flow/display_list_canvas.h

// 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_FLOW_DISPLAY_LIST_CANVAS_H_
#define FLUTTER_FLOW_DISPLAY_LIST_CANVAS_H_

#include "flutter/flow/display_list.h"
#include "flutter/flow/display_list_utils.h"
#include "flutter/fml/logging.h"

#include "third_party/skia/include/core/SkCanvasVirtualEnforcer.h"
#include "third_party/skia/include/utils/SkNoDrawCanvas.h"

// Classes to interact between SkCanvas and DisplayList, including:
// DisplayListCanvasDispatcher:
//     Can be fed to the dispatch() method of a DisplayList to feed
//     the resulting rendering operations to an SkCanvas instance.
// DisplayListCanvasRecorder
//     An adapter that implements an SkCanvas interface which can
//     then be handed to code that outputs to an SkCanvas to capture
//     the output into a Flutter DisplayList.

namespace flutter {

// Receives all methods on Dispatcher and sends them to an SkCanvas
class DisplayListCanvasDispatcher : public virtual Dispatcher,
                                    public SkPaintDispatchHelper {
 public:
  DisplayListCanvasDispatcher(SkCanvas* canvas) : canvas_(canvas) {}

  void save() override;
  void restore() override;
  void saveLayer(const SkRect* bounds, bool restore_with_paint) override;

  void translate(SkScalar tx, SkScalar ty) override;
  void scale(SkScalar sx, SkScalar sy) override;
  void rotate(SkScalar degrees) override;
  void skew(SkScalar sx, SkScalar sy) override;
  void transform2x3(SkScalar mxx,
                    SkScalar mxy,
                    SkScalar mxt,
                    SkScalar myx,
                    SkScalar myy,
                    SkScalar myt) override;
  void transform3x3(SkScalar mxx,
                    SkScalar mxy,
                    SkScalar mxt,
                    SkScalar myx,
                    SkScalar myy,
                    SkScalar myt,
                    SkScalar px,
                    SkScalar py,
                    SkScalar pt) override;

  void clipRect(const SkRect& rect, bool isAA, SkClipOp clip_op) override;
  void clipRRect(const SkRRect& rrect, bool isAA, SkClipOp clip_op) override;
  void clipPath(const SkPath& path, bool isAA, SkClipOp clip_op) override;

  void drawPaint() override;
  void drawColor(SkColor color, SkBlendMode mode) override;
  void drawLine(const SkPoint& p0, const SkPoint& p1) override;
  void drawRect(const SkRect& rect) override;
  void drawOval(const SkRect& bounds) override;
  void drawCircle(const SkPoint& center, SkScalar radius) override;
  void drawRRect(const SkRRect& rrect) override;
  void drawDRRect(const SkRRect& outer, const SkRRect& inner) override;
  void drawPath(const SkPath& path) override;
  void drawArc(const SkRect& bounds,
               SkScalar start,
               SkScalar sweep,
               bool useCenter) override;
  void drawPoints(SkCanvas::PointMode mode,
                  uint32_t count,
                  const SkPoint pts[]) override;
  void drawVertices(const sk_sp<SkVertices> vertices,
                    SkBlendMode mode) override;
  void drawImage(const sk_sp<SkImage> image,
                 const SkPoint point,
                 const SkSamplingOptions& sampling) override;
  void drawImageRect(const sk_sp<SkImage> image,
                     const SkRect& src,
                     const SkRect& dst,
                     const SkSamplingOptions& sampling,
                     SkCanvas::SrcRectConstraint constraint) override;
  void drawImageNine(const sk_sp<SkImage> image,
                     const SkIRect& center,
                     const SkRect& dst,
                     SkFilterMode filter) override;
  void drawImageLattice(const sk_sp<SkImage> image,
                        const SkCanvas::Lattice& lattice,
                        const SkRect& dst,
                        SkFilterMode filter,
                        bool with_paint) override;
  void drawAtlas(const sk_sp<SkImage> atlas,
                 const SkRSXform xform[],
                 const SkRect tex[],
                 const SkColor colors[],
                 int count,
                 SkBlendMode mode,
                 const SkSamplingOptions& sampling,
                 const SkRect* cullRect) override;
  void drawPicture(const sk_sp<SkPicture> picture,
                   const SkMatrix* matrix,
                   bool with_save_layer) override;
  void drawDisplayList(const sk_sp<DisplayList> display_list) override;
  void drawTextBlob(const sk_sp<SkTextBlob> blob,
                    SkScalar x,
                    SkScalar y) override;
  void drawShadow(const SkPath& path,
                  const SkColor color,
                  const SkScalar elevation,
                  bool occludes,
                  SkScalar dpr) override;

 private:
  SkCanvas* canvas_;
};

