FlutterDarwinContextMetalSkia.mm

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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#import "flutter/shell/platform/darwin/graphics/FlutterDarwinContextMetalSkia.h"
 
#include "flutter/common/graphics/persistent_cache.h"
#include "flutter/fml/logging.h"
#include "flutter/shell/common/context_options.h"
#import "flutter/shell/platform/darwin/common/framework/Headers/FlutterMacros.h"
#include "third_party/skia/include/gpu/GrDirectContext.h"
#include "third_party/skia/include/gpu/ganesh/mtl/GrMtlBackendContext.h"
#include "third_party/skia/include/gpu/ganesh/mtl/GrMtlDirectContext.h"
 
FLUTTER_ASSERT_ARC
 
@implementation FlutterDarwinContextMetalSkia
 
- (instancetype)initWithDefaultMTLDevice {
  id<MTLDevice> device = MTLCreateSystemDefaultDevice();
  return [self initWithMTLDevice:device commandQueue:[device newCommandQueue]];
}
 
- (instancetype)initWithMTLDevice:(id<MTLDevice>)device
                     commandQueue:(id<MTLCommandQueue>)commandQueue {
  self = [super init];
  if (self != nil) {
    _device = device;
 
    if (!_device) {
      FML_DLOG(ERROR) << "Could not acquire Metal device.";
      return nil;
    }
 
    _commandQueue = commandQueue;
 
    if (!_commandQueue) {
      FML_DLOG(ERROR) << "Could not create Metal command queue.";
      return nil;
    }
 
    [_commandQueue setLabel:@"Flutter Main Queue"];
 
    CVReturn cvReturn = CVMetalTextureCacheCreate(kCFAllocatorDefault,  // allocator
                                                  nil,      // cache attributes (nil default)
                                                  _device,  // metal device
                                                  nil,      // texture attributes (nil default)
                                                  &_textureCache  // [out] cache
    );
    if (cvReturn != kCVReturnSuccess) {
      FML_DLOG(ERROR) << "Could not create Metal texture cache.";
      return nil;
    }
 
    // The devices are in the same "sharegroup" because they share the same device and command
    // queues for now. When the resource context gets its own transfer queue, this will have to be
    // refactored.
    _mainContext = [self createGrContext];
    _resourceContext = [self createGrContext];
 
    if (!_mainContext || !_resourceContext) {
      FML_DLOG(ERROR) << "Could not create Skia Metal contexts.";
      return nil;
    }
 
    FML_LOG(IMPORTANT) << "Using the Skia rendering backend (Metal).";
 
    _resourceContext->setResourceCacheLimit(0u);
  }
  return self;
}
 
- (sk_sp<GrDirectContext>)createGrContext {
  const auto contextOptions =
      flutter::MakeDefaultContextOptions(flutter::ContextType::kRender, GrBackendApi::kMetal);
  id<MTLDevice> device = _device;
  id<MTLCommandQueue> commandQueue = _commandQueue;
  return [FlutterDarwinContextMetalSkia createGrContext:device commandQueue:commandQueue];
}
 
+ (sk_sp<GrDirectContext>)createGrContext:(id<MTLDevice>)device
                             commandQueue:(id<MTLCommandQueue>)commandQueue {
  const auto contextOptions =
      flutter::MakeDefaultContextOptions(flutter::ContextType::kRender, GrBackendApi::kMetal);
  GrMtlBackendContext backendContext = {};
  // Skia expect arguments to `MakeMetal` transfer ownership of the reference in for release later
  // when the GrDirectContext is collected.
  backendContext.fDevice.reset((__bridge_retained void*)device);
  backendContext.fQueue.reset((__bridge_retained void*)commandQueue);
  return GrDirectContexts::MakeMetal(backendContext, contextOptions);
}
 
- (void)dealloc {
  if (_textureCache) {
    CFRelease(_textureCache);
  }
}
 
- (FlutterDarwinExternalTextureMetal*)
    createExternalTextureWithIdentifier:(int64_t)textureID
                                texture:(NSObject<FlutterTexture>*)texture {
  return [[FlutterDarwinExternalTextureMetal alloc] initWithTextureCache:_textureCache
                                                               textureID:textureID
                                                                 texture:texture
                                                          enableImpeller:NO];
}
 
@end