svg

package module
v0.5.1 Latest Latest
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 Go to latest Published: Jan 15, 2025 License: BSD-3-Clause Imports: 14 Imported by: 4

README

SVG parser and rasterizer

EXPERIMENTAL refactoring of oksvg

Current drawing library support for rasterization:

  • draw2d
    • Limited cap, line join support
    • No support for gradients
    • No support for masks
  • gg
    • Limited cap, line join support
    • Very limited/no suport for gradients
  • rasterx
    • No support for masks

Documentation

Overview

Provides parsing and rendering of SVG images. SVG files are parsed into an abstract representation, which can then be consumed by painting drivers.

Index

Constants

View Source 
const (
	Px unite = iota
	Cm
	Mm
	Pt
	In
	Q
	Pc
	Perc // Special case : percentage (%) relative to the viewbox
)

Absolute units supported.

Variables

View Source 
var DefaultStyle = PathStyle{
	FillOpacity:       1.0,
	LineOpacity:       1.0,
	LineWidth:         2.0,
	UseNonZeroWinding: true,
	Join: JoinOptions{
		MiterLimit:   fToFixed(4.),
		LineJoin:     Bevel,
		TrailLineCap: ButtCap,
	},
	FillerColor: NewPlainColor(0x00, 0x00, 0x00, 0xff),
	Transform:   Identity,
	Masks:       make([]string, 0),
}

DefaultStyle sets the default PathStyle to fill black, winding rule, full opacity, no stroke, ButtCap line end and Bevel line connect.

View Source 
var Identity = Matrix2D{1, 0, 0, 1, 0, 0}

Identity is the identity matrix

Functions

func GetColor 

func GetColor(clr Pattern) color.Color

GetColor is a helper function to get the background color if ReadGradUrl needs it.

Types

type Bounds 

type Bounds struct{ X, Y, W, H float64 }

Bounds defines a bounding box, such as a viewport or a path extent.

type CapMode 

type CapMode uint8

CapMode defines how to draw caps on the ends of lines 

const (
	NilCap CapMode = iota // default value
	ButtCap
	SquareCap
	RoundCap
	CubicCap     // Not part of the SVG2.0 standard.
	QuadraticCap // Not part of the SVG2.0 standard.
)

func (CapMode) String 

func (c CapMode) String() string

type DashOptions 

type DashOptions struct {
	Dash       []float64 // values for the dash pattern (nil or an empty slice for no dashes)
	DashOffset float64   // starting offset into the dash array
}

type ErrorMode 

type ErrorMode uint8

ErrorMode is the for setting how the parser reacts to unparsed elements 

const (
	// IgnoreErrorMode skips unparsed SVG elements
	IgnoreErrorMode ErrorMode = iota
	// WarnErrorMode outputs a warning when an unparsed SVG element is found
	WarnErrorMode
	// StrictErrorMode causes a error when an unparsed SVG element is found
	StrictErrorMode
)

type GapMode 

type GapMode uint8

GapMode defines how to bridge gaps when the miter limit is exceeded, and is not part of the SVG2.0 standard. 

const (
	NilGap GapMode = iota
	FlatGap
	RoundGap
	CubicGap
	QuadraticGap
)

func (GapMode) String 

func (g GapMode) String() string

type GradStop 

type GradStop struct {
	StopColor color.Color
	Offset    float64
	Opacity   float64
}

GradStop represents a stop in the SVG 2.0 gradient specification

type Gradient 

type Gradient struct {
	Direction gradientDirecter
	Stops     []GradStop
	Bounds    Bounds
	Matrix    Matrix2D
	Spread    SpreadMethod
	Units     GradientUnits
}

Gradient holds a description of an SVG 2.0 gradient

func (*Gradient) ApplyPathExtent 

func (g *Gradient) ApplyPathExtent(extent fixed.Rectangle26_6) Matrix2D

ApplyPathExtent use the given path extent to adjust the bounding box, if required by `Units`. The `Direction` field is not modified, but a matrix accounting for both the bouding box and the gradient matrix is returned

type GradientUnits 

type GradientUnits byte

GradientUnits is the type for gradient units 

const (
	ObjectBoundingBox GradientUnits = iota
	UserSpaceOnUse
)

SVG bounds paremater constants

type JoinMode 

type JoinMode uint8

JoinMode type to specify how segments join. 

