glow when touch the screen in android?

问题

when i touch whereever in the screen that point will be glow(nothing but like a flash or glittering) for some time. how to do that? any example or idea?? i have to implement to put buttons on it. exactly when i touch the screen it will glow some time and then the button will appear on the point where i touched.

回答1:

Your going to have to create a custom view and override ontouchevent and draw. Here's a very simple example. you can reference a custom view in an xml layout if you use the package name i.e. com.test.CustomView.

 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;
    }
}   

来源：https://stackoverflow.com/questions/2529481/glow-when-touch-the-screen-in-android