Canvas Interface Reference

import"evg.idl";

Collaboration diagram for Canvas:

Public Member Functions
	Canvas (unsigned long width, unsigned long height, DOMString pixfmt)
	Canvas (unsigned long width, unsigned long height, DOMString pixfmt, ArrayBuffer data, optional unsigned long stride=0, optional unsigned long stride_uv=0)
void	clear (IRect rc, unsigned long r, unsigned long g, unsigned long b, unsigned long a)
void	clear (IRect rc, DOMString color)
void	clear (IRect rc, DOMString color)
void	clearf (IRect rc, double r, double g, double b, double a)
void	clearf (IRect rc, DOMString color)
void	fill (Stencil stencil)
void	fill (Texture texture)
void	fill (GF_EVGMultiTextureMode operand, optional float param=0, Texture texture1, optional Texture texture2=null, optional Texture texture3=null)
void	reassign (ArrayBuffer data)
void	blit (Texture texture, optional IRect dst_wnd=null, optional IRect src_wnd=null, optional BlitParameters params=null)
void	enable_threading (optional int nb_threads=-1)
void	enable_3d ()
Object	toRGB (optional bool as_array=false, Float y, Float u, Float v, optional Float a=1.0)
Object	toRGB (optional bool as_array=false, Vec4f color)
Object	toYUV (optional bool as_array=false, Float r, Float g, Float b, optional Float a=1.0)
Object	toYUV (optional bool as_array=false, Vec4f color)
void	projection (Float32Buffer projection_matrix)
void	modelview (Float32Buffer modelview_matrix)
void	draw_array (Int32Buffer indices, Float32Buffer vertices, optional GF_EVGPrimitiveType primitive_type=GF_EVG_TRIANGLES, optional long nb_components=3)
void	draw_path (Path path, optional float z=0)
void	draw_path (Text text, optional float z=0)
void	clear_depth (float depth)
void	viewport (long x, long y, long width, long height)
void	viewport ()
Shader	new_shader (ShaderType shader_type)

Data Fields
attribute boolean	centered
writeonly Path	path
writeonly Matrix2D	matrix
writeonly IRect	clipper
readonly boolean	has_clipper
attribute unsigned long	compositeOperation
attribute unsigned long	level
attribute AlphaCallback	on_alpha
readonly attribute boolean	is_yuv
readonly attribute unsigned long	depth
Shader	fragment
Shader	vertex
writeonly boolean	ccw
writeonly boolean	backcull
writeonly boolean	antialias
writeonly float	min_depth
writeonly float	max_depth
writeonly float	point_size
writeonly boolean	point_smooth
writeonly float	line_size
writeonly boolean	clip_zero
writeonly GF_EVGDepthTest	depth_test
writeonly boolean	write_depth
Float32Buffer	depth_buffer

Detailed Description

The Canvas object is used to draw vectorial 2D path

Constructor & Destructor Documentation

Canvas() [1/2]

Canvas::Canvas	(	unsigned long	width,
		unsigned long	height,
		DOMString	pixfmt
	)

Canvas constructor. The canvas memory is owned by the canvas object

Parameters

width	the width in pixels of the canvas
height	the height in pixels of the canvas
pixfmt	the pixel fomat of the canvas

Canvas() [2/2]

Canvas::Canvas	(	unsigned long	width,
		unsigned long	height,
		DOMString	pixfmt,
		ArrayBuffer	data,
		optional unsigned long	stride = 0,
		optional unsigned long	stride_uv = 0
	)

Canvas constructor

Parameters

width	the width in pixels of the canvas
height	the height in pixels of the canvas
pixfmt	the pixel fomat of the canvas
data	the data buffer on which to write. The size shall be greater than the size required for the given size and pixel format.
stride	horizontal stride in pixel of the data
stride_uv	horizontal stride in pixel of the data for the U and V planes

Member Function Documentation

clear() [1/3]

void Canvas::clear	(	IRect	rc,
		unsigned long	r,
		unsigned long	g,
		unsigned long	b,
		unsigned long	a
	)

clears the canvas with the given color - see gf_evg_surface_clear

Note

Omitting the last values will assume 0xFF for alpha, and 0 for other values.

Parameters

rc	the rectangle to clear, in pixel coordinates
r	red value, between 0 and 255
g	green value, between 0 and 255
b	blue value, between 0 and 255
a	alpha value, between 0 and 255

clear() [2/3]

void Canvas::clear	(	IRect	rc,
		DOMString	color
	)

clears the canvas with the given color. See gf_evg_surface_clear

Parameters

rc	the rectangle to clear, in pixel coordinates
color	an HTML/SVG color name or an HTML color value formatted as $RRGGBB, #RRGGBB or 0xRRGGBB

clear() [3/3]

void Canvas::clear	(	IRect	rc,
		DOMString	color
	)

clears the canvas with the given color. See gf_evg_surface_clear

Parameters

rc	the rectangle to clear, in pixel coordinates
color	an HTML/SVG color name or an HTML color value formatted as $RRGGBB, #RRGGBB or 0xRRGGBB

clearf() [1/2]

void Canvas::clearf	(	IRect	rc,
		double	r,
		double	g,
		double	b,
		double	a
	)

clears the canvas with the given color

Note

Omitting the last values will assume 1.0 for alpha, and 0.0 for other values. See gf_evg_surface_clear

