Question

在我的应用程序中，我绘制一条线，并希望它在我的手指在屏幕上移动。但是现在只有当我把手指从屏幕上移开时才会重新绘制线条。

怎么办？

以这种方式在SurfaceView中绘制线条：

 canvas.drawLine(0, 0, x_touch, y_touch, paint);

onTouch的代码：

    public boolean onTouchEvent(MotionEvent event) {
         int action = event.getAction() ;
            x_touch = (int) event.getX() ;
            y_touch = (int) event.getY() ;

            if(action == MotionEvent.ACTION_DOWN)
            {                       


            }


        return super.onTouchEvent(event);


    }

Answer 1

由于绘图线程（UIThread）调用onTouchEvent，因此在手指启动之前，您将阻止绘图线程。无论你在if(action == MotionEvent.ACTION_DOWN)需要在一个单独的线程中完成时做什么。例如：

if(action == MotionEvent.ACTION_DOWN) {
    final Runnable runnable = new Runnable() {
        @Override
        public void run() {
            // Draw your line
        }
    }.start();
}

Answer 2

试试这个

Path drawPath = new Path();
Paint drawPaint = new Paint();


@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    // TODO Auto-generated method stub
    super.onSizeChanged(w, h, oldw, oldh);
    canvasBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
    drawCanvas = new Canvas(canvasBitmap);
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    // TODO Auto-generated method stub
    float touchX = event.getX();
    float touchY = event.getY();

    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:
        drawPath.moveTo(touchX, touchY);
        break;
    case MotionEvent.ACTION_MOVE:
        drawPath.lineTo(touchX, touchY);
        break;
    case MotionEvent.ACTION_UP:
        drawCanvas.drawPath(drawPath, drawPaint);
        drawPath.reset();
        break;
    default:
        return false;
    }

    invalidate();//this will cause the onDraw() to execute
    return true;
}

  @Override
protected void onDraw(Canvas canvas) {
    // TODO Auto-generated method stub
    super.onDraw(canvas);
    canvas.drawBitmap(canvasBitmap, 0, 0, canvasPaint);
    canvas.drawPath(drawPath, drawPaint);
}

Answer 3

我的问题以下列方式解决了：

新听众：

public class LintListener implements OnTouchListener {

    public LintListener() {
        // TODO Auto-generated constructor stub
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        int action = event.getAction() ;
         //end_game(true);
            x_touch = (int) event.getX() ;
            y_touch = (int) event.getY() ;

        return true;
    }

}

在创建：

super.onCreate(savedInstanceState);
MySurfaceView msf = new MySurfaceView(this);
setContentView(msf);
    msf.setOnTouchListener(new LintListener());

如何使onTouch连续画线？

3 个答案: