Posts Tagged ‘Android Programming’
Android: reading float values from a XML file
Posted by Dimitri | Filed under Programming
When programming an Android app, data such as integers, drawables and strings can be loaded from XML files through the Resources class, using their automatically generated IDs. But a float can’t be placed in these XML files, since the Resources class won’t generate IDs for it. This post will focus on explaining how to load a float, and some other values from a customized XML file. All code featured in this tutorial is available at the end of the post.
It’s worth mentioning that this example uses the XmlResourceParser class (a XML pull parser) to read the contents from a XML file. This is just one of the three available methods of retrieving the contents of a XML file in Android. That being said, the first thing we are going to need is the XML file. (more…)
Android: changing the ringer volume
Posted by Dimitri | Filed under Programming
Another Android tutorial, this time, explaining how to change the different sound volumes of the Android system, such as the ringer, music and notification loudness. The source code featured below is available for download at the end of the post.
Using a seek bar to control audio’s volume in Android is a lot like changing the screen brightness with a seek bar. However, instead of using a ContentResolver to obtain the service that controls the audio, Android has a class that makes everything easier, named AudioManager. So, the example here will basically obtain a reference to the AudioManager and will use it to get the current ringer volume and use it to set the progress of a seek bar. When changed, the seek bar progress will set the value of the sound volume. Here is the code: (more…)
Android: Loading files from the Assets and Raw folders
Posted by Dimitri | Filed under Programming
This tutorial will explain how to load files from the res/raw and the Assets folder using a String to specify the file name. Yes, there are a lot of tutorials on this subject, but they all use the automatically generated integer IDs from the R class as inputs and not many of them even mention the possibility of loading files from the Assets folder. As a result of depending on the ID, the file reference must be known beforehand.
Instead, the code featured in this post will explain how to find the reference to the file and then load it at runtime based solely on its name. This means that the reference ID and the file don’t even have to exist in the first place, and can be acquired at run time.
Android: take a picture without displaying a preview
Posted by Dimitri | Filed under Programming
Accessing hardware functionality when programming for an Android device is generally quite straightforward. The same can be said about writing an Activity that takes a picture, but Android requires a preview of what the camera will capture to be displayed prior to capturing an image. This post explains how to “cheat” this requirement imposed by the OS, and how to write an application that takes a picture and displays it.
An Eclipse project with all the code explained here is available for download at the end of the post.
Before going into the Activity code, the interface layout (the main.xml file) must be edited to add a Surface View and an Image View to the interface. To add an element, just drag and drop it from the list inside your layout, like this: (more…)
Android: Acessing the gyroscope sensor for simple applications
Posted by Dimitri | Filed under Programming
This post explains how to get values from the gyroscope (or any sensor that returns the device’s relative angle) to create simple application. The reason why I’m stating ‘for simple applications’ is because the code featured here is already deprecated. I’m just explaining how to do it because it still works, and it’s very clean and short to explain, as opposed to the new method, which is much more accurate but more complex to implement.
Still, it’s possible to use it for simple applications, although, if the application requires accuracy from the sensors, such as augmented reality applications or even games, it’s recommended to use the getRotationMatrix() method from the Sensor Manger class instead.
With that said, the following code just prints the rotation values from the gyroscope on the screen: (more…)