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Commit 076f173

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Jeff Brown
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Remove edge slop handling from ScaleGestureDetector.
The edge slop code could violate invariants of ScaleGestureDetector, such as the assumption that if an ACTION_POINTER_DOWN is observed or if getPointerCount() >= 2, then there must be at least two active pointers to choose from. But due to the edge slop handling, it was possible for findNewActiveIndex to return -1 in this case, resulting in a crash. Bug: 6613154 Change-Id: I4e08e38a49ab27dac1be9484e19de086bc43624a
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‎core/java/android/view/ScaleGestureDetector.java‎

Lines changed: 29 additions & 201 deletions
Original file line numberDiff line numberDiff line change
@@ -152,10 +152,6 @@ public void onScaleEnd(ScaleGestureDetector detector) {
152152
private float mPrevPressure;
153153
private long mTimeDelta;
154154

155-
private final float mEdgeSlop;
156-
private float mRightSlopEdge;
157-
private float mBottomSlopEdge;
158-
private boolean mSloppyGesture;
159155
private boolean mInvalidGesture;
160156

161157
// Pointer IDs currently responsible for the two fingers controlling the gesture
@@ -171,10 +167,8 @@ public void onScaleEnd(ScaleGestureDetector detector) {
171167
new InputEventConsistencyVerifier(this, 0) : null;
172168

173169
public ScaleGestureDetector(Context context, OnScaleGestureListener listener) {
174-
ViewConfiguration config = ViewConfiguration.get(context);
175170
mContext = context;
176171
mListener = listener;
177-
mEdgeSlop = config.getScaledEdgeSlop();
178172
}
179173

180174
public boolean onTouchEvent(MotionEvent event) {
@@ -193,171 +187,37 @@ public boolean onTouchEvent(MotionEvent event) {
193187
handled = false;
194188
} else if (!mGestureInProgress) {
195189
switch (action) {
196-
case MotionEvent.ACTION_DOWN: {
197-
mActiveId0 = event.getPointerId(0);
198-
mActive0MostRecent = true;
199-
}
200-
break;
201-
202-
case MotionEvent.ACTION_UP:
203-
reset();
190+
case MotionEvent.ACTION_DOWN: {
191+
mActiveId0 = event.getPointerId(0);
192+
mActive0MostRecent = true;
193+
}
204194
break;
205195

