最近有个播放器手势滑动快进快退的需求，研究了一下Android中GestureDetector的用法，封装了一个工具类，实现了单击、双击、横向滑动(快进快退)、竖向滑动(亮度音量调节)手势。代码参见：https://github.com/ChenSWD/PlayerGestureDetector
1、在播放器中，常用的一些功能一般有：快进快退、亮度音量调节、双击暂停/播放、单击隐藏/显示播放器的UI。。。其中单击与双击事件一般会存在冲突，GestureDetector的onSingleTapConfirmed()方法在单击且不是双击事件时回调，可以很好的避免这个问题。
2、另外代码中实现了根据滑动的速度改变快进/快退速率的功能，参考代码中updateScrollRatio()方法的实现。这里还是贴出代码实现，相应解释参见代码中的注释。
3、需要说明的是GestureDetectorCompat不能检测手势抬起，所以需要单独监听ACTION_UP手势，以识别结束了快进/快退的手势，相关使用参见https://github.com/ChenSWD/PlayerGestureDetector中MainActivity的说明
/**
* 播放器常用手势监听:单击、双击、横向滑动、左右两边边竖向滑动(亮度和声音)
*/
public class PlayerGestureListener extends GestureDetector.SimpleOnGestureListener {
private WeakReference<VideoGestureListener> listener;
private int screenWidth, centerW;
//播放器View的长宽DP
private float dpVideoWidth, dpVideoHeight;
private ScrollMode scrollMode = ScrollMode.NONE;
private long timeStamp;
private int mTouchSlop;
private int scrollRatio = 1; //快进的比率，速度越快，值越大
private int preDpVideoDuration = 0; //每一dp，快进的时长,ms
private float density;
private int totalDuration = 0; //单次快进快退累计值
private float leftTBValue = 0; //单次左边累计值(一般是亮度)
private float rightTBValue = 0; //单次右边累计值(一般是声音)
public PlayerGestureListener(VideoGestureListener listener, Context context) {
this.listener = new WeakReference<>(listener);
WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics outMetrics = new DisplayMetrics();
wm.getDefaultDisplay().getMetrics(outMetrics);
screenWidth = outMetrics.widthPixels;
centerW = screenWidth / 2;
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
density = context.getResources().getDisplayMetrics().density;
}
//设置播放器SurfaceView的宽高
public void setVideoWH(int w, int h) {
dpVideoWidth = w / density;
dpVideoHeight = h / density;
//默认基础总共2分钟，代表的意义：从屏幕一边滑动到另一边，总共可以快进2分钟
preDpVideoDuration = (int) (2 * 60 * 1000 / dpVideoWidth);
}
@Override
public boolean onDown(MotionEvent e) {
scrollMode = ScrollMode.NONE;
timeStamp = System.currentTimeMillis();
totalDuration = 0;
leftTBValue = 0;
rightTBValue = 0;
if (listener.get() != null) {
listener.get().onGestureDown();
}
return true;
}
@Override
public boolean onSingleTapUp(MotionEvent e) {
return super.onSingleTapUp(e);
}
@Override
public void onShowPress(MotionEvent e) {
super.onShowPress(e);
}
@Override
public void onLongPress(MotionEvent e) {
super.onLongPress(e);
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
long time = System.currentTimeMillis();
distanceX = -distanceX;
distanceY = -distanceY;
float dpX = distanceX / density;
float dpY = distanceY / density;
updateScrollRatio(dpX, time - timeStamp);
timeStamp = time;
float xDiff = e2.getX() - e1.getX();
float yDiff = e2.getY() - e1.getY();
if (scrollMode == ScrollMode.NONE) {
//横向滑动
if (Math.abs(xDiff) > mTouchSlop) {
scrollMode = ScrollMode.HORIZONTAL_S;
