SVGo: A Go library for SVG generation

The library generates SVG as defined by the Scalable Vector Graphics 1.1 Specification (http://www.w3.org/TR/SVG11/). Output goes to the specified io.Writer.

Supported SVG elements and functions

Shapes, lines, text

circle, ellipse, polygon, polyline, rect (including roundrects), line, text

Paths

general, arc, cubic and quadratic bezier paths,

Image and Gradients

image, linearGradient, radialGradient,

Transforms

translate, rotate, scale, skewX, skewY

Animation

animate, animateMotion, animateTranslate, animateRotate, animateScale, animateSkewX, animateSkewY

Filter Effects

filter, feBlend, feColorMatrix, feColorMatrix, feComponentTransfer, feComposite, feConvolveMatrix, feDiffuseLighting, feDisplacementMap, feDistantLight, feFlood, feGaussianBlur, feImage, feMerge, feMorphology, feOffset, fePointLight, feSpecularLighting, feSpotLight,feTile, feTurbulence

Metadata elements

desc, defs, g (style, transform, id), marker, mask, pattern, title, (a)ddress, link, script, use

Building and Usage

See svgdef.[svg|png|pdf] for a graphical view of the function calls

Usage: (assuming GOPATH is set)

go get github.com/ajstarks/svgo
go install github.com/ajstarks/svgo/...

You can use godoc to browse the documentation from the command line:

$ go doc github.com/ajstarks/svgo

a minimal program, to generate SVG to standard output.

package main

import (
	"github.com/ajstarks/svgo"
	"os"
)

func main() {
	width := 500
	height := 500
	canvas := svg.New(os.Stdout)
	canvas.Start(width, height)
	canvas.Circle(width/2, height/2, 100)
	canvas.Text(width/2, height/2, "Hello, SVG", "text-anchor:middle;font-size:30px;fill:white")
	canvas.End()
}

Drawing in a web server: (http://localhost:2003/circle)

package main

import (
	"log"
	"github.com/ajstarks/svgo"
	"net/http"
)

func main() {
	http.Handle("/circle", http.HandlerFunc(circle))
	err := http.ListenAndServe(":2003", nil)
	if err != nil {
		log.Fatal("ListenAndServe:", err)
	}
}

func circle(w http.ResponseWriter, req *http.Request) {
  w.Header().Set("Content-Type", "image/svg+xml")
  s := svg.New(w)
  s.Start(500, 500)
  s.Circle(250, 250, 125, "fill:none;stroke:black")
  s.End()
}

You may view the SVG output with a browser that supports SVG (tested on Chrome, Opera, Firefox and Safari), or any other SVG user-agent such as Batik Squiggle.

Graphics Sketching with SVGo and svgplay

Combined with the svgplay command, SVGo can be used to "sketch" with code in a browser.

To use svgplay and SVGo, first go to a directory with your code, and run:

$ svgplay
2014/06/25 22:05:28 ☠ ☠ ☠ Warning: this server allows a client connecting to 127.0.0.1:1999 to execute code on this computer ☠ ☠ ☠

Next open your browser to the svgplay server you just started. svgplay only listens on localhost, and uses port 1999 (guess which year SVG was first introduced) by default

http://localhost:1999/

Enter your code in the textarea, and when you are ready to run press Shift--Enter. The code will be compiled, with the results on the right. To update, change the code and repeat. Note that compilation errors are shown in red under the code. In order for svgplay/SVGo to work, make sure that the io.Writer specified with the New function is os.Stdout.

If you want to sketch with an existing file, enter its URL:

http://localhost:1999/foo.go

SVGo Papers and presentations

SVGo paper from SVGOpen 2011 http://www.svgopen.org/2011/papers/34-SVGo_a_Go_Library_for_SVG_generation
Programming Pictures with SVGo https://speakerdeck.com/u/ajstarks/p/programming-pictures-with-svgo
SVGo Workshop https://speakerdeck.com/u/ajstarks/p/svgo-workshop

Tutorial Video

A video describing how to use the package can be seen on YouTube at http://www.youtube.com/watch?v=ze6O2Dj5gQ4

