Unload widget previews when launcher is not visible

Can save ~1-2MB of RAM

Bug #5104303

Change-Id: I992bec33052f4d2c201e528b5edf384d05960e71

src/com/android/launcher2/AppsCustomizePagedView.java

@@ -393,15 +393,17 @@ public class AppsCustomizePagedView extends PagedViewWithDraggableItems implemen
         mWidgetSpacingLayout.measure(widthSpec, heightSpec);
         mContentWidth = mWidgetSpacingLayout.getContentWidth();
 
+        AppsCustomizeTabHost host = (AppsCustomizeTabHost) getTabHost();
+        final boolean hostIsTransitioning = host.isTransitioning();
+
         // Restore the page
         int page = getPageForComponent(mSaveInstanceStateItemIndex);
-        invalidatePageData(Math.max(0, page));
+        invalidatePageData(Math.max(0, page), hostIsTransitioning);
 
         // Show All Apps cling if we are finished transitioning, otherwise, we will try again when
         // the transition completes in AppsCustomizeTabHost (otherwise the wrong offsets will be
         // returned while animating)
-        AppsCustomizeTabHost host = (AppsCustomizeTabHost) getTabHost();
-        if (!host.isTransitioning()) {
+        if (!hostIsTransitioning) {
             post(new Runnable() {
                 @Override
                 public void run() {
@@ -662,6 +664,18 @@ public class AppsCustomizePagedView extends PagedViewWithDraggableItems implemen
         cancelAllTasks();
     }
 
+    public void clearAllWidgetPages() {
+        cancelAllTasks();
+        int count = getChildCount();
+        for (int i = 0; i < count; i++) {
+            View v = getPageAt(i);
+            if (v instanceof PagedViewGridLayout) {
+                ((PagedViewGridLayout) v).removeAllViewsOnPage();
+                mDirtyPageContent.set(i, true);
+            }
+        }
+    }
+
     private void cancelAllTasks() {
         // Clean up all the async tasks
         Iterator<AppsCustomizeAsyncTask> iter = mRunningTasks.iterator();

src/com/android/launcher2/AppsCustomizeTabHost.java

@@ -366,6 +366,11 @@ public class AppsCustomizeTabHost extends TabHost implements LauncherTransitiona
         }
         mContent.setVisibility(VISIBLE);
 
+        if (!toWorkspace) {
+            // Make sure the current page is loaded (we start loading the side pages after the
+            // transition to prevent slowing down the animation)
+            mAppsCustomizePane.loadAssociatedPages(mAppsCustomizePane.getCurrentPage(), true);
+        }
         if (animated && !delayLauncherTransitionUntilLayout) {
             enableAndBuildHardwareLayer();
         }
@@ -391,6 +396,9 @@ public class AppsCustomizeTabHost extends TabHost implements LauncherTransitiona
             // Dismiss the workspace cling and show the all apps cling (if not already shown)
             l.dismissWorkspaceCling(null);
             mAppsCustomizePane.showAllAppsCling();
+            // Make sure adjacent pages are loaded (we wait until after the transition to
+            // prevent slowing down the animation)
+            mAppsCustomizePane.loadAssociatedPages(mAppsCustomizePane.getCurrentPage());
 
             if (!LauncherApplication.isScreenLarge()) {
                 mAppsCustomizePane.hideScrollingIndicator(false);
@@ -398,6 +406,23 @@ public class AppsCustomizeTabHost extends TabHost implements LauncherTransitiona
         }
     }
 
+    public void onResume() {
+        if (getVisibility() == VISIBLE) {
+            mContent.setVisibility(VISIBLE);
+            // We unload the widget previews when the UI is hidden, so need to reload pages
+            // Load the current page synchronously, and the neighboring pages asynchronously
+            mAppsCustomizePane.loadAssociatedPages(mAppsCustomizePane.getCurrentPage(), true);
+            mAppsCustomizePane.loadAssociatedPages(mAppsCustomizePane.getCurrentPage());
+        }
+    }
+
+    public void onTrimMemory() {
+        mContent.setVisibility(GONE);
+        // Clear the widget pages of all their subviews - this will trigger the widget previews
+        // to delete their bitmaps
+        mAppsCustomizePane.clearAllWidgetPages();
+    }
+
     boolean isTransitioning() {
         return mInTransition;
     }

src/com/android/launcher2/Launcher.java

@@ -36,6 +36,7 @@ import android.content.ActivityNotFoundException;
 import android.content.BroadcastReceiver;
 import android.content.ClipData;
 import android.content.ClipDescription;
+import android.content.ComponentCallbacks2;
 import android.content.ComponentName;
 import android.content.ContentResolver;
 import android.content.Context;
@@ -563,6 +564,7 @@ public final class Launcher extends Activity
         // When we resume Launcher, a different Activity might be responsible for the app
         // market intent, so refresh the icon
         updateAppMarketIcon();
+        mAppsCustomizeTabHost.onResume();
         if (!mWorkspaceLoading) {
             final ViewTreeObserver observer = mWorkspace.getViewTreeObserver();
             final Workspace workspace = mWorkspace;
@@ -2397,6 +2399,14 @@ public final class Launcher extends Activity
         }
     }
 
+    @Override
+    public void onTrimMemory(int level) {
+        super.onTrimMemory(level);
+        if (level == ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN) {
+            mAppsCustomizeTabHost.onTrimMemory();
+        }
+    }
+
     void showWorkspace(boolean animated) {
         Resources res = getResources();
         int stagger = res.getInteger(R.integer.config_appsCustomizeWorkspaceAnimationStagger);

src/com/android/launcher2/PagedView.java

@@ -143,7 +143,7 @@ public abstract class PagedView extends ViewGroup {
 
     private PageSwitchListener mPageSwitchListener;
 
-    private ArrayList<Boolean> mDirtyPageContent;
+    protected ArrayList<Boolean> mDirtyPageContent;
 
     // choice modes
     protected static final int CHOICE_MODE_NONE = 0;

src/com/android/launcher2/PagedViewGridLayout.java

@@ -68,6 +68,12 @@ public class PagedViewGridLayout extends GridLayout implements Page {
                 heightMeasureSpec);
     }
 
+    @Override
+    protected void onDetachedFromWindow() {
+        super.onDetachedFromWindow();
+        mOnLayoutListener = null;
+    }
+
     public void setOnLayoutListener(Runnable r) {
         mOnLayoutListener = r;
     }