Parameters

rc	the rectangle to clear, in pixel coordinates
r	red value, between 0.0 and 1.0
g	green value, between 0.0 and 1.0
b	blue value, between 0.0 and 1.0
a	alpha value, between 0.0 and 1.0

clearf() [2/2]

void Canvas::clearf	(	IRect	rc,
		DOMString	color
	)

clears the canvas with the given color. See gf_evg_surface_clear

Parameters

rc	the rectangle to clear, in pixel coordinates
color	an HTML/SVG color name or an HTML color value formatted as $RRGGBB, #RRGGBB or 0xRRGGBB

fill() [1/3]

void Canvas::fill

(

Stencil

stencil

)

fills the path with the given solid brush or gradient stencil - see gf_evg_surface_fill

Parameters

stencil

the stencil to use

fill() [2/3]

void Canvas::fill

(

Texture

texture

)

fills the path with the given texture - see gf_evg_surface_fill

Parameters

texture

the texture to use

fill() [3/3]

void Canvas::fill	(	GF_EVGMultiTextureMode	operand,
		optional float	param = 0,
		Texture	texture1,
		optional Texture	texture2 = null,
		optional Texture	texture3 = null
	)

fills the path with the given texture(s) - see gf_evg_surface_multi_fill

Parameters

operand	multitexture operand to use
param	float or float array used to control multitexture effect
texture1	the texture or stencil to use as main texture
texture2	the texture or stencil to use as secondary texture
texture3	the texture or stencil to use as third texture

reassign()

void Canvas::reassign

(

ArrayBuffer

data

)

reassign internal data (typically at each new packet)

Warning

This assumes the data layout has not changed (width, height, pixel format, strides). If these are modified, create a new canvas.

Parameters

data	the buffer to use

blit()

void Canvas::blit	(	Texture	texture,
		optional IRect	dst_wnd = null,
		optional IRect	src_wnd = null,
		optional BlitParameters	params = null
	)

blits a texture pixel data onto the surface

Warning

All texture properties (matrix, color matrix, ...) and canvas properties (path, matrix...) are ignored.

This does not perform alpha blending.

The blit operations are usually faster than path fill operations, but only operate on axis-aligned rectangles.

Parameters

texture	the texture to use for pixel source
dst_wnd	the destination rectangle in canvas, must be completely included in canvas. Point{0,0} is top-left and {width,height} is bottom right
src_wnd	the source rectangle from the texture, must be completely included in texture. Point{0,0} is top-left and {width,height} is bottom right
params	the blit operation parameters. If null, let FFMPEG decide

enable_threading()

void Canvas::enable_threading

(

optional int

nb_threads = -1

)

enables threading in rasterizer - see gf_evg_enable_threading

Parameters

nb_threads

the number of extra threads to use, negative values means all cores

enable_3d()

void Canvas::enable_3d

(

)

enables 3D extensions in rasterizer - see gf_evg_surface_enable_3d

toRGB() [1/2]

Object Canvas::toRGB	(	optional bool	as_array = false,
		Float	y,
		Float	u,
		Float	v,
		optional Float	a = 1.0
	)

converts YUV color to RGB

Parameters

as_array	if true, the return object is an array of 4 components, otherwise it is a Vec4f object
y	Y component value
u	Cb/U component value
v	Cr/V component value
a	alpha value, not modified

Returns

the converted value

toRGB() [2/2]

Object Canvas::toRGB	(	optional bool	as_array = false,
		Vec4f	color
	)

converts YUV color to RGB

Parameters

as_array	if true, the return object is an array of 4 components, otherwise it is a Vec4f object
color	the YUV value to convert

Returns

the converted value

toYUV() [1/2]

Object Canvas::toYUV	(	optional bool	as_array = false,
		Float	r,
		Float	g,
		Float	b,
		optional Float	a = 1.0
	)

converts RGB color to YUV

Parameters

as_array	if true, the return object is an array of 4 components, otherwise it is Vec4f object
r	red component value
g	green component value
b	blue component value
a	alpha value, not modified

Returns

the converted value

toYUV() [2/2]

Object Canvas::toYUV	(	optional bool	as_array = false,
		Vec4f	color
	)

converts RGB color to YUV

Parameters

as_array	if true, the return object is an array of 4 components, otherwise it is a Vec4f object
color	the RGB value to convert

Returns

the converted value

projection()

void Canvas::projection

(

Float32Buffer

projection_matrix

)

sets current projection matrix to use

Parameters

projection_matrix

the 16 float coeficients of the matrix, column-first. When using Matrix object, you can pass Matrix.m

modelview()

void Canvas::modelview

(

Float32Buffer

modelview_matrix

)

sets current modelview matrix to use

Parameters

modelview_matrix

the 16 float coeficients of the matrix, column-first. When using Matrix object, you can pass Matrix.m

draw_array()

void Canvas::draw_array	(	Int32Buffer	indices,
		Float32Buffer	vertices,
		optional GF_EVGPrimitiveType	primitive_type = GF_EVG_TRIANGLES,
		optional long	nb_components = 3
	)

draws a set of primitives (see gf_evg_surface_draw_array)

