case 0:
imageView.setTag(integers.get(0));

case 1:
imageView.setTag(integers.get(0));
case 5:
imageView.setTag(integers.get(0));

case 6:
imageView.setTag(integers.get(0));
default:
if(arg0>1 && arg0<=4){
imageView.setTag(integers.get(arg0-1));
}else{
imageView.setTag(integers.get(arg0-3));
}
}

full code is here:

package demo.grid.view;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
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.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.ImageView.ScaleType;

public class DemoGridViewActivity extends Activity {
/** Called when the activity is first created. */

List integers = new ArrayList();

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

for(int i = 0 ; i < 50 ; i++){
integers.add(i);
}

GridView gridView = (GridView)findViewById(R.id.gridView1);
gridView.setAdapter(new GridViewAdaptor());
}

class GridViewAdaptor extends BaseAdapter{

@Override
public int getCount() {
return integers.size()+3;
}

@Override
public Object getItem(int arg0) {
return arg0;
}

@Override
public long getItemId(int arg0) {
return arg0;
}

@Override
public View getView(int arg0, View arg1, ViewGroup arg2) {
ImageView imageView;
if(arg1==null){
imageView = new ImageView(DemoGridViewActivity.this){
@Override
protected void onMeasure(int widthMeasureSpec,
int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension(getMeasuredWidth(), getMeasuredWidth());
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Paint paint = new Paint();
paint.setColor(Color.RED);
paint.setTextSize(36);
canvas.drawText(getTag().toString(), getWidth()/2, getHeight()/2, paint);
}
};
}else{
imageView = (ImageView) arg1;
}

imageView.setLayoutParams(new GridView.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT));
imageView.setBackgroundColor(Color.BLUE);
imageView.setScaleType(ScaleType.FIT_XY);
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
switch(arg0){
case 0:
imageView.setImageBitmap(Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth()/2, bitmap.getHeight()/2));
imageView.setBackgroundColor(Color.RED);
imageView.setTag(integers.get(0));
return imageView;
case 1:
imageView.setImageBitmap(Bitmap.createBitmap(bitmap, bitmap.getWidth()/2, 0, bitmap.getWidth()/2, bitmap.getHeight()/2));
imageView.setBackgroundColor(Color.GREEN);
imageView.setTag(integers.get(0));
return imageView;
case 5:
imageView.setImageBitmap(Bitmap.createBitmap(bitmap, 0, bitmap.getHeight()/2, bitmap.getWidth()/2, bitmap.getHeight()/2));
imageView.setBackgroundColor(Color.YELLOW);
imageView.setTag(integers.get(0));
return imageView;
case 6:
imageView.setImageBitmap(Bitmap.createBitmap(bitmap, bitmap.getWidth()/2, bitmap.getHeight()/2, bitmap.getWidth()/2, bitmap.getHeight()/2));
imageView.setBackgroundColor(Color.MAGENTA);
imageView.setTag(integers.get(0));
return imageView;
default:
if(arg0>1 && arg0<=4){
imageView.setTag(integers.get(arg0-1));
}else{
imageView.setTag(integers.get(arg0-3));
}

imageView.setImageResource(R.drawable.ic_launcher);
return imageView;
}
}

}
}

finally this code for loading images from device sdcard and display in the gridview:

