// 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_DISPLAY_LIST_DISPLAY_LIST_IMAGE_FILTER_H_
#define FLUTTER_DISPLAY_LIST_DISPLAY_LIST_IMAGE_FILTER_H_

#include "flutter/display_list/display_list_attributes.h"
#include "flutter/display_list/display_list_color_filter.h"
#include "flutter/display_list/display_list_comparable.h"
#include "flutter/display_list/display_list_sampling_options.h"
#include "flutter/display_list/display_list_tile_mode.h"
#include "flutter/display_list/types.h"
#include "flutter/fml/logging.h"
#include "third_party/skia/include/effects/SkImageFilters.h"

namespace flutter {

// The DisplayList ImageFilter class. This class implements all of the
// facilities and adheres to the design goals of the |DlAttribute| base
// class.
//
// The objects here define operations that can take a location and one or
// more input pixels and produce a color for that output pixel

// An enumerated type for the recognized ImageFilter operations.
// If a custom ImageFilter outside of the recognized types is needed
// then a |kUnknown| type that simply defers to an SkImageFilter is
// provided as a fallback.
enum class DlImageFilterType {
  kBlur,
  kDilate,
  kErode,
  kMatrix,
  kComposeFilter,
  kColorFilter,
  kUnknown
};

class DlBlurImageFilter;
class DlDilateImageFilter;
class DlErodeImageFilter;
class DlMatrixImageFilter;
class DlComposeImageFilter;
class DlColorFilterImageFilter;

class DlImageFilter
    : public DlAttribute<DlImageFilter, SkImageFilter, DlImageFilterType> {
 public:
  // Return a shared_ptr holding a DlImageFilter representing the indicated
  // Skia SkImageFilter pointer.
  //
  // This method can only detect the ColorFilter type of ImageFilter from an
  // analogous SkImageFilter as there are no "asA..." methods for the other
  // types on SkImageFilter.
  static std::shared_ptr<DlImageFilter> From(const SkImageFilter* sk_filter);

  // Return a shared_ptr holding a DlImageFilter representing the indicated
  // Skia SkImageFilter pointer.
  //
  // This method can only detect the ColorFilter type of ImageFilter from an
  // analogous SkImageFilter as there are no "asA..." methods for the other
  // types on SkImageFilter.
  static std::shared_ptr<DlImageFilter> From(
      const sk_sp<SkImageFilter> sk_filter) {
    return From(sk_filter.get());
  }

  // Return a DlBlurImageFilter pointer to this object iff it is a Blur
  // type of ImageFilter, otherwise return nullptr.
  virtual const DlBlurImageFilter* asBlur() const { return nullptr; }

  // Return a DlDilateImageFilter pointer to this object iff it is a Dilate
  // type of ImageFilter, otherwise return nullptr.
  virtual const DlDilateImageFilter* asDilate() const { return nullptr; }

  // Return a DlErodeImageFilter pointer to this object iff it is an Erode
  // type of ImageFilter, otherwise return nullptr.
  virtual const DlErodeImageFilter* asErode() const { return nullptr; }

  // Return a DlMatrixImageFilter pointer to this object iff it is a Matrix
  // type of ImageFilter, otherwise return nullptr.
  virtual const DlMatrixImageFilter* asMatrix() const { return nullptr; }

  // Return a DlComposeImageFilter pointer to this object iff it is a Compose
  // type of ImageFilter, otherwise return nullptr.
  virtual const DlComposeImageFilter* asCompose() const { return nullptr; }

  // Return a DlColorFilterImageFilter pointer to this object iff it is a
  // ColorFilter type of ImageFilter, otherwise return nullptr.
  virtual const DlColorFilterImageFilter* asColorFilter() const {
    return nullptr;
  }

  // Return a boolean indicating whether the image filtering operation will
  // modify transparent black. This is typically used to determine if applying
  // the ImageFilter to a temporary saveLayer buffer will turn the surrounding
  // pixels non-transparent and therefore expand the bounds.
  virtual bool modifies_transparent_black() const = 0;

  // Return the bounds of the output for this image filtering operation
  // based on the supplied input bounds where both are measured in the local
  // (untransformed) coordinate space.
  //
  // The method will return a pointer to the output_bounds parameter if it
  // can successfully compute the output bounds of the filter, otherwise the
  // method will return a nullptr and the output_bounds will be filled with
  // a best guess for the answer, even if just a copy of the input_bounds.
  virtual SkRect* map_local_bounds(const SkRect& input_bounds,
                                   SkRect& output_bounds) const = 0;

