Apply a new icon cache mechanism for memory improvement

- Avoid loading all app icons at once to decrease memory usage.
- Only load visible icons when entering the apps page.
- Reserve icon placeholder to alleviate icon loading flicker.
- Release icon cache when low memory or leaving apps page.

Bug: 187118427
Bug: 209898662
Test: manual check the smoothness and memory usage of apps pages.
Change-Id: Ifc3c2a73cc88d6e42739df4e8208445afa12e0ea

res/values/config.xml

@@ -586,4 +586,8 @@
     <!-- The ratio to use when using the two-pane settings layout -->
     <item name="config_activity_embed_split_ratio" format="float" type="dimen">0.5</item>
 
+    <!-- The number of visible app icons while entering app list related pages for preloading.
+         Take the "Unrestricted data" page as the example, the visible app icons could be 15
+         on 6.4 inches screen size whether the font size and display size are both small. -->
+    <integer name="config_num_visible_app_icons">20</integer>
 </resources>

src/com/android/settings/SettingsApplication.java

@@ -20,6 +20,7 @@ import android.app.Application;
 
 import com.android.settings.activityembedding.ActivityEmbeddingRulesController;
 import com.android.settings.homepage.SettingsHomepageActivity;
+import com.android.settingslib.applications.AppIconCacheManager;
 
 import java.lang.ref.WeakReference;
 
@@ -44,4 +45,10 @@ public class SettingsApplication extends Application {
     public SettingsHomepageActivity getHomeActivity() {
         return mHomeActivity.get();
     }
+
+    @Override
+    public void onLowMemory() {
+        super.onLowMemory();
+        AppIconCacheManager.getInstance().release();
+    }
 }

src/com/android/settings/applications/manageapplications/ManageApplications.java

@@ -43,6 +43,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageItemInfo;
+import android.graphics.drawable.Drawable;
 import android.net.Uri;
 import android.os.Build;
 import android.os.Bundle;
@@ -125,6 +126,8 @@ import com.android.settings.notification.app.AppNotificationSettings;
 import com.android.settings.widget.LoadingViewController;
 import com.android.settings.wifi.AppStateChangeWifiStateBridge;
 import com.android.settings.wifi.ChangeWifiStateDetails;
+import com.android.settingslib.applications.AppIconCacheManager;
+import com.android.settingslib.applications.AppUtils;
 import com.android.settingslib.applications.ApplicationsState;
 import com.android.settingslib.applications.ApplicationsState.AppEntry;
 import com.android.settingslib.applications.ApplicationsState.AppFilter;
@@ -556,6 +559,7 @@ public class ManageApplications extends InstrumentedFragment
             mApplications.release();
         }
         mRootView = null;
+        AppIconCacheManager.getInstance().release();
     }
 
     @Override
@@ -1323,6 +1327,11 @@ public class ManageApplications extends InstrumentedFragment
             if (DEBUG) {
                 Log.d(TAG, "onRebuildComplete size=" + entries.size());
             }
+
+            // Preload top visible icons of app list.
+            AppUtils.preloadTopIcons(mContext, entries,
+                    mContext.getResources().getInteger(R.integer.config_num_visible_app_icons));
+
             final int filterType = mAppFilter.getFilterType();
             if (filterType == FILTER_APPS_POWER_ALLOWLIST
                     || filterType == FILTER_APPS_POWER_ALLOWLIST_ALL) {
@@ -1480,8 +1489,7 @@ public class ManageApplications extends InstrumentedFragment
             synchronized (entry) {
                 mState.ensureLabelDescription(entry);
                 holder.setTitle(entry.label, entry.labelDescription);
-                mState.ensureIcon(entry);
+                updateIcon(holder, entry);
-                holder.setIcon(entry.icon);
                 updateSummary(holder, entry);
                 updateSwitch(holder, entry);
                 holder.updateDisableView(entry.info);
@@ -1491,6 +1499,20 @@ public class ManageApplications extends InstrumentedFragment
             holder.itemView.setOnClickListener(mManageApplications);
         }
 
+        private void updateIcon(ApplicationViewHolder holder, AppEntry entry) {
+            final Drawable cachedIcon = AppUtils.getIconFromCache(entry);
+            if (cachedIcon != null && entry.mounted) {
+                holder.setIcon(cachedIcon);
+            } else {
+                ThreadUtils.postOnBackgroundThread(() -> {
+                    final Drawable icon = AppUtils.getIcon(mContext, entry);
+                    if (icon != null) {
+                        ThreadUtils.postOnMainThread(() -> holder.setIcon(icon));
+                    }
+                });
+            }
+        }
+
         private void updateSummary(ApplicationViewHolder holder, AppEntry entry) {
             switch (mManageApplications.mListType) {
                 case LIST_TYPE_NOTIFICATION:

src/com/android/settings/datausage/UnrestrictedDataAccess.java

@@ -25,6 +25,7 @@ import android.view.View;
 import com.android.settings.R;
 import com.android.settings.dashboard.DashboardFragment;
 import com.android.settings.search.BaseSearchIndexProvider;
+import com.android.settingslib.applications.AppIconCacheManager;
 import com.android.settingslib.applications.ApplicationsState;
 import com.android.settingslib.applications.ApplicationsState.AppFilter;
 import com.android.settingslib.search.SearchIndexable;
@@ -112,6 +113,12 @@ public class UnrestrictedDataAccess extends DashboardFragment {
         return R.xml.unrestricted_data_access_settings;
     }
 
