Working around incorrect wallpaper offsets being calculated in RTL.

- When launcher starts up, onCreate() triggers the launcher model loader
  to start, which calls bindScreens() to add the workspace pages.  
  However, layout does not happen until the device is unlocked, which 
  means that even though the default screen index and children are there
  the page scrolls are calculated incorrectly, and even in RTL, the 
  page scroll for the 0th screen is zero (it should be at the right
  most edge of the workspace).  This CL works around this by deferring 
  until the first layout after bindScreens() to unlock the wallpaper
  offset from its default bounds.  The workaround is only applied when 
  the launcher activity is first created.

Bug: 28795125
Change-Id: I33da0d7f934f5337d26e69f068f579a32897a837

src/com/android/launcher3/Launcher.java

@@ -1372,6 +1372,9 @@ public class Launcher extends Activity
         mWorkspace.setHapticFeedbackEnabled(false);
         mWorkspace.setOnLongClickListener(this);
         mWorkspace.setup(mDragController);
+        // Until the workspace is bound, ensure that we keep the wallpaper offset locked to the
+        // default state, otherwise we will update to the wrong offsets in RTL
+        mWorkspace.lockWallpaperToDefaultPage();
         mWorkspace.bindAndInitFirstWorkspaceScreen(null /* recycled qsb */);
         mDragController.addDragListener(mWorkspace);
 
@@ -3667,6 +3670,11 @@ public class Launcher extends Activity
             mWorkspace.createCustomContentContainer();
             populateCustomContentContainer();
         }
+
+        // After we have added all the screens, if the wallpaper was locked to the default state,
+        // then notify to indicate that it can be released and a proper wallpaper offset can be
+        // computed before the next layout
+        mWorkspace.unlockWallpaperFromDefaultPageOnNextLayout();
     }
 
     private void bindAddScreens(ArrayList<Long> orderedScreenIds) {

src/com/android/launcher3/Workspace.java

@@ -90,7 +90,6 @@ import com.android.launcher3.widget.PendingAddWidgetInfo;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.concurrent.atomic.AtomicInteger;
 
 /**
  * The workspace is a wide area with a wallpaper and a finite number of pages.
@@ -253,6 +252,7 @@ public class Workspace extends PagedView
     private boolean mWorkspaceFadeInAdjacentScreens;
 
     final WallpaperOffsetInterpolator mWallpaperOffset;
+    private boolean mUnlockWallpaperFromDefaultPageOnLayout;
 
     @Thunk Runnable mDelayedResizeRunnable;
     private Runnable mDelayedSnapToPageRunnable;
@@ -1616,6 +1616,17 @@ public class Workspace extends PagedView
         });
     }
 
+    public void lockWallpaperToDefaultPage() {
+        mWallpaperOffset.setLockToDefaultPage(true);
+    }
+
+    public void unlockWallpaperFromDefaultPageOnNextLayout() {
+        if (mWallpaperOffset.isLockedToDefaultPage()) {
+            mUnlockWallpaperFromDefaultPageOnLayout = true;
+            requestLayout();
+        }
+    }
+
     protected void snapToPage(int whichPage, Runnable r) {
         snapToPage(whichPage, SLOW_PAGE_SNAP_ANIMATION_DURATION, r);
     }
@@ -1797,6 +1808,10 @@ public class Workspace extends PagedView
 
     @Override
     protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
+        if (mUnlockWallpaperFromDefaultPageOnLayout) {
+            mWallpaperOffset.setLockToDefaultPage(false);
+            mUnlockWallpaperFromDefaultPageOnLayout = false;
+        }
         if (mFirstLayout && mCurrentPage >= 0 && mCurrentPage < getChildCount()) {
             mWallpaperOffset.syncWithScroll();
             mWallpaperOffset.jumpToFinal();

src/com/android/launcher3/util/WallpaperOffsetInterpolator.java

@@ -33,6 +33,7 @@ public class WallpaperOffsetInterpolator implements Choreographer.FrameCallback
     private float mFinalOffset = 0.0f;
     private float mCurrentOffset = 0.5f; // to force an initial update
     private boolean mWaitingForUpdate;
+    private boolean mLockedToDefaultPage;
 
     private boolean mAnimating;
     private long mAnimationStartTime;
@@ -68,6 +69,17 @@ public class WallpaperOffsetInterpolator implements Choreographer.FrameCallback
         }
     }
 
+    /**
+     * Locks the wallpaper offset to the offset in the default state of Launcher.
+     */
+    public void setLockToDefaultPage(boolean lockToDefaultPage) {
+        mLockedToDefaultPage = lockToDefaultPage;
+    }
+
+    public boolean isLockedToDefaultPage() {
+        return mLockedToDefaultPage;
+    }
+
     public boolean computeScrollOffset() {
         final float oldOffset = mCurrentOffset;
         if (mAnimating) {
@@ -97,7 +109,7 @@ public class WallpaperOffsetInterpolator implements Choreographer.FrameCallback
         // To match the default wallpaper behavior in the system, we default to either the left
         // or right edge on initialization
         int numScrollingPages = getNumScreensExcludingEmptyAndCustom();
-        if (numScrollingPages <= 1) {
+        if (mLockedToDefaultPage || numScrollingPages <= 1) {
             return mIsRtl ? 1f : 0f;
         }
 
@@ -194,7 +206,7 @@ public class WallpaperOffsetInterpolator implements Choreographer.FrameCallback
 
     public void setFinalX(float x) {
         scheduleUpdate();
-        mFinalOffset = Math.max(0f, Math.min(x, 1.0f));
+        mFinalOffset = Math.max(0f, Math.min(x, 1f));
         if (getNumScreensExcludingEmptyAndCustom() != mNumScreens) {
             if (mNumScreens > 0) {
                 // Don't animate if we're going from 0 screens