Posts Tagged ‘Android Programming’
Android: Initialize View child class object from a XML file
Posted by Dimitri | Filed under Programming
This tutorial shows how to inherit from the View class to create your own customized View element, and how to initialize an object from this child class with parameters defined at a layout XML file. There are two major advantages in this approach over initializing the extended View object at the Activity.
The first is that the Java part of your code remains clean, without a lot of member variable assignments to set the View’s basic parameters. The second and most important, is the possibility to instantly preview the changes at the Graphical Layout tool in Eclipse without the need to execute the application. This means that the space this customized View element takes on the screen can be immediately be seen and adjusted, if necessary.
Android: Bitmap to Integer array
Posted by Dimitri | Filed under Programming
As stated in the title, this post explains how to generate an Integer pixel array from a Bitmap object, that will hold the color information from each pixel of the image. This post also explains the opposite: creating a Bitmap object from an Integer array. This can be useful when one needs to apply effects to Bitmap instances. As usual, an example Eclipse project is available for download at the end of this post. It works both on the emulator and on physical devices running Android 2.0.
So, let’s get to the code. Putting it in a simplified manner, the below Activity decodes a PNG image into a Bitmap object, then, an array is created with the same number of pixels as the image. After that, a method from the Bitmap instance puts the pixel color information in the array. (more…)
Android: obtaining SD card memory information
Posted by Dimitri | Filed under Programming
This Android tutorial explains how to obtain the primary external storage (normally, the SD card) information, such as the total available space and how much memory it has left to be consumed by applications and data. Fortunately, this is a short and simple code, that can be used to create file explorer app, or to check if the SD card has enough space to copy data into the external storage. An example Eclipse project with the source code is available for download at the end of the post. It requires Android 2.1 (Eclair) and works both on a real and emulated devices.
In simple terms, the code below checks for a connected SD card, by querying its state. If a external device was found, it then obtains the external memory’s total and available sizes, returning the values in GB, MB, KB and bytes: (more…)
Android: Disabling anti-aliasing for pixel art
Posted by Dimitri | Filed under Programming
Android is great when it comes to displaying scaled pictures in applications and games since it tries to interpolate the pixels, making the resulting image look as good as possible. That works for almost every case, however, what about pixel art? This behavior isn’t good for that because, after scaling it, the resulting image will be “smoothed out”, invalidating the handcrafted pixel placement.
There are two options in this case: use an image with the correct size and never scale it, or try to disable anything that could be aliasing the image. This post is going to describe how to do the latter. As usual, an example project is available for download at the end of the post. (more…)
Android: Detecting Double Tap Events
Posted by Dimitri | Filed under Featured, Programming
This Android tutorial explains how to create an Activity that “listens” to double tap events. Doing that isn’t as trivial as getting a single tap from the screen, however writing a code that registers when the screen has been touched twice isn’t complex either. The example featured in this post works on the emulator and on a real Android device.
To implement the double tap, some classes and interfaces are going to be needed, but it’s best to show the example Activity code before explaining each one of them: (more…)