Reduce RAM requirements of grayscale icon testing

The isGrayscale family of methods is designed to identify
drawables and bitmaps that apps are using in the largeIcon
position to pose as small icons in order to get the
appropriate background treatment (a solid blue or gray block
in KK/JB, or geniune selvedge denim in ICS/HC).

We can optimize this search two ways:

(1) Reject immediately any largeIcon that is larger than
    largeIcons should be (64x64dp). We could one day simply
    reject, or resize, these in the notification manager,
    but regardless these are not plausible smallIcon
    subsitutes. This new constraint is commemorated in the
    new name, isGrayscaleIcon().

(2) Shrink the bitmap even smaller before scanning it slowly
    in Java.  This lets native_drawBitmap do the heavy
    lifting across the entire bitmap; we need only scan a
    few pixels.

Bug: 16513124
Change-Id: I3a2b79130ed2465a4aedfbb5a556db7f8a7aa132

5 files changed, 80 insertions, 31 deletions

diff --git a/core/java/android/app/Notification.java b/core/java/android/app/Notification.java
index 800734a..0470f3a 100644
--- a/core/java/android/app/Notification.java
+++ b/core/java/android/app/Notification.java
@@ -1916,7 +1916,7 @@ public class Notification implements Parcelable
             mPeople = new ArrayList<String>();
 
             mColorUtil = context.getApplicationInfo().targetSdkVersion < Build.VERSION_CODES.L ?
-                    NotificationColorUtil.getInstance() : null;
+                    NotificationColorUtil.getInstance(mContext) : null;
         }
 
         /**
@@ -2889,7 +2889,7 @@ public class Notification implements Parcelable
         }
 
         private void processLegacyAction(Action action, RemoteViews button) {
-            if (!isLegacy() || mColorUtil.isGrayscale(mContext, action.icon)) {
+            if (!isLegacy() || mColorUtil.isGrayscaleIcon(mContext, action.icon)) {
                 button.setTextViewCompoundDrawablesRelativeColorFilter(R.id.action0, 0,
                         mContext.getResources().getColor(R.color.notification_action_color_filter),
                         PorterDuff.Mode.MULTIPLY);
@@ -2908,7 +2908,7 @@ public class Notification implements Parcelable
          * Apply any necessary background to smallIcons being used in the largeIcon spot.
          */
         private void processSmallIconAsLarge(int largeIconId, RemoteViews contentView) {
-            if (!isLegacy() || mColorUtil.isGrayscale(mContext, largeIconId)) {
+            if (!isLegacy() || mColorUtil.isGrayscaleIcon(mContext, largeIconId)) {
                 applyLargeIconBackground(contentView);
             }
         }
@@ -2919,7 +2919,7 @@ public class Notification implements Parcelable
          */
         // TODO: also check bounds, transparency, that sort of thing.
         private void processLargeLegacyIcon(Bitmap largeIcon, RemoteViews contentView) {
-            if (isLegacy() && mColorUtil.isGrayscale(largeIcon)) {
+            if (isLegacy() && mColorUtil.isGrayscaleIcon(largeIcon)) {
                 applyLargeIconBackground(contentView);
             } else {
                 removeLargeIconBackground(contentView);
@@ -2955,7 +2955,7 @@ public class Notification implements Parcelable
          */
         private void processSmallRightIcon(int smallIconDrawableId,
                 RemoteViews contentView) {
-            if (!isLegacy() || mColorUtil.isGrayscale(mContext, smallIconDrawableId)) {
+            if (!isLegacy() || mColorUtil.isGrayscaleIcon(mContext, smallIconDrawableId)) {
                 contentView.setDrawableParameters(R.id.right_icon, false, -1,
                         0xFFFFFFFF,
                         PorterDuff.Mode.SRC_ATOP, -1);
diff --git a/core/java/com/android/internal/util/ImageUtils.java b/core/java/com/android/internal/util/ImageUtils.java
index a5ce6e0..c153904 100644
--- a/core/java/com/android/internal/util/ImageUtils.java
+++ b/core/java/com/android/internal/util/ImageUtils.java
@@ -17,6 +17,10 @@
 package com.android.internal.util;
 
 import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.Matrix;
+import android.graphics.Paint;
+import android.graphics.PorterDuff;
 
 /**
  * Utility class for image analysis and processing.
@@ -31,17 +35,49 @@ public class ImageUtils {
     // Alpha amount for which values below are considered transparent.
     private static final int ALPHA_TOLERANCE = 50;
 
+    // Size of the smaller bitmap we're actually going to scan.
+    private static final int COMPACT_BITMAP_SIZE = 64; // pixels
+
     private int[] mTempBuffer;
+    private Bitmap mTempCompactBitmap;
+    private Canvas mTempCompactBitmapCanvas;
+    private Paint mTempCompactBitmapPaint;
+    private final Matrix mTempMatrix = new Matrix();
 
