Add COLOR_MODE_A8/ColorMode::A8

Currently unused. This will allow rending into A8 with HWUI

Bug: 193170859
Test: TODO
Change-Id: Ic1e1cb94dfa3dc08cbb174f0a38345d724570372

core/java/android/content/pm/ActivityInfo.java

@@ -304,12 +304,23 @@ public class ActivityInfo extends ComponentInfo implements Parcelable {
      * @see android.R.attr#colorMode
      */
     public static final int COLOR_MODE_HDR = 2;
+    // 3 Corresponds to android::uirenderer::ColorMode::Hdr10.
+    /**
+     * Value of {@link #colorMode} indicating that the activity should use an
+     * 8 bit alpha buffer if the presentation display supports it.
+     *
+     * @see android.R.attr#colorMode
+     * @hide
+     */
+    public static final int COLOR_MODE_A8 = 4;
+
 
     /** @hide */
     @IntDef(prefix = { "COLOR_MODE_" }, value = {
             COLOR_MODE_DEFAULT,
             COLOR_MODE_WIDE_COLOR_GAMUT,
             COLOR_MODE_HDR,
+            COLOR_MODE_A8,
     })
     @Retention(RetentionPolicy.SOURCE)
     public @interface ColorMode {}
@@ -1682,6 +1693,8 @@ public class ActivityInfo extends ComponentInfo implements Parcelable {
                 return "COLOR_MODE_WIDE_COLOR_GAMUT";
             case COLOR_MODE_HDR:
                 return "COLOR_MODE_HDR";
+            case COLOR_MODE_A8:
+                return "COLOR_MODE_A8";
             default:
                 return Integer.toString(colorMode);
         }

core/java/android/view/ViewRootImpl.java

@@ -4916,13 +4916,14 @@ public final class ViewRootImpl implements ViewParent,
         }
     }
 
-    private void updateColorModeIfNeeded(int colorMode) {
+    private void updateColorModeIfNeeded(@ActivityInfo.ColorMode int colorMode) {
         if (mAttachInfo.mThreadedRenderer == null) {
             return;
         }
         // TODO: Centralize this sanitization? Why do we let setting bad modes?
         // Alternatively, can we just let HWUI figure it out? Do we need to care here?
-        if (!getConfiguration().isScreenWideColorGamut()) {
+        if (colorMode != ActivityInfo.COLOR_MODE_A8
+                && !getConfiguration().isScreenWideColorGamut()) {
             colorMode = ActivityInfo.COLOR_MODE_DEFAULT;
         }
         mAttachInfo.mThreadedRenderer.setColorMode(colorMode);

libs/hwui/ColorMode.h

@@ -29,6 +29,8 @@ enum class ColorMode {
     Hdr = 2,
     // HDR Rec2020 + 1010102
     Hdr10 = 3,
+    // Alpha 8
+    A8 = 4,
 };
 
 } // namespace android::uirenderer

libs/hwui/pipeline/skia/SkiaPipeline.cpp

@@ -613,6 +613,10 @@ void SkiaPipeline::setSurfaceColorProperties(ColorMode colorMode) {
             mSurfaceColorType = SkColorType::kRGBA_1010102_SkColorType;
             mSurfaceColorSpace = SkColorSpace::MakeRGB(GetPQSkTransferFunction(), SkNamedGamut::kRec2020);
             break;
+        case ColorMode::A8:
+            mSurfaceColorType = SkColorType::kAlpha_8_SkColorType;
+            mSurfaceColorSpace = nullptr;
+            break;
     }
 }