  // Return the device bounds of the output for this image filtering operation
  // based on the supplied input device bounds where both are measured in the
  // pixel coordinate space and relative to the given rendering ctm. The
  // transform matrix is used to adjust the filter parameters for when it
  // is used in a rendering operation (for example, the blur radius of a
  // Blur filter will expand based on the ctm).
  //
  // The method will return a pointer to the output_bounds parameter if it
  // can successfully compute the output bounds of the filter, otherwise the
  // method will return a nullptr and the output_bounds will be filled with
  // a best guess for the answer, even if just a copy of the input_bounds.
  virtual SkIRect* map_device_bounds(const SkIRect& input_bounds,
                                     const SkMatrix& ctm,
                                     SkIRect& output_bounds) const = 0;

  // Return the input bounds that will be needed in order for the filter to
  // properly fill the indicated output_bounds under the specified
  // transformation matrix. Both output_bounds and input_bounds are taken to
  // be relative to the transformed coordinate space of the provided |ctm|.
  //
  // The method will return a pointer to the input_bounds parameter if it
  // can successfully compute the required input bounds, otherwise the
  // method will return a nullptr and the input_bounds will be filled with
  // a best guess for the answer, even if just a copy of the output_bounds.
  virtual SkIRect* get_input_device_bounds(const SkIRect& output_bounds,
                                           const SkMatrix& ctm,
                                           SkIRect& input_bounds) const = 0;

 protected:
  static SkVector map_vectors_affine(const SkMatrix& ctm,
                                     SkScalar x,
                                     SkScalar y) {
    FML_DCHECK(SkScalarIsFinite(x) && x >= 0);
    FML_DCHECK(SkScalarIsFinite(y) && y >= 0);
    FML_DCHECK(ctm.isFinite() && !ctm.hasPerspective());

    // The x and y scalars would have been used to expand a local space
    // rectangle which is then transformed by ctm. In order to do the
    // expansion correctly, we should look at the relevant math. The
    // 4 corners will be moved outward by the following vectors:
    //     (UL,UR,LR,LL) = ((-x, -y), (+x, -y), (+x, +y), (-x, +y))
    // After applying the transform, each of these vectors could be
    // pointing in any direction so we need to examine each transformed
    // delta vector and how it affected the bounds.
    // Looking at just the affine 2x3 entries of the CTM we can delta
    // transform these corner offsets and get the following:
    //     UL = dCTM(-x, -y) = (- x*m00 - y*m01, - x*m10 - y*m11)
    //     UR = dCTM(+x, -y) = (  x*m00 - y*m01,   x*m10 - y*m11)
    //     LR = dCTM(+x, +y) = (  x*m00 + y*m01,   x*m10 + y*m11)
    //     LL = dCTM(-x, +y) = (- x*m00 + y*m01, - x*m10 + y*m11)
    // The X vectors are all some variation of adding or subtracting
    // the sum of x*m00 and y*m01 or their difference. Similarly the Y
    // vectors are +/- the associated sum/difference of x*m10 and y*m11.
    // The largest displacements, both left/right or up/down, will
    // happen when the signs of the m00/m01/m10/m11 matrix entries
    // coincide with the signs of the scalars, i.e. are all positive.
    return {x * abs(ctm[0]) + y * abs(ctm[1]),
            x * abs(ctm[3]) + y * abs(ctm[4])};
  }

  static SkIRect* inset_device_bounds(const SkIRect& input_bounds,
                                      SkScalar radius_x,
                                      SkScalar radius_y,
                                      const SkMatrix& ctm,
                                      SkIRect& output_bounds) {
    if (ctm.isFinite()) {
      if (ctm.hasPerspective()) {
        SkMatrix inverse;
        if (ctm.invert(&inverse)) {
          SkRect local_bounds = inverse.mapRect(SkRect::Make(input_bounds));
          local_bounds.inset(radius_x, radius_y);
          output_bounds = ctm.mapRect(local_bounds).roundOut();
          return &output_bounds;
        }
      } else {
        SkVector device_radius = map_vectors_affine(ctm, radius_x, radius_y);
        output_bounds = input_bounds.makeInset(floor(device_radius.fX),  //
                                               floor(device_radius.fY));
        return &output_bounds;
      }
    }
    output_bounds = input_bounds;
    return nullptr;
  }

