Set up view state before attaching, jump drawables if needed

View attachment calls jumpDrawablesToCurrentState(), so the view state
needs to be set up prior to attachment. For views that are already
attached but are being moved to a new position, manually jump.

Cleans up comments in methods that were modified.

Bug: 29978498
Change-Id: Ica27b2c60ad7ee98b9d1e4912c4f8b8c248af88d

1 files changed, 57 insertions, 50 deletions

diff --git a/core/java/android/widget/GridView.java b/core/java/android/widget/GridView.java
index 6d7313da0043..b95aa52c11e9 100644
--- a/core/java/android/widget/GridView.java
+++ b/core/java/android/widget/GridView.java
@@ -1407,72 +1407,73 @@ public class GridView extends AbsListView {
 
 
     /**
-     * Obtain the view and add it to our list of children. The view can be made
-     * fresh, converted from an unused view, or used as is if it was in the
-     * recycle bin.
+     * Obtains the view and adds it to our list of children. The view can be
+     * made fresh, converted from an unused view, or used as is if it was in
+     * the recycle bin.
      *
-     * @param position Logical position in the list
-     * @param y Top or bottom edge of the view to add
-     * @param flow if true, align top edge to y. If false, align bottom edge to
-     *        y.
-     * @param childrenLeft Left edge where children should be positioned
-     * @param selected Is this position selected?
-     * @param where to add new item in the list
+     * @param position logical position in the list
+     * @param y top or bottom edge of the view to add
+     * @param flow {@code true} to align top edge to y, {@code false} to align
+     *             bottom edge to y
+     * @param childrenLeft left edge where children should be positioned
+     * @param selected {@code true} if the position is selected, {@code false}
+     *                 otherwise
+     * @param where position at which to add new item in the list
      * @return View that was added
      */
     private View makeAndAddView(int position, int y, boolean flow, int childrenLeft,
             boolean selected, int where) {
-        View child;
-
         if (!mDataChanged) {
             // Try to use an existing view for this position
-            child = mRecycler.getActiveView(position);
-            if (child != null) {
+            final View activeView = mRecycler.getActiveView(position);
+            if (activeView != null) {
                 // Found it -- we're using an existing child
                 // This just needs to be positioned
-                setupChild(child, position, y, flow, childrenLeft, selected, true, where);
-                return child;
+                setupChild(activeView, position, y, flow, childrenLeft, selected, true, where);
+                return activeView;
             }
         }
 
         // Make a new view for this position, or convert an unused view if
-        // possible
-        child = obtainView(position, mIsScrap);
+        // possible.
+        final View child = obtainView(position, mIsScrap);
 
-        // This needs to be positioned and measured
+        // This needs to be positioned and measured.
         setupChild(child, position, y, flow, childrenLeft, selected, mIsScrap[0], where);
 
         return child;
     }
 
     /**
-     * Add a view as a child and make sure it is measured (if necessary) and
+     * Adds a view as a child and make sure it is measured (if necessary) and
      * positioned properly.
      *
-     * @param child The view to add
-     * @param position The position of the view
-     * @param y The y position relative to which this view will be positioned
-     * @param flow if true, align top edge to y. If false, align bottom edge
-     *        to y.
-     * @param childrenLeft Left edge where children should be positioned
-     * @param selected Is this position selected?
-     * @param recycled Has this view been pulled from the recycle bin? If so it
-     *        does not need to be remeasured.
-     * @param where Where to add the item in the list
+     * @param child the view to add
+     * @param position the position of this child
+     * @param y the y position relative to which this view will be positioned
+     * @param flowDown {@code true} to align top edge to y, {@code false} to
+     *                 align bottom edge to y
+     * @param childrenLeft left edge where children should be positioned
+     * @param selected {@code true} if the position is selected, {@code false}
+     *                 otherwise
+     * @param isAttachedToWindow {@code true} if the view is already attached
+     *                           to the window, e.g. whether it was reused, or
+     *                           {@code false} otherwise
+     * @param where position at which to add new item in the list
      *
      */
-    private void setupChild(View child, int position, int y, boolean flow, int childrenLeft,
-            boolean selected, boolean recycled, int where) {
+    private void setupChild(View child, int position, int y, boolean flowDown, int childrenLeft,
+            boolean selected, boolean isAttachedToWindow, int where) {
         Trace.traceBegin(Trace.TRACE_TAG_VIEW, "setupGridItem");
 
         boolean isSelected = selected && shouldShowSelector();
         final boolean updateChildSelected = isSelected != child.isSelected();
         final int mode = mTouchMode;
-        final boolean isPressed = mode > TOUCH_MODE_DOWN && mode < TOUCH_MODE_SCROLL &&
-                mMotionPosition == position;
+        final boolean isPressed = mode > TOUCH_MODE_DOWN && mode < TOUCH_MODE_SCROLL
+                && mMotionPosition == position;
         final boolean updateChildPressed = isPressed != child.isPressed();
-        
-        boolean needToMeasure = !recycled || updateChildSelected || child.isLayoutRequested();
+        final boolean needToMeasure = !isAttachedToWindow || updateChildSelected
+                || child.isLayoutRequested();
 
         // Respect layout params that are already in the view. Otherwise make
         // some up...
@@ -1483,13 +1484,9 @@ public class GridView extends AbsListView {
         p.viewType = mAdapter.getItemViewType(position);
         p.isEnabled = mAdapter.isEnabled(position);
 
-        if (recycled && !p.forceAdd) {
-            attachViewToParent(child, where, p);
-        } else {
-            p.forceAdd = false;
-            addViewInLayout(child, where, p, true);
-        }
-
+        // Set up view state before attaching the view, since we may need to
+        // rely on the jumpDrawablesToCurrentState() call that occurs as part
+        // of view attachment.
         if (updateChildSelected) {
             child.setSelected(isSelected);
             if (isSelected) {
@@ -1510,6 +1507,21 @@ public class GridView extends AbsListView {
             }
         }
 
+        if (isAttachedToWindow && !p.forceAdd) {
+            attachViewToParent(child, where, p);
+
+            // If the view isn't attached, or if it's attached but for a different
+            // position, then jump the drawables.
+            if (!isAttachedToWindow
+                    || (((AbsListView.LayoutParams) child.getLayoutParams()).scrappedFromPosition)
+                            != position) {
+                child.jumpDrawablesToCurrentState();
+            }
+        } else {
+            p.forceAdd = false;
+            addViewInLayout(child, where, p, true);
+        }
+
         if (needToMeasure) {
             int childHeightSpec = ViewGroup.getChildMeasureSpec(
                     MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), 0, p.height);
@@ -1525,7 +1537,7 @@ public class GridView extends AbsListView {
         final int h = child.getMeasuredHeight();
 
         int childLeft;
-        final int childTop = flow ? y : y - h;
+        final int childTop = flowDown ? y : y - h;
 
         final int layoutDirection = getLayoutDirection();
         final int absoluteGravity = Gravity.getAbsoluteGravity(mGravity, layoutDirection);
@@ -1553,15 +1565,10 @@ public class GridView extends AbsListView {
             child.offsetTopAndBottom(childTop - child.getTop());
         }
 
-        if (mCachingStarted) {
+        if (mCachingStarted && !child.isDrawingCacheEnabled()) {
             child.setDrawingCacheEnabled(true);
         }
 
-        if (recycled && (((AbsListView.LayoutParams)child.getLayoutParams()).scrappedFromPosition)
-                != position) {
-            child.jumpDrawablesToCurrentState();
-        }
-
         Trace.traceEnd(Trace.TRACE_TAG_VIEW);
     }