const (
	Arc JoinMode = iota // New in SVG2
	Round
	Bevel
	Miter
	MiterClip // New in SVG2
	ArcClip   // Like MiterClip applied to arcs, and is not part of the SVG2.0 standard.
)

JoinMode constants determine how stroke segments bridge the gap at a join ArcClip mode is like MiterClip applied to arcs, and is not part of the SVG2.0 standard.

func (JoinMode) String 

func (s JoinMode) String() string

type JoinOptions 

type JoinOptions struct {
	MiterLimit   fixed.Int26_6 // he miter cutoff value for miter, arc, miterclip and arcClip joinModes
	LineJoin     JoinMode      // JoinMode for curve segments
	TrailLineCap CapMode       // capping functions for leading and trailing line ends. If one is nil, the other function is used at both ends.

	LeadLineCap CapMode // not part of the standard specification
	LineGap     GapMode // not part of the standard specification. determines how a gap on the convex side of two lines joining is filled
}

type Linear 

type Linear [4]float64

x1, y1, x2, y2

type Matrix2D 

type Matrix2D struct {
	A, B, C, D, E, F float64
}

Matrix2D represents an SVG style matrix

func (Matrix2D) CubicTo 

func (t Matrix2D) CubicTo(m OpCubicTo) (fixed.Point26_6, fixed.Point26_6, fixed.Point26_6)

CubicTo transform the operation `m` by applying `t`

func (Matrix2D) Invert 

func (a Matrix2D) Invert() Matrix2D

Invert returns the inverse matrix

func (Matrix2D) LineTo 

func (t Matrix2D) LineTo(m OpLineTo) fixed.Point26_6

LineTo transform the operation `m` by applying `t`

func (Matrix2D) LineWidthScale added in v0.5.1 

func (t Matrix2D) LineWidthScale() float64

LineWidthScale returns the mean of the horizontal and vertical scaling members. It may be used when scaling line widths with a rasterizer that does not support scaling a line's horizontal and vertical aspects independently.

func (Matrix2D) MoveTo 

func (t Matrix2D) MoveTo(m OpMoveTo) fixed.Point26_6

MoveTo transform the operation `m` by applying `t`

func (Matrix2D) Mult 

func (a Matrix2D) Mult(b Matrix2D) Matrix2D

Mult returns a*b

func (Matrix2D) QuadTo 

func (t Matrix2D) QuadTo(m OpQuadTo) (fixed.Point26_6, fixed.Point26_6)

QuadTo transform the operation `m` by applying `t`

func (Matrix2D) Rotate 

func (a Matrix2D) Rotate(theta float64) Matrix2D

Rotate rotate the matrix by theta

func (Matrix2D) Scale 

func (a Matrix2D) Scale(x, y float64) Matrix2D

Scale matrix in x and y dimensions

func (Matrix2D) SkewX 

func (a Matrix2D) SkewX(theta float64) Matrix2D

SkewX skews the matrix in the X dimension

func (Matrix2D) SkewY 

func (a Matrix2D) SkewY(theta float64) Matrix2D

SkewY skews the matrix in the Y dimension

func (Matrix2D) TFixed 

func (a Matrix2D) TFixed(x fixed.Point26_6) (y fixed.Point26_6)

TFixed transforms a fixed.Point26_6 by the matrix

func (Matrix2D) Transform 

func (a Matrix2D) Transform(x1, y1 float64) (x2, y2 float64)

Transform multiples the input vector by matrix m and outputs the results vector components.

func (Matrix2D) TransformVector 

func (a Matrix2D) TransformVector(x1, y1 float64) (x2, y2 float64)

TransformVector is a modidifed version of Transform that ignores the translation components.

func (Matrix2D) Translate 

func (a Matrix2D) Translate(x, y float64) Matrix2D

Translate translates the matrix to the x , y point

type OpClose 

type OpClose struct{}

OpClose close the current path.

func (OpClose) String 

func (op OpClose) String() string

type OpCubicTo 

type OpCubicTo [3]fixed.Point26_6

OpCubicTo draws a cubic Bezier curve from the current point, and updates it.

func (OpCubicTo) String 

func (op OpCubicTo) String() string

type OpLineTo 

type OpLineTo fixed.Point26_6

OpLineTo draws a line from the current point, and updates it.

func (OpLineTo) String 

func (op OpLineTo) String() string

type OpMoveTo 

type OpMoveTo fixed.Point26_6

OpMoveTo moves the current point.

