Notification: Reuse drawable in Header if Icon unchanged

am: c4337a3569

Change-Id: I8e7da247e9b4d9a9acd46c29ca29d34409bb9453

core/java/android/app/Notification.java

@@ -3256,7 +3256,8 @@ public class Notification implements Parcelable
          * Resets the notification header to its original state
          */
         private void resetNotificationHeader(RemoteViews contentView) {
-            contentView.setImageViewResource(R.id.icon, 0);
+            // Small icon doesn't need to be reset, as it's always set. Resetting would prevent
+            // re-using the drawable when the notification is updated.
             contentView.setBoolean(R.id.notification_header, "setExpanded", false);
             contentView.setTextViewText(R.id.app_name_text, null);
             contentView.setViewVisibility(R.id.chronometer, View.GONE);

core/java/com/android/internal/widget/CachingIconView.java

@@ -0,0 +1,178 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+package com.android.internal.widget;
+
+import android.annotation.DrawableRes;
+import android.annotation.Nullable;
+import android.content.Context;
+import android.content.res.Configuration;
+import android.graphics.Bitmap;
+import android.graphics.drawable.Drawable;
+import android.graphics.drawable.Icon;
+import android.net.Uri;
+import android.text.TextUtils;
+import android.util.AttributeSet;
+import android.view.RemotableViewMethod;
+import android.widget.ImageView;
+import android.widget.RemoteViews;
+
+import libcore.util.Objects;
+
+/**
+ * An ImageView for displaying an Icon. Avoids reloading the Icon when possible.
+ */
+@RemoteViews.RemoteView
+public class CachingIconView extends ImageView {
+
+    private String mLastPackage;
+    private int mLastResId;
+    private boolean mInternalSetDrawable;
+
+    public CachingIconView(Context context, @Nullable AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    @Override
+    @RemotableViewMethod(asyncImpl="setImageIconAsync")
+    public void setImageIcon(@Nullable Icon icon) {
+        if (!testAndSetCache(icon)) {
+            mInternalSetDrawable = true;
+            // This calls back to setImageDrawable, make sure we don't clear the cache there.
+            super.setImageIcon(icon);
+            mInternalSetDrawable = false;
+        }
+    }
+
+    @Override
+    public Runnable setImageIconAsync(@Nullable Icon icon) {
+        resetCache();
+        return super.setImageIconAsync(icon);
+    }
+
+    @Override
+    @RemotableViewMethod(asyncImpl="setImageResourceAsync")
+    public void setImageResource(@DrawableRes int resId) {
+        if (!testAndSetCache(resId)) {
+            mInternalSetDrawable = true;
+            // This calls back to setImageDrawable, make sure we don't clear the cache there.
+            super.setImageResource(resId);
+            mInternalSetDrawable = false;
+        }
+    }
+
+    @Override
+    public Runnable setImageResourceAsync(@DrawableRes int resId) {
+        resetCache();
+        return super.setImageResourceAsync(resId);
+    }
+
+    @Override
+    @RemotableViewMethod(asyncImpl="setImageURIAsync")
+    public void setImageURI(@Nullable Uri uri) {
+        resetCache();
+        super.setImageURI(uri);
+    }
+
+    @Override
+    public Runnable setImageURIAsync(@Nullable Uri uri) {
+        resetCache();
+        return super.setImageURIAsync(uri);
+    }
+
+    @Override
+    public void setImageDrawable(@Nullable Drawable drawable) {
+        if (!mInternalSetDrawable) {
+            // Only clear the cache if we were externally called.
+            resetCache();
+        }
+        super.setImageDrawable(drawable);
+    }
+
+    @Override
+    @RemotableViewMethod
+    public void setImageBitmap(Bitmap bm) {
+        resetCache();
+        super.setImageBitmap(bm);
+    }
+
+    @Override
+    protected void onConfigurationChanged(Configuration newConfig) {
+        super.onConfigurationChanged(newConfig);
+        resetCache();
+    }
+
+    /**
+     * @return true if the currently set image is the same as {@param icon}
+     */
+    private synchronized boolean testAndSetCache(Icon icon) {
+        if (icon != null && icon.getType() == Icon.TYPE_RESOURCE) {
+            String iconPackage = normalizeIconPackage(icon);
+
+            boolean isCached = mLastResId != 0
+                    && icon.getResId() == mLastResId
+                    && Objects.equal(iconPackage, mLastPackage);
+
+            mLastPackage = iconPackage;
+            mLastResId = icon.getResId();
+
+            return isCached;
+        } else {
+            resetCache();
+            return false;
+        }
+    }
+
+    /**
+     * @return true if the currently set image is the same as {@param resId}
+     */
+    private synchronized boolean testAndSetCache(int resId) {
+        boolean isCached;
+        if (resId == 0 || mLastResId == 0) {
+            isCached = false;
+        } else {
+            isCached = resId == mLastResId && null == mLastPackage;
+        }
+        mLastPackage = null;
+        mLastResId = resId;
+        return isCached;
+    }
+
+    /**
+     * Returns the normalized package name of {@param icon}.
+     * @return null if icon is null or if the icons package is null, empty or matches the current
+     *         context. Otherwise returns the icon's package context.
+     */
+    private String normalizeIconPackage(Icon icon) {
+        if (icon == null) {
+            return null;
+        }
+
+        String pkg = icon.getResPackage();
+        if (TextUtils.isEmpty(pkg)) {
+            return null;
+        }
+        if (pkg.equals(mContext.getPackageName())) {
+            return null;
+        }
+        return pkg;
+    }
+
+    private synchronized void resetCache() {
+        mLastResId = 0;
+        mLastPackage = null;
+    }
+}

core/res/res/layout/notification_template_header.xml

@@ -26,7 +26,7 @@
     android:paddingBottom="16dp"
     android:paddingStart="@dimen/notification_content_margin_start"
     android:paddingEnd="16dp">
-    <ImageView
+    <com.android.internal.widget.CachingIconView
         android:id="@+id/icon"
         android:layout_width="18dp"
         android:layout_height="18dp"