Merge "Add theme style flag to WallpaperColors" into oc-dr1-dev
diff --git a/core/java/android/app/WallpaperColors.java b/core/java/android/app/WallpaperColors.java
index 57c7efc..b9d3e75 100644
--- a/core/java/android/app/WallpaperColors.java
+++ b/core/java/android/app/WallpaperColors.java
@@ -26,6 +26,7 @@
 import android.os.Parcelable;
 import android.util.Size;
 
+import com.android.internal.graphics.ColorUtils;
 import com.android.internal.graphics.palette.Palette;
 import com.android.internal.graphics.palette.VariationalKMeansQuantizer;
 
@@ -50,6 +51,14 @@
      */
     public static final int HINT_SUPPORTS_DARK_TEXT = 0x1;
 
+    /**
+     * Specifies that dark theme is preferred over the current wallpaper for best presentation.
+     * <p>
+     * eg. A launcher may set its drawer color to black if this flag is specified.
+     * @hide
+     */
+    public static final int HINT_SUPPORTS_DARK_THEME = 0x2;
+
     // Maximum size that a bitmap can have to keep our calculations sane
     private static final int MAX_BITMAP_SIZE = 112;
 
@@ -61,8 +70,10 @@
     // present in at least MIN_COLOR_OCCURRENCE of the image
     private static final float MIN_COLOR_OCCURRENCE = 0.05f;
 
+    // Decides when dark theme is optimal for this wallpaper
+    private static final float DARK_THEME_MEAN_LUMINANCE = 0.25f;
     // Minimum mean luminosity that an image needs to have to support dark text
-    private static final float BRIGHT_IMAGE_MEAN_LUMINANCE = 0.9f;
+    private static final float BRIGHT_IMAGE_MEAN_LUMINANCE = 0.75f;
     // We also check if the image has dark pixels in it,
     // to avoid bright images with some dark spots.
     private static final float DARK_PIXEL_LUMINANCE = 0.45f;
@@ -169,10 +180,7 @@
             }
         }
 
-        int hints = 0;
-        if (calculateDarkTextSupport(bitmap)) {
-            hints |= HINT_SUPPORTS_DARK_TEXT;
-        }
+        int hints = calculateHints(bitmap);
         return new WallpaperColors(primary, secondary, tertiary, hints);
     }
 
@@ -335,9 +343,9 @@
      * @param source What to read.
      * @return Whether image supports dark text or not.
      */
-    private static boolean calculateDarkTextSupport(Bitmap source) {
+    private static int calculateHints(Bitmap source) {
         if (source == null) {
-            return false;
+            return 0;
         }
 
         int[] pixels = new int[source.getWidth() * source.getHeight()];
@@ -349,22 +357,29 @@
 
         // This bitmap was already resized to fit the maximum allowed area.
         // Let's just loop through the pixels, no sweat!
+        float[] tmpHsl = new float[3];
         for (int i = 0; i < pixels.length; i++) {
-            final float luminance = Color.luminance(pixels[i]);
+            ColorUtils.colorToHSL(pixels[i], tmpHsl);
+            final float luminance = tmpHsl[2];
             final int alpha = Color.alpha(pixels[i]);
-
             // Make sure we don't have a dark pixel mass that will
             // make text illegible.
             if (luminance < DARK_PIXEL_LUMINANCE && alpha != 0) {
                 darkPixels++;
-                if (darkPixels > maxDarkPixels) {
-                    return false;
-                }
             }
-
             totalLuminance += luminance;
         }
-        return totalLuminance / pixels.length > BRIGHT_IMAGE_MEAN_LUMINANCE;
+
+        int hints = 0;
+        double meanLuminance = totalLuminance / pixels.length;
+        if (meanLuminance > BRIGHT_IMAGE_MEAN_LUMINANCE && darkPixels < maxDarkPixels) {
+            hints |= HINT_SUPPORTS_DARK_TEXT;
+        }
+        if (meanLuminance < DARK_THEME_MEAN_LUMINANCE) {
+            hints |= HINT_SUPPORTS_DARK_THEME;
+        }
+
+        return hints;
     }
 