  static SkIRect* outset_device_bounds(const SkIRect& input_bounds,
                                       SkScalar radius_x,
                                       SkScalar radius_y,
                                       const SkMatrix& ctm,
                                       SkIRect& output_bounds) {
    if (ctm.isFinite()) {
      if (ctm.hasPerspective()) {
        SkMatrix inverse;
        if (ctm.invert(&inverse)) {
          SkRect local_bounds = inverse.mapRect(SkRect::Make(input_bounds));
          local_bounds.outset(radius_x, radius_y);
          output_bounds = ctm.mapRect(local_bounds).roundOut();
          return &output_bounds;
        }
      } else {
        SkVector device_radius = map_vectors_affine(ctm, radius_x, radius_y);
        output_bounds = input_bounds.makeOutset(ceil(device_radius.fX),  //
                                                ceil(device_radius.fY));
        return &output_bounds;
      }
    }
    output_bounds = input_bounds;
    return nullptr;
  }
};

class DlBlurImageFilter final : public DlImageFilter {
 public:
  DlBlurImageFilter(SkScalar sigma_x, SkScalar sigma_y, DlTileMode tile_mode)
      : sigma_x_(sigma_x), sigma_y_(sigma_y), tile_mode_(tile_mode) {}
  explicit DlBlurImageFilter(const DlBlurImageFilter* filter)
      : DlBlurImageFilter(filter->sigma_x_,
                          filter->sigma_y_,
                          filter->tile_mode_) {}
  explicit DlBlurImageFilter(const DlBlurImageFilter& filter)
      : DlBlurImageFilter(&filter) {}

  std::shared_ptr<DlImageFilter> shared() const override {
    return std::make_shared<DlBlurImageFilter>(this);
  }

  DlImageFilterType type() const override { return DlImageFilterType::kBlur; }
  size_t size() const override { return sizeof(*this); }

  const DlBlurImageFilter* asBlur() const override { return this; }

  bool modifies_transparent_black() const override { return false; }

  SkRect* map_local_bounds(const SkRect& input_bounds,
                           SkRect& output_bounds) const override {
    output_bounds = input_bounds.makeOutset(sigma_x_ * 3, sigma_y_ * 3);
    return &output_bounds;
  }

  SkIRect* map_device_bounds(const SkIRect& input_bounds,
                             const SkMatrix& ctm,
                             SkIRect& output_bounds) const override {
    return outset_device_bounds(input_bounds, sigma_x_ * 3.0, sigma_y_ * 3.0,
                                ctm, output_bounds);
  }

  SkIRect* get_input_device_bounds(const SkIRect& output_bounds,
                                   const SkMatrix& ctm,
                                   SkIRect& input_bounds) const override {
    // Blurs are symmetric in terms of output-for-input and input-for-output
    return map_device_bounds(output_bounds, ctm, input_bounds);
  }

  SkScalar sigma_x() const { return sigma_x_; }
  SkScalar sigma_y() const { return sigma_y_; }
  DlTileMode tile_mode() const { return tile_mode_; }

  sk_sp<SkImageFilter> skia_object() const override {
    return SkImageFilters::Blur(sigma_x_, sigma_y_, ToSk(tile_mode_), nullptr);
  }

 protected:
  bool equals_(const DlImageFilter& other) const override {
    FML_DCHECK(other.type() == DlImageFilterType::kBlur);
    auto that = static_cast<const DlBlurImageFilter*>(&other);
    return (sigma_x_ == that->sigma_x_ && sigma_y_ == that->sigma_y_ &&
            tile_mode_ == that->tile_mode_);
  }

 private:
  SkScalar sigma_x_;
  SkScalar sigma_y_;
  DlTileMode tile_mode_;
};

class DlDilateImageFilter final : public DlImageFilter {
 public:
  DlDilateImageFilter(SkScalar radius_x, SkScalar radius_y)
      : radius_x_(radius_x), radius_y_(radius_y) {}
  explicit DlDilateImageFilter(const DlDilateImageFilter* filter)
      : DlDilateImageFilter(filter->radius_x_, filter->radius_y_) {}
  explicit DlDilateImageFilter(const DlDilateImageFilter& filter)
      : DlDilateImageFilter(&filter) {}

  std::shared_ptr<DlImageFilter> shared() const override {
    return std::make_shared<DlDilateImageFilter>(this);
  }