package demo.grid.view;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.os.AsyncTask;
import android.os.Bundle;
import android.provider.MediaStore;
import android.provider.MediaStore.Images.Thumbnails;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.ImageView.ScaleType;
public class DemoGridViewActivity extends Activity {
private static final int START_PROGRESS = 10;
List mBitmaps = new ArrayList();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
AsyncTask asyncTask = new AsyncTask(){
@Override
protected void onPreExecute() {
showDialog(START_PROGRESS);
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... params) {
Cursor query = getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, new String[]{MediaStore.Images.Media._ID}, null, null, null);
if(query!=null && query.moveToFirst()){
do{
int columnIndex = query.getColumnIndex(MediaStore.Images.Media._ID);
long origId = query.getLong(columnIndex);
mBitmaps.add(MediaStore.Images.Thumbnails.getThumbnail(getContentResolver(), origId, Thumbnails.MICRO_KIND, null));
}while(query.moveToNext());
query.close();
}
return null;
}
@Override
protected void onPostExecute(Void result) {
removeDialog(START_PROGRESS);
GridView gridView = (GridView)findViewById(R.id.gridView1);
gridView.setAdapter(new GridViewAdaptor());
super.onPostExecute(result);
}
};
asyncTask.execute();
}
@Override
protected Dialog onCreateDialog(int id, Bundle args) {
return new ProgressDialog(this);
}
class GridViewAdaptor extends BaseAdapter{
@Override
public int getCount() {
return mBitmaps.size()+3;
}
@Override
public Object getItem(int arg0) {
return arg0;
}
@Override
public long getItemId(int arg0) {
return arg0;
}
@Override
public View getView(int arg0, View arg1, ViewGroup arg2) {
ImageView imageView;
if(arg1==null){
imageView = new ImageView(DemoGridViewActivity.this){
@Override
protected void onMeasure(int widthMeasureSpec,
int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension(getMeasuredWidth(), getMeasuredWidth());
}
};
}else{
imageView = (ImageView) arg1;
}
imageView.setLayoutParams(new GridView.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT));
imageView.setBackgroundColor(Color.BLUE);
imageView.setScaleType(ScaleType.FIT_XY);

Bitmap bitmap;
switch(arg0){
case 0:
imageView.setPadding(10, 10, 0, 0);
bitmap = mBitmaps.get(0);
imageView.setImageBitmap(Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth()/2, bitmap.getHeight()/2));
imageView.setBackgroundColor(Color.RED);
return imageView;
case 1:
imageView.setPadding(0, 10, 10, 0);
bitmap = mBitmaps.get(0);
imageView.setImageBitmap(Bitmap.createBitmap(bitmap, bitmap.getWidth()/2, 0, bitmap.getWidth()/2, bitmap.getHeight()/2));
imageView.setBackgroundColor(Color.GREEN);
return imageView;
case 5:
imageView.setPadding(10, 0, 0, 10);
bitmap = mBitmaps.get(0);
imageView.setImageBitmap(Bitmap.createBitmap(bitmap, 0, bitmap.getHeight()/2, bitmap.getWidth()/2, bitmap.getHeight()/2));
imageView.setBackgroundColor(Color.YELLOW);
return imageView;
case 6:
imageView.setPadding(0, 0, 10, 10);
bitmap = mBitmaps.get(0);
imageView.setImageBitmap(Bitmap.createBitmap(bitmap, bitmap.getWidth()/2, bitmap.getHeight()/2, bitmap.getWidth()/2, bitmap.getHeight()/2));
imageView.setBackgroundColor(Color.MAGENTA);
return imageView;
default:
if(arg0>1 && arg0<=4){
bitmap = mBitmaps.get(arg0-1);
}else{
bitmap = mBitmaps.get(arg0-3);
}
imageView.setPadding(10, 10, 10, 10);
imageView.setImageBitmap(bitmap);
return imageView;
}
}
}
}

here you have sample code: source code

please check this post for more update: http://sudarnimalan.blogspot.sg/2012/06/android-bigger-image-for-any-of-image.html

Part1 : Useful Eclipse Templates for Android Development

2012-06-19T00:43:00.002-07:00

I normally setup eclipse templates for repeat coding fragments. If you are not aware of eclipse editor templates, just a small example: just open a java code file and type "syso" (shortcut name) and press Ctrl+space then you will see all "System.out.println();" will be inserted by eclipse for you.
To see all existing templates and its shortcut open your eclipse, open the window menu and click on Preference. Inside the Preference dialog , navigate to Java --> Editor --> Templates, Now you see full list there. (Eclipse-->Window-->Preference-->Java-->Editor-->Templates)
You can add your own templates there and make use of them in your coding and make your coding fast. Just click "New.." button, fill the "New Template" Dialog and OK.

