java事件未触发

Question

我试图在canvas上画一个正方形，但只有MotionEvent.ACTION_DOWN运行，然后listener停止

这个想法是，当用户触摸屏幕时，它会得到x1和y1位置，每次触发onTouch时，它必须将矩形frim x1 y1绘制到当前位置，最后在用户放开屏幕后将最后一个位置保存在x2 y2中

我的代码如下所示：

surfaceView.setOnTouchListener(new View.OnTouchListener()
{
    @Override
    public boolean onTouch(View v, MotionEvent event)
    {
        holder = surfaceView.getHolder();
        canvas = holder.lockCanvas();
        if(event.getAction() == MotionEvent.ACTION_DOWN)
        {
            x1=event.getX();
            y1=event.getY();
        }
        else if(event.getAction() == MotionEvent.ACTION_UP)
        {
            x2=event.getX();
            y2=event.getY();
        }
        canvas.drawRect(x1, y1, event.getX(), event.getY(), paint);
        holder.unlockCanvasAndPost(canvas);
        return true;
    }
});

谁能给我举个例子吗

Answer 1

从上述代码中触发操作。尝试下面的代码，你会看到日志

我认为你的问题可能与你得到的分数有关。我不知道你是如何定义x1、y1、x2、y2的，但当声明超出范围时，它们必须是最终的。试试这个

final SurfaceView s = (SurfaceView) findViewById(R.id.surface);

final RectF rect = new RectF();

s.setOnTouchListener(new OnTouchListener() {

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        SurfaceHolder holder = s.getHolder();
        Canvas canvas = holder.lockCanvas();

        if(event.getAction() == MotionEvent.ACTION_DOWN) {
            Log.d("action", "down");
            rect.left = event.getX();
            rect.top = event.getY();
        }
        if(event.getAction() == MotionEvent.ACTION_UP){
            Log.d("action", "up");
            rect.right = event.getX();
            rect.bottom = event.getY();

            Paint paint = new Paint();
            paint.setColor(Color.RED);
            canvas.drawRect(rect, paint);
        }

        holder.unlockCanvasAndPost(canvas);
        return true;
    }
});