cc/paint/paint_worklet_input.h

// Copyright 2018 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_WORKLET_INPUT_H_
#define CC_PAINT_PAINT_WORKLET_INPUT_H_

#include <optional>
#include <string>
#include <utility>
#include <vector>

#include "base/containers/flat_map.h"
#include "base/memory/ref_counted.h"
#include "cc/paint/deferred_paint_record.h"
#include "cc/paint/element_id.h"
#include "cc/paint/paint_image.h"
#include "cc/paint/paint_record.h"

namespace cc {

class CC_PAINT_EXPORT PaintWorkletInput : public DeferredPaintRecord {
 public:
  enum class NativePropertyType {
    kBackgroundColor,
    kClipPath,
    kInvalid,
  };
  bool IsPaintWorkletInput() const final;
  // Uniquely identifies a property from the animation system, so that a
  // PaintWorkletInput can specify the properties it depends on to be painted
  // (and for which it must be repainted if their values change).
  //
  // PropertyKey is designed to support both native and custom properties.
  //   1. Custom properties: The same ElementId will be produced for all custom
  //      properties for a given element. As such we require the custom property
  //      name as an additional key to uniquely identify custom properties.
  //   2. Native properties: When fetching the current value of a native
  //      property from property tree, we need the ElementId, plus knowing which
  //      tree to fetch the value from, and that's why we need the
  //      |native_property_type|.
  // One property key should have either |custom_property_name| or
  // |native_property_type|, and should never have both or neither.
  struct CC_PAINT_EXPORT PropertyKey {
    PropertyKey(const std::string& custom_property_name, ElementId element_id);
    PropertyKey(NativePropertyType native_property_type, ElementId element_id);
    PropertyKey(const PropertyKey&);
    PropertyKey(PropertyKey&&);
    PropertyKey& operator=(PropertyKey&&);
    PropertyKey& operator=(const PropertyKey&);
    ~PropertyKey();

    bool operator==(const PropertyKey& other) const;
    bool operator!=(const PropertyKey& other) const;
    bool operator<(const PropertyKey&) const;

    std::optional<std::string> custom_property_name;
    std::optional<NativePropertyType> native_property_type;
    ElementId element_id;
  };

  // A structure that can hold either a float or color type value, depending
  // on the type of custom property.  Only one of |float_val| and |color_val|
  // should hold value at any time; if neither hold value then we should not use
  // this value.
  // This structure is needed so that PaintWorkletProxyClient::Paint can handle
  // both color and float type custom property values at the same time.
  struct CC_PAINT_EXPORT PropertyValue {
    PropertyValue();
    explicit PropertyValue(float value);
    explicit PropertyValue(SkColor4f value);

    bool has_value() const;
    void reset();

    std::optional<float> float_value;
    std::optional<SkColor4f> color_value;
  };

  virtual int WorkletId() const = 0;

  // Return the list of properties used as an input by this PaintWorkletInput.
  // The values for these properties must be provided when dispatching a worklet
  // job for this input.
  using PropertyKeys = std::vector<PropertyKey>;
  virtual const PropertyKeys& GetPropertyKeys() const = 0;

  bool NeedsLayer() const override;

  // Includes JavaScript and native paint worklets.
  virtual bool IsCSSPaintWorkletInput() const = 0;

  virtual bool ValueChangeShouldCauseRepaint(const PropertyValue& val1,
                                             const PropertyValue& val2) const;

 protected:
  friend class base::RefCountedThreadSafe<PaintWorkletInput>;
  ~PaintWorkletInput() override = default;
};

// PaintWorkletRecordMap ties the input for a PaintWorklet (PaintWorkletInput)
// to the painted output (a PaintRecord). It also stores the PaintImage::Id for
// the PaintWorklet to enable efficient invalidation of dirty PaintWorklets.
using PaintWorkletRecordMap =
    base::flat_map<scoped_refptr<const PaintWorkletInput>,
                   std::pair<PaintImage::Id, std::optional<PaintRecord>>>;

}  // namespace cc

#endif  // CC_PAINT_PAINT_WORKLET_INPUT_H_