Learning

Deploying a Spree application on Heroku

2013-01-01T00:08:00.002-08:00

Heroku is a no-hassle hosting solution for Ruby, Node.js, Clojure, Java, Python, and Scala. It helps the developers to focus on the most important thing i.e creating the most amazing web app ever and forget about servers. Your application can be up and running in minutes. All you need to do is create an app on their servers and then push your code to it using git. They provide a handy utility

Creating a Spree application

2012-12-30T06:47:00.002-08:00

Spree is an open source e-commerce platform that is available as a ruby gem for Ruby on Rails framework. It is intended as a foundation over which developers can build their own e-commerce sites. Prerequisites To use Spree you will need to install following: ruby imagemagick nodejs libxml2 libxml2-dev libssl-dev libxslt-dev postgresql postgresql-server-dev-9.1 If you are using Ubuntu, you

Git: Beware of detached head

2012-12-07T03:04:00.000-08:00

In git, every commit is recognized by a 40-character hash known as commit hash. A git repository is essentially a tree of commits, where each commit points to its ancestor(s). In git, a branch head is the last commit in the branch. A Git branch is simply a pointer to this commit, using its commit hash, in the repository. These pointers are kept in .git/refs/heads directory as files. If you look

Its a free world

2012-11-20T02:23:00.004-08:00

Disclaimer: I am not a web developer. Although I am a CS grad and understand all the concepts involved and have worked on a few websites in my unversity days and little afterwards, but I am not employed as a webdeveloper and am out of touch with this subject and the technologies and services involved. Recently, while working on an eCommerce website for a friend, I came across some amazing

Thank you MIT and Prof. Alan V. Oppenheim

2012-07-19T01:06:00.002-07:00

Recently I needed a refresher in Signals and Systems and luckily I found lecture videos for Signals and Systems by Prof Alan V. Oppenheim from MIT OCW website. Although I have studied Signals and Systems TWICE at the university, I have never understood the concepts the way I do now. These lectures have given me the ability to analytically understand the concepts and have enabled me to create a

How to unblock the Internet (anonymous browsing)

2012-05-16T03:45:00.000-07:00

I am tired of organizations trying to stop their employees from accessing sites like Facebook, MySpace, linkedin and even blogspot and lots of other websites that contain useful work related information. If someone is going to waste time while on job, they will find other ways to do so. Blocking these websites wont change a thing. If you happen to work in such an organization or if you just want

My Kindle Fire with Cyanogenmod 7

2012-04-06T00:11:00.000-07:00

I just installed Cyanogenmod 7 on my Kindle Fire. It took some time to get things right but it looks awesome now. I was really getting tired of Amazon not allowing me to install even free apps. Waiting for Cyanogenmod 9 AKA Ice Cream Sandwich for Kindle Fire :D

C Language: Struct packing and member alignment.

2012-02-21T04:08:00.000-08:00

I know this has been discussed and re-discussed at so many locations and so many times that me writing about it again wont make much of a difference but I still see so many people confused about this that I cant stop my self from writing about it. By default C compilers properly align each member of struct. This means that a 2-byte member e.g. short is aligned on 2-byte boundary, a 4-byte member

Android: How to start vendor specific Alarm Clock on any Android device?

2012-02-16T23:32:00.000-08:00

Alarm clock is a nice to have feature for many applications and because of Intents you dont need to code this functionality in every app where you want it. For Android, adding an Alarm Clock to your application is as simple as launching an Intent for the built-in Alarm Clock of the device. The only issue here is that different manufacturers i.e HTC, Google, Samsung, Sony Ericson have their own

Android: How to transform/scale a bitmap and draw it on Canvas without losing quality

2012-02-09T05:35:00.000-08:00

If you want to rotate a bitmap and paint it on a Canvas in an Android app, you will probably use Canvas.rotate(degrees) to rotate the canvas and then paint your bitmap using any of Canvas.drawBitmap methods. Nothing fancy but the painted image will be too pixelated - except when the rotation is in multiple of 90 degrees. The last argument to all Canvas.drawBitmap* methods is a Paint object and

Android: Debugging your application on real hardware (phone/tablet) on Ubuntu 10.10

2011-12-17T06:28:00.000-08:00

If you own an Android smartphone and want to debug your application on your smartphone instead of emulator, you need to declare your application debuggable and setup your device. To declare your application debuggable, add android:debuggable="true" to element in your application's AndroidManifest.xml To setup your device, connect it to your computer with a usb cable and run following command:

Android: How to start MusicPlayer without specifying any music file

2011-08-31T07:02:00.000-07:00

Recently I needed to launch standard MusicPlayer from withing my app but without specifying any media file. The requirement was to show the MusicPlayer but not to play anything by default. User can then browse their music file and play any music they want, just as they would do if they launched the music player from home screen. There are many resources on the web which discuss how to play

Android: How to install and uninstall an apk to Android Emulator from Ubuntu

2011-07-06T00:57:00.000-07:00

Android emulator that is installed with the SDK does not have Android Market installed. So you can not install apps from the market. But if you can find the .apk file for the app that you are looking for you can still install it. Recently I needed to install Zxing Barcode Scanner app to emulator so that I can use barcode scanning in my app. Zxing's website provides the apk for most recent

DON'T hide pointers

2011-05-23T05:53:00.000-07:00

I have seen alot of code where typedefs are used to create pointer types like: typedef unsigned char *Message;Some people might think that this is a very good thing to do or that it serves some (obscure) purpose but in my opinion such typedefs are plain wrong and evil. They cause alot of errors. Why would a sane person want to hide the fact that a variable of type Message is actually a pointer?

