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Commit 86b32601 authored by Phil Weaver's avatar Phil Weaver
Browse files

Improve a11y ordering 

We use ids to break ties when sorting views just to
guarantee that we won't break sorting. But we don't
want to have our swipe order determined by arbitrary
ids.

Before resorting to such a crude tie-breaker, look at
a view's children to try to break a tie using their
bounds. That sort is more based on what's on the
screen, and will also produce the same result from
the same ui.

Bug: 78348191
Test: Switch access order is much more sensible on
Recents. Also ran a11y cts.

Change-Id: I918eae3b0d27e889a53d05a6ebe925e38ce5d7b4
parent 88a54220

core/java/android/view/ViewGroup.java

+69 −13
Original line number Diff line number Diff line
@@ -8574,6 +8574,8 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager 


        private final Rect mLocation = new Rect();



        private ViewGroup mRoot;



        public View mView;



        private int mLayoutDirection;
@@ -8603,47 +8605,100 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager 
                return 1;

            }



            int boundsResult = compareBoundsOfTree(this, another);

            if (boundsResult != 0) {

                return boundsResult;

            }



            // Just break the tie somehow. The accessibility ids are unique

            // and stable, hence this is deterministic tie breaking.

            return mView.getAccessibilityViewId() - another.mView.getAccessibilityViewId();

        }



        /**

         * Compare two views based on their bounds. Use the bounds of their children to break ties.

         *

         * @param holder1 Holder of first view to compare

         * @param holder2 Holder of second view to compare. Must have the same root at holder1.

         * @return The compare result, with equality if no good comparison was found.

         */

        private static int compareBoundsOfTree(

                ViewLocationHolder holder1, ViewLocationHolder holder2) {

            if (sComparisonStrategy == COMPARISON_STRATEGY_STRIPE) {

                // First is above second.

                if (mLocation.bottom - another.mLocation.top <= 0) {

                if (holder1.mLocation.bottom - holder2.mLocation.top <= 0) {

                    return -1;

                }

                // First is below second.

                if (mLocation.top - another.mLocation.bottom >= 0) {

                if (holder1.mLocation.top - holder2.mLocation.bottom >= 0) {

                    return 1;

                }

            }



            // We are ordering left-to-right, top-to-bottom.

            if (mLayoutDirection == LAYOUT_DIRECTION_LTR) {

                final int leftDifference = mLocation.left - another.mLocation.left;

            if (holder1.mLayoutDirection == LAYOUT_DIRECTION_LTR) {

                final int leftDifference = holder1.mLocation.left - holder2.mLocation.left;

                if (leftDifference != 0) {

                    return leftDifference;

                }

            } else { // RTL

                final int rightDifference = mLocation.right - another.mLocation.right;

                final int rightDifference = holder1.mLocation.right - holder2.mLocation.right;

                if (rightDifference != 0) {

                    return -rightDifference;

                }

            }

            // We are ordering left-to-right, top-to-bottom.

            final int topDifference = mLocation.top - another.mLocation.top;

            final int topDifference = holder1.mLocation.top - holder2.mLocation.top;

            if (topDifference != 0) {

                return topDifference;

            }

            // Break tie by height.

            final int heightDiference = mLocation.height() - another.mLocation.height();

            final int heightDiference = holder1.mLocation.height() - holder2.mLocation.height();

            if (heightDiference != 0) {

                return -heightDiference;

            }

            // Break tie by width.

            final int widthDiference = mLocation.width() - another.mLocation.width();

            if (widthDiference != 0) {

                return -widthDiference;

            final int widthDifference = holder1.mLocation.width() - holder2.mLocation.width();

            if (widthDifference != 0) {

                return -widthDifference;

            }



            // Find a child of each view with different screen bounds.

            final Rect view1Bounds = new Rect();

            final Rect view2Bounds = new Rect();

            final Rect tempRect = new Rect();

            holder1.mView.getBoundsOnScreen(view1Bounds, true);

            holder2.mView.getBoundsOnScreen(view2Bounds, true);

            final View child1 = holder1.mView.findViewByPredicateTraversal((view) -> {

                view.getBoundsOnScreen(tempRect, true);

                return !tempRect.equals(view1Bounds);

            }, null);

            final View child2 = holder2.mView.findViewByPredicateTraversal((view) -> {

                view.getBoundsOnScreen(tempRect, true);

                return !tempRect.equals(view2Bounds);

            }, null);





            // Compare the children recursively

            if ((child1 != null) && (child2 != null)) {

                final ViewLocationHolder childHolder1 =

                        ViewLocationHolder.obtain(holder1.mRoot, child1);

                final ViewLocationHolder childHolder2 =

                        ViewLocationHolder.obtain(holder1.mRoot, child2);

                return compareBoundsOfTree(childHolder1, childHolder2);

            }



            // If only one has a child, use that one

            if (child1 != null) {

                return 1;

            }

            // Just break the tie somehow. The accessibliity ids are unique

            // and stable, hence this is deterministic tie breaking.

            return mView.getAccessibilityViewId() - another.mView.getAccessibilityViewId();



            if (child2 != null) {

                return -1;

            }



            // Give up

            return 0;

        }



        private void init(ViewGroup root, View view) {
@@ -8651,6 +8706,7 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager 
            view.getDrawingRect(viewLocation);

            root.offsetDescendantRectToMyCoords(view, viewLocation);

            mView = view;

            mRoot = root;

            mLayoutDirection = root.getLayoutDirection();

        }