  DlImageFilterType type() const override { return DlImageFilterType::kDilate; }
  size_t size() const override { return sizeof(*this); }

  const DlDilateImageFilter* asDilate() const override { return this; }

  bool modifies_transparent_black() const override { return false; }

  SkRect* map_local_bounds(const SkRect& input_bounds,
                           SkRect& output_bounds) const override {
    output_bounds = input_bounds.makeOutset(radius_x_, radius_y_);
    return &output_bounds;
  }

  SkIRect* map_device_bounds(const SkIRect& input_bounds,
                             const SkMatrix& ctm,
                             SkIRect& output_bounds) const override {
    return outset_device_bounds(input_bounds, radius_x_, radius_y_, ctm,
                                output_bounds);
  }

  SkIRect* get_input_device_bounds(const SkIRect& output_bounds,
                                   const SkMatrix& ctm,
                                   SkIRect& input_bounds) const override {
    return inset_device_bounds(output_bounds, radius_x_, radius_y_, ctm,
                               input_bounds);
  }

  SkScalar radius_x() const { return radius_x_; }
  SkScalar radius_y() const { return radius_y_; }

  sk_sp<SkImageFilter> skia_object() const override {
    return SkImageFilters::Dilate(radius_x_, radius_y_, nullptr);
  }

 protected:
  bool equals_(const DlImageFilter& other) const override {
    FML_DCHECK(other.type() == DlImageFilterType::kDilate);
    auto that = static_cast<const DlDilateImageFilter*>(&other);
    return (radius_x_ == that->radius_x_ && radius_y_ == that->radius_y_);
  }

 private:
  SkScalar radius_x_;
  SkScalar radius_y_;
};

class DlErodeImageFilter final : public DlImageFilter {
 public:
  DlErodeImageFilter(SkScalar radius_x, SkScalar radius_y)
      : radius_x_(radius_x), radius_y_(radius_y) {}
  explicit DlErodeImageFilter(const DlErodeImageFilter* filter)
      : DlErodeImageFilter(filter->radius_x_, filter->radius_y_) {}
  explicit DlErodeImageFilter(const DlErodeImageFilter& filter)
      : DlErodeImageFilter(&filter) {}

  std::shared_ptr<DlImageFilter> shared() const override {
    return std::make_shared<DlErodeImageFilter>(this);
  }

  DlImageFilterType type() const override { return DlImageFilterType::kErode; }
  size_t size() const override { return sizeof(*this); }

  const DlErodeImageFilter* asErode() const override { return this; }

  bool modifies_transparent_black() const override { return false; }

  SkRect* map_local_bounds(const SkRect& input_bounds,
                           SkRect& output_bounds) const override {
    output_bounds = input_bounds.makeInset(radius_x_, radius_y_);
    return &output_bounds;
  }

  SkIRect* map_device_bounds(const SkIRect& input_bounds,
                             const SkMatrix& ctm,
                             SkIRect& output_bounds) const override {
    return inset_device_bounds(input_bounds, radius_x_, radius_y_, ctm,
                               output_bounds);
  }

  SkIRect* get_input_device_bounds(const SkIRect& output_bounds,
                                   const SkMatrix& ctm,
                                   SkIRect& input_bounds) const override {
    return outset_device_bounds(output_bounds, radius_x_, radius_y_, ctm,
                                input_bounds);
  }

  SkScalar radius_x() const { return radius_x_; }
  SkScalar radius_y() const { return radius_y_; }

  sk_sp<SkImageFilter> skia_object() const override {
    return SkImageFilters::Erode(radius_x_, radius_y_, nullptr);
  }

 protected:
  bool equals_(const DlImageFilter& other) const override {
    FML_DCHECK(other.type() == DlImageFilterType::kErode);
    auto that = static_cast<const DlErodeImageFilter*>(&other);
    return (radius_x_ == that->radius_x_ && radius_y_ == that->radius_y_);
  }

 private:
  SkScalar radius_x_;
  SkScalar radius_y_;
};

class DlMatrixImageFilter final : public DlImageFilter {
 public:
  DlMatrixImageFilter(const SkMatrix& matrix, DlImageSampling sampling)
      : matrix_(matrix), sampling_(sampling) {}
  explicit DlMatrixImageFilter(const DlMatrixImageFilter* filter)
      : DlMatrixImageFilter(filter->matrix_, filter->sampling_) {}
  explicit DlMatrixImageFilter(const DlMatrixImageFilter& filter)
      : DlMatrixImageFilter(&filter) {}

  std::shared_ptr<DlImageFilter> shared() const override {
    return std::make_shared<DlMatrixImageFilter>(this);
  }

