1 files changed, 82 insertions, 0 deletions
diff --git a/packages/SystemUI/src/com/android/systemui/ImageUtils.java b/packages/SystemUI/src/com/android/systemui/ImageUtils.java
new file mode 100644
index 0000000..540ba20
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/ImageUtils.java
@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2014 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.systemui;
+
+import android.graphics.Bitmap;
+
+/**
+ * Utility class for image analysis and processing.
+ */
+public class ImageUtils {
+
+    // Amount (max is 255) that two channels can differ before the color is no longer "gray".
+    private static final int TOLERANCE = 20;
+
+    // Alpha amount for which values below are considered transparent.
+    private static final int ALPHA_TOLERANCE = 50;
+
+    private int[] mTempBuffer;
+
+    /**
+     * Checks whether a bitmap is grayscale. Grayscale here means "very close to a perfect
+     * gray".
+     */
+    public boolean isGrayscale(Bitmap bitmap) {
+        final int height = bitmap.getHeight();
+        final int width = bitmap.getWidth();
+        int size = height*width;
+
+        ensureBufferSize(size);
+        bitmap.getPixels(mTempBuffer, 0, width, 0, 0, width, height);
+        for (int i = 0; i < size; i++) {
+            if (!isGrayscale(mTempBuffer[i])) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Makes sure that {@code mTempBuffer} has at least length {@code size}.
+     */
+    private void ensureBufferSize(int size) {
+        if (mTempBuffer == null || mTempBuffer.length < size) {
+            mTempBuffer = new int[size];
+        }
+    }
+
+    /**
+     * Classifies a color as grayscale or not. Grayscale here means "very close to a perfect
+     * gray"; if all three channels are approximately equal, this will return true.
+     *
+     * Note that really transparent colors are always grayscale.
+     */
+    public boolean isGrayscale(int color) {
+        int alpha = 0xFF & (color >> 24);
+        if (alpha < ALPHA_TOLERANCE) {
+            return true;
+        }
+
+        int r = 0xFF & (color >> 16);
+        int g = 0xFF & (color >> 8);
+        int b = 0xFF & color;
+
+        return Math.abs(r - g) < TOLERANCE
+                && Math.abs(r - b) < TOLERANCE
+                && Math.abs(g - b) < TOLERANCE;
+    }
+}