display_list/dl_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_DISPLAY_LIST_DL_CANVAS_H_
#define FLUTTER_DISPLAY_LIST_DL_CANVAS_H_

#include "flutter/display_list/dl_blend_mode.h"
#include "flutter/display_list/dl_paint.h"
#include "flutter/display_list/dl_vertices.h"
#include "flutter/display_list/geometry/dl_geometry_types.h"
#include "flutter/display_list/geometry/dl_path.h"
#include "flutter/display_list/image/dl_image.h"

#include "third_party/skia/include/core/SkM44.h"
#include "third_party/skia/include/core/SkMatrix.h"
#include "third_party/skia/include/core/SkPath.h"
#include "third_party/skia/include/core/SkRRect.h"
#include "third_party/skia/include/core/SkRSXform.h"
#include "third_party/skia/include/core/SkRect.h"
#include "third_party/skia/include/core/SkTextBlob.h"

#include "impeller/typographer/text_frame.h"

namespace flutter {

//------------------------------------------------------------------------------
/// @brief    Developer-facing API for rendering anything *within* the engine.
///
/// |DlCanvas| should be used to render anything in the framework classes (i.e.
/// `lib/ui`), flow and flow layers, embedders, shell, and elsewhere.
///
/// The only state carried by implementations of this interface are the clip
/// and transform which are saved and restored by the |save|, |saveLayer|, and
/// |restore| calls.
///
/// @note      The interface resembles closely the familiar |SkCanvas| interface
///            used throughout the engine.
class DlCanvas {
 public:
  enum class ClipOp {
    kDifference,
    kIntersect,
  };

  enum class PointMode {
    kPoints,   //!< draw each point separately
    kLines,    //!< draw each separate pair of points as a line segment
    kPolygon,  //!< draw each pair of overlapping points as a line segment
  };

  enum class SrcRectConstraint {
    kStrict,
    kFast,
  };

  virtual ~DlCanvas() = default;

  virtual DlISize GetBaseLayerDimensions() const = 0;
  virtual SkImageInfo GetImageInfo() const = 0;

  virtual void Save() = 0;
  virtual void SaveLayer(std::optional<const DlRect>& bounds,
                         const DlPaint* paint = nullptr,
                         const DlImageFilter* backdrop = nullptr) = 0;
  virtual void Restore() = 0;
  virtual int GetSaveCount() const = 0;
  virtual void RestoreToCount(int restore_count) = 0;

  virtual void Translate(DlScalar tx, DlScalar ty) = 0;
  virtual void Scale(DlScalar sx, DlScalar sy) = 0;
  virtual void Rotate(DlScalar degrees) = 0;
  virtual void Skew(DlScalar sx, DlScalar sy) = 0;

  // clang-format off

  // 2x3 2D affine subset of a 4x4 transform in row major order
  virtual void Transform2DAffine(DlScalar mxx, DlScalar mxy, DlScalar mxt,
                                 DlScalar myx, DlScalar myy, DlScalar myt) = 0;
  // full 4x4 transform in row major order
  virtual void TransformFullPerspective(
      DlScalar mxx, DlScalar mxy, DlScalar mxz, DlScalar mxt,
      DlScalar myx, DlScalar myy, DlScalar myz, DlScalar myt,
      DlScalar mzx, DlScalar mzy, DlScalar mzz, DlScalar mzt,
      DlScalar mwx, DlScalar mwy, DlScalar mwz, DlScalar mwt) = 0;
  // clang-format on
  virtual void TransformReset() = 0;
  virtual void Transform(const DlMatrix& matrix) = 0;
  virtual void SetTransform(const DlMatrix& matrix) = 0;

  virtual DlMatrix GetMatrix() const = 0;

  virtual void ClipRect(const DlRect& rect,
                        ClipOp clip_op = ClipOp::kIntersect,
                        bool is_aa = false) = 0;
  virtual void ClipOval(const DlRect& bounds,
                        ClipOp clip_op = ClipOp::kIntersect,
                        bool is_aa = false) = 0;
  virtual void ClipRRect(const SkRRect& rrect,
                         ClipOp clip_op = ClipOp::kIntersect,
                         bool is_aa = false) = 0;
  virtual void ClipPath(const DlPath& path,
                        ClipOp clip_op = ClipOp::kIntersect,
                        bool is_aa = false) = 0;

  /// Conservative estimate of the bounds of all outstanding clip operations
  /// measured in the coordinate space within which this DisplayList will
  /// be rendered.
  virtual DlRect GetDestinationClipCoverage() const = 0;
  /// Conservative estimate of the bounds of all outstanding clip operations
  /// transformed into the local coordinate space in which currently
  /// recorded rendering operations are interpreted.
  virtual DlRect GetLocalClipCoverage() const = 0;

