Limit the maximum size of small notification icons

Right now, the size of small notification icons is unbounded and can cause big memory usage spikes (easily measured as 50MB+). This limits the maximum size of small icon when its set as a bitmap.

Bug:193720474
Bug:209044537

Test: manual via test app
Test: atest NotificationTest
Change-Id: I684fe29d5b473d86280035e00298c8e59f47dbb7

core/java/android/app/Notification.java

@@ -6712,6 +6712,18 @@ public class Notification implements Parcelable
             return;
         }
         boolean isLowRam = ActivityManager.isLowRamDeviceStatic();
+
+        if (mSmallIcon != null
+                // Only bitmap icons can be downscaled.
+                && (mSmallIcon.getType() == Icon.TYPE_BITMAP
+                        || mSmallIcon.getType() == Icon.TYPE_ADAPTIVE_BITMAP)) {
+            Resources resources = context.getResources();
+            int maxSize = resources.getDimensionPixelSize(
+                    isLowRam ? R.dimen.notification_small_icon_size_low_ram
+                            : R.dimen.notification_small_icon_size);
+            mSmallIcon.scaleDownIfNecessary(maxSize, maxSize);
+        }
+
         if (mLargeIcon != null || largeIcon != null) {
             Resources resources = context.getResources();
             Class<? extends Style> style = getNotificationStyle();

core/res/res/values/dimens.xml

@@ -755,6 +755,8 @@
     <dimen name="item_touch_helper_swipe_escape_velocity">120dp</dimen>
     <dimen name="item_touch_helper_swipe_escape_max_velocity">800dp</dimen>
 
+    <!-- The maximum size of the small notification icon. -->
+    <dimen name="notification_small_icon_size">48dp</dimen>
     <!-- The maximum height of any image in a remote view. This is applied to all images in custom remoteviews. This value is determined by the maximum notification height -->
     <dimen name="notification_custom_view_max_image_height">284dp</dimen>
     <!-- The maximum height of any image in a remote view. This is applied to all images in custom remoteviews. This value is determined a maximum notification width -->
@@ -779,6 +781,8 @@
     <!-- The alpha of a disabled notification button -->
     <item type="dimen" format="float" name="notification_action_disabled_alpha">0.5</item>
 
+    <!-- The maximum size of the small notification icon on low memory devices. -->
+    <dimen name="notification_small_icon_size_low_ram">@dimen/notification_small_icon_size</dimen>
     <!-- The maximum height of any image in a remote view. This is applied to all images in custom remoteviews. -->
     <dimen name="notification_custom_view_max_image_height_low_ram">208dp</dimen>
     <!-- The maximum height of any image in a remote view. This is applied to all images in custom remoteviews. -->

core/res/res/values/symbols.xml

@@ -3561,6 +3561,7 @@
   <java-symbol type="style" name="Theme.DeviceDefault.Autofill.Save" />
   <java-symbol type="style" name="Theme.DeviceDefault.Light.Autofill.Save" />
 
+  <java-symbol type="dimen" name="notification_small_icon_size"/>
   <java-symbol type="dimen" name="notification_big_picture_max_height"/>
   <java-symbol type="dimen" name="notification_big_picture_max_width"/>
   <java-symbol type="dimen" name="notification_right_icon_size"/>
@@ -3569,6 +3570,7 @@
   <java-symbol type="dimen" name="notification_custom_view_max_image_height"/>
   <java-symbol type="dimen" name="notification_custom_view_max_image_width"/>
 
+  <java-symbol type="dimen" name="notification_small_icon_size_low_ram"/>
   <java-symbol type="dimen" name="notification_big_picture_max_height_low_ram"/>
   <java-symbol type="dimen" name="notification_big_picture_max_width_low_ram"/>
   <java-symbol type="dimen" name="notification_right_icon_size_low_ram"/>

core/tests/coretests/src/android/app/NotificationTest.java

@@ -39,6 +39,7 @@ import android.content.Intent;
 import android.content.LocusId;
 import android.content.res.ColorStateList;
 import android.content.res.Configuration;
+import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.graphics.Color;
 import android.graphics.drawable.Icon;
@@ -503,6 +504,22 @@ public class NotificationTest {
                 .isGreaterThan(ContrastColorUtil.calculateLuminance(background));
     }
 
+    @Test
+    public void testBuild_ensureSmallIconIsNotTooBig_resizesIcon() {
+        Icon hugeIcon = Icon.createWithBitmap(
+                Bitmap.createBitmap(3000, 3000, Bitmap.Config.ARGB_8888));
+        Notification notification = new Notification.Builder(mContext, "Channel").setSmallIcon(
+                hugeIcon).build();
+
+        Bitmap smallNotificationIcon = notification.getSmallIcon().getBitmap();
+        assertThat(smallNotificationIcon.getWidth()).isEqualTo(
+                mContext.getResources().getDimensionPixelSize(
+                        R.dimen.notification_small_icon_size));
+        assertThat(smallNotificationIcon.getHeight()).isEqualTo(
+                mContext.getResources().getDimensionPixelSize(
+                        R.dimen.notification_small_icon_size));
+    }
+
     @Test
     public void testColors_ensureColors_dayMode_producesValidPalette() {
         Notification.Colors c = new Notification.Colors();