206-
case MotionEvent.ACTION_POINTER_DOWN: {
207-
// We have a new multi-finger gesture
208-
209-
// as orientation can change, query the metrics in touch down
210-
DisplayMetrics metrics = mContext.getResources().getDisplayMetrics();
211-
mRightSlopEdge = metrics.widthPixels - mEdgeSlop;
212-
mBottomSlopEdge = metrics.heightPixels - mEdgeSlop;
213-
214-
if (mPrevEvent != null) mPrevEvent.recycle();
215-
mPrevEvent = MotionEvent.obtain(event);
216-
mTimeDelta = 0;
217-
218-
int index1 = event.getActionIndex();
219-
int index0 = event.findPointerIndex(mActiveId0);
220-
mActiveId1 = event.getPointerId(index1);
221-
if (index0 < 0 || index0 == index1) {
222-
// Probably someone sending us a broken event stream.
223-
index0 = findNewActiveIndex(event, index0 == index1 ? -1 : mActiveId1, index0);
224-
mActiveId0 = event.getPointerId(index0);
225-
}
226-
mActive0MostRecent = false;
227-
228-
setContext(event);
229-
230-
// Check if we have a sloppy gesture. If so, delay
231-
// the beginning of the gesture until we're sure that's
232-
// what the user wanted. Sloppy gestures can happen if the
233-
// edge of the user's hand is touching the screen, for example.
234-
final float edgeSlop = mEdgeSlop;
235-
final float rightSlop = mRightSlopEdge;
236-
final float bottomSlop = mBottomSlopEdge;
237-
float x0 = getRawX(event, index0);
238-
float y0 = getRawY(event, index0);
239-
float x1 = getRawX(event, index1);
240-
float y1 = getRawY(event, index1);
241-
242-
boolean p0sloppy = x0 < edgeSlop || y0 < edgeSlop
243-
|| x0 > rightSlop || y0 > bottomSlop;
244-
boolean p1sloppy = x1 < edgeSlop || y1 < edgeSlop
245-
|| x1 > rightSlop || y1 > bottomSlop;
246-
247-
if (p0sloppy && p1sloppy) {
248-
mFocusX = -1;
249-
mFocusY = -1;
250-
mSloppyGesture = true;
251-
} else if (p0sloppy) {
252-
mFocusX = event.getX(index1);
253-
mFocusY = event.getY(index1);
254-
mSloppyGesture = true;
255-
} else if (p1sloppy) {
256-
mFocusX = event.getX(index0);
257-
mFocusY = event.getY(index0);
258-
mSloppyGesture = true;
259-
} else {
260-
mSloppyGesture = false;
261-
mGestureInProgress = mListener.onScaleBegin(this);
262-
}
263-
}
264-
break;
265-
266-
case MotionEvent.ACTION_MOVE:
267-
if (mSloppyGesture) {
268-
// Initiate sloppy gestures if we've moved outside of the slop area.
269-
final float edgeSlop = mEdgeSlop;
270-
final float rightSlop = mRightSlopEdge;
271-
final float bottomSlop = mBottomSlopEdge;
272-
int index0 = event.findPointerIndex(mActiveId0);
273-
int index1 = event.findPointerIndex(mActiveId1);
274-
275-
float x0 = getRawX(event, index0);
276-
float y0 = getRawY(event, index0);
277-
float x1 = getRawX(event, index1);
278-
float y1 = getRawY(event, index1);
279-
280-
boolean p0sloppy = x0 < edgeSlop || y0 < edgeSlop
281-
|| x0 > rightSlop || y0 > bottomSlop;
282-
boolean p1sloppy = x1 < edgeSlop || y1 < edgeSlop
283-
|| x1 > rightSlop || y1 > bottomSlop;
284-
285-
if (p0sloppy) {
286-
// Do we have a different pointer that isn't sloppy?
287-
int index = findNewActiveIndex(event, mActiveId1, index0);
288-
if (index >= 0) {
289-
index0 = index;
290-
mActiveId0 = event.getPointerId(index);
291-
x0 = getRawX(event, index);
292-
y0 = getRawY(event, index);
293-
p0sloppy = false;
294-
}
295-
}
196+
case MotionEvent.ACTION_UP:
197+
reset();
198+
break;
296199

297-
if (p1sloppy) {
298-
// Do we have a different pointer that isn't sloppy?
299-
int index = findNewActiveIndex(event, mActiveId0, index1);
300-
if (index >= 0) {
301-
index1 = index;
302-
mActiveId1 = event.getPointerId(index);
303-
x1 = getRawX(event, index);
304-
y1 = getRawY(event, index);
305-
p1sloppy = false;
306-
}
307-
}
200+
case MotionEvent.ACTION_POINTER_DOWN: {
201+
// We have a new multi-finger gesture
202+
if (mPrevEvent != null) mPrevEvent.recycle();
203+
mPrevEvent = MotionEvent.obtain(event);
204+
mTimeDelta = 0;
308205

309-
if(p0sloppy && p1sloppy) {
310-
mFocusX = -1;
311-
mFocusY = -1;
312-
} else if (p0sloppy) {
313-
mFocusX = event.getX(index1);
314-
mFocusY = event.getY(index1);
315-
} else if (p1sloppy) {
316-
mFocusX = event.getX(index0);
317-
mFocusY = event.getY(index0);
318-
} else {
319-
mSloppyGesture = false;
320-
mGestureInProgress = mListener.onScaleBegin(this);
206+
int index1 = event.getActionIndex();
207+
int index0 = event.findPointerIndex(mActiveId0);
208+
mActiveId1 = event.getPointerId(index1);
209+
if (index0 < 0 || index0 == index1) {
210+
// Probably someone sending us a broken event stream.
211+
index0 = findNewActiveIndex(event, mActiveId1, -1);
212+
mActiveId0 = event.getPointerId(index0);
321213
}
322-
}
323-
break;
324-
325-
case MotionEvent.ACTION_POINTER_UP:
326-
if (mSloppyGesture) {
327-
final int pointerCount = event.getPointerCount();
328-
final int actionIndex = event.getActionIndex();
329-
final int actionId = event.getPointerId(actionIndex);
330-
331-
if (pointerCount > 2) {
332-
if (actionId == mActiveId0) {
333-
final int newIndex = findNewActiveIndex(event, mActiveId1, actionIndex);
334-
if (newIndex >= 0) mActiveId0 = event.getPointerId(newIndex);
335-
} else if (actionId == mActiveId1) {
336-
final int newIndex = findNewActiveIndex(event, mActiveId0, actionIndex);
337-
if (newIndex >= 0) mActiveId1 = event.getPointerId(newIndex);
338-
}
339-
} else {
340-
// Set focus point to the remaining finger
341-
final int index = event.findPointerIndex(actionId == mActiveId0 ?
342-
mActiveId1 : mActiveId0);
343-
if (index < 0) {
344-
mInvalidGesture = true;
345-
Log.e(TAG, "Invalid MotionEvent stream detected.", new Throwable());
346-
if (mGestureInProgress) {
347-
mListener.onScaleEnd(this);
348-
}
349-
return false;
350-
}
214+
mActive0MostRecent = false;
351215

