Bug 1257939 - initialize BGRX alpha channel to opaque when clearing and ignore uninitialized alpha in texture clients. r=mchang

gfx/2d/2D.h

@@ -1255,7 +1255,7 @@ public:
     CreateRecordingDrawTarget(DrawEventRecorder *aRecorder, DrawTarget *aDT);
 
   static already_AddRefed<DrawTarget>
-    CreateDrawTargetForData(BackendType aBackend, unsigned char* aData, const IntSize &aSize, int32_t aStride, SurfaceFormat aFormat);
+    CreateDrawTargetForData(BackendType aBackend, unsigned char* aData, const IntSize &aSize, int32_t aStride, SurfaceFormat aFormat, bool aUninitialized = false);
 
   static already_AddRefed<ScaledFont>
     CreateScaledFontForNativeFont(const NativeFont &aNativeFont, Float aSize);

gfx/2d/DrawTargetSkia.cpp

@@ -940,10 +940,10 @@ VerifyRGBXFormat(uint8_t* aData, const IntSize &aSize, const int32_t aStride, Su
 #endif
 
 void
-DrawTargetSkia::Init(unsigned char* aData, const IntSize &aSize, int32_t aStride, SurfaceFormat aFormat)
+DrawTargetSkia::Init(unsigned char* aData, const IntSize &aSize, int32_t aStride, SurfaceFormat aFormat, bool aUninitialized)
 {
   MOZ_ASSERT((aFormat != SurfaceFormat::B8G8R8X8) ||
-              VerifyRGBXFormat(aData, aSize, aStride, aFormat));
+              aUninitialized || VerifyRGBXFormat(aData, aSize, aStride, aFormat));
 
   SkBitmap bitmap;
   bitmap.setInfo(MakeSkiaImageInfo(aSize, aFormat), aStride);

gfx/2d/DrawTargetSkia.h

@@ -111,7 +111,7 @@ public:
   virtual void *GetNativeSurface(NativeSurfaceType aType) override;
 
   bool Init(const IntSize &aSize, SurfaceFormat aFormat);
-  void Init(unsigned char* aData, const IntSize &aSize, int32_t aStride, SurfaceFormat aFormat);
+  void Init(unsigned char* aData, const IntSize &aSize, int32_t aStride, SurfaceFormat aFormat, bool aUninitialized = false);
 
 #ifdef USE_SKIA_GPU
   bool InitWithGrContext(GrContext* aGrContext,

gfx/2d/Factory.cpp

@@ -384,7 +384,8 @@ Factory::CreateDrawTargetForData(BackendType aBackend,
                                  unsigned char *aData,
                                  const IntSize &aSize,
                                  int32_t aStride,
-                                 SurfaceFormat aFormat)
+                                 SurfaceFormat aFormat,
+                                 bool aUninitialized)
 {
   MOZ_ASSERT(aData);
   if (!AllowedSurfaceSize(aSize)) {
@@ -400,7 +401,7 @@ Factory::CreateDrawTargetForData(BackendType aBackend,
     {
       RefPtr<DrawTargetSkia> newTarget;
       newTarget = new DrawTargetSkia();
-      newTarget->Init(aData, aSize, aStride, aFormat);
+      newTarget->Init(aData, aSize, aStride, aFormat, aUninitialized);
       retVal = newTarget;
       break;
     }

gfx/layers/BufferTexture.cpp

@@ -10,6 +10,7 @@
 #include "mozilla/gfx/Logging.h"
 #include "mozilla/gfx/2D.h"
 #include "mozilla/fallible.h"
+#include <algorithm>
 
 #ifdef MOZ_WIDGET_GTK
 #include "gfxPlatformGtk.h"
@@ -245,7 +246,7 @@ BufferTextureData::BorrowDrawTarget()
   uint32_t stride = ImageDataSerializer::GetRGBStride(rgb);
   mDrawTarget = gfx::Factory::CreateDrawTargetForData(mMoz2DBackend,
                                                       GetBuffer(), rgb.size(),
-                                                      stride, rgb.format());
+                                                      stride, rgb.format(), true);
 
   if (mDrawTarget) {
     RefPtr<gfx::DrawTarget> dt = mDrawTarget;
@@ -257,7 +258,7 @@ BufferTextureData::BorrowDrawTarget()
   if (mMoz2DBackend != gfx::BackendType::CAIRO) {
     mDrawTarget = gfx::Factory::CreateDrawTargetForData(gfx::BackendType::CAIRO,
                                                         GetBuffer(), rgb.size(),
-                                                        stride, rgb.format());
+                                                        stride, rgb.format(), true);
   }
 
   if (!mDrawTarget) {
@@ -397,7 +398,7 @@ MemoryTextureData::Serialize(SurfaceDescriptor& aOutDescriptor)
   return true;
 }
 
-static bool InitBuffer(uint8_t* buf, size_t bufSize, TextureAllocationFlags aAllocFlags)
+static bool InitBuffer(uint8_t* buf, size_t bufSize, gfx::SurfaceFormat aFormat, TextureAllocationFlags aAllocFlags)
 {
   if (!buf) {
     gfxDebug() << "BufferTextureData: Failed to allocate " << bufSize << " bytes";
@@ -406,8 +407,14 @@ static bool InitBuffer(uint8_t* buf, size_t bufSize, TextureAllocationFlags aAll
 
   if ((aAllocFlags & ALLOC_CLEAR_BUFFER) ||
       (aAllocFlags & ALLOC_CLEAR_BUFFER_BLACK)) {
+    if (aFormat == gfx::SurfaceFormat::B8G8R8X8) {
+      // Even though BGRX was requested, XRGB_UINT32 is what is meant,
+      // so use 0xFF000000 to put alpha in the right place.
+      std::fill_n(reinterpret_cast<uint32_t*>(buf), bufSize / sizeof(uint32_t), 0xFF000000);
+    } else {
       memset(buf, 0, bufSize);
     }
+  }
 
   if (aAllocFlags & ALLOC_CLEAR_BUFFER_WHITE) {
     memset(buf, 0xFF, bufSize);
@@ -436,7 +443,7 @@ MemoryTextureData::Create(gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
   }
 
   uint8_t* buf = new (fallible) uint8_t[bufSize];
-  if (!InitBuffer(buf, bufSize, aAllocFlags)) {
+  if (!InitBuffer(buf, bufSize, aFormat, aAllocFlags)) {
     return nullptr;
   }
 
@@ -513,7 +520,7 @@ ShmemTextureData::Create(gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
   }
 
   uint8_t* buf = shm.get<uint8_t>();
-  if (!InitBuffer(buf, bufSize, aAllocFlags)) {
+  if (!InitBuffer(buf, bufSize, aFormat, aAllocFlags)) {
     return nullptr;
   }
 

gfx/layers/client/TextureClient.cpp

@@ -852,13 +852,6 @@ TextureClient::CreateForRawBufferAccess(ISurfaceAllocator* aAllocator,
     return nullptr;
   }
 
-  if (aFormat == SurfaceFormat::B8G8R8X8 &&
-      (aAllocFlags != TextureAllocationFlags::ALLOC_CLEAR_BUFFER_BLACK) &&
-      aMoz2DBackend == gfx::BackendType::SKIA) {
-    // skia requires alpha component of RGBX textures to be 255.
-    aAllocFlags = TextureAllocationFlags::ALLOC_CLEAR_BUFFER_WHITE;
-  }
-
   TextureData* texData = BufferTextureData::Create(aSize, aFormat, aMoz2DBackend,
                                                    aTextureFlags, aAllocFlags,
                                                    aAllocator);