AlphaImageButton - auto shows disabled state on an ImageButton.

AlphaImageButton.java

import android.content.Context;
import android.util.AttributeSet;
import android.widget.ImageButton;

public class AlphaImageButton extends ImageButton {

    private static final float ENABLED_ALPHA = 1.0f;
    private static final float DISABLED_ALPHA = 0.5f;

    public AlphaImageButton(Context context) {
        super(context);
    }

    public AlphaImageButton(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public AlphaImageButton(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    public void setEnabled(boolean enabled) {
        super.setEnabled(enabled);
        setAlpha((enabled ? ENABLED_ALPHA : DISABLED_ALPHA));
    }
}