Embedded Vector Graphics JavaScript API. More...

Collaboration diagram for EVG JS API:

Data Structures
interface	Canvas

interface	IRect

interface	Rect

interface	Point2D

interface	AlphaCallback

interface	Path

interface	PenSettings

interface	Matrix2D

interface	ColorMatrix

interface	Color

interface	Colorf

interface	Stencil

interface	Texture

interface	ConvolutionKernel

interface	Text

interface	TextMeasure

interface	Matrix

interface	Vec3f

interface	Rectf

interface	Vec4f

interface	VertexAttribInterpolator

interface	VertexAttrib

interface	Shader

interface	BlitParameters

interface	Mesh

Enumerations
enum	ShaderType { GF_EVG_SHADER_FRAGMENT =1 , GF_EVG_SHADER_VERTEX }

enum	AttributeMapType { GF_EVG_VAI_VERTEX_INDEX =0 , GF_EVG_VAI_VERTEX , GF_EVG_VAI_PRIMITIVE }

Functions
long	PixelSize (DOMString pixel_format)

Detailed Description

This module provides bindings for GPAC Vector Graphics Rendering engine called EVG (for Embedded Vector Graphics).

The API is loaded as a JS module with the name "evg":

import * as evg from 'evg'
 
...

The API supports all Vector Graphics from Vector Graphics Rendering, 2D Vector Path, bindings for 2D and 3D matrices and text rendering as used by the Compositor.

The API is a low level access to the software rasterizer and does not follow the Canvas2D API (https://www.w3.org/TR/2dcontext/) but most of the tools required to implement Canvas2D are present in the evg API.

It allows a filter to:

generate new video frames from scratch
use input video frames to generate new frames
generate vector graphics and text directly on input video frames

Whenever pixel coordinates are indicated, 0,0 indicates:

the center of the surface if the surface uses centered coordinates
the top-left of the surface if the surface does not use centered coordinates

Whenever using an object as a parameter to a function, only the parameter names as listed in the corresponding interface object are checked. The name of the interface is not, and it usually does not define any constructor.

Note: Although 10-bit raster is supported for YUV formats (framebuffer and textures), colors are internally handled as 8-bits for solid brush and gradients. This will be updated in the near future.

The 3D extension of Canvas object can be used to draw vectorial 3D meshes and 2D paths.

Warning: The 3D rasterizer is much much slower than WebGL as it is only software and not realy optimized, do not use it for complex 3D scenes.; The 3D rasterizer is still an experimental project: it might not be completely stable and its API may change a lot in the near future.

The 3D rasterizer can however be useful when drawing simple 3D objects over an existing video, as it avoids GPU transfers of the frame data.

The rasterizer supports:

points, lines, triangles, quads, strips and fans
2D texturing using RGBA or YUVA colorspace
perspective correct interpolation
simple antialiasing
depth buffer (float only)
rasterizing in YUVA or RGBA space
a simple shading language for both vertex and fragment processing

The rasterizer does not claim compliancy to any GPU specification, and will likely produce different results than WebGL.

Data Structure Documentation

◆ IRect

interface IRect

rectangle object, pixel coordinate

Data Fields

unsigned long

x

x coordinate in pixels of top-left corner

y coordinate in pixels of top-left corner

unsigned long

w

width of rectangle in pixels

unsigned long

h

height of rectangle in pixels

◆ Rect

interface Rect

rectangle object

Data Fields

unsigned long

x

x coordinate of top-left corner

y coordinate of top-left corner

unsigned long

w

width of rectangle

unsigned long

h

height of rectangle

◆ Point2D

interface Point2D

point object

Data Fields

unsigned long

x

x coordinate of point

y coordinate of point

◆ PenSettings

interface PenSettings

Pen settings, see GF_PenSettings

Data Fields
attribute double	width	pen line width
attribute double	miter	The miter limit of the line joins
attribute double	offset	The initial dash offset in the outline. All points before this offset will be ignored when building the outline
attribute double	length	The author-specified path length. Ignored if <= 0
attribute unsigned long	cap	The style of the lines ends
attribute unsigned long	join	The style of the lines joins
attribute unsigned long	align	The alignment of the outline with regard to the path
attribute unsigned long	dash	The dash style of the line
attribute Array	dashes	The dash pattern used for custom dashing