Package contents

svg.go: Library
newsvg: Coding template command
svgdef: Creates a SVG representation of the API
animate: Animation demo
am: Animate motion demo
amt: Animate transformation demo
android: The Android logo
bubtrail: Bubble trails
bulletgraph: Bullet Graphs (via Stephen Few)
colortab: Display SVG named colors with RGB values
compx: Component diagrams
flower: Random "flowers"
fontcompare: Compare two fonts
f50: Get 50 photos from Flickr based on a query
fe: Filter effects
funnel: Funnel from transparent circles
gradient: Linear and radial gradients
html5logo: HTML5 logo with draggable elements
imfade: Show image fading
lewitt: Version of Sol Lewitt's Wall Drawing 91
ltr: Layer Tennis Remixes
marker: Test markers
paths: Demonstrate SVG paths
pattern: Test patterns
planets: Show the scale of the Solar system
pmap: Proportion maps
randcomp: Compare random number generators
richter: Gerhard Richter's 256 colors
rl: Random lines (port of a Processing demo)
skewabc: Skew ABC
stockproduct: Visualize product and stock prices
svgopher: SVGo Mascot
svgplay: SVGo sketching server
svgplot: Plot data
svgrid: Compose SVG files in a grid
tsg: Twitter Search Grid
tumblrgrid: Tumblr picture grid
turbulence: Turbulence filter effect
vismem: Visualize data from files
webfonts: "Hello, World" with Google Web Fonts
websvg: Generate SVG as a web server

Functions and types

Many functions use x, y to specify an object's location, and w, h to specify the object's width and height. Where applicable, a final optional argument specifies the style to be applied to the object. The style strings follow the SVG standard; name:value pairs delimited by semicolons, or a series of name="value" pairs. For example: "fill:none; opacity:0.3" or fill="none" opacity="0.3" (see: http://www.w3.org/TR/SVG11/styling.html)

The SVG type:

type SVG struct {
    Writer   io.Writer
}

Most operations are methods on this type, specifying the destination io.Writer.

The Offcolor type:

type Offcolor struct {
	Offset  uint8
	Color   string
	Opacity float64
}

is used to specify the offset, color, and opacity of stop colors in linear and radial gradients

The Filterspec type:

type Filterspec struct {
	In string
	In2 string
	Result string
}

is used to specify inputs and results for filter effects

Structure, Scripting, Metadata, Transformation and Links

New(w io.Writer) *SVG

Constructor, Specify the output destination.

Start(w int, h int, attributes ...string)

begin the SVG document with the width w and height h. Optionally add additional elements (such as additional namespaces or scripting events) http://www.w3.org/TR/SVG11/struct.html#SVGElement

Startview(w, h, minx, miny, vw, vh int)

begin the SVG document with the width w, height h, with a viewBox at minx, miny, vw, vh. http://www.w3.org/TR/SVG11/struct.html#SVGElement

Startunit(w int, h int, unit string, ns ...string)

begin the SVG document, with width and height in the specified units. Optionally add additional elements (such as additional namespaces or scripting events) http://www.w3.org/TR/SVG11/struct.html#SVGElement

Startpercent(w int, h int, ns ...string)

begin the SVG document, with width and height in percent. Optionally add additional elements (such as additional namespaces or scripting events) http://www.w3.org/TR/SVG11/struct.html#SVGElement

StartviewUnit(w, h int, unit string, minx, miny, vw, vh int)

begin the SVG document with the width w, height h, in the specified unit, with a viewBox at minx, miny, vw, vh. http://www.w3.org/TR/SVG11/struct.html#SVGElement

End()

end the SVG document

Script(scriptype string, data ...string)

Script defines a script with a specified type, (for example "application/javascript"). if the first variadic argument is a link, use only the link reference. Otherwise, treat variadic arguments as the text of the script (marked up as CDATA). if no data is specified, simply close the script element. http://www.w3.org/TR/SVG/script.html

Style(scriptype string, data ...string)

Style defines a script with a specified type, (for example "text/css"). if the first variadic argument is a link, use only the link reference. Otherwise, treat variadic arguments as the text of the script (marked up as CDATA). if no data is specified, simply close the style element. https://www.w3.org/TR/SVG/styling.html#StyleElement

Group(s ...string)

begin a group, with arbitrary attributes http://www.w3.org/TR/SVG11/struct.html#GElement

Gstyle(s string)

begin a group, with the specified style. http://www.w3.org/TR/SVG11/struct.html#GElement

Gid(s string)

begin a group, with the specified id.