  /// Return true iff the supplied bounds are easily shown to be outside
  /// of the current clip bounds. This method may conservatively return
  /// false if it cannot make the determination.
  virtual bool QuickReject(const DlRect& bounds) const = 0;

  virtual void DrawPaint(const DlPaint& paint) = 0;
  virtual void DrawColor(DlColor color,
                         DlBlendMode mode = DlBlendMode::kSrcOver) = 0;
  void Clear(DlColor color) { DrawColor(color, DlBlendMode::kSrc); }
  virtual void DrawLine(const DlPoint& p0,
                        const DlPoint& p1,
                        const DlPaint& paint) = 0;
  virtual void DrawDashedLine(const DlPoint& p0,
                              const DlPoint& p1,
                              DlScalar on_length,
                              DlScalar off_length,
                              const DlPaint& paint) = 0;
  virtual void DrawRect(const DlRect& rect, const DlPaint& paint) = 0;
  virtual void DrawOval(const DlRect& bounds, const DlPaint& paint) = 0;
  virtual void DrawCircle(const DlPoint& center,
                          DlScalar radius,
                          const DlPaint& paint) = 0;
  virtual void DrawRRect(const SkRRect& rrect, const DlPaint& paint) = 0;
  virtual void DrawDRRect(const SkRRect& outer,
                          const SkRRect& inner,
                          const DlPaint& paint) = 0;
  virtual void DrawPath(const DlPath& path, const DlPaint& paint) = 0;
  virtual void DrawArc(const DlRect& bounds,
                       DlScalar start,
                       DlScalar sweep,
                       bool useCenter,
                       const DlPaint& paint) = 0;
  virtual void DrawPoints(PointMode mode,
                          uint32_t count,
                          const DlPoint pts[],
                          const DlPaint& paint) = 0;
  virtual void DrawVertices(const std::shared_ptr<DlVertices>& vertices,
                            DlBlendMode mode,
                            const DlPaint& paint) = 0;
  virtual void DrawImage(const sk_sp<DlImage>& image,
                         const DlPoint& point,
                         DlImageSampling sampling,
                         const DlPaint* paint = nullptr) = 0;
  virtual void DrawImageRect(
      const sk_sp<DlImage>& image,
      const DlRect& src,
      const DlRect& dst,
      DlImageSampling sampling,
      const DlPaint* paint = nullptr,
      SrcRectConstraint constraint = SrcRectConstraint::kFast) = 0;
  virtual void DrawImageRect(
      const sk_sp<DlImage>& image,
      const DlIRect& src,
      const DlRect& dst,
      DlImageSampling sampling,
      const DlPaint* paint = nullptr,
      SrcRectConstraint constraint = SrcRectConstraint::kFast) {
    auto float_src = DlRect::MakeLTRB(src.GetLeft(), src.GetTop(),
                                      src.GetRight(), src.GetBottom());
    DrawImageRect(image, float_src, dst, sampling, paint, constraint);
  }
  void DrawImageRect(const sk_sp<DlImage>& image,
                     const DlRect& dst,
                     DlImageSampling sampling,
                     const DlPaint* paint = nullptr,
                     SrcRectConstraint constraint = SrcRectConstraint::kFast) {
    DrawImageRect(image, image->GetBounds(), dst, sampling, paint, constraint);
  }
  virtual void DrawImageNine(const sk_sp<DlImage>& image,
                             const DlIRect& center,
                             const DlRect& dst,
                             DlFilterMode filter,
                             const DlPaint* paint = nullptr) = 0;
  virtual void DrawAtlas(const sk_sp<DlImage>& atlas,
                         const SkRSXform xform[],
                         const DlRect tex[],
                         const DlColor colors[],
                         int count,
                         DlBlendMode mode,
                         DlImageSampling sampling,
                         const DlRect* cullRect,
                         const DlPaint* paint = nullptr) = 0;
  virtual void DrawDisplayList(const sk_sp<DisplayList> display_list,
                               DlScalar opacity = SK_Scalar1) = 0;

  virtual void DrawTextFrame(
      const std::shared_ptr<impeller::TextFrame>& text_frame,
      DlScalar x,
      DlScalar y,
      const DlPaint& paint) = 0;

  virtual void DrawTextBlob(const sk_sp<SkTextBlob>& blob,
                            DlScalar x,
                            DlScalar y,
                            const DlPaint& paint) = 0;
  virtual void DrawShadow(const DlPath& path,
                          const DlColor color,
                          const DlScalar elevation,
                          bool transparent_occluder,
                          DlScalar dpr) = 0;

  virtual void Flush() = 0;

  static constexpr DlScalar kShadowLightHeight = 600;
  static constexpr DlScalar kShadowLightRadius = 800;

  static DlRect ComputeShadowBounds(const DlPath& path,
                                    float elevation,
                                    DlScalar dpr,
                                    const DlMatrix& ctm);

