Android Performance Tuning Exercise: Over-drawing

Exercise:https://github.com/zhangbz/AndroidUIPorblems

View over drawing

Turn on "Debug GPU over Drawing" in developer options

Judging criteria

Colorless: Not over-drawn, that is, only once

Blue: one-times over-drawn

Green: Twice times over-drawn

Light red: three times times over-drawn

Red: four times times or more over-drawn

Practice

Where "This is Test" four times or more multiples of the drawing, its background three times times, Button twice times, the text button in three times times, the background one times.

Mainactivity optimization

First analyze the layout file, found that nested linearlayout set the same background color as the parent linearlaytout, so delete its background color settings, the effect is as follows

Then, due to some themes from Android, window will be added by default to a solid color background, because the activity interface has a background full of the screen, so we can get rid of the activity's default drawing, in Mainactivity's OnCreate () method to modify the code.

  protected void OnCreate (Bundle savedinstancestate) {        super.oncreate (savedinstancestate);        Setcontentview (r.layout.activity_main);        GetWindow (). setbackgrounddrawable (null);//new Code        //...    }

The effect is as follows:

At this point, the page is eliminated by over three times times and over-drawn.

Overdrawview optimization

The original implementation method is as follows, due to the overlay of the graphics drawn in the OnDraw () method, resulting in over-rendering

@Override    protected void OnDraw (canvas canvas) {        super.ondraw (canvas);        int width = getwidth ();        int height = getheight ();        Mpaint.setcolor (Color.gray);        Canvas.drawrect (0, 0, width, height, mpaint);        Mpaint.setcolor (Color.cyan);        Canvas.drawrect (0, HEIGHT/4, width, height, mpaint);        Mpaint.setcolor (Color.dkgray);        Canvas.drawrect (0, HEIGHT/3, width, height, mpaint);        Mpaint.setcolor (Color.ltgray);        Canvas.drawrect (0, HEIGHT/2, width, height, mpaint);    }

Modify the code to avoid overwriting each other

    @Override    protected void OnDraw (canvas canvas) {        super.ondraw (canvas);        int width = getwidth ();        int height = getheight ();        Mpaint.setcolor (Color.gray);        Canvas.drawrect (0, 0, width, HEIGHT/4, mpaint);        Mpaint.setcolor (Color.cyan);        Canvas.drawrect (0, HEIGHT/4, width, HEIGHT/3, mpaint);        Mpaint.setcolor (Color.dkgray);        Canvas.drawrect (0, HEIGHT/3, width, HEIGHT/2, mpaint);        Mpaint.setcolor (Color.ltgray);        Canvas.drawrect (0, HEIGHT/2, width, height, mpaint);    }

Optimization effect

Busyondraw optimization

There is a noticeable lag when clicking the button, which can be judged from the following code, which should be caused by the time-consuming operation in the OnDraw () method

@Override    protected void OnDraw (canvas canvas) {        super.ondraw (canvas);        for (int i = 0; i < i++) {            System.out.println ("canvas = [" + Canvas + "]" + i);        }        Paint paint = new paint ();        Paint.setcolor (color.red);        Paint.setstyle (Paint.Style.STROKE);        Paint.setstrokewidth (4);        int radius = math.min (GetWidth (), getheight ())/2;        Canvas.drawcircle (GetWidth ()/2, GetHeight ()/2, radius, paint);    }

Optimization scenario: Move time-consuming operations into child threads

  New Thread (New Runnable () {            @Override public            void Run () {for                (int i = 0; i <; i++) {                    SYSTEM.O UT.PRINTLN ("canvas = [" + Canvas + "]" + i);}}        ). Start ();

Android Performance Tuning Exercise: Over-drawing