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#pragma once
#include "Resource.h"
#include <memory>
namespace cru::platform::graphics {
/**
* \remarks Geometry implementation is a disaster zone of platform problems.
* Here are some notes. For geometry object:
* 1. Some platforms just lack the concept of geometry, like web canvas. Even if
* there is one, it usually has limited capabilities. They only allow you to
* create path right on the context and use it directly. The geometry itself
* can't be separated from context and stored independently, not to mention run
* some functions. You can't even create a geometry from current state of
* context. In one word, context -x-> geometry, geometry is weak.
* 2. Doing hit test right on the geometry is not supported on some platform.
* The geometry needs to be put on the context first.
* 3. Transform a geometry to create a new geometry is not supported on some
* platforms. You can transform the context, but no for geometry itself
* independently.
* 4. Create a geometry of a stroke of another geometry is not suppored more
* widely.
*
* Workarounds:
* 1. If the platform didn't support path at all, although not a platform does
* so far, record the commands and replay it on context when it is used.
* 2. If the geometry can't do hit test itself, always attach a canvas with it,
* and when do hit test, put it on context first.
* 3. If transform a geometry to create a new geometry is not supported, zip the
* original geometry and a transform matrix. When it is used on context, restore
* geometry and matrix the same time.
* 4. There is no good workaround for 4, so don't use it, maybe.
*
* Also note for 3, even we can workaround like that, but there are cases it
* does not work. Like if we add the support for adding an existing path to a
* new path, transform can only be performed on context and we can't construct a
* geometry from context, then it fails.
*
* For geometry builder:
* It is hard to conclude the common commands of all platforms. Some have this,
* others not. Some don't have this, but others do. There are some common
* commands that should be used frequently. If some platforms do not support it,
* do it yourself to implement it with existing commands and fancy algorithm.
*
*/
struct CRU_PLATFORM_GRAPHICS_API IGeometry : virtual IGraphicsResource {
/**
* \remarks Because I designed CreateStrokeGeometry first, which might be not
* that rational. So the default implementation calls that method and do the
* test. New implementation should override this.
*/
virtual bool StrokeContains(float width, const Point& point);
virtual bool FillContains(const Point& point) = 0;
virtual Rect GetBounds() = 0;
/**
* \remarks See class doc for platform limitation.
*/
virtual std::unique_ptr<IGeometry> Transform(const Matrix& matrix) = 0;
/**
* \remarks This method is a little quirky. It is originated from Direct2D,
* but many platforms do not support this, I guess. So don't use this anymore.
*/
virtual std::unique_ptr<IGeometry> CreateStrokeGeometry(float width);
};
/**
* \remarks We always run into platform porting problems. When I designed this
* interface, I thought every platform would support GetCurrentPosition.
* However, this is not actually true.
* For web canvas, it turns out that it can't get current position. So I have to
* not implement or use it, which disables every relative actions because they
* depend on it. But luckily, the web canvas path can be constructed from svg
* path (see https://developer.mozilla.org/en-US/docs/Web/API/Path2D/Path2D). So
* I come up with a new idea that first create a geometry describe itself in
* svg, and then construct path from it. And all relative methods should become
* virtual so it can override them.
*/
struct CRU_PLATFORM_GRAPHICS_API IGeometryBuilder : virtual IGraphicsResource {
virtual Point GetCurrentPosition() = 0;
virtual void MoveTo(const Point& point) = 0;
virtual void RelativeMoveTo(const Point& offset);
virtual void LineTo(const Point& point) = 0;
void LineTo(float x, float y) { LineTo(Point(x, y)); }
virtual void RelativeLineTo(const Point& offset);
void RelativeLineTo(float x, float y) { RelativeLineTo(Point(x, y)); }
virtual void CubicBezierTo(const Point& start_control_point,
const Point& end_control_point,
const Point& end_point) = 0;
virtual void RelativeCubicBezierTo(const Point& start_control_offset,
const Point& end_control_offset,
const Point& end_offset);
virtual void QuadraticBezierTo(const Point& control_point,
const Point& end_point) = 0;
virtual void RelativeQuadraticBezierTo(const Point& control_offset,
const Point& end_offset);
virtual void ArcTo(const Point& radius, float angle, bool is_large_arc,
bool is_clockwise, const Point& end_point);
virtual void RelativeArcTo(const Point& radius, float angle,
bool is_large_arc, bool is_clockwise,
const Point& end_offset);
virtual void CloseFigure(bool close) = 0;
virtual std::unique_ptr<IGeometry> Build() = 0;
virtual void ParseAndApplySvgPathData(StringView path_d);
};
std::unique_ptr<IGeometry> CRU_PLATFORM_GRAPHICS_API
CreateGeometryFromSvgPathData(IGraphicsFactory* factory, StringView path_d);
} // namespace cru::platform::graphics
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