src/ui/lib/escher/defaults/default_shader_program_factory.h

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef SRC_UI_LIB_ESCHER_DEFAULTS_DEFAULT_SHADER_PROGRAM_FACTORY_H_
#define SRC_UI_LIB_ESCHER_DEFAULTS_DEFAULT_SHADER_PROGRAM_FACTORY_H_

#include "src/lib/fxl/memory/ref_counted.h"
#include "src/ui/lib/escher/util/hash_map.h"
#include "src/ui/lib/escher/util/hasher.h"
#include "src/ui/lib/escher/vk/shader_module_template.h"
#include "src/ui/lib/escher/vk/shader_program.h"
#include "src/ui/lib/escher/vk/shader_program_factory.h"

namespace escher {

// Provides the default implementation of ShaderProgramFactory; Escher creates
// an instance of this class and implements ShaderProgramFactory by delegating
// to it.  NOTE: programs generated by DefaultShaderProgramFactory are cached.
class DefaultShaderProgramFactory final : public ShaderProgramFactory {
 public:
  DefaultShaderProgramFactory(EscherWeakPtr escher, HackFilesystemPtr filesystem);
  ~DefaultShaderProgramFactory() override;

  // Exposed so that the client can call InitializeWithRealFiles() upon the
  // filesystem.  This is hacky and will change in the future.
  const HackFilesystemPtr& filesystem() const { return filesystem_; }

  // Clear all cached programs and other data.
  void Clear();

  // Obtain a lazily-generated and cached ShaderModuleTemplate corresponding to
  // the specified shader stage and source code.
  ShaderModuleTemplatePtr ObtainShaderModuleTemplate(ShaderStage stage,
                                                     const std::string& source_path);

 private:
  friend class Escher;

  // |ShaderProgramFactory|.  Public so that Escher::GetProgram() can delegate
  // to it.
  ShaderProgramPtr GetProgramImpl(const std::string shader_paths[EnumCount<ShaderStage>()],
                                  ShaderVariantArgs args) override;

  // This is used for paranoid debug-mode verification that we don't have hash
  // collisions.  Otherwise, we'd simply stash the ShaderProgramPtr.
  struct Record {
    ShaderProgramPtr ptr;
#ifndef NDEBUG
    std::string paths[6];
    ShaderVariantArgs args;
#endif
  };

  const EscherWeakPtr escher_;
  HackFilesystemPtr filesystem_;
  HashMap<Hash, Record> programs_;
  std::unordered_map<std::string, ShaderModuleTemplatePtr> templates_;
};

}  // namespace escher

#endif  // SRC_UI_LIB_ESCHER_DEFAULTS_DEFAULT_SHADER_PROGRAM_FACTORY_H_