cc/paint/paint_flags.h

// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CC_PAINT_PAINT_FLAGS_H_
#define CC_PAINT_PAINT_FLAGS_H_

#include <string>
#include <utility>

#include "base/compiler_specific.h"
#include "cc/paint/color_filter.h"
#include "cc/paint/draw_looper.h"
#include "cc/paint/paint_export.h"
#include "cc/paint/path_effect.h"
#include "third_party/skia/include/core/SkPaint.h"
#include "third_party/skia/include/core/SkSamplingOptions.h"
#include "ui/gfx/display_color_spaces.h"

class SkCanvas;
class SkPath;

namespace cc {
class PaintFilter;
class PaintShader;

// Minimal set of commonly used paint state. Using a minimal set means PaintOps
// takes up less space in memory as well as less data to read/write.
class CC_PAINT_EXPORT CorePaintFlags {
 public:
  CorePaintFlags();
  CorePaintFlags(const CorePaintFlags& flags) = default;
  bool operator==(const CorePaintFlags& other) const;
  ~CorePaintFlags() = default;

  enum Style {
    kFill_Style = SkPaint::kFill_Style,
    kStroke_Style = SkPaint::kStroke_Style,
  };
  ALWAYS_INLINE Style getStyle() const {
    return static_cast<Style>(bitfields_.style_);
  }
  ALWAYS_INLINE void setStyle(Style style) { bitfields_.style_ = style; }
  // TODO(crbug.com/40249893): Remove this function
  ALWAYS_INLINE SkColor getColor() const { return color_.toSkColor(); }
  ALWAYS_INLINE const SkColor4f& getColor4f() const { return color_; }
  ALWAYS_INLINE void setColor(SkColor color) {
    color_ = SkColor4f::FromColor(color);
  }
  ALWAYS_INLINE void setColor(SkColor4f color) { color_ = color; }
  ALWAYS_INLINE float getAlphaf() const { return color_.fA; }
  ALWAYS_INLINE bool isFullyTransparent() const { return color_.fA == 0.0f; }
  ALWAYS_INLINE bool isOpaque() const { return color_.fA >= 1.0f; }
  template <class F>
    requires(std::is_same_v<F, float>)
  ALWAYS_INLINE void setAlphaf(F a) {
    color_.fA = a;
  }
  ALWAYS_INLINE void setBlendMode(SkBlendMode mode) {
    bitfields_.blend_mode_ = static_cast<uint32_t>(mode);
  }
  ALWAYS_INLINE SkBlendMode getBlendMode() const {
    return static_cast<SkBlendMode>(bitfields_.blend_mode_);
  }
  ALWAYS_INLINE bool isAntiAlias() const { return bitfields_.antialias_; }
  ALWAYS_INLINE void setAntiAlias(bool aa) { bitfields_.antialias_ = aa; }
  ALWAYS_INLINE bool isDither() const { return bitfields_.dither_; }
  ALWAYS_INLINE void setDither(bool dither) { bitfields_.dither_ = dither; }

  ALWAYS_INLINE void setArcClosed(bool value) {
    bitfields_.is_arc_closed_ = value;
  }
  ALWAYS_INLINE bool isArcClosed() const { return bitfields_.is_arc_closed_; }

  enum class FilterQuality {
    kNone,
    kLow,
    kMedium,
    kHigh,
    kLast = kHigh,
  };

  enum class ScalingOperation {
    kDefault,  // legacy behavior
    kUnknown,
    kUpscale  // strict upscale (scaling up both horizontally and vertically)
  };

  ALWAYS_INLINE void setFilterQuality(FilterQuality quality) {
    bitfields_.filter_quality_ = static_cast<uint32_t>(quality);
  }
  ALWAYS_INLINE FilterQuality getFilterQuality() const {
    return static_cast<FilterQuality>(bitfields_.filter_quality_);
  }
  enum class DynamicRangeLimit {
    kStandard,
    kHigh,
    kConstrainedHigh,
    kLast = kConstrainedHigh,
  };
  // Represents a weighted arithmetic mean of "standard", "constrained-high" and
  // "high" in log-luminance space (which is equivalent to a geometric mean in
  // linear luminance).
  struct CC_PAINT_EXPORT DynamicRangeLimitMixture {
    // The default constructor is equivalent to DynamicRangeLimit::kHigh.
    DynamicRangeLimitMixture() = default;
    explicit DynamicRangeLimitMixture(DynamicRangeLimit limit) {
      switch (limit) {
        case DynamicRangeLimit::kStandard:
          standard_mix = 1.f;
          break;
        case DynamicRangeLimit::kConstrainedHigh:
          constrained_high_mix = 1.f;
          break;
        case DynamicRangeLimit::kHigh:
          break;
      }
    }
    DynamicRangeLimitMixture(float standard_mix, float constrained_high_mix)
        : standard_mix(standard_mix),
          constrained_high_mix(constrained_high_mix) {}
    friend bool operator==(const DynamicRangeLimitMixture&,
                           const DynamicRangeLimitMixture&) = default;
    // Compute the effective HDR headroom when this limit is applied to
    // `target_hdr_headroom`.
    float ComputeEffectiveHdrHeadroom(float target_hdr_headroom) const;

