画圆不用切换activity？

Question

所以，我有一个应用程序，在主 activity（主屏幕）上有一张地图（一个 jpg 文件）。

现在我想在这张地图上画一个圆圈，因为用户会搜索一个位置，然后，我想用一个圆圈标记这个位置，请问如何实现？

我已经试过了：

    @Override
protected void onDraw(Canvas canvas) {
    // TODO Auto-generated method stub
    super.onDraw(canvas);

    paint.setStyle(Paint.Style.STROKE);
    canvas.drawCircle(50, 50, 30, paint);
}

在我的 DrawDis class 和我的主要 activity class 中，我得到了这个：

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //setContentView(R.layout.activity_main);


    //RelativeLayout relativeLayout = new RelativeLayout(this);
    //relativeLayout.setLayoutParams(new RelativeLayout.LayoutParams(
            //ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));

    //setContentView(relativeLayout);

    //relativeLayout.addView(new DrawDis(this));
}

我知道创建新布局会改变整个屏幕，但我应该如何在不改变的情况下只绘制到屏幕上？activity？

Answer 1

下面的代码片段将在用户触摸图像的任何地方绘制一个圆圈。

另见 link

image.setOnTouchListener(new OnTouchListener() {
        public boolean onTouch(View arg0, MotionEvent arg1) {
            System.out.println("Touch recieved at "+arg1.getX() + " " + arg1.getY());
            touchX = (arg1.getX());
            touchY = (arg1.getY());

            System.out.println("Touch recieved at "+touchX + " " + touchY);
            image.setImageBitmap(createImage());

            return true;
        }
    });


public Bitmap createImage(){
        Bitmap image = bmp.copy(Bitmap.Config.RGB_565, true);
        Canvas canvas = new Canvas(image);
        Paint paint = new Paint();
        paint.setStyle(Paint.Style.STROKE);
        paint.setColor(Color.GREEN);


         touchX=touchX- image.getWidth() / 2;
         touchY=touchY- image.getHeight() / 2;

        canvas.drawCircle(touchX, touchY, radius, paint);
        System.out.println("Drew a circle at "+touchX+" " + touchY+" with a radius of "+radius+".");
        return image;
    }

画圆不用切换activity？

Draw circle without having to switch activity?

geometry

android

draw