image_filter.cc

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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.
 
#include "impeller/display_list/image_filter.h"
#include "fml/logging.h"
#include "impeller/display_list/color_filter.h"
#include "impeller/display_list/skia_conversions.h"
#include "impeller/entity/contents/filters/color_filter_contents.h"
#include "impeller/entity/contents/filters/filter_contents.h"
#include "impeller/entity/contents/filters/inputs/filter_input.h"
 
namespace impeller {
 
std::shared_ptr<FilterContents> WrapInput(const flutter::DlImageFilter* filter,
                                          const FilterInput::Ref& input) {
  FML_DCHECK(filter);
 
  switch (filter->type()) {
    case flutter::DlImageFilterType::kBlur: {
      auto blur_filter = filter->asBlur();
      FML_DCHECK(blur_filter);
 
      return FilterContents::MakeGaussianBlur(
          input,                                                    //
          Sigma(blur_filter->sigma_x()),                            //
          Sigma(blur_filter->sigma_y()),                            //
          static_cast<Entity::TileMode>(blur_filter->tile_mode()),  //
          FilterContents::BlurStyle::kNormal                        //
      );
    }
    case flutter::DlImageFilterType::kDilate: {
      auto dilate_filter = filter->asDilate();
      FML_DCHECK(dilate_filter);
 
      return FilterContents::MakeMorphology(
          input,                              //
          Radius(dilate_filter->radius_x()),  //
          Radius(dilate_filter->radius_y()),  //
          FilterContents::MorphType::kDilate  //
      );
    }
    case flutter::DlImageFilterType::kErode: {
      auto erode_filter = filter->asErode();
      FML_DCHECK(erode_filter);
 
      return FilterContents::MakeMorphology(
          input,                             //
          Radius(erode_filter->radius_x()),  //
          Radius(erode_filter->radius_y()),  //
          FilterContents::MorphType::kErode  //
      );
    }
    case flutter::DlImageFilterType::kMatrix: {
      auto matrix_filter = filter->asMatrix();
      FML_DCHECK(matrix_filter);
 
      auto matrix = skia_conversions::ToMatrix(matrix_filter->matrix());
      auto desc =
          skia_conversions::ToSamplerDescriptor(matrix_filter->sampling());
      return FilterContents::MakeMatrixFilter(input, matrix, desc);
    }
    case flutter::DlImageFilterType::kLocalMatrix: {
      auto matrix_filter = filter->asLocalMatrix();
      FML_DCHECK(matrix_filter);
      FML_DCHECK(matrix_filter->image_filter());
 
      auto matrix = skia_conversions::ToMatrix(matrix_filter->matrix());
      return FilterContents::MakeLocalMatrixFilter(
          FilterInput::Make(
              WrapInput(matrix_filter->image_filter().get(), input)),
          matrix);
    }
    case flutter::DlImageFilterType::kColorFilter: {
      auto image_color_filter = filter->asColorFilter();
      FML_DCHECK(image_color_filter);
      auto color_filter = image_color_filter->color_filter();
      FML_DCHECK(color_filter);
 
      // When color filters are used as image filters, set the color filter's
      // "absorb opacity" flag to false. For image filters, the snapshot
      // opacity needs to be deferred until the result of the filter chain is
      // being blended with the layer.
      return WrapWithGPUColorFilter(color_filter.get(), input,
                                    ColorFilterContents::AbsorbOpacity::kNo);
    }
    case flutter::DlImageFilterType::kCompose: {
      auto compose = filter->asCompose();
      FML_DCHECK(compose);
 
      auto outer_dl_filter = compose->outer();
      auto inner_dl_filter = compose->inner();
      if (!outer_dl_filter) {
        return WrapInput(inner_dl_filter.get(), input);
      }
      if (!inner_dl_filter) {
        return WrapInput(outer_dl_filter.get(), input);
      }
      FML_DCHECK(outer_dl_filter && inner_dl_filter);
 
      return WrapInput(
          outer_dl_filter.get(),
          FilterInput::Make(WrapInput(inner_dl_filter.get(), input)));
    }
  }
  FML_UNREACHABLE();
}
 
}  // namespace impeller