Setup default pixel formats.

impeller/compiler/compiler_unittests.cc

@@ -30,6 +30,7 @@ class CompilerTest : public ::testing::Test {
       return false;
     }
     Compiler::SourceOptions compiler_options(fixture_name);
+    compiler_options.target_platform = Compiler::TargetPlatform::kMacOS;
     compiler_options.working_directory = std::make_shared<fml::UniqueFD>(
         flutter::testing::OpenFixturesDirectory());
     Reflector::Options reflector_options;

impeller/playground/playground.mm

@@ -13,6 +13,7 @@
 #include "impeller/playground/playground.h"
 #include "impeller/renderer/allocator.h"
 #include "impeller/renderer/backend/metal/context_mtl.h"
+#include "impeller/renderer/backend/metal/formats_mtl.h"
 #include "impeller/renderer/backend/metal/surface_mtl.h"
 #include "impeller/renderer/backend/metal/texture_mtl.h"
 #include "impeller/renderer/context.h"
@@ -127,7 +128,8 @@ static void PlaygroundKeyCallback(GLFWwindow* window,
   NSWindow* cocoa_window = ::glfwGetCocoaWindow(window);
   CAMetalLayer* layer = [CAMetalLayer layer];
   layer.device = ContextMTL::Cast(*renderer_.GetContext()).GetMTLDevice();
-  layer.pixelFormat = MTLPixelFormatBGRA8Unorm;
+  // This pixel format is one of the documented supported formats.
+  layer.pixelFormat = ToMTLPixelFormat(PixelFormat::kDefaultColor);
   cocoa_window.contentView.layer = layer;
   cocoa_window.contentView.wantsLayer = YES;
 
@@ -175,6 +177,7 @@ CompressedImage compressed_image(
   }
 
   auto texture_descriptor = TextureDescriptor{};
+  // We just converted to RGBA above.
   texture_descriptor.format = PixelFormat::kR8G8B8A8UNormInt;
   texture_descriptor.size = image.GetSize();
   texture_descriptor.mip_count = 1u;

impeller/renderer/backend/metal/formats_mtl.h

@@ -17,6 +17,28 @@ namespace impeller {
 
 class RenderTarget;
 
+constexpr PixelFormat FromMTLPixelFormat(MTLPixelFormat format) {
+  switch (format) {
+    case MTLPixelFormatInvalid:
+      return PixelFormat::kUnknown;
+    case MTLPixelFormatBGRA8Unorm:
+      return PixelFormat::kB8G8R8A8UNormInt;
+    case MTLPixelFormatBGRA8Unorm_sRGB:
+      return PixelFormat::kB8G8R8A8UNormIntSRGB;
+    case MTLPixelFormatDepth32Float_Stencil8:
+      return PixelFormat::kD32FloatS8UNormInt;
+    case MTLPixelFormatRGBA8Unorm:
+      return PixelFormat::kR8G8B8A8UNormInt;
+    case MTLPixelFormatStencil8:
+      return PixelFormat::kS8UInt;
+    case MTLPixelFormatRGBA8Unorm_sRGB:
+      return PixelFormat::kR8G8B8A8UNormIntSRGB;
+    default:
+      return PixelFormat::kUnknown;
+  }
+  return PixelFormat::kUnknown;
+}
+
 constexpr MTLPixelFormat ToMTLPixelFormat(PixelFormat format) {
   switch (format) {
     case PixelFormat::kUnknown:

impeller/renderer/backend/metal/surface_mtl.mm

@@ -6,6 +6,7 @@
 
 #include "flutter/fml/trace_event.h"
 #include "impeller/base/validation.h"
+#include "impeller/renderer/backend/metal/formats_mtl.h"
 #include "impeller/renderer/backend/metal/texture_mtl.h"
 #include "impeller/renderer/render_target.h"
 
@@ -27,46 +28,60 @@
     return nullptr;
   }
 
-  TextureDescriptor msaa_tex_desc;
-  msaa_tex_desc.type = TextureType::k2DMultisample;
-  msaa_tex_desc.sample_count = SampleCount::kCount4;
-  msaa_tex_desc.format = PixelFormat::kB8G8R8A8UNormInt;
-  msaa_tex_desc.size = {
+  const auto color_format =
+      FromMTLPixelFormat(current_drawable.texture.pixelFormat);
+
+  if (color_format == PixelFormat::kUnknown) {
+    VALIDATION_LOG << "Unknown drawable color format.";
+    return nullptr;
+  }
+
+  TextureDescriptor color0_tex_desc;
+  color0_tex_desc.type = TextureType::k2DMultisample;
+  color0_tex_desc.sample_count = SampleCount::kCount4;
+  color0_tex_desc.format = color_format;
+  color0_tex_desc.size = {
       static_cast<ISize::Type>(current_drawable.texture.width),
       static_cast<ISize::Type>(current_drawable.texture.height)};
-  msaa_tex_desc.usage = static_cast<uint64_t>(TextureUsage::kRenderTarget);
+  color0_tex_desc.usage = static_cast<uint64_t>(TextureUsage::kRenderTarget);
 
   auto msaa_tex = context->GetPermanentsAllocator()->CreateTexture(
-      StorageMode::kDeviceTransient, msaa_tex_desc);
+      StorageMode::kDeviceTransient, color0_tex_desc);
   if (!msaa_tex) {
-    FML_LOG(ERROR) << "Could not allocate MSAA resolve texture.";
+    VALIDATION_LOG << "Could not allocate MSAA resolve texture.";
     return nullptr;
   }
 
   msaa_tex->SetLabel("ImpellerOnscreenColor4xMSAA");
 