Parameters

indices	array of indices in the vertex buffer for the primitives to draw
vertices	the vertices to use
primitive_type	the type of primitive to draw
nb_components	the number of components per vertex (eg, 2, 3)

draw_path() [1/2]

void Canvas::draw_path	(	Path	path,
		optional float	z = 0
	)

draws a path (see gf_evg_surface_draw_path)

Parameters

path	the path to draw
z	the z value to assign to points in the path

draw_path() [2/2]

void Canvas::draw_path	(	Text	text,
		optional float	z = 0
	)

draws a text (see gf_evg_surface_draw_path)

Parameters

text	the text to draw
z	the z value to assign to points in the text's path

clear_depth()

void Canvas::clear_depth

(

float

depth

)

clears the depth buffer (see gf_evg_surface_clear_depth)

Parameters

depth

the depth value to set

viewport() [1/2]

void Canvas::viewport	(	long	x,
		long	y,
		long	width,
		long	height
	)

sets the viewport (see gf_evg_surface_viewport)

Parameters

x	the horizontal coordinate of the top-left corner of the viewport
y	the vertical coordinate of the top-left corner of the viewport
width	the width of the viewport
height	the height of the viewport

viewport() [2/2]

void Canvas::viewport

(

)

sets the viewport to full canvas {0,0,width,height} (see gf_evg_surface_viewport)

new_shader()

Shader Canvas::new_shader

(

ShaderType

shader_type

)

creats a new shader

Returns

the new shader

Parameters

shader_type

the desired shader type

Field Documentation

centered

attribute boolean Canvas::centered

indicates if surface coordinates are centered or not - see gf_evg_surface_set_center_coords

path

writeonly Path Canvas::path

path to draw - see gf_evg_surface_set_path. The path object is either a Path or a Text

matrix

writeonly Matrix2D Canvas::matrix

matrix to apply to path - see gf_evg_surface_set_matrix.

Note

A same path can be drawn several times with different matrices, null means no matrix.

clipper

writeonly IRect Canvas::clipper

clipper in pixel coordinates - see gf_evg_surface_set_clipper

Note

A same path can be drawn several times with different clipper, null means no clipper. Clipper applies to both fill and clear functions

has_clipper

readonly boolean Canvas::has_clipper

true if cliper is active on canvas

compositeOperation

attribute unsigned long Canvas::compositeOperation

composite operation for alpha surfaces - see gf_evg_surface_set_composite_mode

level

attribute unsigned long Canvas::level

AA level of canvas - see gf_evg_surface_get_raster_level and gf_evg_surface_set_raster_level

Note

This is always equal to GF_RASTER_HIGH_QUALITY when the path drawn is a text object

on_alpha

attribute AlphaCallback Canvas::on_alpha

alpha custom callback composite operation for alpha surfaces - see gf_evg_surface_set_alpha_callback Default is undefined at creation time

is_yuv

readonly attribute boolean Canvas::is_yuv

set to true of canvas is a YUV-based format, false if RGB-based format

depth

readonly attribute unsigned long Canvas::depth

number of bits per component (8, 10, etc)

fragment

Shader Canvas::fragment

fragment shader to use, set to NULL to disable pixel writing.

vertex

Shader Canvas::vertex

vertex shader to use, set to NULL to disable vertex shading, in which case the currently defined projection and modelview matrices will be used

ccw

writeonly boolean Canvas::ccw

set face orientation to counter-clockwise or clockwise (see gf_evg_surface_set_ccw)

backcull

writeonly boolean Canvas::backcull

backface culling enabled (see gf_evg_surface_set_backcull), default is true

antialias

writeonly boolean Canvas::antialias

antialiased enabled (see gf_evg_surface_set_antialias), default is true

min_depth

writeonly float Canvas::min_depth

min depth (see gf_evg_surface_set_min_depth), default is 0

max_depth

writeonly float Canvas::max_depth

max depth (see gf_evg_surface_set_max_depth), default is 1.0

point_size

writeonly float Canvas::point_size

point size (see gf_evg_surface_set_point_size), default is 1.0

point_smooth

writeonly boolean Canvas::point_smooth

point smoothing enabled (see gf_evg_surface_set_point_smooth), default is false

line_size

writeonly float Canvas::line_size

line size (see gf_evg_surface_set_line_size), default is 1.0

clip_zero

writeonly boolean Canvas::clip_zero

clip zero enabled (see gf_evg_surface_set_clip_zero), default is false

depth_test

writeonly GF_EVGDepthTest Canvas::depth_test

depth test mode (see gf_evg_set_depth_test), default is GF_EVGDEPTH_LESS

write_depth

writeonly boolean Canvas::write_depth

write depth buffer enabled (see gf_evg_surface_write_depth), default is true

depth_buffer

Float32Buffer Canvas::depth_buffer

depth buffer (see gf_evg_surface_set_depth_buffer).

Warning

Default is null