updateVideoTime((int) (preDpVideoDuration * xDiff));
}
//纵向滑动
else if (Math.abs(yDiff) > mTouchSlop) {
if (e1.getX() < centerW) {
scrollMode = ScrollMode.LEFT_TB;
} else {
scrollMode = ScrollMode.RIGHT_TB;
}
}
}
//快进快退
else if (scrollMode == ScrollMode.HORIZONTAL_S) {
updateVideoTime((int) (preDpVideoDuration * scrollRatio * dpX));
} else if (scrollMode == ScrollMode.LEFT_TB) {
updateVideoLeftTB(dpY / dpVideoHeight);
} else if (scrollMode == ScrollMode.RIGHT_TB) {
updateVideoRightTB(dpY / dpVideoHeight);
}
return true;
}
@Override
public boolean onDoubleTap(MotionEvent e) {
if (listener.get() != null) {
listener.get().onGestureDoubleClick();
}
//双击事件
return super.onDoubleTap(e);
}
@Override
public boolean onDoubleTapEvent(MotionEvent e) {
return super.onDoubleTapEvent(e);
}
@Override
public boolean onSingleTapConfirmed(MotionEvent e) {
if (listener.get() != null) {
listener.get().onGestureSingleClick();
}
//单击事件，在双击事件发生时不会产生这个事件，所以用这个回调作为播放器单击事件
return super.onSingleTapConfirmed(e);
}
/***
* 根据滑动速度更新速度比率值，这样可以在滑动速率较快时，快进的速度也会变快，可以根据需要调整
* 根据实验，正常速度一般在10~40dp/s
* @param dpX：横向滑动距离 dp
* @param duration：时间间隔 ms
*/
private void updateScrollRatio(float dpX, long duration) {
int ratio = (int) ((Math.abs(dpX) / duration) * 1000);
if (ratio < 20) {
scrollRatio = 1;
} else if (ratio < 40) {
scrollRatio = 3;
} else if (ratio < 70) {
scrollRatio = 7;
} else if (ratio < 100) {
scrollRatio = 13;
} else if (ratio < 300) {
scrollRatio = 18;
} else if (ratio < 500) {
scrollRatio = 24;
} else if (ratio < 800) {
scrollRatio = 31;
} else if (ratio < 1000) {
scrollRatio = 40;
} else {
scrollRatio = 60;
}
}
//累积快进进度,totalDuration：当前快进的总值，负值代表是要快退
private void updateVideoTime(int duration) {
totalDuration += duration;
if (listener.get() != null) {
listener.get().onGestureUpdateVideoTime(totalDuration);
}
}
//累积亮度
private void updateVideoLeftTB(float ratio) {
leftTBValue += ratio;
if (listener.get() != null) {
listener.get().onGestureLeftTB(leftTBValue);
}
}
//累积声音
private void updateVideoRightTB(float ratio) {
rightTBValue += ratio;
if (listener.get() != null) {
listener.get().onGestureRightTB(rightTBValue);
}
}
public interface VideoGestureListener {
/***
* 手指在Layout左半部上下滑动时候调用，一般是亮度手势
* 从View底部滑动到顶部，代表从0升到1
* @param ratio：0-1 之间，1代表最亮，0代表最暗
*/
void onGestureLeftTB(float ratio);
/***
* 手指在Layout右半部上下滑动时候调用，一般是音量手势
* 从View底部滑动到顶部，代表从0升到1
* @param ratio：0-1 之间，1代表音量最大，0代表音量最低
*/
void onGestureRightTB(float ratio);
/**
* @param duration :快进快退,大于0快进，小于0快退
*/
void onGestureUpdateVideoTime(int duration);
//单击手势，确认是单击的时候调用
void onGestureSingleClick();
//双击手势，确认是双击的时候调用，可用于播放器暂停
void onGestureDoubleClick();
void onGestureDown();
}
private enum ScrollMode {
NONE, //初始值
LEFT_TB, //左边上下滑动(调节亮度)
RIGHT_TB, //右边上下滑动(调节声音)
HORIZONTAL_S, //横向滑动(快进快退)
SINGLE_CLICK, //单击
DOUBLE_CLICK //双击
}
}