  DlImageFilterType type() const override { return DlImageFilterType::kMatrix; }
  size_t size() const override { return sizeof(*this); }

  const SkMatrix& matrix() const { return matrix_; }
  DlImageSampling sampling() const { return sampling_; }

  const DlMatrixImageFilter* asMatrix() const override { return this; }

  bool modifies_transparent_black() const override { return false; }

  SkRect* map_local_bounds(const SkRect& input_bounds,
                           SkRect& output_bounds) const override {
    output_bounds = matrix_.mapRect(input_bounds);
    return &output_bounds;
  }

  SkIRect* map_device_bounds(const SkIRect& input_bounds,
                             const SkMatrix& ctm,
                             SkIRect& output_bounds) const override {
    SkMatrix matrix;
    if (!ctm.invert(&matrix)) {
      output_bounds = input_bounds;
      return nullptr;
    }
    matrix.postConcat(matrix_);
    matrix.postConcat(ctm);
    SkRect device_rect;
    matrix.mapRect(&device_rect, SkRect::Make(input_bounds));
    output_bounds = device_rect.roundOut();
    return &output_bounds;
  }

  SkIRect* get_input_device_bounds(const SkIRect& output_bounds,
                                   const SkMatrix& ctm,
                                   SkIRect& input_bounds) const override {
    SkMatrix matrix = SkMatrix::Concat(ctm, matrix_);
    SkMatrix inverse;
    if (!matrix.invert(&inverse)) {
      input_bounds = output_bounds;
      return nullptr;
    }
    inverse.postConcat(ctm);
    SkRect bounds;
    bounds.set(output_bounds);
    inverse.mapRect(&bounds);
    input_bounds = bounds.roundOut();
    return &input_bounds;
  }

  sk_sp<SkImageFilter> skia_object() const override {
    return SkImageFilters::MatrixTransform(matrix_, ToSk(sampling_), nullptr);
  }

 protected:
  bool equals_(const DlImageFilter& other) const override {
    FML_DCHECK(other.type() == DlImageFilterType::kMatrix);
    auto that = static_cast<const DlMatrixImageFilter*>(&other);
    return (matrix_ == that->matrix_ && sampling_ == that->sampling_);
  }

 private:
  SkMatrix matrix_;
  DlImageSampling sampling_;
};

class DlComposeImageFilter final : public DlImageFilter {
 public:
  DlComposeImageFilter(std::shared_ptr<DlImageFilter> outer,
                       std::shared_ptr<DlImageFilter> inner)
      : outer_(std::move(outer)), inner_(std::move(inner)) {}
  DlComposeImageFilter(const DlImageFilter* outer, const DlImageFilter* inner)
      : outer_(outer->shared()), inner_(inner->shared()) {}
  DlComposeImageFilter(const DlImageFilter& outer, const DlImageFilter& inner)
      : DlComposeImageFilter(&outer, &inner) {}
  explicit DlComposeImageFilter(const DlComposeImageFilter* filter)
      : DlComposeImageFilter(filter->outer_, filter->inner_) {}
  explicit DlComposeImageFilter(const DlComposeImageFilter& filter)
      : DlComposeImageFilter(&filter) {}

  std::shared_ptr<DlImageFilter> shared() const override {
    return std::make_shared<DlComposeImageFilter>(this);
  }

  DlImageFilterType type() const override {
    return DlImageFilterType::kComposeFilter;
  }
  size_t size() const override { return sizeof(*this); }

  std::shared_ptr<DlImageFilter> outer() const { return outer_; }
  std::shared_ptr<DlImageFilter> inner() const { return inner_; }

  const DlComposeImageFilter* asCompose() const override { return this; }

  bool modifies_transparent_black() const override {
    if (inner_ && inner_->modifies_transparent_black()) {
      return true;
    }
    if (outer_ && outer_->modifies_transparent_black()) {
      return true;
    }
    return false;
  }

