Overall understanding of Android touch event processing, android touch

Overall understanding of Android touch event processing, android touch

First look at several functions:When talking about Android touch event processing, many people will immediately think of some troublesome functions. Here we will list them to stimulate your little nerves:

    @Override    public boolean onTouchEvent(MotionEvent event) {        return super.onTouchEvent(event);    }    @Override    public boolean dispatchTouchEvent(MotionEvent ev) {        return super.dispatchTouchEvent(ev);    }    @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        return super.onInterceptTouchEvent(ev);    }    @Override    public boolean onTouch(View v, MotionEvent event) {        return false;    }

Well, today, let's take a look at the functions of these four functions and their call relationships to clarify the touch event processing mechanism.

I. Let's take two of them first:

    @Override    public boolean onTouchEvent(MotionEvent event) {        return super.onTouchEvent(event);    }    @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        return super.onInterceptTouchEvent(ev);    }

1.1 first, it is clear that Android event distribution and processing areTop-downThe first time a touch event is sent to the View on the outermost layer.
1.2 here is an example: we assume that multiple viewgroups in a window form a big family, with the maximum number of views on the outermost layer and the minimum number of views on the innermost layer, then, compare a touch event to an apple event. If an event (an apple is obtained) occurs, the following will happen:

Apple's transfer process:

Grandpa --> dad --> Sun Tzu.

If Grandpa eats the apple, we say the event was consumed.

See:

Further detailed analysis:

So far, is there a general grasp of the message transmission mechanism in Android,
Next, let's clarify some details.