+    @Override
+    public void onDestroyView() {
+        super.onDestroyView();
+        AppIconCacheManager.getInstance().release();
+    }
+
     public static final BaseSearchIndexProvider SEARCH_INDEX_DATA_PROVIDER =
             new BaseSearchIndexProvider(R.xml.unrestricted_data_access_settings);
 }

src/com/android/settings/datausage/UnrestrictedDataAccessPreference.java

@@ -16,6 +16,7 @@ package com.android.settings.datausage;
 import static com.android.settingslib.RestrictedLockUtilsInternal.checkIfMeteredDataRestricted;
 
 import android.content.Context;
+import android.graphics.drawable.Drawable;
 import android.os.UserHandle;
 import android.view.View;
 
@@ -26,8 +27,10 @@ import com.android.settings.applications.appinfo.AppInfoDashboardFragment;
 import com.android.settings.dashboard.DashboardFragment;
 import com.android.settingslib.RestrictedLockUtils.EnforcedAdmin;
 import com.android.settingslib.RestrictedPreferenceHelper;
+import com.android.settingslib.applications.AppUtils;
 import com.android.settingslib.applications.ApplicationsState;
 import com.android.settingslib.applications.ApplicationsState.AppEntry;
+import com.android.settingslib.utils.ThreadUtils;
 import com.android.settingslib.widget.AppSwitchPreference;
 
 public class UnrestrictedDataAccessPreference extends AppSwitchPreference implements
@@ -39,6 +42,7 @@ public class UnrestrictedDataAccessPreference extends AppSwitchPreference implem
     private final DataSaverBackend mDataSaverBackend;
     private final DashboardFragment mParentFragment;
     private final RestrictedPreferenceHelper mHelper;
+    private Drawable mCacheIcon;
 
     public UnrestrictedDataAccessPreference(final Context context, AppEntry entry,
             ApplicationsState applicationsState, DataSaverBackend dataSaverBackend,
@@ -56,8 +60,13 @@ public class UnrestrictedDataAccessPreference extends AppSwitchPreference implem
                 UserHandle.getUserId(entry.info.uid)));
         updateState();
         setKey(generateKey(mEntry));
-        if (mEntry.icon != null) {
+
-            setIcon(mEntry.icon);
+        mCacheIcon = AppUtils.getIconFromCache(mEntry);
+        if (mCacheIcon != null) {
+            setIcon(mCacheIcon);
+        } else {
+            // Set empty icon as default.
+            setIcon(R.drawable.empty_icon);
         }
     }
 
@@ -101,16 +110,13 @@ public class UnrestrictedDataAccessPreference extends AppSwitchPreference implem
 
     @Override
     public void onBindViewHolder(PreferenceViewHolder holder) {
-        if (mEntry.icon == null) {
+        if (mCacheIcon == null) {
-            holder.itemView.post(new Runnable() {
+            ThreadUtils.postOnBackgroundThread(() -> {
-                @Override
+                final Drawable icon = AppUtils.getIcon(getContext(), mEntry);
-                public void run() {
+                ThreadUtils.postOnMainThread(() -> {
-                    // Ensure we have an icon before binding.
+                    setIcon(icon);
-                    mApplicationsState.ensureIcon(mEntry);
+                    mCacheIcon = icon;
-                    // This might trigger us to bind again, but it gives an easy way to only
+                });
-                    // load the icon once its needed, so its probably worth it.
-                    setIcon(mEntry.icon);
-                }
             });
         }
         final boolean disabledByAdmin = isDisabledByAdmin();

src/com/android/settings/datausage/UnrestrictedDataAccessPreferenceController.java

@@ -29,6 +29,7 @@ import com.android.settings.applications.AppStateBaseBridge;
 import com.android.settings.core.BasePreferenceController;
 import com.android.settings.dashboard.DashboardFragment;
 import com.android.settings.overlay.FeatureFactory;
+import com.android.settingslib.applications.AppUtils;
 import com.android.settingslib.applications.ApplicationsState;
 import com.android.settingslib.applications.ApplicationsState.AppEntry;
 import com.android.settingslib.applications.ApplicationsState.AppFilter;
@@ -125,6 +126,10 @@ public class UnrestrictedDataAccessPreferenceController extends BasePreferenceCo
             return;
         }
 
+        // Preload top visible icons of app list.
+        AppUtils.preloadTopIcons(mContext, apps,
+                mContext.getResources().getInteger(R.integer.config_num_visible_app_icons));
+
         // Create apps key set for removing useless preferences
         final Set<String> appsKeySet = new TreeSet<>();
         // Add or update preferences