     /**
      * Checks whether a bitmap is grayscale. Grayscale here means "very close to a perfect
      * gray".
+     *
+     * Instead of scanning every pixel in the bitmap, we first resize the bitmap to no more than
+     * COMPACT_BITMAP_SIZE^2 pixels using filtering. The hope is that any non-gray color elements
+     * will survive the squeezing process, contaminating the result with color.
      */
     public boolean isGrayscale(Bitmap bitmap) {
-        final int height = bitmap.getHeight();
-        final int width = bitmap.getWidth();
-        int size = height*width;
+        int height = bitmap.getHeight();
+        int width = bitmap.getWidth();
+
+        // shrink to a more manageable (yet hopefully no more or less colorful) size
+        if (height > COMPACT_BITMAP_SIZE || width > COMPACT_BITMAP_SIZE) {
+            if (mTempCompactBitmap == null) {
+                mTempCompactBitmap = Bitmap.createBitmap(
+                        COMPACT_BITMAP_SIZE, COMPACT_BITMAP_SIZE, Bitmap.Config.ARGB_8888
+                );
+                mTempCompactBitmapCanvas = new Canvas(mTempCompactBitmap);
+                mTempCompactBitmapPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
+                mTempCompactBitmapPaint.setFilterBitmap(true);
+            }
+            mTempMatrix.reset();
+            mTempMatrix.setScale(
+                    (float) COMPACT_BITMAP_SIZE / width,
+                    (float) COMPACT_BITMAP_SIZE / height,
+                    0, 0);
+            mTempCompactBitmapCanvas.drawColor(0, PorterDuff.Mode.SRC); // select all, erase
+            mTempCompactBitmapCanvas.drawBitmap(bitmap, mTempMatrix, mTempCompactBitmapPaint);
+            bitmap = mTempCompactBitmap;
+            width = height = COMPACT_BITMAP_SIZE;
+        }
 
+        final int size = height*width;
         ensureBufferSize(size);
         bitmap.getPixels(mTempBuffer, 0, width, 0, 0, width, height);
         for (int i = 0; i < size; i++) {
diff --git a/core/java/com/android/internal/util/NotificationColorUtil.java b/core/java/com/android/internal/util/NotificationColorUtil.java
index 665055c..3249ea3 100644
--- a/core/java/com/android/internal/util/NotificationColorUtil.java
+++ b/core/java/com/android/internal/util/NotificationColorUtil.java
@@ -50,23 +50,36 @@ public class NotificationColorUtil {
     private final WeakHashMap<Bitmap, Pair<Boolean, Integer>> mGrayscaleBitmapCache =
             new WeakHashMap<Bitmap, Pair<Boolean, Integer>>();
 
-    public static NotificationColorUtil getInstance() {
+    private final int mGrayscaleIconMaxSize; // @dimen/notification_large_icon_width (64dp)
+
+    public static NotificationColorUtil getInstance(Context context) {
         synchronized (sLock) {
             if (sInstance == null) {
-                sInstance = new NotificationColorUtil();
+                sInstance = new NotificationColorUtil(context);
             }
             return sInstance;
         }
     }
 
+    private NotificationColorUtil(Context context) {
+        mGrayscaleIconMaxSize = context.getResources().getDimensionPixelSize(
+                com.android.internal.R.dimen.notification_large_icon_width);
+    }
+
     /**
-     * Checks whether a bitmap is grayscale. Grayscale here means "very close to a perfect
-     * gray".
+     * Checks whether a Bitmap is a small grayscale icon.
+     * Grayscale here means "very close to a perfect gray"; icon means "no larger than 64dp".
      *
      * @param bitmap The bitmap to test.
-     * @return Whether the bitmap is grayscale.
+     * @return True if the bitmap is grayscale; false if it is color or too large to examine.
      */
-    public boolean isGrayscale(Bitmap bitmap) {
+    public boolean isGrayscaleIcon(Bitmap bitmap) {
+        // quick test: reject large bitmaps
+        if (bitmap.getWidth() > mGrayscaleIconMaxSize
+                || bitmap.getHeight() > mGrayscaleIconMaxSize) {
+            return false;
+        }
+
         synchronized (sLock) {
             Pair<Boolean, Integer> cached = mGrayscaleBitmapCache.get(bitmap);
             if (cached != null) {
@@ -92,22 +105,22 @@ public class NotificationColorUtil {
     }
 