    std::string ToString() const;

    float standard_mix = 0.f;
    float constrained_high_mix = 0.f;
    // The weight for "high" is implicit and calculated as "one minus the
    // others".
  };
  ALWAYS_INLINE void setDynamicRangeLimit(DynamicRangeLimitMixture limit) {
    bitfields_.dynamic_range_limit_standard_mix_ =
        static_cast<uint32_t>(.5f + ((1 << 7) - 1) * limit.standard_mix);
    bitfields_.dynamic_range_limit_constrained_high_mix_ =
        static_cast<uint32_t>(.5f +
                              ((1 << 7) - 1) * limit.constrained_high_mix);
  }
  ALWAYS_INLINE DynamicRangeLimitMixture getDynamicRangeLimit() const {
    return DynamicRangeLimitMixture(
        /*standard_mix=*/(1.f / ((1 << 7) - 1)) *
            bitfields_.dynamic_range_limit_standard_mix_,
        /*constrained_high_mix=*/(1.f / ((1 << 7) - 1)) *
            bitfields_.dynamic_range_limit_constrained_high_mix_);
  }
  ALWAYS_INLINE bool useDarkModeForImage() const {
    return bitfields_.use_dark_mode_for_image_;
  }
  ALWAYS_INLINE void setUseDarkModeForImage(bool use_dark_mode_for_image) {
    bitfields_.use_dark_mode_for_image_ = use_dark_mode_for_image;
  }
  ALWAYS_INLINE SkScalar getStrokeWidth() const { return width_; }
  ALWAYS_INLINE void setStrokeWidth(SkScalar width) { width_ = width; }
  ALWAYS_INLINE SkScalar getStrokeMiter() const { return miter_limit_; }
  ALWAYS_INLINE void setStrokeMiter(SkScalar miter) { miter_limit_ = miter; }
  enum Cap {
    kButt_Cap = SkPaint::kButt_Cap,    //!< begin/end contours with no extension
    kRound_Cap = SkPaint::kRound_Cap,  //!< begin/end contours with a
                                       //! semi-circle extension
    kSquare_Cap = SkPaint::kSquare_Cap,  //!< begin/end contours with a half
                                         //! square extension
    kLast_Cap = kSquare_Cap,
    kDefault_Cap = kButt_Cap
  };
  ALWAYS_INLINE Cap getStrokeCap() const {
    return static_cast<Cap>(bitfields_.cap_type_);
  }
  ALWAYS_INLINE void setStrokeCap(Cap cap) { bitfields_.cap_type_ = cap; }
  enum Join {
    kMiter_Join = SkPaint::kMiter_Join,
    kRound_Join = SkPaint::kRound_Join,
    kBevel_Join = SkPaint::kBevel_Join,
    kLast_Join = kBevel_Join,
    kDefault_Join = kMiter_Join
  };
  ALWAYS_INLINE Join getStrokeJoin() const {
    return static_cast<Join>(bitfields_.join_type_);
  }
  ALWAYS_INLINE void setStrokeJoin(Join join) { bitfields_.join_type_ = join; }

  bool IsValid() const;

 private:
  friend class PaintOpReader;
  friend class PaintOpWriter;

  // Match(ish) SkPaint defaults.  SkPaintDefaults is not public, so this
  // just uses these values and ignores any SkUserConfig overrides.
  SkColor4f color_ = SkColors::kBlack;
  float width_ = 0.f;
  float miter_limit_ = 4.f;

  struct PaintFlagsBitfields {
    uint32_t antialias_ : 1;
    uint32_t dither_ : 1;
    uint32_t cap_type_ : 2;
    uint32_t join_type_ : 2;
    uint32_t style_ : 2;
    uint32_t blend_mode_ : 5;
    uint32_t filter_quality_ : 2;
    uint32_t dynamic_range_limit_standard_mix_ : 7;
    uint32_t dynamic_range_limit_constrained_high_mix_ : 7;
    // Specifies whether the compositor should use a dark mode filter when
    // rasterizing image on the draw op with this PaintFlags.
    uint32_t use_dark_mode_for_image_ : 1;
    // Whether the arc should be drawn as a closed path.
    uint32_t is_arc_closed_ : 1;
  };

  union {
    PaintFlagsBitfields bitfields_;
    uint32_t bitfields_uint_;
  };
};

class CC_PAINT_EXPORT PaintFlags final : public CorePaintFlags {
 public:
  // Sentinel value for targeted HDR headroom.
  class TargetedHdrHeadroom {
   public:
    // Read the value from the PlaybackParams at playback time.
    static constexpr float kFromPlaybackParams = -1.0f;
    // Ignore all HDR metadata and draw with no tone mapping. This will also
    // ignore the HDR reference white metadata, which is only desirable when
    // making internal copies to the same color space.
    static constexpr float kDisableEverything = -2.0f;
  };

