atlas_contents.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_ENTITY_CONTENTS_ATLAS_CONTENTS_H_
#define FLUTTER_IMPELLER_ENTITY_CONTENTS_ATLAS_CONTENTS_H_
 
#include <memory>
 
#include "impeller/core/sampler_descriptor.h"
#include "impeller/entity/contents/contents.h"
#include "impeller/entity/entity.h"
#include "impeller/geometry/color.h"
 
namespace impeller {
 
struct VertexBuffer;
 
// Interface wrapper to allow usage of DL pointer data without copying (or
// circular imports).
class AtlasGeometry {
 public:
  virtual bool ShouldUseBlend() const = 0;
 
  virtual bool ShouldSkip() const = 0;
 
  virtual VertexBuffer CreateSimpleVertexBuffer(
      HostBuffer& host_buffer) const = 0;
 
  virtual VertexBuffer CreateBlendVertexBuffer(
      HostBuffer& host_buffer) const = 0;
 
  virtual Rect ComputeBoundingBox() const = 0;
 
  virtual const std::shared_ptr<Texture>& GetAtlas() const = 0;
 
  virtual const SamplerDescriptor& GetSamplerDescriptor() const = 0;
 
  virtual BlendMode GetBlendMode() const = 0;
 
  virtual bool ShouldInvertBlendMode() const { return true; }
 
  /// @brief The source rect of the draw in texture coordinates if a strict
  ///        source rect should be applied, or nullopt.
  ///
  /// See also `Canvas::AttemptColorFilterOptimization`
  virtual std::optional<Rect> GetStrictSrcRect() const { return std::nullopt; }
};
 
/// @brief An atlas geometry that adapts for drawImageRect.
class DrawImageRectAtlasGeometry : public AtlasGeometry {
 public:
  DrawImageRectAtlasGeometry(std::shared_ptr<Texture> texture,
                             const Rect& source,
                             const Rect& destination,
                             const Color& color,
                             BlendMode blend_mode,
                             const SamplerDescriptor& desc,
                             bool use_strict_src_rect = false);
 
  ~DrawImageRectAtlasGeometry();
 
  bool ShouldUseBlend() const override;
 
  bool ShouldSkip() const override;
 
  VertexBuffer CreateSimpleVertexBuffer(HostBuffer& host_buffer) const override;
 
  VertexBuffer CreateBlendVertexBuffer(HostBuffer& host_buffer) const override;
 
  Rect ComputeBoundingBox() const override;
 
  const std::shared_ptr<Texture>& GetAtlas() const override;
 
  const SamplerDescriptor& GetSamplerDescriptor() const override;
 
  BlendMode GetBlendMode() const override;
 
  bool ShouldInvertBlendMode() const override;
 
  std::optional<Rect> GetStrictSrcRect() const override;
 
 private:
  const std::shared_ptr<Texture> texture_;
  const Rect source_;
  const Rect destination_;
  const Color color_;
  const BlendMode blend_mode_;
  const SamplerDescriptor desc_;
  const bool use_strict_src_rect_;
};
 
class AtlasContents final : public Contents {
 public:
  explicit AtlasContents();
 
  ~AtlasContents() override;
 
  void SetGeometry(AtlasGeometry* geometry);
 
  void SetAlpha(Scalar alpha);
 
  // |Contents|
  std::optional<Rect> GetCoverage(const Entity& entity) const override;
 
  // |Contents|
  bool Render(const ContentContext& renderer,
              const Entity& entity,
              RenderPass& pass) const override;
 
 private:
  AtlasGeometry* geometry_ = nullptr;
  Scalar alpha_ = 1.0;
 
  AtlasContents(const AtlasContents&) = delete;
 
  AtlasContents& operator=(const AtlasContents&) = delete;
};
 
/// A specialized atlas class for applying a color matrix filter to a
/// drawImageRect call.
class ColorFilterAtlasContents final : public Contents {
 public:
  explicit ColorFilterAtlasContents();
 
  ~ColorFilterAtlasContents() override;
 
  void SetGeometry(AtlasGeometry* geometry);
 
  void SetAlpha(Scalar alpha);
 
  void SetMatrix(ColorMatrix matrix);
 
  // |Contents|
  std::optional<Rect> GetCoverage(const Entity& entity) const override;
 
  // |Contents|
  bool Render(const ContentContext& renderer,
              const Entity& entity,
              RenderPass& pass) const override;
 
 private:
  // These contents are created temporarily on the stack and never stored.
  // The referenced geometry is also stack allocated and will be de-allocated
  // after the contents are.
  AtlasGeometry* geometry_ = nullptr;
  ColorMatrix matrix_;
  Scalar alpha_ = 1.0;
 
  ColorFilterAtlasContents(const ColorFilterAtlasContents&) = delete;
 
  ColorFilterAtlasContents& operator=(const ColorFilterAtlasContents&) = delete;
};
 
}  // namespace impeller
 
#endif  // FLUTTER_IMPELLER_ENTITY_CONTENTS_ATLAS_CONTENTS_H_