Invert image color on click [Android]

Question

I'm trying to do something like android default alarm clock app. When you click on the clock the icon turns black.

I have seen that there is only one clock image on android, ic_lock_idle_alarm. Then I think that android invert image programmatically.

I don't know how I could to do that.

I tried to set the invert image, created by photoshop with setBackgroundResource but the "black image" overlaps white image.

Otherwise I don't know which is the best approach.

Some advices? :-)

Answer 1

The Android default alarm clock app does not actually use ic_lock_idle_alarm but instead two PNG images from within the app, namely ic_clock_alarm_on (the normal icon) and ic_clock_alarm_selected (the black version). The black version is activated using android:state_pressed="true" android:state_window_focused="true" in a Drawable State List . This is also how I would recommend you to do it since it is for use cases like this Drawable State Lists exist, and since it is much easier than to do it programmatically.