  PaintFlags();
  PaintFlags(const PaintFlags& flags);
  explicit PaintFlags(const CorePaintFlags& flags);
  PaintFlags(PaintFlags&& other);
  ~PaintFlags();
  PaintFlags& operator=(const PaintFlags& other);
  PaintFlags& operator=(PaintFlags&& other);

  bool CanConvertToCorePaintFlags() const;
  CorePaintFlags ToCorePaintFlags() const;

  bool nothingToDraw() const;

  ALWAYS_INLINE const sk_sp<ColorFilter>& getColorFilter() const {
    return color_filter_;
  }
  ALWAYS_INLINE void setColorFilter(sk_sp<ColorFilter> filter) {
    color_filter_ = std::move(filter);
  }

  ALWAYS_INLINE const PaintShader* getShader() const { return shader_.get(); }

  // Returns true if the shader has been set on the flags.
  ALWAYS_INLINE bool HasShader() const { return !!shader_; }

  // Returns whether the shader is opaque. Note that it is only valid to call
  // this function if HasShader() returns true.
  bool ShaderIsOpaque() const;

  void setShader(sk_sp<PaintShader> shader);

  ALWAYS_INLINE const sk_sp<PathEffect>& getPathEffect() const {
    return path_effect_;
  }
  ALWAYS_INLINE void setPathEffect(sk_sp<PathEffect> effect) {
    path_effect_ = std::move(effect);
  }
  bool getFillPath(const SkPath& src,
                   SkPath* dst,
                   const SkRect* cull_rect = nullptr,
                   SkScalar res_scale = 1) const;

  ALWAYS_INLINE const sk_sp<PaintFilter>& getImageFilter() const {
    return image_filter_;
  }
  void setImageFilter(sk_sp<PaintFilter> filter);

  ALWAYS_INLINE const sk_sp<DrawLooper>& getLooper() const {
    return draw_looper_;
  }
  ALWAYS_INLINE void setLooper(sk_sp<DrawLooper> looper) {
    draw_looper_ = std::move(looper);
  }

  // Sets the targeted HDR headroom. The targeted HDR headroom property
  // indicates the HDR headroom value that (adjusted by the dynamic range
  // limit) will be used for tone mapping. The range of meaningful values is
  // [0, infinity], with infinity indicating to tone map using the maximum
  // HDR headroom. The default is TargetedHdrHeadroom::kFromPlaybackParams,
  // which indicates to use the HDR headroom specified in PlaybackParams,
  // specified at playback time.
  ALWAYS_INLINE void setTargetedHdrHeadroom(float value) {
    targeted_hdr_headroom_ = value;
  }
  // Gets the targeted HDR headroom.
  ALWAYS_INLINE float getTargetedHdrHeadroom() const {
    return targeted_hdr_headroom_;
  }

  // Returns true if this (of a drawOp) allows the sequence
  // saveLayerAlphaf/drawOp/restore to be folded into a single drawOp by baking
  // the alpha in the saveLayerAlphaf into the flags of the drawOp.
  bool SupportsFoldingAlpha() const;

  // SkPaint does not support loopers, so callers of SkToPaint need
  // to check for loopers manually (see getLooper()).
  SkPaint ToSkPaint() const;

  template <typename Proc>
  void DrawToSk(SkCanvas* canvas, Proc proc) const {
    SkPaint paint = ToSkPaint();
    if (const sk_sp<DrawLooper>& looper = getLooper()) {
      looper->Apply(canvas, paint, proc);
    } else {
      proc(canvas, paint);
    }
  }

  static SkSamplingOptions FilterQualityToSkSamplingOptions(
      FilterQuality filter_quality);
  static SkSamplingOptions FilterQualityToSkSamplingOptions(
      FilterQuality filter_quality,
      ScalingOperation scaling_op);

  bool EqualsForTesting(const PaintFlags& other) const;

  // If `content_color_usage` is not null, the function should update
  // `*content_color_usage` to be
  // max(*content_color_usage, max_content_color_usage_of_the_flags).
  bool HasDiscardableImages(
      gfx::ContentColorUsage* content_color_usage = nullptr) const;

 private:
  friend class PaintOpReader;
  friend class PaintOpWriter;

  // See documentation at `setTargetedHdrHeadroom`.
  float targeted_hdr_headroom_ = TargetedHdrHeadroom::kFromPlaybackParams;
  sk_sp<PathEffect> path_effect_;
  sk_sp<PaintShader> shader_;
  sk_sp<ColorFilter> color_filter_;
  sk_sp<DrawLooper> draw_looper_;
  sk_sp<PaintFilter> image_filter_;
};

}  // namespace cc

#endif  // CC_PAINT_PAINT_FLAGS_H_