func (OpMoveTo) String 

func (op OpMoveTo) String() string

type OpQuadTo 

type OpQuadTo [2]fixed.Point26_6

OpQuadTo draws a quadratic Bezier curve from the current point, and updates it.

func (OpQuadTo) String 

func (op OpQuadTo) String() string

type Operation 

type Operation interface {
	// SVG text representation of the command
	fmt.Stringer
}

Operation groups the different SVG commands

type Path 

type Path []Operation

Path describes a sequence of basic SVG operations, which should not be nil Higher-level shapes may be reduced to a path.

func (*Path) Clear 

func (p *Path) Clear()

Clear zeros the path slice

func (*Path) CubeBezier 

func (p *Path) CubeBezier(b, c, d fixed.Point26_6)

CubeBezier adds a cubic segment to the current curve.

func (*Path) Line 

func (p *Path) Line(b fixed.Point26_6)

Line adds a linear segment to the current curve.

func (*Path) QuadBezier 

func (p *Path) QuadBezier(b, c fixed.Point26_6)

QuadBezier adds a quadratic segment to the current curve.

func (*Path) Start 

func (p *Path) Start(a fixed.Point26_6)

Start starts a new curve at the given point.

func (*Path) Stop 

func (p *Path) Stop(closeLoop bool)

Stop joins the ends of the path

func (Path) String 

func (p Path) String() string

String returns a readable representation of a Path.

func (Path) ToSVGPath 

func (p Path) ToSVGPath() string

ToSVGPath returns a string representation of the path

type PathStyle 

type PathStyle struct {
	FillOpacity, LineOpacity float64
	LineWidth                float64
	UseNonZeroWinding        bool

	Join                    JoinOptions
	Dash                    DashOptions
	FillerColor, LinerColor Pattern // either PlainColor or Gradient

	Masks []string

	Transform Matrix2D // current transform
}

PathStyle holds the state of the SVG style

type Pattern 

type Pattern interface {
	// contains filtered or unexported methods
}

Pattern groups a basic color and a gradient pattern A nil value may by used to indicated that the function (fill or stroke) is off

type PlainColor 

type PlainColor struct {
	color.NRGBA
}

func NewPlainColor 

func NewPlainColor(r, g, b, a uint8) PlainColor

type Radial 

type Radial [6]float64

cx, cy, fx, fy, r, fr

type SpreadMethod 

type SpreadMethod byte

SpreadMethod is the type for spread parameters 

const (
	PadSpread SpreadMethod = iota
	ReflectSpread
	RepeatSpread
)

SVG spread parameter constants

type StrokeOptions 

type StrokeOptions struct {
	LineWidth fixed.Int26_6 // width of the line
	Join      JoinOptions
	Dash      DashOptions
}

type Svg 

type Svg struct {
	ViewBox      Bounds
	Titles       []string // Title elements collect here
	Descriptions []string // Description elements collect here
	SvgPaths     []SvgPath
	Transform    Matrix2D
	SvgMasks     map[string]*SvgMask

	Width, Height string // top level width and height attributes
	// contains filtered or unexported fields
}

Svg holds data from parsed SVGs. See the `Draw` methods to use it.

func Parse 

func Parse(stream io.Reader, errMode ErrorMode) (*Svg, error)

Parse reads the Icon from the given io.Reader This only supports a sub-set of SVG, but is enough to draw many svgs. errMode determines if the svg ignores, errors out, or logs a warning if it does not handle an element found in the svg file.

func ParseFile 

func ParseFile(name string, errMode ErrorMode) (*Svg, error)

ParseFile reads the SVG from the named file This only supports a sub-set of SVG, but is enough to draw many svgs. errMode determines if the svg ignores, errors out, or logs a warning if it does not handle an element found in the svg file.

type SvgMask added in v0.3.0 

type SvgMask struct {
	ID string

	X, Y float64
	W, H float64

	SvgPaths  []SvgPath
	Transform Matrix2D
}

SvgMask is an SVG element that defines a mask for the referenced elements.

type SvgPath 

type SvgPath struct {
	Path  Path
	Style PathStyle
}

SvgPath binds a style to a path

Source Files

View all Source files

Directories

Path Synopsis
draw2d
draw2d/example
gg
gg/example
rasterx
rasterx/example

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