Need the image id from xml attributes custom widget

Question

I have a custom control (very simple for now) that is like a button. It needs to display an unpressed and a pressed image. It appears multiple times in the activity and has different pairs of images depending on where it's used. Think of toolbar icons - similar to that.

Here's an extract of my layout:

<TableLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:MyApp="http://schemas.android.com/apk/res/com.example.mockup"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent" >

  <TableRow>
    <com.example.mockup.ImageGestureButton
      android:id="@+id/parent_arrow"
      android:src="@drawable/parent_arrow"
      MyApp:srcPressed="@drawable/parent_arrow_pressed"
      ... />
     ...
  </TableRow>
</TableLayout>

attrs.xml:

<?xml version="1.0" encoding="utf-8"?> 
<resources> 
    <declare-styleable name="ImageGestureButton"> 
        <attr name="srcPressed" format="reference" /> 
    </declare-styleable> 
</resources> 

And, in the R.java, one finds:

public static final class drawable {
    public static final int parent_arrow=0x7f020003;
    public static final int parent_arrow_pressed=0x7f020004;
    ...
}

During widget instantiation, I want to determine the ids declared in the activity xml. How do I do that? I've tried this (I updated my original post with working code; so, the following works.)

public class ImageGestureButton extends ImageView
   implements View.OnTouchListener
{
  private Drawable unpressedImage;
  private Drawable pressedImage;

  public ImageGestureButton (Context context, AttributeSet attrs)
  {
    super(context, attrs);
    setOnTouchListener (this);

    unpressedImage = getDrawable();

    TypedArray a = context.obtainStyledAttributes (attrs, R.styleable.ImageGestureButton, 0, 0);
    pressedImage = a.getDrawable (R.styleable.ImageGestureButton_srcPressed);
  }

  public boolean onTouch (View v, MotionEvent e)
  {
    if (e.getAction() == MotionEvent.ACTION_DOWN)
    {
      setImageDrawable (pressedImage);
    }
    else if (e.getAction() == MotionEvent.ACTION_UP)
    {
      setImageDrawable (unpressedImage);
    }

    return false;
  }
}

Answer 1

If you want to get the drawable use TypedArray.getDrawable(). In your example you are using getString().

In your declare-styleable use

   <attr name="srcPressed" format="reference" /> 

Answer 2

If you want the actual resource ID for the Drawable, rather than the fully resolved Drawable it's self, you can do this:

TypedArray a = context.obtainStyledAttributes( attrs, R.styleable.FooLayout );
TypedValue value = new TypedValue();
a.getValue( R.styleable.FooLayout_some_attr, value );
Log.d( "DEBUG", "This is the actual resource ID: " + value.resourceId );