区分缩放和移动 Google 地图？

Question

我的目标是在相机移动时出现 ImageView，但仅在用户移动地图时出现，而不是在放大或缩小时出现。如何区分两者？

我尝试使用 OnCameraMove 和 OnCameraIdle 侦听器，但缩放被注册为移动，并且 OnCameraMoveStartedListener 只能在移动是否与用户相关时才能注册。

此外，在缩放时，我需要将缩放居中。希望这是有道理的。

Answer 1

不幸的是，没有办法区分缩放和移动地图。但是，有一种 hacky 方法可以完成您正在寻找的内容。您可以创建一个扩展 FrameLayout 的包装类。在包装器内部重写 dispatchTouchEvent 方法并实现处理缩放/拖动或任何需要区分用户交互的逻辑。例如，要检测缩放，我们只需要确保有 2 个手指，它们已经移动到某个阈值之外并且它们正在向相反的方向移动。为此，我们必须重写 dispatchTouchEvent

switch (ev.getAction()) {
case MotionEvent.ACTION_MOVE:
boolean isPrimMoving = isScrollGesture(event, 0, mPrimStartTouchEventX,
mPrimStartTouchEventY);
boolean isSecMoving = (mPtrCount > 1 && isScrollGesture(event, 1,
mSecStartTouchEventX, mSecStartTouchEventY));
if (mPtrCount > 1 && isPinchGesture(event)) {
Log.d("TAG", "PINCH! OUCH!");
} else if (isPrimMoving || isSecMoving) {
    // A 1 finger or 2 finger scroll.
    if (isPrimMoving && isSecMoving) {
      Log.d("TAG", "Two finger scroll");
    } else {
      Log.d("TAG", "One finger scroll");
    }}
break;

该类将声明一个接口，该接口将根据用户交互更新活动。然后，在您的片段中启动该类

mTouchView = new myWrapperClass(getActivity());
mTouchView.addView(mOriginalContentView);
return mTouchView;

你需要覆盖 onTouch

private float mPrimStartTouchEventX = -1;
private float mPrimStartTouchEventY = -1;
private float mSecStartTouchEventX = -1;
private float mSecStartTouchEventY = -1;
private float mPrimSecStartTouchDistance = 0;
...
@Override
public boolean onTouch(View v, MotionEvent event) {
  int action = (event.getAction() & MotionEvent.ACTION_MASK);

  switch (action) {
    case MotionEvent.ACTION_POINTER_DOWN:
    case MotionEvent.ACTION_DOWN:
      mPtrCount++;
      if (mPtrCount == 1) {
        mPrimStartTouchEventX = event.getX(0);
        mPrimStartTouchEventY = event.getY(0);
        Log.d("TAG", String.format("POINTER ONE X = %.5f, Y = %.5f", mPrimStartTouchEventX, mPrimStartTouchEventY));
      }
      if (mPtrCount == 2) {
        // Starting distance between fingers
        mSecStartTouchEventX = event.getX(1);
        mSecStartTouchEventY = event.getY(1);
        mPrimSecStartTouchDistance = distance(event, 0, 1);
        Log.d("TAG", String.format("POINTER TWO X = %.5f, Y = %.5f", mSecStartTouchEventX, mSecStartTouchEventY));
      }

      break;
    case MotionEvent.ACTION_POINTER_UP:
    case MotionEvent.ACTION_UP:
      mPtrCount--;
      if (mPtrCount < 2) {
        mSecStartTouchEventX = -1;
        mSecStartTouchEventY = -1;
      }
      if (mPtrCount < 1) {
        mPrimStartTouchEventX = -1;
        mPrimStartTouchEventY = -1;
      }
      break;

    case MotionEvent.ACTION_MOVE:
      Log.d("TAG", "Move " + mPtrCount);
      break;

  }

  return true;
}

编辑：下面是isPinchGesture & isScrollGesture的实现

private boolean isPinchGesture(MotionEvent event) {
  if (event.getPointerCount() == 2) {
    final float distanceCurrent = distance(event, 0, 1);
    final float diffPrimX = mPrimStartTouchEventX - event.getX(0);
    final float diffPrimY = mPrimStartTouchEventY - event.getY(0);
    final float diffSecX = mSecStartTouchEventX - event.getX(1);
    final float diffSecY = mSecStartTouchEventY - event.getY(1);

    if (Math.abs(distanceCurrent - mPrimSecStartTouchDistance) > mViewScaledTouchSlop
            // and the fingers are moving in opposing directions
            && (diffPrimY * diffSecY) <= 0
            && (diffPrimX * diffSecX) <= 0) {
      return true;
    }
  }

  return false;
}
private boolean isScrollGesture(MotionEvent event, int ptrIndex, float originalX, float originalY){
  float moveX = Math.abs(event.getX(ptrIndex) - originalX);
  float moveY = Math.abs(event.getY(ptrIndex) - originalY);

  if (moveX > mViewScaledTouchSlop || moveY > mViewScaledTouchSlop) {
   return true;
  }
  return false;
}

编辑 2：您可以使用 ScaleGestureDetector 使用 OnTouchListener 在 Android 中检测捏合手势。 欲了解更多信息：https://developer.android.com/training/gestures/scale.html

static class MyPinchListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
  @Override
  public boolean onScale(ScaleGestureDetector detector) {
    Log.d("TAG", "PINCH! OUCH!");
    return true;
  }
}
/* Using it */
ScaleGestureDetector mScaleDetector = 
             new ScaleGestureDetector(this, new MyPinchListener());
mGestureView.setOnTouchListener(new View.OnTouchListener() {
  @Override
  public boolean onTouch(View v, MotionEvent event) {
    mScaleDetector.onTouchEvent(event);
    return true;
  }
});