◆ Color

interface Color

color object

Data Fields
unsigned long	r	red component - if absent, default to 0
unsigned long	g	green component - if absent, default to 0
unsigned long	b	blue component - if absent, default to 0
unsigned long	a	alpha component - if absent, default to 255

◆ Colorf

interface Colorf

color object

Data Fields
double	r	red component - if absent, default to 0
double	g	green component - if absent, default to 0
double	b	blue component - if absent, default to 0
double	a	alpha component - if absent, default to 1.0

◆ ConvolutionKernel

interface ConvolutionKernel

convolution kernel interface

Data Fields
attribute unsigned long	w	kernel width - shall be an odd number
attribute unsigned long	h	kernel height - shall be an odd number
attribute unsigned long	norm	kernel normalization. If 0 or undefined, no normalization is applied
attribute Array	k	kernel coeficients. The coeficients are unsigned integers, and there shall be at least w * h coefficients

◆ TextMeasure

interface TextMeasure

text measurement interface

Data Fields
double	width	measured width of text
double	height	measured height of text
unsigned long	em_size	size of EM box of font
unsigned long	ascent	ascent of font
unsigned long	descent	descent of font
unsigned long	line_spacing	line spacing of font
unsigned long	underlined	underline position in EM box
unsigned long	baseline	baseline position in EM box
unsigned long	max_advance_h	max horizontal advance of any glyphs in font
unsigned long	max_advance_v	max vertical advance of any glyphs in font
boolean	right_to_left	set to true if text is right to left, false otherwise

◆ Vec3f

interface Vec3f

3D vector object

Data Fields
attribute float	x	X coordinate
attribute float	y	Y coordinate
attribute float	z	Z coordinate

◆ Rectf

interface Rectf

rectangle object

Data Fields
attribute float	x	X coordinate
attribute float	y	Y coordinate
attribute float	width	width
attribute float	height	height

◆ Vec4f

interface Vec4f

4D vector object

Data Fields
attribute float	x	X coordinate
attribute float	y	Y coordinate
attribute float	z	Z coordinate
attribute float	w	4th dimension same as 'q' or 'alpha'
attribute float	q	4th dimension same as 'w' or 'alpha'
attribute float	alpha	4th dimension same as 'q' or 'w'

◆ BlitParameters

interface BlitParameters

Parameter object for canvas texture blit

Data Fields
DOMString	mode	name of the scale mode - see `gpac -hx ffsws`. If undefined, let FFMPEG decide
double	p1	first parameter of scale mode, if any
double	p2	second parameter of scale mode, if any

Enumeration Type Documentation

◆ ShaderType

enum ShaderType

defined shader types

Enumerator
GF_EVG_SHADER_FRAGMENT	shader is a fragment shader
GF_EVG_SHADER_VERTEX	shader is a vertex

◆ AttributeMapType

enum AttributeMapType

Map type for vertex attributes and vertex attribute interpolators

Enumerator
GF_EVG_VAI_VERTEX_INDEX	one vertex attribute is given for each vertex index
GF_EVG_VAI_VERTEX	one vertex attribute is given for each vertex
GF_EVG_VAI_PRIMITIVE	one vertex attribute is given for each primitive

Function Documentation

◆ PixelSize()

long PixelSize ( DOMString pixel_format )

queries size in bytes of a pixel for a given pixel format

Parameters

pixel_format the desired pixel format

Returns: the size in bytes

Data Structures

Enumerations

Functions

Detailed Description

Data Structure Documentation

◆ IRect

◆ Rect

◆ Point2D

◆ PenSettings

◆ Color

◆ Colorf

◆ ConvolutionKernel

◆ TextMeasure

◆ Vec3f

◆ Rectf

◆ Vec4f

◆ BlitParameters

Enumeration Type Documentation

◆ ShaderType

◆ AttributeMapType

Function Documentation

◆ PixelSize()