Android 如何在垂直位置绘制点&；用手指在这些点之间画一条线？

我试图在屏幕上画两个点&当我触摸点1并将其拖动到点2时，需要从点1到点2画一条线

如下图所示

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遵循此代码触摸事件进行拖动

@Override
public boolean onTouchEvent (MotionEvent event) {

  if (event.getAction() == MotionEvent.ACTION_DOWN) {

    start_x = event.getX();
    start_y = event.getY();     

  } else if (event.getAction() == MotionEvent.ACTION_MOVE) {

    //create the line from start_x and start_y to the current location
    //don't forget to invalidate the View otherwise your line won't get redrawn

  } else if (event.getAction() == MotionEvent.ACTION_UP) {

    //might not need anything here

  }

对于绘制线，请遵循此链接

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对于本例，我需要扩展活动或视图？您需要扩展活动并实现OnTouchlistner