1. In android, in case if we want to get logs we want to insert "Log.i" statements with proper message. This template will be useful for that.

Name: alog
Context: Java statements
Description: android log statement
Pattern: Log.i(TAG,"::${enclosing_method}:"+"${cursor}");

Now,For Example, in side onCreate if you type alog and press Ctrl+space you will get:
Log.i(TAG, "::onCreate:" + "");

2. In #1 you see, we have to pass a TAG, normally this should be the Class name of the method we define in the top. I used to go for a full qualified name of any class. Sometime this will be useful in case of Custom Views to copy its name to crate layout XML files.

Name: atag
Context: Java type members
Description: android log tag
Pattern:

@SuppressWarnings("unused")
private static final String TAG = "${enclosing_package}.${enclosing_type}";

Ex: @SuppressWarnings("unused")
private static final String TAG = "demo.DemoAcitity";

3. Inside the activity most we have to find View By Id and call some method on it.

Name: afind
Context: Java
Description: android find view
Pattern:

${type} ${new_name} = (${type})findViewById(R.id.${cursor});

type afind and press Ctrl+Space, then you will get:
type| new_name = (type)findViewById(R.id.);

for example if that is a button then, type Button or But and press Ctrl+Space then you will get:
Button new_name = (Button)findViewById(R.id.);

Then press Tab cursor will move to new_name
Button new_name = (Button)findViewById(R.id.);

Type the name you want for the variable, then press Tab cursor will move after ".id.":
Button button = (Button)findViewById(R.id.|);
The just press Ctrl+space and choose the id from the list.

So you will end as follows:
Button button = (Button)findViewById(R.id.btn_add);

In android we mostly do this in onCreate method and assign to member variable. and refer from other method. Now you right click on the variable name choose Refactor and choose "Convert Local Variable to Field" this will create a Field for you.

here i have uploaded the template file.

Part 2 : Useful Eclipse Templates for Android Development

Android: LinearLayout, Dynamically Arranging Views

2012-06-18T23:03:00.001-07:00

Let see how to arrange buttons according to the user selection as shown below:

<LinearLayout android:orientation="vertical" android:id="@+id/linearLayout1"

android:layout_height="fill_parent" android:layout_width="fill_parent">

<Button android:text="Button" android:id="@+id/button0"

android:layout_height="fill_parent" android:layout_width="fill_parent"

android:layout_weight="1">Button>

<Button android:text="Button" android:id="@+id/button1"

android:layout_height="fill_parent" android:layout_width="fill_parent"

android:layout_weight="1" android:visibility="gone">Button>

<Button android:text="Button" android:id="@+id/button2"

android:layout_height="fill_parent" android:layout_weight="1"

android:layout_width="fill_parent" android:visibility="gone">Button>

LinearLayout>

Following java code would change the visibility according to the user selection.

@Override

public void onCheckedChanged(RadioGroup group, int checkedId) {

switch(group.getCheckedRadioButtonId()){

case R.id.radio0:

button0.setVisibility(View.VISIBLE);

button1.setVisibility(View.GONE);

button2.setVisibility(View.GONE);

break;

case R.id.radio1:

button0.setVisibility(View.VISIBLE);

button1.setVisibility(View.VISIBLE);

button2.setVisibility(View.GONE);

break;

case R.id.radio2:

button0.setVisibility(View.VISIBLE);

button1.setVisibility(View.VISIBLE);

button2.setVisibility(View.VISIBLE);

break;

}

Let see if we want a layout to change as show below:

This can be down in two ways.

