如何查看用户是否在屏幕上的同一位置按下 2 秒？

Question

我有一个简单的自定义视图，其中包含 onDraw 和 onTouchEvent 方法。我需要以某种方式检查用户是否将手指放在同一位置（Y 坐标）超过 2 秒。

编辑：添加了描述和代码。

我的简单自定义视图正在做的是在用户手指下方绘制一条水平线。当您在屏幕上上下移动时，水平线会跟随您。 如果用户在同一位置按住手指 2 秒，我要做的是升起一个标志（布尔值） - 换句话说，如果这条线围绕某个 Y 坐标2 秒。

public class RateView extends View {

float touchY = (getHeight() / 2);
boolean isPressed = false;
Paint paint = new Paint();

//Bunch of standard constructors

private void init(Context context, AttributeSet attr) {
    paint.setColor(ContextCompat.getColor(context, R.color.line));
    paint.setStrokeWidth(10);
    paint.setAntiAlias(true);
}

@Override
public void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    //If pressed -> draw horizontal line
    if (isPressed) {
        canvas.drawLine(0, touchY, (canvas.getWidth()), touchY, paint);
    }
}

@Override
public boolean onTouchEvent(MotionEvent motionEvent) {

    switch (motionEvent.getAction()) {
        case MotionEvent.ACTION_DOWN:
            isPressed = true;

            break;
        case MotionEvent.ACTION_MOVE:
            touchY = motionEvent.getY();

            break;
        case MotionEvent.ACTION_UP:
            isPressed = false;

            break;
    }
    invalidate();
    return true;
}}

Answer 1

您可以将 runnable 与 runnable 结合使用来实现此目的。您可以运行一个 Runnable，它仅在仍然按下视图并且执行期间的 y 坐标在第一次启动 runnable 时的 y 坐标范围内时在两秒钟后执行您想要的内容。代码将如下所示。

boolean mViewIsPressed = false;
float yCoordPrev;
float yCoordCurr;
Runnable runnable;

@Override
public boolean onTouchEvent(final MotionEvent event) {
    // MotionEvent object holds X-Y values
    if(event.getAction() == MotionEvent.ACTION_DOWN) {
        String text = "You click at x = " + event.getX() + " and y = " + event.getY();
        Log.d("debug-x: ", String.valueOf(event.getX()));
        Log.d("debug-y: ", String.valueOf(event.getY()));
        Toast.makeText(this, text, Toast.LENGTH_LONG).show();
        yCoordPrev = event.getY();

        runnable = new Runnable() {
            public void run() {


                //Check if user is still holding down on the view
                if (mViewIsPressed) {
                    yCoordCurr = event.getY();

                    //Check if position that is being held down is the same (or within range) as 2 seconds ago
                    if ((yCoordCurr < yCoordPrev+10) && (yCoordCurr > yCoordPrev -10) ){
                        //Do what you want here after 2 seconds of pressing
                        Log.d("debugFireEvent: ", "fire");
                    }
                }
            }
        };

        handler.postDelayed(runnable, 2000);
        mViewIsPressed = true;


    }
    if(event.getAction() == MotionEvent.ACTION_UP) {
        if(mViewIsPressed) {
            mViewIsPressed = false;
            yCoordCurr = event.getY();
            //Cancel the runnable because the user stopped pressing
            handler.removeCallbacks(runnable);
            }
        }
    return super.onTouchEvent(event);
}

您可以在 runnable 中使用 if 语句中的范围，更准确地说是 if ((yCoordCurr < yCoordPrev+10) && (yCoordCurr > yCoordPrev -10) )，但由于即使用户仍在同一位置按下手指也会移动一点，我认为最好有一个范围。