继承ImageView在上面画圆

public class CustomView extends ImageView{?public CustomView(Context context, AttributeSet attrs, int defStyle) {?? ? super(context, attrs, defStyle);?}?public CustomView(Context context, AttributeSet attrs) {?? ? super(context, attrs);?}?public CustomView(Context context) {?? ? super(context);?}?boolean drawGlow = false;?//this is the pixel coordinates of the screen?float glowX = 0;?float glowY = 0;?//this is the radius of the circle we are drawing?float radius = 20;?//this is the paint object which specifies the color and alpha level ?//of the circle we draw?Paint paint = new Paint();?{?? ? paint.setAntiAlias(true);?? ? paint.setColor(Color.WHITE);?? ? paint.setAlpha(50);?};??@Override?public void draw(Canvas canvas){?? ? super.draw(canvas);?? ? if(drawGlow)?? ? ? ? canvas.drawCircle(glowX, glowY, radius, paint);?}?@Override?public boolean onTouchEvent(MotionEvent event){?? ? if(event.getAction() == MotionEvent.ACTION_DOWN){?? ? ? ? drawGlow = true;?? ? }else if(event.getAction() == MotionEvent.ACTION_UP)?? ? ? ? drawGlow = false;??? ? glowX = event.getX();?? ? glowY = event.getY();?? ? this.invalidate();?? ? return true;?}?

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上面的CustomView你也可以在xml中引用只是你需要加包名

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