From 818328c482092655cea6296b9dc99279e473ea93 Mon Sep 17 00:00:00 2001
From: John Reck <jreck@google.com>
Date: Tue, 9 May 2023 17:50:33 -0400
Subject: [PATCH] Support decoding gainmaps to alpha8 with BitmapFactory.

Bug: 271174821
Test: android.graphics.cts.GainmapTest
Change-Id: Ifdb285ea3f6bb6a3de44b216d1b4bb2c1826469a
---
 libs/hwui/jni/BitmapFactory.cpp | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/libs/hwui/jni/BitmapFactory.cpp b/libs/hwui/jni/BitmapFactory.cpp
index 38d17de166e98..8abcd9a59122d 100644
--- a/libs/hwui/jni/BitmapFactory.cpp
+++ b/libs/hwui/jni/BitmapFactory.cpp
@@ -194,7 +194,11 @@ static bool decodeGainmap(std::unique_ptr<SkStream> gainmapStream, const SkGainm
         ALOGE("Can not create a codec for Gainmap.");
         return false;
     }
-    SkColorType decodeColorType = codec->computeOutputColorType(kN32_SkColorType);
+    SkColorType decodeColorType = kN32_SkColorType;
+    if (codec->getInfo().colorType() == kGray_8_SkColorType) {
+        decodeColorType = kGray_8_SkColorType;
+    }
+    decodeColorType = codec->computeOutputColorType(decodeColorType);
     sk_sp<SkColorSpace> decodeColorSpace = codec->computeOutputColorSpace(decodeColorType, nullptr);
 
     SkISize size = codec->getSampledDimensions(sampleSize);
@@ -217,7 +221,11 @@ static bool decodeGainmap(std::unique_ptr<SkStream> gainmapStream, const SkGainm
     const SkImageInfo decodeInfo = SkImageInfo::Make(size.width(), size.height(), decodeColorType,
                                                      alphaType, decodeColorSpace);
 
-    const SkImageInfo& bitmapInfo = decodeInfo;
+    SkImageInfo bitmapInfo = decodeInfo;
+    if (decodeColorType == kGray_8_SkColorType) {
+        // We treat gray8 as alpha8 in Bitmap's API surface
+        bitmapInfo = bitmapInfo.makeColorType(kAlpha_8_SkColorType);
+    }
     SkBitmap decodeBitmap;
     sk_sp<Bitmap> nativeBitmap = nullptr;