Option 01: changing the layout XML file to use the weight sum:

<LinearLayout android:orientation="vertical" android:id="@+id/linearLayout1"

android:layout_height="fill_parent" android:layout_width="fill_parent" android:weightSum="3">

<Button android:text="Button" android:id="@+id/button0"

android:layout_width="fill_parent"

android:layout_weight="1" android:layout_height="0dip">Button>

<Button android:text="Button" android:id="@+id/button1"

android:layout_width="fill_parent"

android:layout_weight="1" android:visibility="gone" android:layout_height="0dip"> Button>

<Button android:text="Button" android:id="@+id/button2"

android:layout_weight="1"

android:layout_width="fill_parent" android:visibility="gone" android:layout_height="0dip">Button>

LinearLayout>

Option 02: using java code:

@Override

public void onCheckedChanged(RadioGroup group, int checkedId) {

switch(group.getCheckedRadioButtonId()){

case R.id.radio0:

button0.setVisibility(View.VISIBLE);

button1.setVisibility(View.INVISIBLE);

button2.setVisibility(View. INVISIBLE);

break;

case R.id.radio1:

button0.setVisibility(View.VISIBLE);

button1.setVisibility(View.VISIBLE);

button2.setVisibility(View. INVISIBLE);

break;

case R.id.radio2:

button0.setVisibility(View.VISIBLE);

button1.setVisibility(View.VISIBLE);

button2.setVisibility(View.VISIBLE);

break;

}

option 01 you should change the xml file and in option 02 you should change the java code.

Android: Expand Liner Layout Beyond its Width

2012-05-19T21:15:00.000-07:00

In android, the layout weight parameter in the liner layout is very useful to layout views with relative ratios. Say you want to arrange two frames left and right, and right frame take quoter and right take the balance.

We can simply create this using following layout xml. Only thing is to noted down is, the width should be set to 0dip and weight to be set to 0.25 or 0.75 according to the requirement. That all.

<?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="horizontal"

android:weightSum="1" >

<FrameLayout

android:layout_width="0dip"

android:layout_height="match_parent"

android:layout_weight="0.75"

android:background="#FF0000" >

</FrameLayout>

<FrameLayout

android:layout_width="fill_parent"

android:layout_height="match_parent"

android:layout_weight="0.25"

android:background="#00FF00" >

<ToggleButton

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center" />

</FrameLayout>

</LinearLayout>

But in our case, we wanted to add another frame next to the right frame its width also 0.75 of the screen and in some user action, by moving the screen, the left frame should be hidden and 3rd frame should be shown.

So we created custom liner layout by extending the liner layout, where we override the on measure method to adjust its size by 0.75 of its size.

public class ExpandedLinearLayout extends LinearLayout {
@SuppressWarnings("unused")
private static final String TAG = "demo.beyond.layout.ExpandedLinearLayout";
public ExpandedLinearLayout(Context context) {
super(context);
}
public ExpandedLinearLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
public ExpandedLinearLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension((int) (1.75f*getMeasuredWidth()), getMeasuredHeight());
}
}

And add another new frame to above layout with weight 0.75.

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

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

.................

<FrameLayout

android:layout_width="0dip"

android:layout_height="match_parent"

android:layout_weight="0.75"

android:background="#0000FF" >

</FrameLayout>

</LinearLayout>

Then we add the animation for the on click.

public class DemoExpandLayoutActivity extends Activity implements OnClickListener {
private LinearLayout mLinearLayout;
private FrameLayout mFrameLayout1;
private ToggleButton mToggleButton;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mLinearLayout = (LinearLayout)findViewById(R.id.frame);
mFrameLayout1 = (FrameLayout)findViewById(R.id.frameLayout1);
mToggleButton = (ToggleButton)findViewById(R.id.toggleButton1);
mToggleButton.setOnClickListener(this);
}

@Override
public void onClick(View arg0) {
float factor = 1.0f*mFrameLayout1.getWidth()/mLinearLayout.getWidth();
if(mToggleButton.isChecked()){
mLinearLayout.setTranslationX(-mFrameLayout1.getWidth());
TranslateAnimation translateAnimation = new TranslateAnimation(
TranslateAnimation.RELATIVE_TO_PARENT,
factor,
TranslateAnimation.RELATIVE_TO_PARENT,
0.0f,
TranslateAnimation.RELATIVE_TO_PARENT,
0.0f,
TranslateAnimation.RELATIVE_TO_PARENT,
0.0f);
translateAnimation.setDuration(1000);
LayoutAnimationController layoutAnimationController = new LayoutAnimationController(translateAnimation,0.1f);
mLinearLayout.setLayoutAnimation(layoutAnimationController);
}else{
mLinearLayout.setTranslationX(0);
TranslateAnimation translateAnimation = new TranslateAnimation(
TranslateAnimation.RELATIVE_TO_PARENT,
-factor,
TranslateAnimation.RELATIVE_TO_PARENT,
0.0f,
TranslateAnimation.RELATIVE_TO_PARENT,
0.0f,
TranslateAnimation.RELATIVE_TO_PARENT,
0.0f);
translateAnimation.setDuration(1000);
LayoutAnimationController layoutAnimationController = new LayoutAnimationController(translateAnimation,-0.1f);
mLinearLayout.setLayoutAnimation(layoutAnimationController);
}
}
}

