实现通过上滑或者下滑来切换前后摄像头的功能

• 在vendor/mediatek/proprietary/packages/apps/Camera/src/com/android/camera/GestureDispatcher.java中定义一个实现上滑下滑动作的监听接口

  public interface GestureScrollListener{
      	public boolean onDown(float x,float y, int width, int height);
      	public boolean onScroll(float dx,float dy,float totalX,float totalY);
      	public boolean onFling(MotionEvent e1,MotionEvent e2,float velocityX,float velocityY);
      	public boolean onUp();
      	public boolean onScale(float focusX,float focusY,float scale);
      	public boolean onScaleBegin(float focusX,float focusY);
      }

  
  
• 并在该类中实例化一个GestureScrollListener接口，同时定义一个设置手势滑动的监听器方法

  private GestureScrollListener mGestureScrollListener;
      public void setGestureScrollListener(GestureScrollListener listener){
      	mGestureScrollListener=listener;
      }

  
  
• 在该类重写的方法onScroll中添加

  if(mGestureScrollListener!=null&&mGestureScrollListener.onScroll(dx,dy,totalX,totalY)){
      	return false;
      }

  
  
• 在该类重写的方法onFling中添加

  if(mGestureScrollListener!=null&&mGestureScrollListener.onFling(e1,e2,velocityX,velocityY)){
      	return false;
      }

  
  
• 在该类重写的方法onScaleBegin中添加

  if(mGestureScrollListener!=null&&mGestureScrollListener.onScaleBegin(focusX,focusY)){
      	return false;
      }

  
  
• 在该类重写的方法onScale中添加

  if(mGestureScrollListener!=null&&mGestureScrollListener.onScale(focusX,focusY,scale)){
      	return false;
      }

  
  
• 在该类重写的方法onDown中添加

  if(mGestureScrollListener!=null&&mGestureScrollListener.onDown(vertex[0],vertex[1],(int)vertex[2],(int)vertex[3])){
      	return;
      }

  
  
• 在该类重写的方法onUp中添加

  if(mGestureScrollListener!=null&&mGestureScrollListener.onUp()){
      	return;
      }

  
  
• 在vendor/mediatek/proprietary/packages/apps/Camera/src/com/android/camera/manager/PickerManager.java中定义一个继承了GestureScrollListener的类MyGestureScrollListener，添加内容如下：

  public class MyGestureScrollListener implements GestureScrollListener{
      	private boolean isScroll=false;
      	private boolean isScaled=false;
      	private float mTotalX=0;
      	private float mTotalY=0;
      	private long beginTouchTime=0;
      	private long endTouchTime=0;
      	private void CameraActivity mCameraActivity;
      	public void setCameraActivity(CameraActivity mCameraActivity){
      		this.mCameraActivity=mCameraActivity;
      	}
      	@Override
      	public bollean onScroll(float dx,float dy,float totalX,float totalY){
      		Log.i(TAG,"onScroll("+dx+","+dy+","+totalX+","+totalY+")");
      		if(!isScroll){
      			isScroll=true;
      		}
      		mTotalX=totalX;
      		mTotalY=totalY;
      		return false;
      	}
      	
      	@Override
      	public boolean onFling(MotionEvent e1,MotionEvent e2,float velocityX,float velocityY){
      		Log.i(TAG,"[onFling] ("+velocityX+", "+velocityY+")");
      		Log.d(TAG,"isScroll="+Boolean.toString(isScroll));
      		Log.d(TAG,"isScaled="+Boolean.toString(isScaled));
      		Log.d(TAG,"mCameraActivity.getCurrentMode()="+mCameraActivity.getCurrentMode());
      		if(!isScaled && isScroll && (mCameraActivity.getCurrentMode()!=ModePicker.MODE_VIDEO)){
      			endTouchTime=System.currentTimeMillis();
      			float time=Long.valueOf(endTouchTime-beginTouchTime).floatValue();
      			Log.d(TAG,"time ="+time+" mTotalX"+mTotalX+" mTotalY"+mTotalY+" beginTouchTime="+beginTouchTime);
      		if((Math.ads(mTotalY)>Math.abs(mTotalX))&&(Math.abs(mTotalY)>50)&&((Math.abs(mTotalY)/time)>((float)500/1000))){
      			Log.d(TAG,"Check over");
      			if(mCameraPicker!=null){
      				mCameraPicker.onClick(null);
      			}
      			else{
      				Log.d(TAG,"mCameraPicker=null");
      			}
      		}
      		return false;
      	}
      		
      	@Override
      	public boolean onScaleBegin(float focusX,float focusY){
      		Log.i(TAG,"onScaleBegin("+focusX+","+focusY+")");
      		isScaled=true;
      		return false;
      	}
      	
      	@Override
      	public boolean onScale(float focusX,float focusY,float scale){
      		Log.i(TAG,"onScale("+focusX+", "+focusY+", "+scale);
      		return false;
      	}
      	
      	@Override
      	public boolean onDown(float x,float y,int width,int height){
      		beginTouchTime=System.currentTimeMillis();
      		Log.i(TAG,"onDown()");
      		return false;
      	}
      	
      	@Override
      	public boolean onUp(){
      		Log.i(TAG,"onUp");
      		beginTouchTime=0;
      		endTouchTime=0;
      		isScaled=false;
      		isScroll=false;
      		return false;
      	}
      }
      

  
  
• 在vendor/mediatek/proprietary/packages/apps/Camera/src/com/android/camera/CameraActivity.java中添加GestureScrollListener对象和设置手势滑动监听器的方法

  private GestureScrollListener mGestureScrollListener;
      public void setGestureScrollListener(GestureScrollListener listener){
      	mGestureScrollListener=listener;
      }

  
  
• 调用GestureDispatcher的设置监听器的方法

  mGestureDispatcher.setGestureScrollListener(mGestureScrollListener);

  
  
• 在vendor/mediatek/proprietary/packages/apps/Camera/src/com/android/camera/bridge/CameraAppUiImpl.java中定义一个MyGestureScrollListener对象，并将活动传入该监听器对象，同时给活动传入该监听器

  MyGestureScrollListener mGestureScrollListener=mPickerManage.new MyGestureScrollLisener();
      mGestureScrollListener.setCameraActivity(mCameraActivity);
      mCameraActivity.setGestureScrollListener(mGestureScrollListener);