352-
mActiveId0 = event.getPointerId(index);
216+
setContext(event);
353217

354-
mActive0MostRecent = true;
355-
mActiveId1 = -1;
356-
mFocusX = event.getX(index);
357-
mFocusY = event.getY(index);
358-
}
218+
mGestureInProgress = mListener.onScaleBegin(this);
219+
break;
359220
}
360-
break;
361221
}
362222
} else {
363223
// Transform gesture in progress - attempt to handle it
@@ -381,8 +241,7 @@ public boolean onTouchEvent(MotionEvent event) {
381241
" with bad state while a gesture was in progress. " +
382242
"Did you forget to pass an event to " +
383243
"ScaleGestureDetector#onTouchEvent?");
384-
index0 = findNewActiveIndex(event,
385-
mActiveId0 == mActiveId1 ? -1 : mActiveId1, index0);
244+
index0 = findNewActiveIndex(event, mActiveId1, -1);
386245
mActiveId0 = event.getPointerId(index0);
387246
}
388247

@@ -483,49 +342,19 @@ public boolean onTouchEvent(MotionEvent event) {
483342
return handled;
484343
}
485344

486-
private int findNewActiveIndex(MotionEvent ev, int otherActiveId, int oldIndex) {
345+
private int findNewActiveIndex(MotionEvent ev, int otherActiveId, int removedPointerIndex) {
487346
final int pointerCount = ev.getPointerCount();
488347

489348
// It's ok if this isn't found and returns -1, it simply won't match.
490349
final int otherActiveIndex = ev.findPointerIndex(otherActiveId);
491-
int newActiveIndex = -1;
492350

493-
// Pick a new id and update tracking state. Only pick pointers not on the slop edges.
351+
// Pick a new id and update tracking state.
494352
for (int i = 0; i < pointerCount; i++) {
495-
if (i != oldIndex && i != otherActiveIndex) {
496-
final float edgeSlop = mEdgeSlop;
497-
final float rightSlop = mRightSlopEdge;
498-
final float bottomSlop = mBottomSlopEdge;
499-
float x = getRawX(ev, i);
500-
float y = getRawY(ev, i);
501-
if (x >= edgeSlop && y >= edgeSlop && x <= rightSlop && y <= bottomSlop) {
502-
newActiveIndex = i;
503-
break;
504-
}
353+
if (i != removedPointerIndex && i != otherActiveIndex) {
354+
return i;
505355
}
506356
}
507-
508-
return newActiveIndex;
509-
}
510-
511-
/**
512-
* MotionEvent has no getRawX(int) method; simulate it pending future API approval.
513-
*/
514-
private static float getRawX(MotionEvent event, int pointerIndex) {
515-
if (pointerIndex < 0) return Float.MIN_VALUE;
516-
if (pointerIndex == 0) return event.getRawX();
517-
float offset = event.getRawX() - event.getX();
518-
return event.getX(pointerIndex) + offset;
519-
}
520-
521-
/**
522-
* MotionEvent has no getRawY(int) method; simulate it pending future API approval.
523-
*/
524-
private static float getRawY(MotionEvent event, int pointerIndex) {
525-
if (pointerIndex < 0) return Float.MIN_VALUE;
526-
if (pointerIndex == 0) return event.getRawY();
527-
float offset = event.getRawY() - event.getY();
528-
return event.getY(pointerIndex) + offset;
357+
return -1;
529358
}
530359

531360
private void setContext(MotionEvent curr) {
@@ -588,7 +417,6 @@ private void reset() {
588417
mCurrEvent.recycle();
589418
mCurrEvent = null;
590419
}
591-
mSloppyGesture = false;
592420
mGestureInProgress = false;
593421
mActiveId0 = -1;
594422
mActiveId1 = -1;

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