But that didn't quit worked out, because liner layout ignores views If those out side the weight sum.

But if we add views as match patent, with layout weights, liner layout behaves differently. It draws all the views beyond its boundary.
In this case the actual width of each view was not proportional to layout weight what we set in layout XML.
So to find out the relation, I just try for different values and plot the following graph and got the below equation.

I couldn't find any direct evidence in android code base or may have to check some more android source code. But this is good enough to calculate the proper values for us.

Then I changed the layout XML with those values.

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

<demo.beyond.layout.ExpandedLinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:id="@+id/frame"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:orientation="horizontal"

android:weightSum="1" >

<FrameLayout

android:id="@+id/frameLayout1"

android:layout_width="fill_parent"

android:layout_height="match_parent"

android:layout_weight="0.125"

android:background="#FF0000" >

</FrameLayout>

<FrameLayout

android:id="@+id/frameLayout2"

android:layout_width="fill_parent"

android:layout_height="match_parent"

android:layout_weight="0.375"

android:background="#00FF00" >

<ToggleButton

android:id="@+id/toggleButton1"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center" />

</FrameLayout>

<FrameLayout

android:id="@+id/frameLayout3"

android:layout_width="fill_parent"

android:layout_height="match_parent"

android:layout_weight="0.125"

android:background="#0000FF" >

</FrameLayout>

</demo.beyond.layout.ExpandedLinearLayout>

Further more I modified the expanded liner layout with this formula, so that it can use in all cases.

@Override

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

super.onMeasure(widthMeasureSpec, heightMeasureSpec);

int numberOfChild = getChildCount();

float totalWidth = 0;

for(int i = 0;i < numberOfChild;i++){

totalWidth+=getMeasuredWidth()

*(1 - 2*((LinearLayout.LayoutParams)getChildAt(i).getLayoutParams()).weight);

}

setMeasuredDimension((int) totalWidth, getMeasuredHeight());

}

Source Code : http://dl.dropbox.com/u/7717254/DemoExpandLayout.zip

Here I have uploaded the source code, try it your self and let me know your feedback or let me know if you have any other option.

Android: How to Check if Media Scanner is Running?

2012-05-15T23:39:00.001-07:00

In our application, some of the action need to be blocked while android media scanner running (For example loading existing media and listing down).

In this case, we couldn't find a direct API to check if Media Scanner is running. We could find following two options:
Option 01:
Android will broadcast Intent.ACTION_MEDIA_SCANNER_STARTED, Intent.ACTION_MEDIA_SCANNER_FINISHED in starting and finishing of scanning respectively. So we create following BroadcastReceiver:

public class MediaScannerBroadcastReceiver extends BroadcastReceiver {
public static boolean mMedaiScanning = false;
@Override
public void onReceive(Context context, Intent intent) {
if(intent.getAction().equals(Intent.ACTION_MEDIA_SCANNER_STARTED)){
mMedaiScanning = true;
}
if(intent.getAction().equals(Intent.ACTION_MEDIA_SCANNER_FINISHED)){
mMedaiScanning = false;
}
}
}

And register this in manifest file:

<receiver android:name=" MediaScannerBroadcastReceiver">
< intent-filter>

   < action android:name="android.intent.action.MEDIA_SCANNER_FINISHED" >  < /action>
< action android:name="android.intent.action.MEDIA_SCANNER_STARTED" >  < /action>
   < data android:scheme="file" >  < /data>
< /intent-filter>
</receiver>

Then in cases we we wanted to check the condition we sued as following:
if( MediaScannerBroadcastReceiver.mMedaiScanning){
.....
}

But, most of the devices will run Media Scanner in boot up, in adding SDCard or mount/unmount devices to PC. In those cases our application is invoked and loaded into memory.

