engine/shell/platform/embedder/embedder_layers.cc

// 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 "flutter/shell/platform/embedder/embedder_layers.h"

#include <algorithm>

namespace flutter {

EmbedderLayers::EmbedderLayers(SkISize frame_size,
                               double device_pixel_ratio,
                               SkMatrix root_surface_transformation)
    : frame_size_(frame_size),
      device_pixel_ratio_(device_pixel_ratio),
      root_surface_transformation_(root_surface_transformation) {}

EmbedderLayers::~EmbedderLayers() = default;

void EmbedderLayers::PushBackingStoreLayer(const FlutterBackingStore* store) {
  FlutterLayer layer = {};

  layer.struct_size = sizeof(FlutterLayer);
  layer.type = kFlutterLayerContentTypeBackingStore;
  layer.backing_store = store;

  const auto layer_bounds =
      SkRect::MakeWH(frame_size_.width(), frame_size_.height());

  const auto transformed_layer_bounds =
      root_surface_transformation_.mapRect(layer_bounds);

  layer.offset.x = transformed_layer_bounds.x();
  layer.offset.y = transformed_layer_bounds.y();
  layer.size.width = transformed_layer_bounds.width();
  layer.size.height = transformed_layer_bounds.height();

  presented_layers_.push_back(layer);
}

static std::unique_ptr<FlutterPlatformViewMutation> ConvertMutation(
    double opacity) {
  FlutterPlatformViewMutation mutation = {};
  mutation.type = kFlutterPlatformViewMutationTypeOpacity;
  mutation.opacity = opacity;
  return std::make_unique<FlutterPlatformViewMutation>(mutation);
}

static std::unique_ptr<FlutterPlatformViewMutation> ConvertMutation(
    const SkRect& rect) {
  FlutterPlatformViewMutation mutation = {};
  mutation.type = kFlutterPlatformViewMutationTypeClipRect;
  mutation.clip_rect.left = rect.left();
  mutation.clip_rect.top = rect.top();
  mutation.clip_rect.right = rect.right();
  mutation.clip_rect.bottom = rect.bottom();
  return std::make_unique<FlutterPlatformViewMutation>(mutation);
}

static FlutterSize VectorToSize(const SkVector& vector) {
  FlutterSize size = {};
  size.width = vector.x();
  size.height = vector.y();
  return size;
}

static std::unique_ptr<FlutterPlatformViewMutation> ConvertMutation(
    const SkRRect& rrect) {
  FlutterPlatformViewMutation mutation = {};
  mutation.type = kFlutterPlatformViewMutationTypeClipRoundedRect;
  const auto& rect = rrect.rect();
  mutation.clip_rounded_rect.rect.left = rect.left();
  mutation.clip_rounded_rect.rect.top = rect.top();
  mutation.clip_rounded_rect.rect.right = rect.right();
  mutation.clip_rounded_rect.rect.bottom = rect.bottom();
  mutation.clip_rounded_rect.upper_left_corner_radius =
      VectorToSize(rrect.radii(SkRRect::Corner::kUpperLeft_Corner));
  mutation.clip_rounded_rect.upper_right_corner_radius =
      VectorToSize(rrect.radii(SkRRect::Corner::kUpperRight_Corner));
  mutation.clip_rounded_rect.lower_right_corner_radius =
      VectorToSize(rrect.radii(SkRRect::Corner::kLowerRight_Corner));
  mutation.clip_rounded_rect.lower_left_corner_radius =
      VectorToSize(rrect.radii(SkRRect::Corner::kLowerLeft_Corner));
  return std::make_unique<FlutterPlatformViewMutation>(mutation);
}

static std::unique_ptr<FlutterPlatformViewMutation> ConvertMutation(
    const SkMatrix& matrix) {
  FlutterPlatformViewMutation mutation = {};
  mutation.type = kFlutterPlatformViewMutationTypeTransformation;
  mutation.transformation.scaleX = matrix[SkMatrix::kMScaleX];
  mutation.transformation.skewX = matrix[SkMatrix::kMSkewX];
  mutation.transformation.transX = matrix[SkMatrix::kMTransX];
  mutation.transformation.skewY = matrix[SkMatrix::kMSkewY];
  mutation.transformation.scaleY = matrix[SkMatrix::kMScaleY];
  mutation.transformation.transY = matrix[SkMatrix::kMTransY];
  mutation.transformation.pers0 = matrix[SkMatrix::kMPersp0];
  mutation.transformation.pers1 = matrix[SkMatrix::kMPersp1];
  mutation.transformation.pers2 = matrix[SkMatrix::kMPersp2];
  return std::make_unique<FlutterPlatformViewMutation>(mutation);
}

