Android中View位置和触摸事件详解

width = right-left
height = bottom - top

// 换算关系
x = left + translationX
y = top + translationY

// 转换为dp
Log.e(TAG, "width:" + (getRight() - getLeft()));
Log.e(TAG, "宽度（dp）:" + Utils.px2dip(context, (getRight() - getLeft())));
Log.e(TAG, "height:" + (getBottom() - getTop()));
Log.e(TAG, "高度（dp）:" + Utils.px2dip(context, (getBottom() - getTop())));

// dp转为px
public static int dp2px(Context context, float dpValue) {
 final float scale = context.getResources().getDisplayMetrics().density;
 return (int) (dpValue * scale + 0.5f);
}

// px转为dp
public static int px2dp(Context context, float pxValue) {
 final float scale = context.getResources().getDisplayMetrics().density;
 return (int) (pxValue / scale + 0.5f);
}

ViewConfiguration.get(getContext()).getScaledTouchSlop();

 float x = 0, y = 0;
 @Override
 public boolean onTouchEvent(MotionEvent event) {
// 获取TouchSlop（滑动最小距离）
  float slop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
  switch (event.getAction()) {
   case MotionEvent.ACTION_DOWN:
    Log.e(TAG, "onTouchEvent: " + "按下");
    Log.e(TAG, "getX: " + event.getX());
    Log.e(TAG, "getY: " + event.getY());
    Log.e(TAG, "getRawX: " + event.getRawX());
    Log.e(TAG, "getRawY: " + event.getRawY());

    x = event.getX();
    y = event.getY();

    break;
   case MotionEvent.ACTION_MOVE:
    Log.e(TAG, "onTouchEvent: " + "移动");
    break;
   case MotionEvent.ACTION_UP:
    Log.e(TAG, "onTouchEvent: " + "松开" + x);
    if (event.getX() - x > slop) {
     Log.e(TAG, "onTouchEvent: " + "往右滑动" + event.getX());
    } else if (x - event.getX() > slop) {
     Log.e(TAG, "onTouchEvent: " + "往左滑动" + event.getX());
    } else {
     Log.e(TAG, "onTouchEvent: " + "无效滑动" + event.getX());
    }
    x = 0;
    y = 0;
    break;
  }
  // 返回true，拦截这个事件
  // 返回false，不拦截
  return true;
 }

// 解决长按屏幕后无法拖动的现象，但是这样会无法识别长按事件
mGestureDetector.setIsLongpressEnable(false);

return mGestureDetector.onTouchEvent(event);

private GestureDetector mGestureDetector;
... ...
private void init(Context context){
  this.mContext = context;
  mGestureDetector = new GestureDetector(mContext,onGestureListener);
  mGestureDetector.setOnDoubleTapListener(onDoubleTapListener);
  //解决长按屏幕无法拖动,但是会造成无法识别长按事件
 //mGestureDetector.setIsLongpressEnabled(false);
 }
 
 @Override
 public boolean onTouchEvent(MotionEvent event) {
  // 接管onTouchEvent
  return mGestureDetector.onTouchEvent(event);
 }
 
 GestureDetector.OnGestureListener onGestureListener = new GestureDetector.OnGestureListener() {
  @Override
  public boolean onDown(MotionEvent e) {
   Log.i(TAG, "onDown: 按下");
   return true;
  }
 
  @Override
  public void onShowPress(MotionEvent e) {
   Log.i(TAG, "onShowPress: 刚碰上还没松开");
  }
 
  @Override
  public boolean onSingleTapUp(MotionEvent e) {
   Log.i(TAG, "onSingleTapUp: 轻轻一碰后马上松开");
   return true;
  }
 
  @Override
  public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
   Log.i(TAG, "onScroll: 按下后拖动");
   return true;
  }
 
  @Override
  public void onLongPress(MotionEvent e) {
   Log.i(TAG, "onLongPress: 长按屏幕");
  }
 
  @Override
  public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
   Log.i(TAG, "onFling: 滑动后松开");
   return true;
  }
 };
 
 GestureDetector.OnDoubleTapListener onDoubleTapListener = new GestureDetector.OnDoubleTapListener() {
  @Override
  public boolean onSingleTapConfirmed(MotionEvent e) {
   Log.i(TAG, "onSingleTapConfirmed: 严格的单击");
   return true;
  }
 
  @Override
  public boolean onDoubleTap(MotionEvent e) {
   Log.i(TAG, "onDoubleTap: 双击");
   return true;
  }
 
  @Override
  public boolean onDoubleTapEvent(MotionEvent e) {
   Log.i(TAG, "onDoubleTapEvent: 表示发生双击行为");
   return true;
  }
 };

private float x = 0, y = 0;
@Override
public boolean onTouchEvent(MotionEvent event) {
 switch (event.getAction()) {
  case MotionEvent.ACTION_DOWN:
   x = event.getRawX();
   y = event.getRawY();
   break;
  case MotionEvent.ACTION_MOVE:

   float rawX = event.getRawX();
   float rawY = event.getRawY();

   float translationX = getTranslationX();
   float translationY = getTranslationY();

   float deltaX = (rawX - x) + translationX;
   float deltaY = (rawY - y) + translationY;

   setTranslation(deltaX, deltaY);

   x = event.getRawX();
   y = event.getRawY();
   break;
  case MotionEvent.ACTION_UP:
   break;
 }
 return true;
}

private void setTranslation(float deltaX, float deltaY) {
 // 正数往右，负数往左
 setTranslationX(deltaX);
 setTranslationY(deltaY);
}