| // Copyright 2014 Google Inc. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #ifndef COBALT_RENDER_TREE_BRUSH_H_ |
| #define COBALT_RENDER_TREE_BRUSH_H_ |
| |
| #include <cmath> |
| #include <utility> |
| #include <vector> |
| |
| #include "base/compiler_specific.h" |
| #include "base/memory/scoped_ptr.h" |
| #include "cobalt/base/type_id.h" |
| #include "cobalt/math/point_f.h" |
| #include "cobalt/math/size_f.h" |
| #include "cobalt/render_tree/brush_visitor.h" |
| #include "cobalt/render_tree/color_rgba.h" |
| |
| namespace cobalt { |
| namespace render_tree { |
| |
| // A base class of all render tree brushes. |
| class Brush { |
| public: |
| virtual ~Brush() {} |
| |
| // A type-safe branching. |
| virtual void Accept(BrushVisitor* visitor) const = 0; |
| |
| // Returns an ID that is unique to the brush type. This can be used to |
| // polymorphically identify what type a brush is. |
| virtual base::TypeId GetTypeId() const = 0; |
| }; |
| |
| class SolidColorBrush : public Brush { |
| public: |
| explicit SolidColorBrush(const ColorRGBA& color) : color_(color) {} |
| |
| // A type-safe branching. |
| void Accept(BrushVisitor* visitor) const OVERRIDE; |
| |
| base::TypeId GetTypeId() const OVERRIDE { |
| return base::GetTypeId<SolidColorBrush>(); |
| } |
| |
| const ColorRGBA& color() const { return color_; } |
| |
| private: |
| ColorRGBA color_; |
| }; |
| |
| // ColorStops are used to describe linear and radial gradients. For linear |
| // gradients, |position| represents the faction between the source and |
| // destination points that |color| should be applied. For radial gradients, |
| // it represents the fraction between the center point and radius at which |
| // |color| should apply. In both cases, 0 <= |position| <= 1. |
| struct ColorStop { |
| ColorStop() : position(-1) {} |
| ColorStop(float position, const ColorRGBA& color) |
| : position(position), color(color) {} |
| |
| float position; |
| ColorRGBA color; |
| }; |
| |
| // Returns true if and only if two color stops are very close to each other. |
| inline bool IsNear(const render_tree::ColorStop& lhs, |
| const render_tree::ColorStop& rhs, float epsilon) { |
| if (std::fabs(lhs.position - rhs.position) > epsilon) return false; |
| return lhs.color == rhs.color; |
| } |
| |
| typedef std::vector<ColorStop> ColorStopList; |
| |
| bool IsNear(const render_tree::ColorStopList& lhs, |
| const render_tree::ColorStopList& rhs, float epsilon); |
| |
| // Calculate the source and destination points to use for a linear gradient |
| // of the specified angle to cover the given frame. |
| // |
| // The method of defining the source and destination points for the linear |
| // gradient are defined here: |
| // https://www.w3.org/TR/2012/CR-css3-images-20120417/#linear-gradients |
| // |
| // "Starting from the center of the gradient box, extend a line at the |
| // specified angle in both directions. The ending point is the point on the |
| // gradient line where a line drawn perpendicular to the gradient line would |
| // intersect the corner of the gradient box in the specified direction. The |
| // starting point is determined identically, but in the opposite direction." |
| std::pair<math::PointF, math::PointF> LinearGradientPointsFromAngle( |
| float ccw_radians_from_right, const math::SizeF& frame_size); |
| |
| // Linear gradient brushes can be used to fill a shape with a linear color |
| // gradient with arbitrary many color stops. It is specified by a source |
| // and destination point, which define a line segment along which the color |
| // stops apply, each having a position between 0 and 1 representing the |
| // position of the stop along that line. Interpolation occurs in premultiplied |
| // alpha space. |
| // NOTE: The source and destination points may lie inside or outside the shape |
| // which uses the gradient brush. Always consider the shape as a mask over the |
| // gradient whose first and last color stops extend infinitely in their |
| // respective directions. |
| class LinearGradientBrush : public Brush { |
| public: |
| // The ColorStopList passed into LienarGradientBrush must have at least two |
| // stops and they must be sorted in order of increasing position. |
| LinearGradientBrush(const math::PointF& source, const math::PointF& dest, |