  SkRect* map_local_bounds(const SkRect& input_bounds,
                           SkRect& output_bounds) const override {
    SkRect cur_bounds = input_bounds;
    // We set this result in case neither filter is present.
    output_bounds = input_bounds;
    if (inner_) {
      if (!inner_->map_local_bounds(cur_bounds, output_bounds)) {
        return nullptr;
      }
      cur_bounds = output_bounds;
    }
    if (outer_) {
      if (!outer_->map_local_bounds(cur_bounds, output_bounds)) {
        return nullptr;
      }
    }
    return &output_bounds;
  }

  SkIRect* map_device_bounds(const SkIRect& input_bounds,
                             const SkMatrix& ctm,
                             SkIRect& output_bounds) const override {
    SkIRect cur_bounds = input_bounds;
    // We set this result in case neither filter is present.
    output_bounds = input_bounds;
    if (inner_) {
      if (!inner_->map_device_bounds(cur_bounds, ctm, output_bounds)) {
        return nullptr;
      }
      cur_bounds = output_bounds;
    }
    if (outer_) {
      if (!outer_->map_device_bounds(cur_bounds, ctm, output_bounds)) {
        return nullptr;
      }
    }
    return &output_bounds;
  }

  SkIRect* get_input_device_bounds(const SkIRect& output_bounds,
                                   const SkMatrix& ctm,
                                   SkIRect& input_bounds) const override {
    SkIRect cur_bounds = output_bounds;
    // We set this result in case neither filter is present.
    input_bounds = output_bounds;
    if (outer_) {
      if (!outer_->get_input_device_bounds(cur_bounds, ctm, input_bounds)) {
        return nullptr;
      }
      cur_bounds = output_bounds;
    }
    if (inner_) {
      if (!inner_->get_input_device_bounds(cur_bounds, ctm, input_bounds)) {
        return nullptr;
      }
    }
    return &input_bounds;
  }

  sk_sp<SkImageFilter> skia_object() const override {
    return SkImageFilters::Compose(outer_->skia_object(),
                                   inner_->skia_object());
  }

 protected:
  bool equals_(const DlImageFilter& other) const override {
    FML_DCHECK(other.type() == DlImageFilterType::kComposeFilter);
    auto that = static_cast<const DlComposeImageFilter*>(&other);
    return (Equals(outer_, that->outer_) && Equals(inner_, that->inner_));
  }

 private:
  std::shared_ptr<DlImageFilter> outer_;
  std::shared_ptr<DlImageFilter> inner_;
};

class DlColorFilterImageFilter final : public DlImageFilter {
 public:
  explicit DlColorFilterImageFilter(std::shared_ptr<DlColorFilter> filter)
      : color_filter_(std::move(filter)) {}
  explicit DlColorFilterImageFilter(const DlColorFilter* filter)
      : color_filter_(filter->shared()) {}
  explicit DlColorFilterImageFilter(const DlColorFilter& filter)
      : color_filter_(filter.shared()) {}
  explicit DlColorFilterImageFilter(const DlColorFilterImageFilter* filter)
      : DlColorFilterImageFilter(filter->color_filter_) {}
  explicit DlColorFilterImageFilter(const DlColorFilterImageFilter& filter)
      : DlColorFilterImageFilter(&filter) {}

  std::shared_ptr<DlImageFilter> shared() const override {
    return std::make_shared<DlColorFilterImageFilter>(color_filter_);
  }

  DlImageFilterType type() const override {
    return DlImageFilterType::kColorFilter;
  }
  size_t size() const override { return sizeof(*this); }

  const std::shared_ptr<DlColorFilter> color_filter() const {
    return color_filter_;
  }

  const DlColorFilterImageFilter* asColorFilter() const override {
    return this;
  }

  bool modifies_transparent_black() const override {
    if (color_filter_) {
      return color_filter_->modifies_transparent_black();
    }
    return false;
  }

  SkRect* map_local_bounds(const SkRect& input_bounds,
                           SkRect& output_bounds) const override {
    output_bounds = input_bounds;
    return modifies_transparent_black() ? nullptr : &output_bounds;
  }

