gesture:手势；detector:检测器
GestureDetector类提供了两个接口：OnGestureListener，OnDoubleTapListener，一个被static修饰的内部类：
SimpleOnGestureListener；实现OnGestureListener接口时需要重写全部的手势处理方法：
onDown()：手指触摸屏幕的瞬间
onFling()：手指在屏幕上迅速移动并松开
onLongPress():手指长按屏幕
onScroll()：手指在屏幕上滑动
onShowPress():手指按在屏幕上时，在长按之前
onSlingleTapUp():手指离开屏幕时
onDoubleTap():双击屏幕时
- 而继承SimpleOnGestureListener类，只需要重写需要的方法即可：
class MyGestureListener extends GestureDetector.SimpleOnGestureListener {
/**
* MotionEvent e1 手势起点事件
* MotionEvent e2 手势终点事件
* distanceX x轴方向上移动的速度/s
* distanceY Y轴方向上移动的速度/s
*/
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
float distanceY) {
Log.d(DEBUG_TAG, "onScroll: " + e1.toString()+e2.toString());
return true;
}
}
- activity，view 中使用手势需要重写onTouchEvent()
//activity
@Override
public boolean onTouchEvent(MotionEvent event){
if(this.mMyGestureListener.onTouchEvent(event))
return true;
return super.onTouchEvent(event);
}
//view
mView.setOnTouchListener(new OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
if(this.mMyGestureListener.onTouchEvent(event))
return true;
return super.onTouchEvent(event);
}
});
- 场景：视屏播放时，在屏幕左侧上下滑动，调节亮度；屏幕右侧上下滑动，调节音量
@Override
public boolean onDown(MotionEvent e) {
firstTouch = true;
return super.onDown(e);
}
/**
* 滑动
*/
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
if (e1 != null && e2 != null) {
float mOldX = e1.getX(), mOldY = e1.getY();
float deltaY = mOldY - e2.getY();
float deltaX = mOldX - e2.getX();
if (firstTouch) {
//x偏移量的绝对值 大于 y偏移量的绝对值时 为水平滑动，否则为竖直滑动
toSeek = Math.abs(distanceX) >= Math.abs(distanceY);
//将屏幕分为左右两个，一个控制亮度，一个控制音量
volumeControl = mOldX > activity.getResources().getDisplayMetrics().widthPixels * 0.5f;
firstTouch = false;
}
if (!toSeek) {
float percent = deltaY / videoView.getHeight();
if (volumeControl) {
onVolumeSlide(percent);
} else {
onBrightnessSlide(percent);
}
} else {
//水平滑动操作
...
}
}
return super.onScroll(e1, e2, distanceX, distanceY);
}
/**
* 滑动改变声音大小
*
* @param percent
*/
private void onVolumeSlide(float percent) {
if (volume == -1) {
volume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);
if (volume < 0)
volume = 0;
}
int index = (int) (percent / 2 * mMaxVolume) + volume;
if (index > mMaxVolume) {
index = mMaxVolume;
} else if (index < 0) {
index = 0;
}
volume = index;
// 改变音量
audioManager.setStreamVolume(AudioManager.STREAM_MUSIC, index, 0);
}
/**
* 滑动改变亮度
*
* @param percent
*/
private void onBrightnessSlide(float percent) {
if (brightness < 0) {
//获取屏幕亮度
brightness = activity.getWindow().getAttributes().screenBrightness;
if (brightness <= 0.00f) {
brightness = 0.5f;
} else if (brightness >= 0.01f) {
brightness = 0.01f;
}
}
//设置屏幕亮度
WindowManager.LayoutParams lpa = activity.getWindow().getAttributes();
lpa.screenBrightness = brightness + percent / 3;
brightness = lpa.screenBrightness;
if (lpa.screenBrightness > 1.0f) {
lpa.screenBrightness = 1.0f;
} else if (lpa.screenBrightness < 0.01f) {
lpa.screenBrightness = 0.01f;
}
activity.getWindow().setAttributes(lpa);
}
- 场景：双击暂停播放
/**
* 双击:播放or暂停
*/
@Override
public boolean onDoubleTap(MotionEvent e) {
if (isPlaying()) {
pause();
mPlayPause.setSelected(true);
} else {
start();
mPlayPause.setSelected(false);
}
return true;
}
