ScrollView multiple pointer support. Fixed a bug where ScrollView (bc4e7533) · Commits · e / os / android_frameworks_base

core/java/android/widget/ScrollView.java

+65 −15

Original line number	Diff line number	Diff line
		@@ -116,6 +116,18 @@ public class ScrollView extends FrameLayout {
		private int mMinimumVelocity;
		private int mMaximumVelocity;

		/**
		* ID of the active pointer. This is used to retain consistency during
		* drags/flings if multiple pointers are used.
		*/
		private int mActivePointerId = INVALID_POINTER;

		/**
		* Sentinel value for no current active pointer.
		* Used by {@link #mActivePointerId}.
		*/
		private static final int INVALID_POINTER = -1;

		public ScrollView(Context context) {
		this(context, null);
		}
		@@ -392,10 +404,8 @@ public class ScrollView extends FrameLayout {
		return true;
		}

		final float y = ev.getY();

		switch (action) {
		case MotionEvent.ACTION_MOVE:
		switch (action & MotionEvent.ACTION_MASK) {
		case MotionEvent.ACTION_MOVE: {
		/*
		* mIsBeingDragged == false, otherwise the shortcut would have caught it. Check
		* whether the user has moved far enough from his original down touch.
		@@ -405,21 +415,29 @@ public class ScrollView extends FrameLayout {
		* Locally do absolute value. mLastMotionY is set to the y value
		* of the down event.
		*/
		final int pointerIndex = ev.findPointerIndex(mActivePointerId);
		final float y = ev.getY(pointerIndex);
		final int yDiff = (int) Math.abs(y - mLastMotionY);
		if (yDiff > mTouchSlop) {
		mIsBeingDragged = true;
		mLastMotionY = y;
		}
		break;
		}

		case MotionEvent.ACTION_DOWN:
		case MotionEvent.ACTION_DOWN: {
		final float y = ev.getY();
		if (!inChild((int)ev.getX(), (int)y)) {
		mIsBeingDragged = false;
		break;
		}

		/* Remember location of down touch */
		/*
		* Remember location of down touch.
		* ACTION_DOWN always refers to pointer index 0.
		*/
		mLastMotionY = y;
		mActivePointerId = ev.getPointerId(0);

		/*
		* If being flinged and user touches the screen, initiate drag;
		@@ -428,11 +446,16 @@ public class ScrollView extends FrameLayout {
		*/
		mIsBeingDragged = !mScroller.isFinished();
		break;
		}

		case MotionEvent.ACTION_CANCEL:
		case MotionEvent.ACTION_UP:
		/* Release the drag */
		mIsBeingDragged = false;
		mActivePointerId = INVALID_POINTER;
		break;
		case MotionEvent.ACTION_POINTER_UP:
		onSecondaryPointerUp(ev);
		break;
		}

		@@ -458,10 +481,9 @@ public class ScrollView extends FrameLayout {
		mVelocityTracker.addMovement(ev);

		final int action = ev.getAction();
		final float y = ev.getY();

		switch (action) {
		case MotionEvent.ACTION_DOWN:
		switch (action & MotionEvent.ACTION_MASK) {
		case MotionEvent.ACTION_DOWN: {
		/*
		* If being flinged and user touches, stop the fling. isFinished
		* will be false if being flinged.
		@@ -470,29 +492,33 @@ public class ScrollView extends FrameLayout {
		mScroller.abortAnimation();
		}

		if (!inChild((int)ev.getX(), (int)y)) {
		mIsBeingDragged = false;
		final float y = ev.getY();
		if (!(mIsBeingDragged = inChild((int)ev.getX(), (int)y))) {
		return false;
		}

		// Remember where the motion event started
		mLastMotionY = y;
		mActivePointerId = ev.getPointerId(0);
		break;
		}
		case MotionEvent.ACTION_MOVE:
		if (mIsBeingDragged) {
		// Scroll to follow the motion event
		final int activePointerIndex = ev.findPointerIndex(mActivePointerId);
		final float y = ev.getY(activePointerIndex);
		final int deltaY = (int) (mLastMotionY - y);
		mLastMotionY = y;

		overscrollBy(0, deltaY, 0, mScrollY, 0, getScrollRange(),
		0, getOverscrollMax());
		break;
		}
		break;
		case MotionEvent.ACTION_UP:
		if (mIsBeingDragged) {
		final VelocityTracker velocityTracker = mVelocityTracker;
		velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
		int initialVelocity = (int) velocityTracker.getYVelocity();
		int initialVelocity = (int) velocityTracker.getYVelocity(mActivePointerId);

		if (getChildCount() > 0) {
		if ((Math.abs(initialVelocity) > mMinimumVelocity)) {
		@@ -505,15 +531,39 @@ public class ScrollView extends FrameLayout {
		}
		}

		mActivePointerId = INVALID_POINTER;
		mIsBeingDragged = false;

		if (mVelocityTracker != null) {
		mVelocityTracker.recycle();
		mVelocityTracker = null;
		}
		}
		break;
		case MotionEvent.ACTION_POINTER_UP:
		onSecondaryPointerUp(ev);
		break;
		}
		return true;
		}

		private void onSecondaryPointerUp(MotionEvent ev) {
		final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >>
		MotionEvent.ACTION_POINTER_INDEX_SHIFT;
		final int pointerId = ev.getPointerId(pointerIndex);
		if (pointerId == mActivePointerId) {
		// This was our active pointer going up. Choose a new
		// active pointer and adjust accordingly.
		// TODO: Make this decision more intelligent.
		final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
		mLastMotionY = ev.getY(newPointerIndex);
		mActivePointerId = ev.getPointerId(newPointerIndex);
		if (mVelocityTracker != null) {
		mVelocityTracker.clear();
		}
		}
		}

		@Override
		protected void onOverscrolled(int scrollX, int scrollY,
		boolean clampedX, boolean clampedY) {