color_filter.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_AIKS_COLOR_FILTER_H_
#define FLUTTER_IMPELLER_AIKS_COLOR_FILTER_H_
 
#include "impeller/entity/contents/filters/color_filter_contents.h"
#include "impeller/geometry/color.h"
 
namespace impeller {
 
struct Paint;
 
/*******************************************************************************
 ******* ColorFilter
 ******************************************************************************/
 
class ColorFilter {
 public:
  /// A procedure that filters a given unpremultiplied color to produce a new
  /// unpremultiplied color.
  using ColorFilterProc = std::function<Color(Color)>;
 
  ColorFilter();
 
  virtual ~ColorFilter();
 
  static std::shared_ptr<ColorFilter> MakeBlend(BlendMode blend_mode,
                                                Color color);
 
  static std::shared_ptr<ColorFilter> MakeMatrix(ColorMatrix color_matrix);
 
  static std::shared_ptr<ColorFilter> MakeSrgbToLinear();
 
  static std::shared_ptr<ColorFilter> MakeLinearToSrgb();
 
  static std::shared_ptr<ColorFilter> MakeComposed(
      const std::shared_ptr<ColorFilter>& outer,
      const std::shared_ptr<ColorFilter>& inner);
 
  /// @brief  Wraps the given filter input with a GPU-based filter that will
  ///         perform the color operation. The given input will first be
  ///         rendered to a texture and then filtered.
  ///
  ///         Note that this operation has no consideration for the original
  ///         geometry mask of the filter input. And the entire input texture is
  ///         treated as color information.
  virtual std::shared_ptr<ColorFilterContents> WrapWithGPUColorFilter(
      std::shared_ptr<FilterInput> input,
      ColorFilterContents::AbsorbOpacity absorb_opacity) const = 0;
 
  /// @brief Returns a function that can be used to filter unpremultiplied
  ///        Impeller Colors on the CPU.
  virtual ColorFilterProc GetCPUColorFilterProc() const = 0;
 
  virtual std::shared_ptr<ColorFilter> Clone() const = 0;
};
 
/*******************************************************************************
 ******* BlendColorFilter
 ******************************************************************************/
 
class BlendColorFilter final : public ColorFilter {
 public:
  BlendColorFilter(BlendMode blend_mode, Color color);
 
  ~BlendColorFilter() override;
 
  // |ColorFilter|
  std::shared_ptr<ColorFilterContents> WrapWithGPUColorFilter(
      std::shared_ptr<FilterInput> input,
      ColorFilterContents::AbsorbOpacity absorb_opacity) const override;
 
  // |ColorFilter|
  ColorFilterProc GetCPUColorFilterProc() const override;
 
  // |ColorFilter|
  std::shared_ptr<ColorFilter> Clone() const override;
 
 private:
  BlendMode blend_mode_;
  Color color_;
};
 
/*******************************************************************************
 ******* MatrixColorFilter
 ******************************************************************************/
 
class MatrixColorFilter final : public ColorFilter {
 public:
  explicit MatrixColorFilter(ColorMatrix color_matrix);
 
  ~MatrixColorFilter() override;
 
  // |ColorFilter|
  std::shared_ptr<ColorFilterContents> WrapWithGPUColorFilter(
      std::shared_ptr<FilterInput> input,
      ColorFilterContents::AbsorbOpacity absorb_opacity) const override;
 
  // |ColorFilter|
  ColorFilterProc GetCPUColorFilterProc() const override;
 
  // |ColorFilter|
  std::shared_ptr<ColorFilter> Clone() const override;
 
 private:
  ColorMatrix color_matrix_;
};
 
/*******************************************************************************
 ******* SrgbToLinearColorFilter
 ******************************************************************************/
 
class SrgbToLinearColorFilter final : public ColorFilter {
 public:
  explicit SrgbToLinearColorFilter();
 
  ~SrgbToLinearColorFilter() override;
 
  // |ColorFilter|
  std::shared_ptr<ColorFilterContents> WrapWithGPUColorFilter(
      std::shared_ptr<FilterInput> input,
      ColorFilterContents::AbsorbOpacity absorb_opacity) const override;
 
  // |ColorFilter|
  ColorFilterProc GetCPUColorFilterProc() const override;
 
  // |ColorFilter|
  std::shared_ptr<ColorFilter> Clone() const override;
};
 
/*******************************************************************************
 ******* LinearToSrgbColorFilter
 ******************************************************************************/
 
class LinearToSrgbColorFilter final : public ColorFilter {
 public:
  explicit LinearToSrgbColorFilter();
 
  ~LinearToSrgbColorFilter() override;
 
  // |ColorFilter|
  std::shared_ptr<ColorFilterContents> WrapWithGPUColorFilter(
      std::shared_ptr<FilterInput> input,
      ColorFilterContents::AbsorbOpacity absorb_opacity) const override;
 
  // |ColorFilter|
  ColorFilterProc GetCPUColorFilterProc() const override;
 
  // |ColorFilter|
  std::shared_ptr<ColorFilter> Clone() const override;
};
 
/// @brief Applies color filters as f(g(x)), where x is the input color.
class ComposedColorFilter final : public ColorFilter {
 public:
  ComposedColorFilter(const std::shared_ptr<ColorFilter>& outer,
                      const std::shared_ptr<ColorFilter>& inner);
 
  ~ComposedColorFilter() override;
 
  // |ColorFilter|
  std::shared_ptr<ColorFilterContents> WrapWithGPUColorFilter(
      std::shared_ptr<FilterInput> input,
      ColorFilterContents::AbsorbOpacity absorb_opacity) const override;
 
  // |ColorFilter|
  ColorFilterProc GetCPUColorFilterProc() const override;
 
  // |ColorFilter|
  std::shared_ptr<ColorFilter> Clone() const override;
 
 private:
  std::shared_ptr<ColorFilter> outer_;
  std::shared_ptr<ColorFilter> inner_;
};
 
}  // namespace impeller
 
#endif  // FLUTTER_IMPELLER_AIKS_COLOR_FILTER_H_