     /**
-     * Checks whether a drawable is grayscale. Grayscale here means "very close to a perfect
-     * gray".
+     * Checks whether a Drawable is a small grayscale icon.
+     * Grayscale here means "very close to a perfect gray"; icon means "no larger than 64dp".
      *
      * @param d The drawable to test.
-     * @return Whether the drawable is grayscale.
+     * @return True if the bitmap is grayscale; false if it is color or too large to examine.
      */
-    public boolean isGrayscale(Drawable d) {
+    public boolean isGrayscaleIcon(Drawable d) {
         if (d == null) {
             return false;
         } else if (d instanceof BitmapDrawable) {
             BitmapDrawable bd = (BitmapDrawable) d;
-            return bd.getBitmap() != null && isGrayscale(bd.getBitmap());
+            return bd.getBitmap() != null && isGrayscaleIcon(bd.getBitmap());
         } else if (d instanceof AnimationDrawable) {
             AnimationDrawable ad = (AnimationDrawable) d;
             int count = ad.getNumberOfFrames();
-            return count > 0 && isGrayscale(ad.getFrame(0));
+            return count > 0 && isGrayscaleIcon(ad.getFrame(0));
         } else if (d instanceof VectorDrawable) {
             // We just assume you're doing the right thing if using vectors
             return true;
@@ -117,16 +130,16 @@ public class NotificationColorUtil {
     }
 
     /**
-     * Checks whether a drawable with a resoure id is grayscale. Grayscale here means "very close
-     * to a perfect gray".
+     * Checks whether a drawable with a resoure id is a small grayscale icon.
+     * Grayscale here means "very close to a perfect gray"; icon means "no larger than 64dp".
      *
      * @param context The context to load the drawable from.
-     * @return Whether the drawable is grayscale.
+     * @return True if the bitmap is grayscale; false if it is color or too large to examine.
      */
-    public boolean isGrayscale(Context context, int drawableResId) {
+    public boolean isGrayscaleIcon(Context context, int drawableResId) {
         if (drawableResId != 0) {
             try {
-                return isGrayscale(context.getDrawable(drawableResId));
+                return isGrayscaleIcon(context.getDrawable(drawableResId));
             } catch (Resources.NotFoundException ex) {
                 Log.e(TAG, "Drawable not found: " + drawableResId);
                 return false;
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java b/packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java
index ce29407..f691411 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java
@@ -38,9 +38,6 @@ import android.content.pm.UserInfo;
 import android.content.res.Configuration;
 import android.content.res.Resources;
 import android.database.ContentObserver;
-import android.graphics.Bitmap;
-import android.graphics.BitmapFactory;
-import android.graphics.Color;
 import android.graphics.drawable.Drawable;
 import android.os.AsyncTask;
 import android.os.Build;
@@ -177,7 +174,7 @@ public abstract class BaseStatusBar extends SystemUI implements
     // public mode, private notifications, etc
     private boolean mLockscreenPublicMode = false;
     private final SparseBooleanArray mUsersAllowingPrivateNotifications = new SparseBooleanArray();
-    private NotificationColorUtil mNotificationColorUtil = NotificationColorUtil.getInstance();
+    private NotificationColorUtil mNotificationColorUtil;
 
     private UserManager mUserManager;
 
@@ -435,6 +432,8 @@ public abstract class BaseStatusBar extends SystemUI implements
         mDevicePolicyManager = (DevicePolicyManager)mContext.getSystemService(
                 Context.DEVICE_POLICY_SERVICE);
 
+        mNotificationColorUtil = NotificationColorUtil.getInstance(mContext);
+
         mNotificationData = new NotificationData(this);
 
         mDreamManager = IDreamManager.Stub.asInterface(
@@ -1305,7 +1304,7 @@ public abstract class BaseStatusBar extends SystemUI implements
 
             Drawable iconDrawable = StatusBarIconView.getIcon(mContext, ic);
             icon.setImageDrawable(iconDrawable);
-            if (mNotificationColorUtil.isGrayscale(iconDrawable)) {
+            if (mNotificationColorUtil.isGrayscaleIcon(iconDrawable)) {
                 icon.setBackgroundResource(
                         com.android.internal.R.drawable.notification_icon_legacy_bg);
                 int padding = mContext.getResources().getDimensionPixelSize(
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/NotificationOverflowIconsView.java b/packages/SystemUI/src/com/android/systemui/statusbar/NotificationOverflowIconsView.java
index c75bd28..c4c9dac 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/NotificationOverflowIconsView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/NotificationOverflowIconsView.java
@@ -36,7 +36,7 @@ public class NotificationOverflowIconsView extends IconMerger {
     private TextView mMoreText;
     private int mTintColor;
     private int mIconSize;
-    private NotificationColorUtil mNotificationColorUtil = new NotificationColorUtil();
+    private NotificationColorUtil mNotificationColorUtil;
 
     public NotificationOverflowIconsView(Context context, AttributeSet attrs) {
         super(context, attrs);
@@ -45,6 +45,7 @@ public class NotificationOverflowIconsView extends IconMerger {
     @Override
     protected void onFinishInflate() {
         super.onFinishInflate();
+        mNotificationColorUtil = NotificationColorUtil.getInstance(getContext());
         mTintColor = getResources().getColor(R.color.keyguard_overflow_content_color);
         mIconSize = getResources().getDimensionPixelSize(
                 com.android.internal.R.dimen.status_bar_icon_size);