Posts Tagged ‘Android Programming’
Android: Changing image color saturation
Posted by Dimitri | Filed under Programming
It’s the 100th post on 41 Post! This Android programming tutorial shows how to control the color saturation of an image using a SeekBar. The code featured in this post has been tested at an emulated and on a real device both running Android 2.1 . An example project with the code featured below is available at the end of the post.
As previously described, a SeekBar is going to be used to control the saturation of an Bitmap object that is rendered at the screen using a ImageView. Since a screenshot is far more descriptive then trying to explain how the application user interface will end up looking like, here’s a screenshot: (more…)
Android: how to rotate a View element
Posted by Dimitri | Filed under Featured, Programming
Another Android programming tutorial, this time, explaining how to rotate a View element using two distinct approaches. Not only that, but this post also presents a brief explanation on the advantages and disadvantages of each approach. The code featured here has been tested on both the emulator and on a real device running Android 2.1 . Before going any further, please bear in mind that from Android 3.0 (API level 11), a setRotation() method has been added to the View class, therefore, it should be used instead of the code described in this article, which focuses on lower level APIs.
The first and perhaps most direct method of rotating a View element is to create a class that inherits from a View widget that needs to be rotated, for example, the TextView or the Button. Then, inside this class, the onDraw() method must be overridden. (more…)
Android: rendering a path with a Bitmap fill
Posted by Dimitri | Filed under Programming
This Android tutorial shows how to render a Path that is filled by a Bitmap and displays stroke in a different color. It also explains how to manipulate the texture coordinates to make it independent of the position of the path, just like a mask, but without using any of the PorterDuff rendering modes. The code featured in this code was created and tested on Android 2.1, both on a real and at an emulated device.
Here’s a video of the example application in action:
If you can’t play the video, don’t worry: there is a screenshot of the application at the bottom of this post.
Android: Creating a two color LED notification
Posted by Dimitri | Filed under Featured, Programming
Another programming tutorial, this time, showing how to make the built-in notification LED on a Android device continuously alternate between two colors. That said, by the time this article is being written, it’s recommended to try this code on a real Android device that has a notification LED instead of running the application on the emulator. Also, the Activity featured below has been created to work on devices with Android 2.0 or later. All code featured in this article is available for download at the end of the post.
To continuously change the colors of the LED, it’s necessary to create and initialize a Notification object that changes the LED colors and post this notification using a handle to the system’s notification service (using a instance of the NotificationManager class). The notification is then canceled, its LED color is changed and the notification is posted again and the process is repeated over and over making the colors swap back and forth. (more…)
Android: Obtaining the current orientation using a BroadcastReceiver
Posted by Dimitri | Filed under Programming
This Android tutorial explains how to create a Broadcast Receiver that detects screen orientation changes that are triggered by rotating the device. Since screen orientation changes don’t happen every second, it’s better to detect it using a BroadcastReceiver instead of a Service. Both can be used to execute tasks on the background, but the BroadcastReceiver execution will be triggered only when the desired Intent is filtered (in this case, a screen orientation change). Right after the execution, the background task is killed, which is ideal since a BroadcastReceiver can be created to obtain the new screen orientation only after it has changed.