-  TextureDescriptor onscreen_tex_desc;
-  onscreen_tex_desc.format = PixelFormat::kB8G8R8A8UNormInt;
-  onscreen_tex_desc.size = msaa_tex_desc.size;
-  onscreen_tex_desc.usage = static_cast<uint64_t>(TextureUsage::kRenderTarget);
+  TextureDescriptor color0_resolve_tex_desc;
+  color0_resolve_tex_desc.format = color_format;
+  color0_resolve_tex_desc.size = color0_tex_desc.size;
+  color0_resolve_tex_desc.usage =
+      static_cast<uint64_t>(TextureUsage::kRenderTarget);
 
   ColorAttachment color0;
   color0.texture = msaa_tex;
   color0.clear_color = Color::DarkSlateGray();
   color0.load_action = LoadAction::kClear;
   color0.store_action = StoreAction::kMultisampleResolve;
-  color0.resolve_texture =
-      std::make_shared<TextureMTL>(onscreen_tex_desc, current_drawable.texture);
+  color0.resolve_texture = std::make_shared<TextureMTL>(
+      color0_resolve_tex_desc, current_drawable.texture);
 
   TextureDescriptor stencil0_tex;
   stencil0_tex.type = TextureType::k2DMultisample;
   stencil0_tex.sample_count = SampleCount::kCount4;
-  stencil0_tex.format = PixelFormat::kS8UInt;
-  stencil0_tex.size = msaa_tex_desc.size;
+  stencil0_tex.format = PixelFormat::kDefaultStencil;
+  stencil0_tex.size = color0_tex_desc.size;
   stencil0_tex.usage =
       static_cast<TextureUsageMask>(TextureUsage::kRenderTarget);
   auto stencil_texture = context->GetPermanentsAllocator()->CreateTexture(
       StorageMode::kDeviceTransient, stencil0_tex);
+
+  if (!stencil_texture) {
+    VALIDATION_LOG << "Could not create stencil texture.";
+    return nullptr;
+  }
   stencil_texture->SetLabel("ImpellerOnscreenStencil");
 
   StencilAttachment stencil0;

impeller/renderer/formats.h

@@ -51,8 +51,17 @@ enum class PixelFormat {
   kB8G8R8A8UNormInt,
   kB8G8R8A8UNormIntSRGB,
   kS8UInt,
+
   // Esoteric formats only used as render targets.
   kD32FloatS8UNormInt,
+
+  // Defaults. If you don't know which ones to use, these are usually a safe
+  // bet.
+  //
+  // On Metal, this is a support format for layer drawable and can be used to
+  // specify the format of the resolve texture if needed.
+  kDefaultColor = kB8G8R8A8UNormInt,
+  kDefaultStencil = kS8UInt,
 };
 
 enum class BlendFactor {

impeller/renderer/pipeline_builder.h

@@ -99,7 +99,7 @@ struct PipelineBuilder {
       // Configure the sole color attachments pixel format. This is by
       // convention.
       ColorAttachmentDescriptor color0;
-      color0.format = PixelFormat::kB8G8R8A8UNormInt;
+      color0.format = PixelFormat::kDefaultColor;
       color0.blending_enabled = true;
       desc.SetColorAttachmentDescriptor(0u, std::move(color0));
     }
@@ -109,7 +109,7 @@ struct PipelineBuilder {
       StencilAttachmentDescriptor stencil0;
       stencil0.stencil_compare = CompareFunction::kLessEqual;
       desc.SetStencilAttachmentDescriptors(stencil0);
-      desc.SetStencilPixelFormat(PixelFormat::kS8UInt);
+      desc.SetStencilPixelFormat(PixelFormat::kDefaultStencil);
     }
 
     return true;

impeller/renderer/render_target.cc

@@ -182,13 +182,13 @@ RenderTarget RenderTarget::CreateOffscreen(const Context& context,
   }
 
   TextureDescriptor color_tex0;
-  color_tex0.format = PixelFormat::kB8G8R8A8UNormInt;
+  color_tex0.format = PixelFormat::kDefaultColor;
   color_tex0.size = size;
   color_tex0.usage = static_cast<uint64_t>(TextureUsage::kRenderTarget) |
                      static_cast<uint64_t>(TextureUsage::kShaderRead);
 
   TextureDescriptor stencil_tex0;
-  stencil_tex0.format = PixelFormat::kS8UInt;
+  stencil_tex0.format = PixelFormat::kDefaultStencil;
   stencil_tex0.size = size;
   stencil_tex0.usage =
       static_cast<TextureUsageMask>(TextureUsage::kRenderTarget);