  SkIRect* map_device_bounds(const SkIRect& input_bounds,
                             const SkMatrix& ctm,
                             SkIRect& output_bounds) const override {
    output_bounds = input_bounds;
    return modifies_transparent_black() ? nullptr : &output_bounds;
  }

  SkIRect* get_input_device_bounds(const SkIRect& output_bounds,
                                   const SkMatrix& ctm,
                                   SkIRect& input_bounds) const override {
    return map_device_bounds(output_bounds, ctm, input_bounds);
  }

  sk_sp<SkImageFilter> skia_object() const override {
    return SkImageFilters::ColorFilter(color_filter_->skia_object(), nullptr);
  }

 protected:
  bool equals_(const DlImageFilter& other) const override {
    FML_DCHECK(other.type() == DlImageFilterType::kColorFilter);
    auto that = static_cast<const DlColorFilterImageFilter*>(&other);
    return Equals(color_filter_, that->color_filter_);
  }

 private:
  std::shared_ptr<DlColorFilter> color_filter_;
};

// A wrapper class for a Skia ImageFilter of unknown type. The above 4 types
// are the only types that can be constructed by Flutter using the
// ui.ImageFilter class so this class should be rarely used. The main use
// would come from the |DisplayListCanvasRecorder| recording Skia rendering
// calls that originated outside of the Flutter dart code. This would
// primarily happen in the Paragraph code that renders the text using the
// SkCanvas interface which we capture into DisplayList data structures.
class DlUnknownImageFilter final : public DlImageFilter {
 public:
  explicit DlUnknownImageFilter(sk_sp<SkImageFilter> sk_filter)
      : sk_filter_(std::move(sk_filter)) {}
  explicit DlUnknownImageFilter(const SkImageFilter* sk_filter)
      : sk_filter_(sk_ref_sp(sk_filter)) {}
  explicit DlUnknownImageFilter(const DlUnknownImageFilter* filter)
      : DlUnknownImageFilter(filter->sk_filter_) {}
  explicit DlUnknownImageFilter(const DlUnknownImageFilter& filter)
      : DlUnknownImageFilter(&filter) {}

  DlImageFilterType type() const override {
    return DlImageFilterType::kUnknown;
  }
  size_t size() const override { return sizeof(*this); }

  std::shared_ptr<DlImageFilter> shared() const override {
    return std::make_shared<DlUnknownImageFilter>(this);
  }

  bool modifies_transparent_black() const override {
    if (!sk_filter_) {
      return false;
    }
    return !sk_filter_->canComputeFastBounds();
  }

  SkRect* map_local_bounds(const SkRect& input_bounds,
                           SkRect& output_bounds) const override {
    if (modifies_transparent_black()) {
      output_bounds = input_bounds;
      return nullptr;
    }
    output_bounds = sk_filter_->computeFastBounds(input_bounds);
    return &output_bounds;
  }

  SkIRect* map_device_bounds(const SkIRect& input_bounds,
                             const SkMatrix& ctm,
                             SkIRect& output_bounds) const override {
    if (modifies_transparent_black()) {
      output_bounds = input_bounds;
      return nullptr;
    }
    output_bounds = sk_filter_->filterBounds(
        input_bounds, ctm, SkImageFilter::kForward_MapDirection);
    return &output_bounds;
  }

  SkIRect* get_input_device_bounds(const SkIRect& output_bounds,
                                   const SkMatrix& ctm,
                                   SkIRect& input_bounds) const override {
    if (modifies_transparent_black()) {
      input_bounds = output_bounds;
      return nullptr;
    }
    input_bounds = sk_filter_->filterBounds(
        output_bounds, ctm, SkImageFilter::kReverse_MapDirection);
    return &input_bounds;
  }

  sk_sp<SkImageFilter> skia_object() const override { return sk_filter_; }

  virtual ~DlUnknownImageFilter() = default;

 protected:
  bool equals_(const DlImageFilter& other) const override {
    FML_DCHECK(other.type() == DlImageFilterType::kUnknown);
    auto that = static_cast<DlUnknownImageFilter const*>(&other);
    return sk_filter_ == that->sk_filter_;
  }

 private:
  sk_sp<SkImageFilter> sk_filter_;
};

}  // namespace flutter

#endif  // FLUTTER_DISPLAY_LIST_DISPLAY_LIST_IMAGE_FILTER_H_