void EmbedderLayers::PushPlatformViewLayer(
    FlutterPlatformViewIdentifier identifier,
    const EmbeddedViewParams& params) {
  {
    FlutterPlatformView view = {};
    view.struct_size = sizeof(FlutterPlatformView);
    view.identifier = identifier;

    const auto& mutators = params.mutatorsStack;

    std::vector<const FlutterPlatformViewMutation*> mutations_array;

    if (std::distance(mutators.Bottom(), mutators.Top()) > 0) {
      // If there are going to be any mutations, they must first take into
      // account the transformation for the device pixel ratio and root surface
      // transformation.
      auto base_xformation =
          SkMatrix::Concat(root_surface_transformation_,
                           SkMatrix::MakeScale(device_pixel_ratio_));
      if (!base_xformation.isIdentity()) {
        mutations_array.push_back(
            mutations_referenced_.emplace_back(ConvertMutation(base_xformation))
                .get());
      }
    }

    for (auto i = mutators.Bottom(); i != mutators.Top(); ++i) {
      const auto& mutator = *i;
      switch (mutator->GetType()) {
        case MutatorType::clip_rect: {
          mutations_array.push_back(
              mutations_referenced_
                  .emplace_back(ConvertMutation(mutator->GetRect()))
                  .get());
        } break;
        case MutatorType::clip_rrect: {
          mutations_array.push_back(
              mutations_referenced_
                  .emplace_back(ConvertMutation(mutator->GetRRect()))
                  .get());
        } break;
        case MutatorType::clip_path: {
          // Unsupported mutation.
        } break;
        case MutatorType::transform: {
          const auto& matrix = mutator->GetMatrix();
          if (!matrix.isIdentity()) {
            mutations_array.push_back(
                mutations_referenced_.emplace_back(ConvertMutation(matrix))
                    .get());
          }
        } break;
        case MutatorType::opacity: {
          const double opacity =
              std::clamp(mutator->GetAlphaFloat(), 0.0f, 1.0f);
          if (opacity < 1.0) {
            mutations_array.push_back(
                mutations_referenced_.emplace_back(ConvertMutation(opacity))
                    .get());
          }
        } break;
      }
    }

    if (mutations_array.size() > 0) {
      auto mutations =
          std::make_unique<std::vector<const FlutterPlatformViewMutation*>>(
              mutations_array);
      mutations_arrays_referenced_.emplace_back(std::move(mutations));

      view.mutations_count = mutations_array.size();
      view.mutations = mutations_arrays_referenced_.back().get()->data();
    }

    platform_views_referenced_.emplace_back(
        std::make_unique<FlutterPlatformView>(view));
  }

  FlutterLayer layer = {};

  layer.struct_size = sizeof(FlutterLayer);
  layer.type = kFlutterLayerContentTypePlatformView;
  layer.platform_view = platform_views_referenced_.back().get();

  const auto layer_bounds =
      SkRect::MakeXYWH(params.offsetPixels.x(),                          //
                       params.offsetPixels.y(),                          //
                       params.sizePoints.width() * device_pixel_ratio_,  //
                       params.sizePoints.height() * device_pixel_ratio_  //
      );

  const auto transformed_layer_bounds =
      root_surface_transformation_.mapRect(layer_bounds);

  layer.offset.x = transformed_layer_bounds.x();
  layer.offset.y = transformed_layer_bounds.y();
  layer.size.width = transformed_layer_bounds.width();
  layer.size.height = transformed_layer_bounds.height();

  presented_layers_.push_back(layer);
}  // namespace flutter

/// @note Procedure doesn't copy all closures.
void EmbedderLayers::InvokePresentCallback(
    const PresentCallback& callback) const {
  std::vector<const FlutterLayer*> presented_layers_pointers;
  presented_layers_pointers.reserve(presented_layers_.size());
  for (const auto& layer : presented_layers_) {
    presented_layers_pointers.push_back(&layer);
  }
  callback(std::move(presented_layers_pointers));
}

}  // namespace flutter