// Receives all methods on SkCanvas and sends them to a DisplayListBuilder
class DisplayListCanvasRecorder
    : public SkCanvasVirtualEnforcer<SkNoDrawCanvas>,
      public SkRefCnt {
 public:
  DisplayListCanvasRecorder(const SkRect& bounds);

  const sk_sp<DisplayListBuilder> builder() { return builder_; }

  sk_sp<DisplayList> Build();

  void didConcat44(const SkM44&) override;
  void didSetM44(const SkM44&) override { FML_DCHECK(false); }
  void didTranslate(SkScalar, SkScalar) override;
  void didScale(SkScalar, SkScalar) override;

  void onClipRect(const SkRect& rect,
                  SkClipOp op,
                  ClipEdgeStyle edgeStyle) override;
  void onClipRRect(const SkRRect& rrect,
                   SkClipOp op,
                   ClipEdgeStyle edgeStyle) override;
  void onClipPath(const SkPath& path,
                  SkClipOp op,
                  ClipEdgeStyle edgeStyle) override;

  void willSave() override;
  SaveLayerStrategy getSaveLayerStrategy(const SaveLayerRec&) override;
  void didRestore() override;

  void onDrawPaint(const SkPaint& paint) override;
  void onDrawBehind(const SkPaint&) override { FML_DCHECK(false); }
  void onDrawRect(const SkRect& rect, const SkPaint& paint) override;
  void onDrawRRect(const SkRRect& rrect, const SkPaint& paint) override;
  void onDrawDRRect(const SkRRect& outer,
                    const SkRRect& inner,
                    const SkPaint& paint) override;
  void onDrawOval(const SkRect& rect, const SkPaint& paint) override;
  void onDrawArc(const SkRect& rect,
                 SkScalar startAngle,
                 SkScalar sweepAngle,
                 bool useCenter,
                 const SkPaint& paint) override;
  void onDrawPath(const SkPath& path, const SkPaint& paint) override;
  void onDrawRegion(const SkRegion& region, const SkPaint& paint) override {
    FML_DCHECK(false);
  }

  void onDrawTextBlob(const SkTextBlob* blob,
                      SkScalar x,
                      SkScalar y,
                      const SkPaint& paint) override;

  void onDrawPatch(const SkPoint cubics[12],
                   const SkColor colors[4],
                   const SkPoint texCoords[4],
                   SkBlendMode mode,
                   const SkPaint& paint) override {
    FML_DCHECK(false);
  }
  void onDrawPoints(SkCanvas::PointMode mode,
                    size_t count,
                    const SkPoint pts[],
                    const SkPaint& paint) override;
  void onDrawVerticesObject(const SkVertices* vertices,
                            SkBlendMode mode,
                            const SkPaint& paint) override;

  void onDrawImage2(const SkImage*,
                    SkScalar dx,
                    SkScalar dy,
                    const SkSamplingOptions&,
                    const SkPaint*) override;
  void onDrawImageRect2(const SkImage*,
                        const SkRect& src,
                        const SkRect& dst,
                        const SkSamplingOptions&,
                        const SkPaint*,
                        SrcRectConstraint) override;
  void onDrawImageLattice2(const SkImage*,
                           const Lattice&,
                           const SkRect& dst,
                           SkFilterMode,
                           const SkPaint*) override;
  void onDrawAtlas2(const SkImage*,
                    const SkRSXform[],
                    const SkRect src[],
                    const SkColor[],
                    int count,
                    SkBlendMode,
                    const SkSamplingOptions&,
                    const SkRect* cull,
                    const SkPaint*) override;

  void onDrawEdgeAAQuad(const SkRect& rect,
                        const SkPoint clip[4],
                        SkCanvas::QuadAAFlags aaFlags,
                        const SkColor4f& color,
                        SkBlendMode mode) override {
    FML_DCHECK(0);
  }

  void onDrawAnnotation(const SkRect& rect,
                        const char key[],
                        SkData* value) override {
    FML_DCHECK(false);
  }
  void onDrawShadowRec(const SkPath&, const SkDrawShadowRec&) override;

