Merge "Only use the gainmap shader if we might need it" into main am: 5c8faa654d

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/2833770

Change-Id: Id298bf47aac1869ab97cae1aec74a4feb476a0eb
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

2 files changed, 34 insertions, 2 deletions

diff --git a/libs/hwui/SkiaCanvas.cpp b/libs/hwui/SkiaCanvas.cpp
index 8394c3cd4175..ea9b6c90a65f 100644
--- a/libs/hwui/SkiaCanvas.cpp
+++ b/libs/hwui/SkiaCanvas.cpp
@@ -588,10 +588,40 @@ void SkiaCanvas::drawMesh(const Mesh& mesh, sk_sp<SkBlender> blender, const Pain
 // Canvas draw operations: Bitmaps
 // ----------------------------------------------------------------------------
 
+bool SkiaCanvas::useGainmapShader(Bitmap& bitmap) {
+    // If the bitmap doesn't have a gainmap, don't use the gainmap shader
+    if (!bitmap.hasGainmap()) return false;
+
+    // If we don't have an owned canvas, then we're either hardware accelerated or drawing
+    // to a picture - use the gainmap shader out of caution. Ideally a picture canvas would
+    // use a drawable here instead to defer making that decision until the last possible
+    // moment
+    if (!mCanvasOwned) return true;
+
+    auto info = mCanvasOwned->imageInfo();
+
+    // If it's an unknown colortype then it's not a bitmap-backed canvas
+    if (info.colorType() == SkColorType::kUnknown_SkColorType) return true;
+
+    skcms_TransferFunction tfn;
+    info.colorSpace()->transferFn(&tfn);
+
+    auto transferType = skcms_TransferFunction_getType(&tfn);
+    switch (transferType) {
+        case skcms_TFType_HLGish:
+        case skcms_TFType_HLGinvish:
+        case skcms_TFType_PQish:
+            return true;
+        case skcms_TFType_Invalid:
+        case skcms_TFType_sRGBish:
+            return false;
+    }
+}
+
 void SkiaCanvas::drawBitmap(Bitmap& bitmap, float left, float top, const Paint* paint) {
     auto image = bitmap.makeImage();
 
-    if (bitmap.hasGainmap()) {
+    if (useGainmapShader(bitmap)) {
         Paint gainmapPaint = paint ? *paint : Paint();
         sk_sp<SkShader> gainmapShader = uirenderer::MakeGainmapShader(
                 image, bitmap.gainmap()->bitmap->makeImage(), bitmap.gainmap()->info,
@@ -618,7 +648,7 @@ void SkiaCanvas::drawBitmap(Bitmap& bitmap, float srcLeft, float srcTop, float s
     SkRect srcRect = SkRect::MakeLTRB(srcLeft, srcTop, srcRight, srcBottom);
     SkRect dstRect = SkRect::MakeLTRB(dstLeft, dstTop, dstRight, dstBottom);
 
-    if (bitmap.hasGainmap()) {
+    if (useGainmapShader(bitmap)) {
         Paint gainmapPaint = paint ? *paint : Paint();
         sk_sp<SkShader> gainmapShader = uirenderer::MakeGainmapShader(
                 image, bitmap.gainmap()->bitmap->makeImage(), bitmap.gainmap()->info,
diff --git a/libs/hwui/SkiaCanvas.h b/libs/hwui/SkiaCanvas.h
index b785989f35cb..9cb50ed5b081 100644
--- a/libs/hwui/SkiaCanvas.h
+++ b/libs/hwui/SkiaCanvas.h
@@ -223,6 +223,8 @@ private:
 
     void drawPoints(const float* points, int count, const Paint& paint, SkCanvas::PointMode mode);
 
+    bool useGainmapShader(Bitmap& bitmap);
+
     class Clip;
 
     std::unique_ptr<SkCanvas> mCanvasOwned;  // Might own a canvas we allocated.