Canvas Class Reference

Manages a unique drawing surface and context. More...

#include <canvas.h>

Public Member Functions
	Canvas (const shared_cairo_surface_t &surface) noexcept
	Construct a canvas with an already existing surface.
	Canvas (const shared_cairo_surface_t &surface, PixelFormat format) noexcept
	Construct a canvas with an already existing surface, and specify the format of the surface the canvas create a copy to.
	Canvas (const Size &size, PixelFormat format=PixelFormat::argb8888) noexcept
	Construct a canvas with the specified format and size.
	Canvas (const SizeF &size, PixelFormat format=PixelFormat::argb8888) noexcept
	Construct a canvas with the specified format and size.
EGT_NODISCARD shared_cairo_t	context () const
	Get the context for the Canvas.
void	copy (const shared_cairo_surface_t &surface)
	Create a copy of a surface.
void	copy (const shared_cairo_surface_t &surface, const RectF &rect)
EGT_NODISCARD PixelFormat	format () const
	Get the format of the surface.
void	reallocate (const Size &size, PixelFormat format=PixelFormat::argb8888)
	Reallocate the canvas to a different size.
void	reallocate (const SizeF &size, PixelFormat format=PixelFormat::argb8888)
	Reallocate the canvas to a different size.
EGT_NODISCARD Size	size () const
	Get the size of the surface.
EGT_NODISCARD shared_cairo_surface_t	surface () const
	Get the surface for the Canvas.
void	zero ()
	Fill the surface with zero (including for transparency channel if applicable).

Protected Attributes
shared_cairo_t	m_cr
	The context of the canvas.
shared_cairo_surface_t	m_surface
	The surface of the canvas.

Detailed Description

Manages a unique drawing surface and context.

This can be created and directly drawn to with Painter.

This is useful, for example, if you need a temporary or intermediate buffer for drawing to.

Example

Canvas canvas(Size(100,100));
Painter painter(canvas.context());
...

Constructor & Destructor Documentation

Canvas() [1/4]

Canvas ( const Size &  size, PixelFormat  format = PixelFormat::argb8888  )

explicitnoexcept

Construct a canvas with the specified format and size.

Parameters

[in]	size	The size of the canvas.
[in]	format	The pixel format for the canvas.

Note

The canvas contents are undefined. zero() can be used to initialize it.

Canvas() [2/4]

Canvas ( const SizeF &  size, PixelFormat  format = PixelFormat::argb8888  )

explicitnoexcept

Construct a canvas with the specified format and size.

Parameters

[in]	size	The size of the canvas.
[in]	format	The pixel format for the canvas.

Note

The canvas contents are undefined. zero() can be used to initialize it.

Canvas() [3/4]

Canvas ( const shared_cairo_surface_t &  surface )

explicitnoexcept

Construct a canvas with an already existing surface.

The canvas will create a copy of the supplied surface.

Parameters

[in]

surface

The surface to copy from. A copy will be made.

Canvas() [4/4]

Canvas ( const shared_cairo_surface_t &  surface, PixelFormat  format  )

noexcept

Construct a canvas with an already existing surface, and specify the format of the surface the canvas create a copy to.

The canvas will create a copy of the supplied surface.

Parameters

[in]	surface	The surface to copy from. A copy will be made.
[in]	format	The pixel format for the canvas.

Member Function Documentation

context()

EGT_NODISCARD shared_cairo_t context ( ) const

inline

Get the context for the Canvas.

copy() [1/2]

void copy

(

const shared_cairo_surface_t &

surface

)

Create a copy of a surface.

copy() [2/2]

void copy	(	const shared_cairo_surface_t &	surface,
		const RectF &	rect
	)

format()

EGT_NODISCARD PixelFormat format

(

)

const

Get the format of the surface.

reallocate() [1/2]

void reallocate	(	const Size &	size,
		PixelFormat	format = PixelFormat::argb8888
	)

Reallocate the canvas to a different size.

Parameters

[in]	size	The size of the canvas.
[in]	format	The pixel format for the canvas.

reallocate() [2/2]

void reallocate	(	const SizeF &	size,
		PixelFormat	format = PixelFormat::argb8888
	)

Reallocate the canvas to a different size.

Parameters

[in]	size	The size of the canvas.
[in]	format	The pixel format for the canvas.

size()

EGT_NODISCARD Size size

(

)

const

Get the size of the surface.

surface()

EGT_NODISCARD shared_cairo_surface_t surface ( ) const

inline

Get the surface for the Canvas.

zero()

void zero

(

)

Fill the surface with zero (including for transparency channel if applicable).

Note

This is not done by default when creating a canvas.

Member Data Documentation

m_cr

shared_cairo_t m_cr

protected

The context of the canvas.

m_surface

shared_cairo_surface_t m_surface

protected

The surface of the canvas.