Android: Display a Title on a Location Marker (an OverlayItem) in Android MapView

2011-05-22T12:55:00.000-07:00

I recently needed to display a title over a location marker in Android MapView. I was realy surprised to find out that there is no direct functionality available for doing this. Although the second argument in OverlayItem's constructor is Title and one would think that there must be some way to display this text as title over the marker but strangely there isnt. Anyway, if you are trying to do

VPTCL Wireless: Connect to internet using VPTCL from Ubuntu 10.04

2011-05-21T11:35:00.000-07:00

PTCL DSL is great. Its cheap and offers good (reasonable) speed. But PTCL landlines are very untrustworthy and you never know when it will stop working. So I keep VPTCL as my backup internet connection. It is not fast but it works and has almost no down time. PTCL provides drivers and documentation for connecting to internet with VPTCL but everything is for Windows. So you are at loss if you are

Android: "Application not installed" error when trying to install an app from sdcard

2011-05-06T04:13:00.000-07:00

When programming for Android using Eclipse + ADT plugin, whenever you build your app, your application's installable file (.apk) is created in Bin directory under the project folder. This apk file can be used to test your application on any Android device. Recently when I wanted to test my app, I decided to use the export wizard to export an apk file instead of using the one created in Bin

How to enable ARM1136JFS (ARM v6) MMU to have one to one mapping between physical and virtual address space?

2011-05-06T04:05:00.001-07:00

Sometime ago I wanted to enable L2 cache on an ARM1136-JFS based processor. The problem with this ARM core is that you cant enable L2 cache without enabling MMU and enabling MMU means to have a physical to virtual address mapping. But I didnt need any virtual memory and only wanted to enable L2 cache. The only way that I could think of was to create a one-to-one physical-to-virtual address

Android: How to sign your application

2011-05-02T02:16:00.000-07:00

If you want to install and run your Android app on your phone or if you want to market it, you need to sign your app. Signing apps helps prevent the user from fraudulent apps. Signing your app is simple and can be done with standard tools i.e keytool and jarsigner that come with a Java JDK. To sign your app first generate a valid key. You can use the following command for that purpose: keytool

Android Tabbed Layout with single activity.

2011-04-30T13:37:00.000-07:00

In Android, the content for each tab in a Tab Layout can be implemented in one of two ways: 1. Use tabs to switch views within the same activity.2. Use tabs to switch between different activities.The tutorial in the Android documentation shows how to do it the 2nd way i.e use tabs to switch between activities but I couldnt find a reasonable example of the first case so I have created one and the

Install Firefox 4 in Ubuntu

2011-03-29T02:16:00.000-07:00

Firefox 4 is available for Ubuntu 10.04 and 10.10. To install it use the following commands sudo add-apt-repository ppa:mozillateam/firefox-stable sudo apt-get update sudo apt-get upgrade This will update your Firefox to version 4. Note that this will not install Firefox 4 side by side with your previous version as used to be the case with beta versions. As this installs the stable release

git bare repos

2011-03-01T07:28:00.000-08:00

A normal git repository is a directory that contains: Our files: Files and directories that we have created and which contain our data. These files and directories are collectively known as working tree. .git directory: This folder contains all of the Git's control files. A bare git repository does not have working tree and it also does not have .git directory either. All of the Git's control and

5 useful Grep options that you must know

2011-02-24T01:55:00.000-08:00

Grep is a very handy utility for searching for a pattern in files. While it has many options, every grep user should at-least know the following five options -R, -r, --recursive This option makes grep search all the files in the specified directory and its sub-directories, recursively. This specifically comes in handy for programmers when they are looking for the declaration or all uses of some

OpenSUSE: turn firewall off

2011-02-10T01:32:00.000-08:00

To disable the firewall on OpenSUSE use the following command as root user: /sbin/SuSEfirewall2 offTo turn it back on use: /sbin/SuSEfirewall2 on

Remove envelope icon from Indicator Applet

2011-01-30T01:50:00.000-08:00

The envelope icon in Indicator Applet really annoys me. It unnecessarily increases the number of clicks needed to open an application like Empathy or Pidgin. To remove that icon uninstall the indicator-messages package using following command: sudo apt-get remove indicator-messagesThis makes that envelope icon disappear and applications start appearing in Notification Area.