| const ColorStopList& color_stops); |
| LinearGradientBrush(const std::pair<math::PointF, math::PointF>& source_dest, |
| const ColorStopList& color_stops) |
| : LinearGradientBrush(source_dest.first, source_dest.second, |
| color_stops) |
| {} |
| |
| // Creates a 2-stop linear gradient from source to dest. |
| LinearGradientBrush(const math::PointF& source, const math::PointF& dest, |
| const ColorRGBA& source_color, |
| const ColorRGBA& dest_color); |
| LinearGradientBrush(const std::pair<math::PointF, math::PointF>& source_dest, |
| const ColorRGBA& source_color, |
| const ColorRGBA& dest_color) |
| : LinearGradientBrush(source_dest.first, source_dest.second, |
| source_color, dest_color) |
| {} |
| |
| struct Data { |
| Data(); |
| Data(const math::PointF& source, const math::PointF& dest, |
| const ColorStopList& color_stops); |
| Data(const math::PointF& source, const math::PointF& dest); |
| |
| math::PointF source_; |
| math::PointF dest_; |
| |
| ColorStopList color_stops_; |
| }; |
| |
| // A type-safe branching. |
| void Accept(BrushVisitor* visitor) const OVERRIDE; |
| |
| base::TypeId GetTypeId() const OVERRIDE { |
| return base::GetTypeId<LinearGradientBrush>(); |
| } |
| |
| // Returns the source and destination points of the linear gradient. |
| const math::PointF& source() const { return data_.source_; } |
| const math::PointF& dest() const { return data_.dest_; } |
| |
| // Returns the list of color stops along the line segment between the source |
| // and destination points. |
| const ColorStopList& color_stops() const { return data_.color_stops_; } |
| |
| // Returns true if, and only if the brush is horizontal. |
| bool IsHorizontal(float epsilon = 0.001f) const { |
| return std::abs(data_.source_.y() - data_.dest_.y()) < epsilon; |
| } |
| |
| // Returns true if, and only if the brush is vertical. |
| bool IsVertical(float epsilon = 0.001f) const { |
| return std::abs(data_.source_.x() - data_.dest_.x()) < epsilon; |
| } |
| |
| const Data& data() const { return data_; } |
| |
| private: |
| Data data_; |
| }; |
| |
| // A radial gradient brush can be used to fill a shape with a color gradient |
| // that expands from a given center point up to a specified radius. The list |
| // of color stops have position values between 0 and 1 which represent the |
| // distance between the center point and the specified x-axis radius that the |
| // color should apply to. Interpolation occurs in premultiplied alpha space. |
| class RadialGradientBrush : public Brush { |
| public: |
| // The ColorStopList passed into RadialGradientBrush must have at least two |
| // stops and they must be sorted in order of increasing position. |
| RadialGradientBrush(const math::PointF& center, float radius, |
| const ColorStopList& color_stops); |
| |
| // Constructor that allows for ellipses instead of circles. |
| RadialGradientBrush(const math::PointF& center, float radius_x, |
| float radius_y, const ColorStopList& color_stops); |
| |
| // Creates a 2-stop radial gradient. |
| RadialGradientBrush(const math::PointF& center, float radius, |
| const ColorRGBA& source_color, |
| const ColorRGBA& dest_color); |
| |
| // Constructor for ellipses instead of circles. |
| RadialGradientBrush(const math::PointF& center, float radius_x, |
| float radius_y, const ColorRGBA& source_color, |
| const ColorRGBA& dest_color); |
| |
| // A type-safe branching. |
| void Accept(BrushVisitor* visitor) const OVERRIDE; |
| |
| base::TypeId GetTypeId() const OVERRIDE { |
| return base::GetTypeId<RadialGradientBrush>(); |
| } |
| |
| // Returns the source and destination points of the linear gradient. |
| const math::PointF& center() const { return center_; } |
| float radius_x() const { return radius_x_; } |
| float radius_y() const { return radius_y_; } |
| |
| // Returns the list of color stops from the center point to the radius. |
| const ColorStopList& color_stops() const { return color_stops_; } |
| |
| private: |
| math::PointF center_; |
| float radius_x_; |
| float radius_y_; |
| |
| ColorStopList color_stops_; |
| }; |
| |
| scoped_ptr<Brush> CloneBrush(const Brush* brush); |
| |
| } // namespace render_tree |
| } // namespace cobalt |
| |
| #endif // COBALT_RENDER_TREE_BRUSH_H_ |