Android Tutorial - Android Image Resources

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Android generates resource IDs for image files placed in the /res/drawable subdirectory.

The supported image types include .gif, .jpg, and .png. Each image file in this directory generates a unique ID from its base file name.

If the image file name is sample_image.jpg, then the resource ID generated is R.drawable.sample_image.

You will get an error for two file names with the same base file name. The subdirectories underneath /res/drawable are ignored.

Example

The following code shows how to use the image resource in XML layout definitions.

<Button
      android:id="@+id/button1"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:text="Dial"
      android:background="@drawable/sample_image"
/>

The following code shows how to retrieve an image in Java and set it to a UI object like a button.

BitmapDrawable d = activity.getResources().getDrawable(R.drawable.sample_image);
button.setBackgroundDrawable(d);

//or you can set the background directly from the Resource Id
button.setBackgroundResource(R.drawable.sample_image);

Android also supports a special type of image called a stretchable image.

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