我正在开发一个与图像视图旋转、移动和缩放相关的应用程序。在此图像视图中，旋转和缩放效果最好。当移动图像视图时，它正在移动但不受控制并进入屏幕外。如何仅控制屏幕的此图像视图？
在此我使用手势检测器进行图像视图移动。
我的代码是::
public class MoveGestureDetector extends BaseGestureDetector {
/**
* Listener which must be implemented which is used by MoveGestureDetector
* to perform callbacks to any implementing class which is registered to a
* MoveGestureDetector via the constructor.
*
* @see MoveGestureDetector.SimpleOnMoveGestureListener
*/
public interface OnMoveGestureListener {
public boolean onMove(MoveGestureDetector detector);
public boolean onMoveBegin(MoveGestureDetector detector);
public void onMoveEnd(MoveGestureDetector detector);
}
/**
* Helper class which may be extended and where the methods may be
* implemented. This way it is not necessary to implement all methods
* of OnMoveGestureListener.
*/
public static class SimpleOnMoveGestureListener implements OnMoveGestureListener {
public boolean onMove(MoveGestureDetector detector) {
return false;
}
public boolean onMoveBegin(MoveGestureDetector detector) {
return true;
}
public void onMoveEnd(MoveGestureDetector detector) {
// Do nothing, overridden implementation may be used
}
}
private static final PointF FOCUS_DELTA_ZERO = new PointF();
private final OnMoveGestureListener mListener;
private PointF mCurrFocusInternal;
private PointF mPrevFocusInternal;
private PointF mFocusExternal = new PointF();
private PointF mFocusDeltaExternal = new PointF();
public MoveGestureDetector(Context context, OnMoveGestureListener listener) {
super(context);
mListener = listener;
}
@Override
protected void handleStartProgressEvent(int actionCode, MotionEvent event){
switch (actionCode) {
case MotionEvent.ACTION_DOWN:
resetState(); // In case we missed an UP/CANCEL event
mPrevEvent = MotionEvent.obtain(event);
mTimeDelta = 0;
updateStateByEvent(event);
break;
case MotionEvent.ACTION_MOVE:
mGestureInProgress = mListener.onMoveBegin(this);
break;
}
}
@Override
protected void handleInProgressEvent(int actionCode, MotionEvent event){
switch (actionCode) {
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
mListener.onMoveEnd(this);
resetState();
break;
case MotionEvent.ACTION_MOVE:
updateStateByEvent(event);
if (mCurrPressure / mPrevPressure > PRESSURE_THRESHOLD) {
final boolean updatePrevious = mListener.onMove(this);
if (updatePrevious) {
mPrevEvent.recycle();
mPrevEvent = MotionEvent.obtain(event);
}
}
break;
}
}
protected void updateStateByEvent(MotionEvent curr) {
super.updateStateByEvent(curr);
final MotionEvent prev = mPrevEvent;
// Focus intenal
mCurrFocusInternal = determineFocalPoint(curr);
mPrevFocusInternal = determineFocalPoint(prev);
boolean mSkipNextMoveEvent = prev.getPointerCount() != curr.getPointerCount();
mFocusDeltaExternal = mSkipNextMoveEvent ? FOCUS_DELTA_ZERO : new PointF(mCurrFocusInternal.x - mPrevFocusInternal.x, mCurrFocusInternal.y - mPrevFocusInternal.y);
mFocusExternal.x += mFocusDeltaExternal.x;
mFocusExternal.y += mFocusDeltaExternal.y;
}
/**
* Determine (multi)finger focal point (a.k.a. center point between all
* fingers)
* @param MotionEvent e
* @return PointF focal point
*/
private PointF determineFocalPoint(MotionEvent e){
final int pCount = e.getPointerCount();
float x = 0f;
float y = 0f;
for(int i = 0; i < pCount; i++){
x += e.getX(i);
y += e.getY(i);
}
return new PointF(x/pCount, y/pCount);
}
public float getFocusX() {
return mFocusExternal.x;
}
public float getFocusY() {
return mFocusExternal.y;
}
public PointF getFocusDelta() {
return mFocusDeltaExternal;
}
}
谢谢...