Option 02:
found that the media scanner service insert and delete a record into media store when starting and finishing the scanning. So we try to check the record in the media store as follows:

private boolean isMediaScannerRunning() {

Cursor query = getContentResolver().query(MediaStore.getMediaScannerUri(),

new String[]{MediaStore.MEDIA_SCANNER_VOLUME}, null, null, null);

if(query!=null){

if(query.moveToFirst()){

int columnIndex = query.getColumnIndex(MediaStore.MEDIA_SCANNER_VOLUME);

String volumeName = query.getString(columnIndex);

if(volumeName!=null){

return true;

}

query.close();

}

return false;

}

This option will not load the application while media scanner running. But need to consider its costly operation in query.

Lets check both options for its pros and cons.

Part 7: Thoughts of “How we do?” - Reading from Near vs Far

2011-10-01T21:46:00.000-07:00

Say you are traveling in a bus and trying to read a board on both sides of the road. First board is on the same side where you are traveling and the second board on the other side of the road. Both has same text. And the board on the opposite side has enough font size to read it from the bus which you are traveling. Normally we can only star reading once we come inside the visual angle of the board.

Assume you are reading both boards in two different situation from start to end while bus moving in same speed. You will understand that, you can read more from the board which is in the opposite side. So when we are traveling, without reducing our speed, we can't read more from near, rather from far we can. But the distance should be enough to identify the letters, that all.

Now, let see how we can apply this into a real life situations.

Team leaders, if your team members are currently working in a project with a constant speed. And you are hearing some new project opportunity. It is not good to wait until your project got confirm and then bring it to the members to their close attention. Because members have to slowdown their current project in order to prepare the new project. Instead of that, if you let them prepare the new project early as possible in a relax mode, this will not much affect the current project speed.

Here one of the different between close attention and relax mode would be, in close attention team leader will expect and check for updates very frequently, rather in relax mode leader could wait until the team member bring updates to leaders' table or expect and check update occasionally.

One concern may be: change in the project detail will make the preparation waste, but that is not fully true. Because if we have already prepared and then you summaries the different from early draft we don't need much effect to override the new changes. If the project details totally change, then of cause all the initial preparation is waste. Mostly that not the case.

But for the success of relax mode approach, team member should have enough skill level. They should be proactive to prepare project in early stage, self motivated to prepare project and provide updates. They should be able manage and balance work load in preparation new project with the current project.

Feather more, letting the team member to prepare the project early will lead to understand any unclear or impossible areas in the project so that the project could be modify accordingly. This will help in project executions very much.

So, I feel it is better to do go for a early preparation of new project. Both team leaders and members should understand the pros and cons in this approach and should act accordingly. This will bring a best team and best product in the end.

Let me find out another real example as above and meet you another post. Bye

Android : Drawing View with shapes plotted in r theta (r,θ) relation

2011-10-01T09:38:00.000-07:00

r = 0.875*width/2+0.125cos(12θ)

r - width/2*cos(4θ)

r - width/2

Say you want to create views which contains shares as shown above. In those each circle drawn in (r,θ) relation. I implemented following onDraw method with possible two options.

Option 1. Rotating canvas and drawing circles - this is direct use of (r , θ)

Option 2. Converting points into x,y plan coordinate and drawing the circle.

