Fix misc. bugs in AbsListView smooth scrolling. (e69370e1) · Commits · e / os / android_frameworks_base

core/java/android/widget/AbsListView.java

+93 −11

Original line number	Diff line number	Diff line
		@@ -3985,7 +3985,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
		}

		class PositionScroller implements Runnable {
		private static final int SCROLL_DURATION = 400;
		private static final int SCROLL_DURATION = 200;

		private static final int MOVE_DOWN_POS = 1;
		private static final int MOVE_UP_POS = 2;
		@@ -4006,21 +4006,35 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
		mExtraScroll = ViewConfiguration.get(mContext).getScaledFadingEdgeLength();
		}

		void start(int position) {
		void start(final int position) {
		stop();

		final int childCount = getChildCount();
		if (childCount == 0) {
		// Can't scroll without children.
		if (mDataChanged) {
		// But we might have something in a minute.
		post(new Runnable() {
		@Override public void run() {
		start(position);
		}
		});
		}
		return;
		}

		final int firstPos = mFirstPosition;
		final int lastPos = firstPos + getChildCount() - 1;
		final int lastPos = firstPos + childCount - 1;

		int viewTravelCount;
		if (position <= firstPos) {
		if (position < firstPos) {
		viewTravelCount = firstPos - position + 1;
		mMode = MOVE_UP_POS;
		} else if (position >= lastPos) {
		} else if (position > lastPos) {
		viewTravelCount = position - lastPos + 1;
		mMode = MOVE_DOWN_POS;
		} else {
		// Already on screen, nothing to do
		scrollToVisible(position, INVALID_POSITION, SCROLL_DURATION);
		return;
		}

		@@ -4036,7 +4050,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
		postOnAnimation(this);
		}

		void start(int position, int boundPosition) {
		void start(final int position, final int boundPosition) {
		stop();

		if (boundPosition == INVALID_POSITION) {
		@@ -4044,11 +4058,25 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
		return;
		}

		final int childCount = getChildCount();
		if (childCount == 0) {
		// Can't scroll without children.
		if (mDataChanged) {
		// But we might have something in a minute.
		post(new Runnable() {
		@Override public void run() {
		start(position, boundPosition);
		}
		});
		}
		return;
		}

		final int firstPos = mFirstPosition;
		final int lastPos = firstPos + getChildCount() - 1;
		final int lastPos = firstPos + childCount - 1;

		int viewTravelCount;
		if (position <= firstPos) {
		if (position < firstPos) {
		final int boundPosFromLast = lastPos - boundPosition;
		if (boundPosFromLast < 1) {
		// Moving would shift our bound position off the screen. Abort.
		@@ -4064,7 +4092,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
		viewTravelCount = posTravel;
		mMode = MOVE_UP_POS;
		}
		} else if (position >= lastPos) {
		} else if (position > lastPos) {
		final int boundPosFromFirst = boundPosition - firstPos;
		if (boundPosFromFirst < 1) {
		// Moving would shift our bound position off the screen. Abort.
		@@ -4081,7 +4109,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
		mMode = MOVE_DOWN_POS;
		}
		} else {
		// Already on screen, nothing to do
		scrollToVisible(position, boundPosition, SCROLL_DURATION);
		return;
		}

		@@ -4137,6 +4165,60 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
		postOnAnimation(this);
		}

		/**
		* Scroll such that targetPos is in the visible padded region without scrolling
		* boundPos out of view. Assumes targetPos is onscreen.
		*/
		void scrollToVisible(int targetPos, int boundPos, int duration) {
		final int firstPos = mFirstPosition;
		final int childCount = getChildCount();
		final int lastPos = firstPos + childCount - 1;
		final int paddedTop = mListPadding.top;
		final int paddedBottom = getHeight() - mListPadding.bottom;

		if (targetPos < firstPos \|\| targetPos > lastPos) {
		Log.w(TAG, "scrollToVisible called with targetPos " + targetPos +
		" not visible [" + firstPos + ", " + lastPos + "]");
		}
		if (boundPos < firstPos \|\| boundPos > lastPos) {
		// boundPos doesn't matter, it's already offscreen.
		boundPos = INVALID_POSITION;
		}

		final View targetChild = getChildAt(targetPos - firstPos);
		final int targetTop = targetChild.getTop();
		final int targetBottom = targetChild.getBottom();
		int scrollBy = 0;

		if (targetBottom > paddedBottom) {
		scrollBy = targetBottom - paddedBottom;
		}
		if (targetTop < paddedTop) {
		scrollBy = targetTop - paddedTop;
		}

		if (scrollBy == 0) {
		return;
		}

		if (boundPos >= 0) {
		final View boundChild = getChildAt(boundPos - firstPos);
		final int boundTop = boundChild.getTop();
		final int boundBottom = boundChild.getBottom();
		final int absScroll = Math.abs(scrollBy);

		if (scrollBy < 0 && boundBottom + absScroll > paddedBottom) {
		// Don't scroll the bound view off the bottom of the screen.
		scrollBy = Math.max(0, boundBottom - paddedBottom);
		} else if (scrollBy > 0 && boundTop - absScroll < paddedTop) {
		// Don't scroll the bound view off the top of the screen.
		scrollBy = Math.min(0, boundTop - paddedTop);
		}
		}

		smoothScrollBy(scrollBy, duration);
		}

		void stop() {
		removeCallbacks(this);
		}