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android – canvas没有更新

Android 发布时间：2022-04-28 发布网站：大佬教程 code.js-code.com

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@H_403_2@

我在这个视图中创建了一个视图,我想在获取用户触摸屏幕的像素之后显示该框,但是onDraw方法不是将画布更新为触摸屏幕.你们能帮助我吗？

public class PlayView extends View
{
float width,height;
float touchatX,touchatY;
Boolean isanyBox;

public void init()
{
    isanyBox = false;

}


    @Override
protected void onSizeChanged(int w,int h,int oldw,int oldh) 
 {
   // TODO Auto-generated method stub

   width = w/6f;
   height = h/6f;

    super.onSizeChanged(w,h,oldw,oldh);
}

public PlayView(Context context)
   {
       super(context);
       setFocusable(true);
       setFocusableInTouchMode(true);
       init();
   }


     @Override
    public Boolean onTouchEvent(MotionEvent event) 
  {
    // TODO Auto-generated method stub

   isanyBox = true;
   touchatX = (event.getX()/6)*6;
   touchatY = (event.getY()/6)*6;

    return super.onTouchEvent(event);
}

   public void onDraw(Canvas canvas)
 {
   Paint lineColor = new Paint();
   lineColor.setColor(Color.bLACK);

   //Box property
   Paint BoxColor = new Paint();
   BoxColor.setColor(Color.bLUE);

   //Draw horizontal lines
   for(int i=0; i<6; i++)
   {
      canvas.drawLine(0,i*height,getWidth(),lineColor);
   }

   //Draw vertical lines
   for(int j=0; j<6; j++)
   {
       canvas.drawLine(j*width,j*width,getHeight(),lineColor);
   }

  // if(isanyBox)
  // {
   canvas.drawRect(touchatX+1,touchatY+2,touchatX+width-1,touchatY+height-2,BoxColor);
  // }


  }
 }

解决方法

put invalidate();进入onTouchEvent,

@Override
    public Boolean onTouchEvent(MotionEvent event) {
        // TODO Auto-generated method stub

        isanyBox = true;
        touchatX = (event.getX() / 6) * 6;
        touchatY = (event.getY() / 6) * 6;
        invalidate();

        return super.onTouchEvent(event);
    }

@H_403_2@