@Override
protected void onDraw(Canvas canvas) {
float width = getWidth()/2;
float height = getHeight()/2;
Paint paint = new Paint();
paint.setColor(Color.RED);
//Option 1
long time = System.currentTimeMillis();
canvas.save();
canvas.translate(width, height);
for(int i = 0 ; i < 13;i++){
canvas.drawCircle(width, 0, width*0.2f, paint);
canvas.rotate(-15);
}
canvas.restore();
Log.i(TAG, "::onDraw:" + "time 1 = " + (System.currentTimeMillis()-time));
//Option 2
long time1 = System.currentTimeMillis();
canvas.save();
canvas.translate(width, height);
float angle = 0;
for(int i = 0 ; i < 13;i++){
float radian = (float) (Math.PI*angle/180.0f);
canvas.drawCircle((float) (width*Math.cos(radian)),
(float) (width*Math.sin(radian)), width*0.2f, paint);
angle+=15;
}
canvas.restore();
Log.i(TAG, "::onDraw:" + "time 2 = " + (System.currentTimeMillis()-time1));
}

Since above coding draw only 13 circles, I couldn't find a clear different in execution time for both options. So I change the code to draw 180 circle as follows:

@Override
protected void onDraw(Canvas canvas) {
float width = getWidth()/2;
float height = getHeight()/2;
Paint paint = new Paint();
paint.setColor(Color.RED);
long time1 = System.currentTimeMillis();
canvas.save();
canvas.translate(width, height);
for(int i = 0 ; i < 180;i++){
float radius = width;
canvas.drawCircle(radius, 0, 2.0f, paint);
canvas.rotate(-1);
}
canvas.restore();
time1 = System.currentTimeMillis()-time1;
long time2 = System.currentTimeMillis();
canvas.save();
canvas.translate(width, height);
for(int i = 0 ; i < 180;i++){
float radian = (float) (Math.PI*i/180.0f);
float radius = width;
canvas.drawCircle((float) (radius*Math.cos(radian)),
(float) (radius*Math.sin(radian)), 2.0f, paint);
}
canvas.restore();
time2 = System.currentTimeMillis()-time2;
Log.i(TAG, "::onDraw:" + "time1,time2, (time1-time2) = "
+ time1 + ","+time2+","+(time1-time2));
}

Now i could see clear different and Option 2 is faster than Option 1.

INFO/demo.theta.DemoRTheta(5302): ::onDraw:time1,time2, (time1-time2) = 62,35,27
INFO/demo.theta.DemoRTheta(5302): ::onDraw:time1,time2, (time1-time2) = 66,36,30
INFO/demo.theta.DemoRTheta(5302): ::onDraw:time1,time2, (time1-time2) = 66,37,29
INFO/demo.theta.DemoRTheta(5302): ::onDraw:time1,time2, (time1-time2) = 63,35,28
INFO/demo.theta.DemoRTheta(5302): ::onDraw:time1,time2, (time1-time2) = 68,34,34
INFO/demo.theta.DemoRTheta(5302): ::onDraw:time1,time2, (time1-time2) = 63,35,28
INFO/demo.theta.DemoRTheta(5302): ::onDraw:time1,time2, (time1-time2) = 61,35,26
INFO/demo.theta.DemoRTheta(5302): ::onDraw:time1,time2, (time1-time2) = 59,35,24
INFO/demo.theta.DemoRTheta(5302): ::onDraw:time1,time2, (time1-time2) = 68,40,28
INFO/demo.theta.DemoRTheta(5302): ::onDraw:time1,time2, (time1-time2) = 75,32,43
INFO/demo.theta.DemoRTheta(5302): ::onDraw:time1,time2, (time1-time2) = 65,32,33
INFO/demo.theta.DemoRTheta(5302): ::onDraw:time1,time2, (time1-time2) = 52,36,16

Here you have expresions for other above graphs.

float radian = (float) (Math.PI*i/180.0f);

float radius = width;

float radius = (float) (width*Math.cos(4*radian));

float radius = (float) (0.875f*width+0.125f*width*Math.cos(12*radian));

But Option 2 needs some extra calculation to translate (r , θ) into (x, y), in above examples we needed to determine only center of the circle.
Let see some of the view as follows.

canvas.save();
canvas.translate(width, height);
for(int i = 0 ; i < 72;i++){
canvas.drawLine(width*0.8F, 0, width*1.0f, 0, paint);
canvas.rotate(5);
}
canvas.restore();

