texture_gles.h

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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.
 
#ifndef FLUTTER_IMPELLER_RENDERER_BACKEND_GLES_TEXTURE_GLES_H_
#define FLUTTER_IMPELLER_RENDERER_BACKEND_GLES_TEXTURE_GLES_H_
 
#include <bitset>
 
#include "fml/logging.h"
#include "impeller/base/backend_cast.h"
#include "impeller/core/texture.h"
#include "impeller/renderer/backend/gles/handle_gles.h"
#include "impeller/renderer/backend/gles/reactor_gles.h"
 
namespace impeller {
 
class TextureGLES final : public Texture,
                          public BackendCast<TextureGLES, Texture> {
 public:
  enum class Type {
    kTexture,
    kTextureMultisampled,
    kRenderBuffer,
    kRenderBufferMultisampled,
  };
 
  //----------------------------------------------------------------------------
  /// @brief      Create a texture by wrapping an external framebuffer object
  ///             whose lifecycle is owned by the caller.
  ///
  ///             This is useful for creating a render target for the default
  ///             window managed framebuffer.
  ///
  /// @param[in]  reactor  The reactor
  /// @param[in]  desc     The description
  /// @param[in]  fbo      The fbo
  ///
  /// @return     If a texture representation of the framebuffer could be
  ///             created.
  ///
  static std::shared_ptr<TextureGLES> WrapFBO(
      std::shared_ptr<ReactorGLES> reactor,
      TextureDescriptor desc,
      GLuint fbo);
 
  //----------------------------------------------------------------------------
  /// @brief      Create a texture by wrapping an external OpenGL texture
  ///             handle. Ownership of the texture handle is assumed by the
  ///             reactor.
  ///
  /// @param[in]  reactor          The reactor
  /// @param[in]  desc             The description
  /// @param[in]  external_handle  The external handle
  ///
  /// @return     If a texture representation of the framebuffer could be
  ///             created.
  ///
  static std::shared_ptr<TextureGLES> WrapTexture(
      std::shared_ptr<ReactorGLES> reactor,
      TextureDescriptor desc,
      HandleGLES external_handle);
 
  //----------------------------------------------------------------------------
  /// @brief      Create a "texture" that is never expected to be bound/unbound
  ///             explicitly or initialized in any way. It only exists to setup
  ///             a render pass description.
  ///
  /// @param[in]  reactor  The reactor
  /// @param[in]  desc     The description
  ///
  /// @return     If a texture placeholder could be created.
  ///
  static std::shared_ptr<TextureGLES> CreatePlaceholder(
      std::shared_ptr<ReactorGLES> reactor,
      TextureDescriptor desc);
 
  TextureGLES(std::shared_ptr<ReactorGLES> reactor,
              TextureDescriptor desc,
              bool threadsafe = false);
 
  // |Texture|
  ~TextureGLES() override;
 
  // |Texture|
  bool IsValid() const override;
 
  std::optional<GLuint> GetGLHandle() const;
 
  [[nodiscard]] bool Bind() const;
 
  [[nodiscard]] bool GenerateMipmap();
 
  enum class AttachmentType {
    kColor0,
    kDepth,
    kStencil,
  };
  [[nodiscard]] bool SetAsFramebufferAttachment(
      GLenum target,
      AttachmentType attachment_type) const;
 
  Type GetType() const;
 
  bool IsWrapped() const;
 
  /// @brief Reset the internal texture state so that the reactor will not free
  ///        the associated handle.
  void Leak();
 
  std::optional<GLuint> GetFBO() const;
 
  //----------------------------------------------------------------------------
  /// @brief      Indicates that all texture storage has already been allocated
  ///             and contents initialized.
  ///
  ///             This is similar to calling `MarkSliceInitialized` with all
  ///             slices.
  ///
  /// @see        MarkSliceInitialized.
  ///
  void MarkContentsInitialized();
 
  //----------------------------------------------------------------------------
  /// @brief      Indicates that a specific texture slice has been initialized.
  ///
  /// @param[in]  slice  The slice to mark as being initialized.
  ///
  void MarkSliceInitialized(size_t slice) const;
 
  bool IsSliceInitialized(size_t slice) const;
 
  //----------------------------------------------------------------------------
  /// @brief      Attach a sync fence to this texture that will be waited on
  ///             before encoding a rendering operation that references it.
  ///
  /// @param[in]  fence  A handle to a sync fence.
  ///
  void SetFence(HandleGLES fence);
 
  /// Store the FBO object for recycling in the 2D renderer.
  ///
  /// The color0 texture used by the 2D renderer will use this texture
  /// object to store the associated FBO the first time it is used.
  void SetCachedFBO(HandleGLES fbo);
 
  /// Retrieve the cached FBO object, or a dead handle if there is no object.
  const HandleGLES& GetCachedFBO() const;
 
  // Visible for testing.
  std::optional<HandleGLES> GetSyncFence() const;
 
  // visible for testing
  Type ComputeTypeForBinding(GLenum target) const;
 
 private:
  std::shared_ptr<ReactorGLES> reactor_;
  const Type type_;
  HandleGLES handle_;
  mutable std::optional<HandleGLES> fence_ = std::nullopt;
  mutable std::bitset<6> slices_initialized_ = 0;
  const bool is_wrapped_;
  const std::optional<GLuint> wrapped_fbo_;
  HandleGLES cached_fbo_ = HandleGLES::DeadHandle();
  bool is_valid_ = false;
 
  TextureGLES(std::shared_ptr<ReactorGLES> reactor,
              TextureDescriptor desc,
              bool threadsafe,
              std::optional<GLuint> fbo,
              std::optional<HandleGLES> external_handle);
 
  // |Texture|
  void SetLabel(std::string_view label) override;
 
  // |Texture|
  void SetLabel(std::string_view label, std::string_view trailing) override;
 
  // |Texture|
  bool OnSetContents(const uint8_t* contents,
                     size_t length,
                     size_t slice) override;
 
  // |Texture|
  bool OnSetContents(std::shared_ptr<const fml::Mapping> mapping,
                     size_t slice) override;
 
  // |Texture|
  ISize GetSize() const override;
 
  // |Texture|
  Scalar GetYCoordScale() const override;
 
  void InitializeContentsIfNecessary() const;
 
  TextureGLES(const TextureGLES&) = delete;
 
  TextureGLES& operator=(const TextureGLES&) = delete;
};
 
}  // namespace impeller
 
#endif  // FLUTTER_IMPELLER_RENDERER_BACKEND_GLES_TEXTURE_GLES_H_