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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 <memory>
#include <vector>
#include "flutter/flow/embedded_views.h"
#include "flutter/flow/instrumentation.h"
#include "flutter/flow/raster_cache.h"
#include "flutter/flow/texture.h"
#include "flutter/fml/build_config.h"
#include "flutter/fml/compiler_specific.h"
#include "flutter/fml/logging.h"
#include "flutter/fml/macros.h"
#include "flutter/fml/trace_event.h"
#include "third_party/skia/include/core/SkCanvas.h"
#include "third_party/skia/include/core/SkColor.h"
#include "third_party/skia/include/core/SkColorFilter.h"
#include "third_party/skia/include/core/SkMatrix.h"
#include "third_party/skia/include/core/SkPath.h"
#include "third_party/skia/include/core/SkPicture.h"
#include "third_party/skia/include/core/SkRRect.h"
#include "third_party/skia/include/core/SkRect.h"
#include "third_party/skia/include/utils/SkNWayCanvas.h"
#if defined(OS_FUCHSIA)
#include "flutter/flow/scene_update_context.h" //nogncheck
#include "lib/ui/scenic/cpp/resources.h" //nogncheck
#include "lib/ui/scenic/cpp/session.h" //nogncheck
#endif // defined(OS_FUCHSIA)
namespace flutter {
static constexpr SkRect kGiantRect = SkRect::MakeLTRB(-1E9F, -1E9F, 1E9F, 1E9F);
// This should be an exact copy of the Clip enum in painting.dart.
enum Clip { none, hardEdge, antiAlias, antiAliasWithSaveLayer };
struct PrerollContext {
RasterCache* raster_cache;
GrContext* gr_context;
ExternalViewEmbedder* view_embedder;
MutatorsStack& mutators_stack;
SkColorSpace* dst_color_space;
SkRect cull_rect;
bool surface_needs_readback;
// These allow us to paint in the end of subtree Preroll.
const Stopwatch& raster_time;
const Stopwatch& ui_time;
TextureRegistry& texture_registry;
const bool checkerboard_offscreen_layers;
// These allow us to make use of the scene metrics during Preroll.
float frame_physical_depth;
float frame_device_pixel_ratio;
// These allow us to track properties like elevation, opacity, and the
// prescence of a platform view during Preroll.
float total_elevation = 0.0f;
bool has_platform_view = false;
bool is_opaque = true;
#if defined(OS_FUCHSIA)
// True if, during the traversal so far, we have seen a child_scene_layer.
// Informs whether a layer needs to be system composited.
bool child_scene_layer_exists_below = false;
#endif // defined(OS_FUCHSIA)
// Represents a single composited layer. Created on the UI thread but then
// subquently used on the Rasterizer thread.
class Layer {
virtual ~Layer();
virtual void Preroll(PrerollContext* context, const SkMatrix& matrix);
// Used during Preroll by layers that employ a saveLayer to manage the
// PrerollContext settings with values affected by the saveLayer mechanism.
// This object must be created before calling Preroll on the children to
// set up the state for the children and then restore the state upon
// destruction.
class AutoPrerollSaveLayerState {
[[nodiscard]] static AutoPrerollSaveLayerState Create(
PrerollContext* preroll_context,
bool save_layer_is_active = true,
bool layer_itself_performs_readback = false);
AutoPrerollSaveLayerState(PrerollContext* preroll_context,
bool save_layer_is_active,
bool layer_itself_performs_readback);
PrerollContext* preroll_context_;
bool save_layer_is_active_;
bool layer_itself_performs_readback_;
bool prev_surface_needs_readback_;
struct PaintContext {
// When splitting the scene into multiple canvases (e.g when embedding
// a platform view on iOS) during the paint traversal we apply the non leaf
// flow layers to all canvases, and leaf layers just to the "current"
// canvas. Applying the non leaf layers to all canvases ensures that when
// we switch a canvas (when painting a PlatformViewLayer) the next canvas
// has the exact same state as the current canvas.
// The internal_nodes_canvas is a SkNWayCanvas which is used by non leaf
// and applies the operations to all canvases.
// The leaf_nodes_canvas is the "current" canvas and is used by leaf
// layers.
SkCanvas* internal_nodes_canvas;
SkCanvas* leaf_nodes_canvas;
GrContext* gr_context;
ExternalViewEmbedder* view_embedder;
const Stopwatch& raster_time;
const Stopwatch& ui_time;
TextureRegistry& texture_registry;
const RasterCache* raster_cache;
const bool checkerboard_offscreen_layers;
// These allow us to make use of the scene metrics during Paint.
float frame_physical_depth;
float frame_device_pixel_ratio;
// Calls SkCanvas::saveLayer and restores the layer upon destruction. Also
// draws a checkerboard over the layer if that is enabled in the PaintContext.
class AutoSaveLayer {
[[nodiscard]] static AutoSaveLayer Create(const PaintContext& paint_context,
const SkRect& bounds,
const SkPaint* paint);
[[nodiscard]] static AutoSaveLayer Create(
const PaintContext& paint_context,
const SkCanvas::SaveLayerRec& layer_rec);
AutoSaveLayer(const PaintContext& paint_context,
const SkRect& bounds,
const SkPaint* paint);
AutoSaveLayer(const PaintContext& paint_context,
const SkCanvas::SaveLayerRec& layer_rec);
const PaintContext& paint_context_;
const SkRect bounds_;
virtual void Paint(PaintContext& context) const = 0;
#if defined(OS_FUCHSIA)
// Updates the system composited scene.
virtual void UpdateScene(SceneUpdateContext& context);
virtual void CheckForChildLayerBelow(PrerollContext* context);
bool needs_system_composite() const { return needs_system_composite_; }
void set_needs_system_composite(bool value) {
needs_system_composite_ = value;
const SkRect& paint_bounds() const { return paint_bounds_; }
// This must be set by the time Preroll() returns otherwise the layer will
// be assumed to have empty paint bounds (paints no content).
void set_paint_bounds(const SkRect& paint_bounds) {
paint_bounds_ = paint_bounds;
bool needs_painting() const { return !paint_bounds_.isEmpty(); }
uint64_t unique_id() const { return unique_id_; }
#if defined(OS_FUCHSIA)
bool child_layer_exists_below_ = false;
SkRect paint_bounds_;
uint64_t unique_id_;
bool needs_system_composite_;
static uint64_t NextUniqueID();
} // namespace flutter