  void onDrawDrawable(SkDrawable* drawable, const SkMatrix* matrix) override {
    FML_DCHECK(false);
  }
  void onDrawPicture(const SkPicture* picture,
                     const SkMatrix* matrix,
                     const SkPaint* paint) override;

  enum class DrawType {
    // The operation will be an image operation
    kImageOpType,
    // The operation will be an imageRect operation
    kImageRectOpType,
    // The operation will be a fill or stroke depending on the paint.style
    kDrawOpType,
    // The operation will be a fill (ignoring paint.style)
    kFillOpType,
    // The operation will be a stroke (ignoring paint.style)
    kStrokeOpType,
    // The operation will be a saveLayer with a paint object
    kSaveLayerOpType,
  };

  void RecordPaintAttributes(const SkPaint* paint, DrawType type);

 private:
  sk_sp<DisplayListBuilder> builder_;

  // Mask bits for the various attributes that might be needed for a given
  // operation.
  // clang-format off
  static constexpr int kAaNeeded_            = 1 << 0;
  static constexpr int kColorNeeded_         = 1 << 1;
  static constexpr int kBlendNeeded_         = 1 << 2;
  static constexpr int kInvertColorsNeeded_  = 1 << 3;
  static constexpr int kPaintStyleNeeded_    = 1 << 4;
  static constexpr int kStrokeStyleNeeded_   = 1 << 5;
  static constexpr int kShaderNeeded_        = 1 << 6;
  static constexpr int kColorFilterNeeded_   = 1 << 7;
  static constexpr int kImageFilterNeeded_   = 1 << 8;
  static constexpr int kPathEffectNeeded_    = 1 << 9;
  static constexpr int kMaskFilterNeeded_    = 1 << 10;
  static constexpr int kDitherNeeded_        = 1 << 11;
  // clang-format on

  // Combinations of the above mask bits that are common to typical "draw"
  // calls.
  // Note that the strokeStyle_ is handled conditionally depending on whether
  // the paintStyle_ attribute value is synchronized. It can also be manually
  // specified for operations that will be always stroking, like [drawLine].
  static constexpr int kPaintMask_ = kAaNeeded_ | kColorNeeded_ |
                                     kBlendNeeded_ | kInvertColorsNeeded_ |
                                     kColorFilterNeeded_ | kShaderNeeded_ |
                                     kDitherNeeded_ | kImageFilterNeeded_;
  static constexpr int kDrawMask_ = kPaintMask_ | kPaintStyleNeeded_ |
                                    kMaskFilterNeeded_ | kPathEffectNeeded_;
  static constexpr int kStrokeMask_ = kPaintMask_ | kStrokeStyleNeeded_ |
                                      kMaskFilterNeeded_ | kPathEffectNeeded_;
  static constexpr int kImageMask_ = kColorNeeded_ | kBlendNeeded_ |
                                     kInvertColorsNeeded_ |
                                     kColorFilterNeeded_ | kDitherNeeded_ |
                                     kImageFilterNeeded_ | kMaskFilterNeeded_;
  static constexpr int kImageRectMask_ = kImageMask_ | kAaNeeded_;
  static constexpr int kSaveLayerMask_ =
      kColorNeeded_ | kBlendNeeded_ | kInvertColorsNeeded_ |
      kColorFilterNeeded_ | kImageFilterNeeded_;

  bool current_aa_ = false;
  bool current_dither_ = false;
  SkColor current_color_ = 0xFF000000;
  SkBlendMode current_blend_ = SkBlendMode::kSrcOver;
  SkPaint::Style current_style_ = SkPaint::Style::kFill_Style;
  SkScalar current_stroke_width_ = 0.0;
  SkScalar current_miter_limit_ = 4.0;
  SkPaint::Cap current_cap_ = SkPaint::Cap::kButt_Cap;
  SkPaint::Join current_join_ = SkPaint::Join::kMiter_Join;
  sk_sp<SkBlender> current_blender_;
  sk_sp<SkShader> current_shader_;
  sk_sp<SkColorFilter> current_color_filter_;
  sk_sp<SkImageFilter> current_image_filter_;
  sk_sp<SkPathEffect> current_path_effect_;
  sk_sp<SkMaskFilter> current_mask_filter_;
};

}  // namespace flutter

#endif  // FLUTTER_FLOW_DISPLAY_LIST_CANVAS_H_