Gtransform(s string)

begin a group, with the specified transform, end with Gend(). http://www.w3.org/TR/SVG11/coords.html#TransformAttribute

Translate(x, y int)

begins coordinate translation to (x,y), end with Gend(). http://www.w3.org/TR/SVG11/coords.html#TransformAttribute

Scale(n float64)

scales the coordinate system by n, end with Gend(). http://www.w3.org/TR/SVG11/coords.html#TransformAttribute

ScaleXY(x, y float64)

scales the coordinate system by x, y. End with Gend(). http://www.w3.org/TR/SVG11/coords.html#TransformAttribute

SkewX(a float64)

SkewX skews the x coordinate system by angle a, end with Gend(). http://www.w3.org/TR/SVG11/coords.html#TransformAttribute

SkewY(a float64)

SkewY skews the y coordinate system by angle a, end with Gend(). http://www.w3.org/TR/SVG11/coords.html#TransformAttribute

SkewXY(ax, ay float64)

SkewXY skews x and y coordinate systems by ax, ay respectively, end with Gend(). http://www.w3.org/TR/SVG11/coords.html#TransformAttribute

Rotate(r float64)

rotates the coordinate system by r degrees, end with Gend(). http://www.w3.org/TR/SVG11/coords.html#TransformAttribute

TranslateRotate(x, y int, r float64)

translates the coordinate system to (x,y), then rotates to r degrees, end with Gend().

RotateTranslate(x, y int, r float64)

rotates the coordinate system r degrees, then translates to (x,y), end with Gend().

Gend()

end the group (must be paired with Gstyle, Gtransform, Gid).

ClipPath(s ...string)

Begin a ClipPath http://www.w3.org/TR/SVG/masking.html#ClippingPaths

ClipEnd()

End a ClipPath http://www.w3.org/TR/SVG/masking.html#ClippingPaths

Def()

begin a definition block. http://www.w3.org/TR/SVG11/struct.html#DefsElement

DefEnd()

end a definition block.

Marker(id string, x, y, w, h int, s ...string)

define a marker http://www.w3.org/TR/SVG11/painting.html#MarkerElement

MarkerEnd()

end a marker

Mask(id string, x int, y int, w int, h int, s ...string)

creates a mask with a specified id, dimension, and optional style. http://www.w3.org/TR/SVG/masking.html

MaskEnd()

ends the Mask element.

Pattern(id string, x, y, width, height int, putype string, s ...string)

define a Pattern with the specified dimensions, the putype can be either "user" or "obj", which sets the patternUnits attribute to be either userSpaceOnUse or objectBoundingBox. http://www.w3.org/TR/SVG11/pservers.html#Patterns

Desc(s string)

specify the text of the description. http://www.w3.org/TR/SVG11/struct.html#DescElement

Title(s string)

specify the text of the title. http://www.w3.org/TR/SVG11/struct.html#TitleElement

Link(href string, title string)

begin a link named "href", with the specified title. http://www.w3.org/TR/SVG11/linking.html#Links

LinkEnd()

end the link.

Use(x int, y int, link string, s ...string)

place the object referenced at link at the location x, y. http://www.w3.org/TR/SVG11/struct.html#UseElement

Shapes

Circle(x int, y int, r int, s ...string)

draw a circle, centered at x,y with radius r. http://www.w3.org/TR/SVG11/shapes.html#CircleElement

Ellipse(x int, y int, w int, h int, s ...string)

draw an ellipse, centered at x,y with radii w, and h. http://www.w3.org/TR/SVG11/shapes.html#EllipseElement

Polygon(x []int, y []int, s ...string)

draw a series of line segments using an array of x, y coordinates. http://www.w3.org/TR/SVG11/shapes.html#PolygonElement

Rect(x int, y int, w int, h int, s ...string)

draw a rectangle with upper left-hand corner at x,y, with width w, and height h. http://www.w3.org/TR/SVG11/shapes.html#RectElement

CenterRect(x int, y int, w int, h int, s ...string)

draw a rectangle with its center at x,y, with width w, and height h.

