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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.photoeditor.actions;
     18 
     19 import android.content.Context;
     20 import android.util.AttributeSet;
     21 import android.view.GestureDetector;
     22 import android.view.MotionEvent;
     23 import android.view.View;
     24 
     25 /**
     26  * A view that detects user gestures and touch motions.
     27  */
     28 class TouchView extends View {
     29 
     30     /**
     31      * Listener of swipes.
     32      */
     33     public interface SwipeListener {
     34 
     35         void onSwipeLeft();
     36 
     37         void onSwipeRight();
     38 
     39         void onSwipeUp();
     40 
     41         void onSwipeDown();
     42     }
     43 
     44     /**
     45      * Listener of single tap confirmed (click).
     46      */
     47     public interface SingleTapListener {
     48 
     49         void onSingleTap(float x, float y);
     50     }
     51 
     52     private final GestureDetector gestureDetector;
     53 
     54     private SwipeListener swipeListener;
     55     private SingleTapListener singleTapListener;
     56 
     57     public TouchView(Context context, AttributeSet attrs) {
     58         super(context, attrs);
     59 
     60         final int swipeThreshold = (int) (500 * getResources().getDisplayMetrics().density);
     61         gestureDetector = new GestureDetector(
     62                 context, new GestureDetector.SimpleOnGestureListener() {
     63 
     64             @Override
     65             public boolean onDown(MotionEvent e) {
     66                 // GestureDetector onTouchEvent returns true for fling events only when their
     67                 // preceding down events are consumed.
     68                 return true;
     69             }
     70 
     71             @Override
     72             public boolean onSingleTapUp(MotionEvent e) {
     73                 if (singleTapListener != null) {
     74                     singleTapListener.onSingleTap(e.getX(), e.getY());
     75                 }
     76                 return true;
     77             }
     78 
     79             @Override
     80             public boolean onFling(
     81                     MotionEvent me1, MotionEvent me2, float velocityX, float velocityY) {
     82                 if (swipeListener != null) {
     83                     float absX = Math.abs(velocityX);
     84                     float absY = Math.abs(velocityY);
     85                     float deltaX = me2.getX() - me1.getX();
     86                     float deltaY = me2.getY() - me1.getY();
     87                     int travelX = getWidth() / 4;
     88                     int travelY = getHeight() / 4;
     89                     if (velocityX > swipeThreshold && absY < absX && deltaX > travelX) {
     90                         swipeListener.onSwipeRight();
     91                     } else if (velocityX < -swipeThreshold && absY < absX && deltaX < -travelX) {
     92                         swipeListener.onSwipeLeft();
     93                     } else if (velocityY < -swipeThreshold && absX < absY && deltaY < -travelY) {
     94                         swipeListener.onSwipeUp();
     95                     } else if (velocityY > swipeThreshold && absX < absY / 2 && deltaY > travelY) {
     96                         swipeListener.onSwipeDown();
     97                     }
     98                 }
     99                 return true;
    100             }
    101         });
    102         gestureDetector.setIsLongpressEnabled(false);
    103     }
    104 
    105     public void setSwipeListener(SwipeListener listener) {
    106         swipeListener = listener;
    107     }
    108 
    109     public void setSingleTapListener(SingleTapListener listener) {
    110         singleTapListener = listener;
    111     }
    112 
    113     @Override
    114     public boolean onTouchEvent(MotionEvent event) {
    115         return isEnabled() && gestureDetector.onTouchEvent(event);
    116     }
    117 }
    118