     private static Size calculateOptimalSize(int width, int height) {
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBar.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBar.java
index a882e7a..20c2ad6 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBar.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBar.java
@@ -4576,15 +4576,10 @@
         final boolean useDarkText = mColorExtractor.getColors(which, true /* ignoreVisibility */)
                 .supportsDarkText();
         // And wallpaper defines if QS should be light or dark.
-        boolean useDarkTheme = false;
-        final WallpaperColors systemColors =
-                mColorExtractor.getWallpaperColors(WallpaperManager.FLAG_SYSTEM);
-        if (systemColors != null) {
-            int mainColor = systemColors.getPrimaryColor().toArgb();
-            float[] hsl = new float[3];
-            ColorUtils.colorToHSL(mainColor, hsl);
-            useDarkTheme = hsl[2] < 0.2f;
-        }
+        WallpaperColors systemColors = mColorExtractor
+                .getWallpaperColors(WallpaperManager.FLAG_SYSTEM);
+        final boolean useDarkTheme = systemColors != null
+                && (systemColors.getColorHints() & WallpaperColors.HINT_SUPPORTS_DARK_THEME) != 0;
 
         // Enable/disable dark UI.
         if (isUsingDarkTheme() != useDarkTheme) {
diff --git a/tests/Internal/src/android/app/WallpaperColorsTest.java b/tests/Internal/src/android/app/WallpaperColorsTest.java
new file mode 100644
index 0000000..5bbd82b
--- /dev/null
+++ b/tests/Internal/src/android/app/WallpaperColorsTest.java
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2017 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 android.app;
+
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
+import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@SmallTest
+@RunWith(AndroidJUnit4.class)
+public class WallpaperColorsTest {
+
+    @Test
+    public void supportsDarkTextOverrideTest() {
+        final Color color = Color.valueOf(Color.WHITE);
+        // Default should not support dark text!
+        WallpaperColors colors = new WallpaperColors(color, null, null, 0);
+        Assert.assertTrue("Default behavior is not to support dark text",
+                (colors.getColorHints() & WallpaperColors.HINT_SUPPORTS_DARK_TEXT) == 0);
+
+        // Override it
+        colors = new WallpaperColors(color, null, null, WallpaperColors.HINT_SUPPORTS_DARK_TEXT);
+        Assert.assertFalse("Forcing dark text support doesn't work",
+                (colors.getColorHints() & WallpaperColors.HINT_SUPPORTS_DARK_TEXT) == 0);
+    }
+
+    /**
+     * Sanity check to guarantee that white supports dark text and black doesn't
+     */
+    @Test
+    public void colorHintsTest() {
+        Bitmap image = Bitmap.createBitmap(30, 30, Bitmap.Config.ARGB_8888);
+        Canvas canvas = new Canvas(image);
+
+        canvas.drawColor(Color.WHITE);
+        int hints = WallpaperColors.fromBitmap(image).getColorHints();
+        boolean supportsDarkText = (hints & WallpaperColors.HINT_SUPPORTS_DARK_TEXT) != 0;
+        boolean supportsDarkTheme = (hints & WallpaperColors.HINT_SUPPORTS_DARK_THEME) != 0;
+        Assert.assertTrue("White surface should support dark text", supportsDarkText);
+        Assert.assertFalse("White surface shouldn't support dark theme", supportsDarkTheme);
+
+        canvas.drawColor(Color.BLACK);
+        hints = WallpaperColors.fromBitmap(image).getColorHints();
+        supportsDarkText = (hints & WallpaperColors.HINT_SUPPORTS_DARK_TEXT) != 0;
+        supportsDarkTheme = (hints & WallpaperColors.HINT_SUPPORTS_DARK_THEME) != 0;
+        Assert.assertFalse("Black surface shouldn't support dark text", supportsDarkText);
+        Assert.assertTrue("Black surface should support dark theme", supportsDarkTheme);
+
+        Paint paint = new Paint();
+        paint.setStyle(Paint.Style.FILL);
+        paint.setColor(Color.BLACK);
+        canvas.drawColor(Color.WHITE);
+        canvas.drawRect(0, 0, 8, 8, paint);
+        supportsDarkText = (WallpaperColors.fromBitmap(image)
+                .getColorHints() & WallpaperColors.HINT_SUPPORTS_DARK_TEXT) != 0;
+        Assert.assertFalse("Light surface shouldn't support dark text "
+                + "when it contains dark pixels", supportsDarkText);
+    }
+}