Now we have to find start x,y and end x,y that need extra calculation and extra analysis effect to come up with that expresion.
Next one is more interesting need to use Path.

canvas.save();
canvas.translate(width, height);
for(int i = 0 ; i < 18;i++){
Path path = new Path();
path.moveTo(width*0.8F, 0);
path.lineTo(width, width*0.1F);
path.lineTo(width, -width*0.1F);
path.lineTo(width*0.8F, 0);
canvas.drawPath(path, paint);
canvas.rotate(20);
}
canvas.restore();

Now you can find translation expression and can find out which one is faster in each cases.
Enjoy!

Grid, Adaptor, left to right into top to bottom

2011-09-27T08:45:00.000-07:00

Say we have list of object as follows,

list =

.size() = 14

and need to show it in grid control that scroll vertically as follows,

// assume we want three columns.

int columns = 3;

// first calculate number of rows.

int rows = (columns-1+list.size())/columns;

Or into grid control that scroll horizontally as follows,

//assume we want three rows.

int rows = 3;

// first calculate number of rows.

int columns = (rows-1+list.size())/rows;

Mostly we use adaptor to fetch the item to show in each cell.

In this case adaptor can choose the index equal to position,

int index = position;

return list.get(index);

But say some cases we may have to change to order in display. for example. top to bottom as shown below:

But if the control fetch base on position from left to right as show below:

then, we need to add proper calculation inside the adaptor:

int index =position/columns+position%columns*rows;
return list.get(index);

Android: Aligning Custom Views at Base Line

2011-09-15T06:11:00.000-07:00

Have you ever try to align a non-symmetric custom view at a custom base line as follows?

I tried it using base line attribute of Relative Layout.

First adjust the size of view:

@Override

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

super.onMeasure(widthMeasureSpec, heightMeasureSpec);

//Height should be always width * 7 / 12

setMeasuredDimension(getMeasuredWidth(), getMeasuredWidth()*7/12);

}

Then Override the getBaseLine method:

@Override

public int getBaseline() {

//base line is from bottom to width/12 (radius of the blue circle)

return getMeasuredHeight()-getMeasuredWidth()/12;

}

Following onDraw method would explain the reason for the above calculation:

@Override

protected void onDraw(Canvas canvas) {

Paint paint = new Paint();

paint.setAntiAlias(true);

//Draw the half circle

paint.setColor(Color.GRAY);

float width = getWidth();

float height = getHeight();

canvas.save();

canvas.translate(width/2, height-width/12);

canvas.drawArc(new RectF(-width/3, -width/3, +width/3, width/3), 0, -180, true, paint);

//Draw small circles

paint.setColor(Color.DKGRAY);

RectF rectF = new RectF(-width/2+width/24, -width/12+width/24, -width/3-width/24, +width/12-width/24);

canvas.drawOval(rectF, paint);

for(int i = 0 ; i < 15 ;i++){

canvas.rotate(12f);

canvas.drawOval(rectF, paint);

}

//Draw blue circle

paint.setColor(Color.BLUE);

canvas.rotate(-180+30);

canvas.drawOval(new RectF(-width/2, -width/12, -width/3, +width/12), paint);

//Draw red arrow

paint.setColor(Color.RED);

Path path = new Path();

path.moveTo(-width*5/12, 0);

path.lineTo(10, -width/12);

path.lineTo(0, 0);

path.lineTo(10, +width/12);

path.close();

canvas.drawPath(path, paint);

canvas.restore();

}

Finally, create a layout xml as following:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<demo.ui.testing.DemoUITesting
android:layout_height="fill_parent" android:layout_width="fill_parent"
android:layout_alignBaseline="@+id/radioButton1"
android:layout_toRightOf="@+id/radioButton1">
<RadioButton android:layout_width="wrap_content"
android:layout_height="wrap_content" android:id="@+id/radioButton1"
android:layout_centerVertical="true">
</RelativeLayout>

Enjoy!.