Roundrect(x int, y int, w int, h int, rx int, ry int, s ...string)

draw a rounded rectangle with upper the left-hand corner at x,y, with width w, and height h. The radii for the rounded portion is specified by rx (width), and ry (height).

Square(x int, y int, s int, style ...string)

draw a square with upper left corner at x,y with sides of length s.

Paths

Path(p string, s ...style)

draw the arbitrary path as specified in p, according to the style specified in s. http://www.w3.org/TR/SVG11/paths.html

Arc(sx int, sy int, ax int, ay int, r int, large bool, sweep bool, ex int, ey int, s ...string)

draw an elliptical arc beginning coordinate at sx,sy, ending coordinate at ex, ey width and height of the arc are specified by ax, ay, the x axis rotation is r

if sweep is true, then the arc will be drawn in a "positive-angle" direction (clockwise), if false, the arc is drawn counterclockwise.

if large is true, the arc sweep angle is greater than or equal to 180 degrees, otherwise the arc sweep is less than 180 degrees. http://www.w3.org/TR/SVG11/paths.html#PathDataEllipticalArcCommands

Bezier(sx int, sy int, cx int, cy int, px int, py int, ex int, ey int, s ...string)

draw a cubic bezier curve, beginning at sx,sy, ending at ex,ey with control points at cx,cy and px,py. http://www.w3.org/TR/SVG11/paths.html#PathDataCubicBezierCommands

Qbezier(sx int, sy int, cx int, cy int, ex int, ey int, tx int, ty int, s ...string)

draw a quadratic bezier curve, beginning at sx, sy, ending at tx,ty with control points are at cx,cy, ex,ey. http://www.w3.org/TR/SVG11/paths.html#PathDataQuadraticBezierCommands

Qbez(sx int, sy int, cx int, cy int, ex int, ey int, s...string)

draws a quadratic bezier curver, with optional style beginning at sx,sy, ending at ex, sy with the control point at cx, cy. http://www.w3.org/TR/SVG11/paths.html#PathDataQuadraticBezierCommands

Lines

Line(x1 int, y1 int, x2 int, y2 int, s ...string)

draw a line segment between x1,y1 and x2,y2. http://www.w3.org/TR/SVG11/shapes.html#LineElement

Polyline(x []int, y []int, s ...string)

draw a polygon using coordinates specified in x,y arrays. http://www.w3.org/TR/SVG11/shapes.html#PolylineElement

Image and Text

Image(x int, y int, w int, h int, link string, s ...string)

place at x,y (upper left hand corner), the image with width w, and height h, referenced at link. http://www.w3.org/TR/SVG11/struct.html#ImageElement

Text(x int, y int, t string, s ...string)

Place the specified text, t at x,y according to the style specified in s. http://www.w3.org/TR/SVG11/text.html#TextElement

Textlines(x, y int, s []string, size, spacing int, fill, align string)

Places lines of text in s, starting at x,y, at the specified size, fill, and alignment, and spacing.

Textpath(t string, pathid string, s ...string)

places optionally styled text along a previously defined path. http://www.w3.org/TR/SVG11/text.html#TextPathElement

Color

RGB(r int, g int, b int) string

creates a style string for the fill color designated by the (r)ed, g(reen), (b)lue components. http://www.w3.org/TR/css3-color/

RGBA(r int, g int, b int, a float64) string

as above, but includes the color's opacity as a value between 0.0 (fully transparent) and 1.0 (opaque).

Gradients

LinearGradient(id string, x1, y1, x2, y2 uint8, sc []Offcolor)

constructs a linear color gradient identified by id, along the vector defined by (x1,y1), and (x2,y2). The stop color sequence defined in sc. Coordinates are expressed as percentages. http://www.w3.org/TR/SVG11/pservers.html#LinearGradients

RadialGradient(id string, cx, cy, r, fx, fy uint8, sc []Offcolor)

constructs a radial color gradient identified by id, centered at (cx,cy), with a radius of r. (fx, fy) define the location of the focal point of the light source. The stop color sequence defined in sc. Coordinates are expressed as percentages. http://www.w3.org/TR/SVG11/pservers.html#RadialGradients