  // -----------------------------------------------------------------
  // SkObject Compatibility section - deprecated...
  // -----------------------------------------------------------------

  SkISize GetBaseLayerSize() const {
    return ToSkISize(GetBaseLayerDimensions());
  }

  void SaveLayer(const SkRect* bounds,
                 const DlPaint* paint = nullptr,
                 const DlImageFilter* backdrop = nullptr) {
    auto optional_bounds = ToOptDlRect(bounds);
    SaveLayer(optional_bounds, paint, backdrop);
  }

  void Transform(const SkMatrix* matrix) {
    if (matrix) {
      Transform(*matrix);
    }
  }
  void Transform(const SkM44* matrix44) {
    if (matrix44) {
      Transform(*matrix44);
    }
  }
  void Transform(const SkMatrix& matrix) { Transform(ToDlMatrix(matrix)); }
  void Transform(const SkM44& m44) { Transform(ToDlMatrix(m44)); }
  void SetTransform(const SkMatrix* matrix) {
    if (matrix) {
      SetTransform(*matrix);
    }
  }
  void SetTransform(const SkM44* matrix44) {
    if (matrix44) {
      SetTransform(*matrix44);
    }
  }
  void SetTransform(const SkMatrix& matrix) {
    SetTransform(ToDlMatrix(matrix));
  }
  void SetTransform(const SkM44& m44) { SetTransform(ToDlMatrix(m44)); }

  /// Returns the 4x4 full perspective transform representing all transform
  /// operations executed so far in this DisplayList within the enclosing
  /// save stack.
  SkM44 GetTransformFullPerspective() const { return ToSkM44(GetMatrix()); }
  /// Returns the 3x3 partial perspective transform representing all transform
  /// operations executed so far in this DisplayList within the enclosing
  /// save stack.
  SkMatrix GetTransform() const { return ToSkMatrix(GetMatrix()); }

  void ClipRect(const SkRect& rect,
                ClipOp clip_op = ClipOp::kIntersect,
                bool is_aa = false) {
    ClipRect(ToDlRect(rect), clip_op, is_aa);
  }

  void ClipOval(const SkRect& bounds,
                ClipOp clip_op = ClipOp::kIntersect,
                bool is_aa = false) {
    ClipOval(ToDlRect(bounds), clip_op, is_aa);
  }
  void ClipPath(const SkPath& path,
                ClipOp clip_op = ClipOp::kIntersect,
                bool is_aa = false) {
    ClipPath(DlPath(path), clip_op, is_aa);
  }

  SkRect GetDestinationClipBounds() const {
    return ToSkRect(GetDestinationClipCoverage());
  }
  SkRect GetLocalClipBounds() const { return ToSkRect(GetLocalClipCoverage()); }
  bool QuickReject(const SkRect& bounds) const {
    return QuickReject(ToDlRect(bounds));
  }

