How to highlight ImageView when focused or clicked?

If you don't have another drawable for the pressed state you can use setColorFilterto achieve a simple tint effect.

It behaves just like pressed state selector so when the image is pressed it changes the background to light grey color.

final ImageView image = (ImageView) findViewById(R.id.my_image);
image.setOnTouchListener(new View.OnTouchListener() {
        private Rect rect;

        @Override
        public boolean onTouch(View v, MotionEvent event) {
            if(event.getAction() == MotionEvent.ACTION_DOWN){
                image.setColorFilter(Color.argb(50, 0, 0, 0));
                rect = new Rect(v.getLeft(), v.getTop(), v.getRight(), v.getBottom());
            }
            if(event.getAction() == MotionEvent.ACTION_UP){
                image.setColorFilter(Color.argb(0, 0, 0, 0));
            }
            if(event.getAction() == MotionEvent.ACTION_MOVE){
                if(!rect.contains(v.getLeft() + (int) event.getX(), v.getTop() + (int) event.getY())){
                    image.setColorFilter(Color.argb(0, 0, 0, 0));
                } 
            }
            return false;
        }
    });

It handles moving finger outside the view boundaries, thus if it occurs, it restores a default background.

It's important to return false from onTouch method when you want to support onClickListner too.

Use selectableItemBackground as a background:

android:background="?android:attr/selectableItemBackground"

You need to assign the src attribute of the ImageView a state list drawable. In other words, that state list would have a different image for selected, pressed, not selected, etc. - that's how the Twitter App does it.

So if you had an ImageView:

<ImageView style="@style/TitleBarLogo"
            android:contentDescription="@string/description_logo"
            android:src="@drawable/title_logo" />

The src drawable (title_logo.xml) would look like this:

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_focused="true" android:state_pressed="true" android:drawable="@drawable/title_logo_pressed"/>
    <item android:state_focused="false" android:state_pressed="true" android:drawable="@drawable/title_logo_pressed"/>
    <item android:state_focused="true" android:drawable="@drawable/title_logo_selected"/>
    <item android:state_focused="false" android:state_pressed="false" android:drawable="@drawable/title_logo_default"/>
</selector>

The Google IO Schedule app has a good example of this.