  void DrawLine(const SkPoint& p0, const SkPoint& p1, const DlPaint& paint) {
    DrawLine(ToDlPoint(p0), ToDlPoint(p1), paint);
  }
  void DrawRect(const SkRect& rect, const DlPaint& paint) {
    DrawRect(ToDlRect(rect), paint);
  }
  void DrawOval(const SkRect& bounds, const DlPaint& paint) {
    DrawOval(ToDlRect(bounds), paint);
  }
  void DrawCircle(const SkPoint& center,
                  DlScalar radius,
                  const DlPaint& paint) {
    DrawCircle(ToDlPoint(center), radius, paint);
  }
  void DrawPath(const SkPath& path, const DlPaint& paint) {
    DrawPath(DlPath(path), paint);
  }
  void DrawArc(const SkRect& bounds,
               DlScalar start,
               DlScalar sweep,
               bool useCenter,
               const DlPaint& paint) {
    DrawArc(ToDlRect(bounds), start, sweep, useCenter, paint);
  }
  void DrawPoints(PointMode mode,
                  uint32_t count,
                  const SkPoint pts[],
                  const DlPaint& paint) {
    DrawPoints(mode, count, ToDlPoints(pts), paint);
  }
  void DrawImage(const sk_sp<DlImage>& image,
                 const SkPoint& point,
                 DlImageSampling sampling,
                 const DlPaint* paint = nullptr) {
    DrawImage(image, ToDlPoint(point), sampling, paint);
  }
  void DrawImageRect(const sk_sp<DlImage>& image,
                     const SkRect& src,
                     const SkRect& dst,
                     DlImageSampling sampling,
                     const DlPaint* paint = nullptr,
                     SrcRectConstraint constraint = SrcRectConstraint::kFast) {
    DrawImageRect(image, ToDlRect(src), ToDlRect(dst), sampling, paint,
                  constraint);
  }
  void DrawImageRect(const sk_sp<DlImage>& image,
                     const SkIRect& src,
                     const SkRect& dst,
                     DlImageSampling sampling,
                     const DlPaint* paint = nullptr,
                     SrcRectConstraint constraint = SrcRectConstraint::kFast) {
    DrawImageRect(image, ToDlRect(src), ToDlRect(dst), sampling, paint,
                  constraint);
  }
  void DrawImageRect(const sk_sp<DlImage>& image,
                     const SkRect& dst,
                     DlImageSampling sampling,
                     const DlPaint* paint = nullptr,
                     SrcRectConstraint constraint = SrcRectConstraint::kFast) {
    DrawImageRect(image, image->GetBounds(), ToDlRect(dst), sampling, paint,
                  constraint);
  }
  void DrawImageNine(const sk_sp<DlImage>& image,
                     const SkIRect& center,
                     const SkRect& dst,
                     DlFilterMode filter,
                     const DlPaint* paint = nullptr) {
    DrawImageNine(image, ToDlIRect(center), ToDlRect(dst), filter, paint);
  }
  void DrawAtlas(const sk_sp<DlImage>& atlas,
                 const SkRSXform xform[],
                 const SkRect tex[],
                 const DlColor colors[],
                 int count,
                 DlBlendMode mode,
                 DlImageSampling sampling,
                 const SkRect* cullRect,
                 const DlPaint* paint = nullptr) {
    DrawAtlas(atlas, xform, ToDlRects(tex), colors, count, mode, sampling,
              ToDlRect(cullRect), paint);
  }
  void DrawShadow(const SkPath& path,
                  const DlColor color,
                  const DlScalar elevation,
                  bool transparent_occluder,
                  DlScalar dpr) {
    DrawShadow(DlPath(path), color, elevation, transparent_occluder, dpr);
  }

  static SkRect ComputeShadowBounds(const SkPath& path,
                                    float elevation,
                                    DlScalar dpr,
                                    const SkMatrix& ctm) {
    return ToSkRect(
        ComputeShadowBounds(DlPath(path), elevation, dpr, ToDlMatrix(ctm)));
  }

#define ENABLE_DL_CANVAS_BACKWARDS_COMPATIBILITY \
  using DlCanvas::GetBaseLayerSize;              \
                                                 \
  using DlCanvas::SaveLayer;                     \
                                                 \
  using DlCanvas::Transform;                     \
  using DlCanvas::SetTransform;                  \
  using DlCanvas::GetTransformFullPerspective;   \
  using DlCanvas::GetTransform;                  \
                                                 \
  using DlCanvas::ClipRect;                      \
  using DlCanvas::ClipOval;                      \
  using DlCanvas::ClipPath;                      \
                                                 \
  using DlCanvas::GetDestinationClipBounds;      \
  using DlCanvas::GetLocalClipBounds;            \
  using DlCanvas::QuickReject;                   \
                                                 \
  using DlCanvas::DrawLine;                      \
  using DlCanvas::DrawRect;                      \
  using DlCanvas::DrawOval;                      \
  using DlCanvas::DrawCircle;                    \
  using DlCanvas::DrawPath;                      \
  using DlCanvas::DrawArc;                       \
  using DlCanvas::DrawPoints;                    \
  using DlCanvas::DrawImage;                     \
  using DlCanvas::DrawImageRect;                 \
  using DlCanvas::DrawImageNine;                 \
  using DlCanvas::DrawAtlas;                     \
  using DlCanvas::DrawShadow;
};

class DlAutoCanvasRestore {
 public:
  DlAutoCanvasRestore(DlCanvas* canvas, bool do_save) : canvas_(canvas) {
    if (canvas) {
      canvas_ = canvas;
      restore_count_ = canvas->GetSaveCount();
      if (do_save) {
        canvas_->Save();
      }
    } else {
      canvas_ = nullptr;
      restore_count_ = 0;
    }
  }

  ~DlAutoCanvasRestore() { Restore(); }

  void Restore() {
    if (canvas_) {
      canvas_->RestoreToCount(restore_count_);
      canvas_ = nullptr;
    }
  }

 private:
  DlCanvas* canvas_;
  int restore_count_;

  FML_DISALLOW_COPY_ASSIGN_AND_MOVE(DlAutoCanvasRestore);
};

}  // namespace flutter

#endif  // FLUTTER_DISPLAY_LIST_DL_CANVAS_H_