Animation

Animate(link, attr string, from, to int, duration float64, repeat int, s ...string)

Animate animates the item referenced by the link, using the specified attribute The animation starts at coordinate from, terminates at to, and repeats as specified. Addtional attributes may be added as needed. https://www.w3.org/TR/SVG11/animate.html#AnimateElement

AnimateMotion(link, path string, duration float64, repeat int, s ...string)

AnimateMotion animates the referenced object link along the specified path https://www.w3.org/TR/SVG11/animate.html#AnimateMotionElement

AnimateTranslate(link string, fx, fy, tx, ty int, duration float64, repeat int, s ...string)

AnimateTranslate animates the translation transformation (link refers to the object to animate, fx, fy are from coordinates, tx, ty are the to coordinates) https://www.w3.org/TR/SVG11/animate.html#AnimateTransformElement

AnimateRotate(link string, fs, fc, fe, ts, tc, te int, duration float64, repeat int, s ...string)

AnimateRotate animates the rotation transformation (link refers to the object to animate, f[s,c,e] are the from start, center, and end angles, t[s,c,e] are the start, center, and end angles) https://www.w3.org/TR/SVG11/animate.html#AnimateTransformElement

AnimateScale(link string, from, to, duration float64, repeat int, s ...string)

AnimateScale animates the scale transformation (link refers to the object to animate, from and to specify the scaling factor) https://www.w3.org/TR/SVG11/animate.html#AnimateTransformElement

AnimateSkewX(link string, from, to, duration float64, repeat int, s ...string)

AnimateSkewX animates the skewX transformation ((link refers to the object to animate, from and to specify the skew angle) https://www.w3.org/TR/SVG11/animate.html#AnimateTransformElement

AnimateSkewY(link string, from, to, duration float64, repeat int, s ...string)

AnimateSkewY animates the skewY transformation (link refers to the object to animate, and from and to specify the skew angle) https://www.w3.org/TR/SVG11/animate.html#AnimateTransformElement

Filter Effects

Filter(id string, s ...string)

Filter begins a filter set Standard reference: http://www.w3.org/TR/SVG11/filters.html#FilterElement

Fend()

Fend ends a filter set Standard reference: http://www.w3.org/TR/SVG11/filters.html#FilterElement

FeBlend(fs Filterspec, mode string, s ...string)

FeBlend specifies a Blend filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#feBlendElement

FeColorMatrix(fs Filterspec, values [20]float64, s ...string)

FeColorMatrix specifies a color matrix filter primitive, with matrix values Standard reference: http://www.w3.org/TR/SVG11/filters.html#feColorMatrixElement

FeColorMatrixHue(fs Filterspec, value float64, s ...string)

FeColorMatrix specifies a color matrix filter primitive, with hue values Standard reference: http://www.w3.org/TR/SVG11/filters.html#feColorMatrixElement

FeColorMatrixSaturate(fs Filterspec, value float64, s ...string)

FeColorMatrix specifies a color matrix filter primitive, with saturation values Standard reference: http://www.w3.org/TR/SVG11/filters.html#feColorMatrixElement

FeColorMatrixLuminence(fs Filterspec, s ...string)

FeColorMatrix specifies a color matrix filter primitive, with luminence values Standard reference: http://www.w3.org/TR/SVG11/filters.html#feColorMatrixElement

FeComponentTransfer()

FeComponentTransfer begins a feComponent filter Element> Standard reference: http://www.w3.org/TR/SVG11/filters.html#feComponentTransferElement

FeCompEnd()

FeCompEnd ends a feComponent filter Element>

FeComposite(fs Filterspec, operator string, k1, k2, k3, k4 int, s ...string)

FeComposite specifies a feComposite filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#feCompositeElement

FeConvolveMatrix(fs Filterspec, matrix [9]int, s ...string)

FeConvolveMatrix specifies a feConvolveMatrix filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#feConvolveMatrixElement

 FeDiffuseLighting(fs Filterspec, scale, constant float64, s ...string)

FeDiffuseLighting specifies a diffuse lighting filter primitive, a container for light source Element>s, end with DiffuseEnd()

 FeDiffEnd()

FeDiffuseEnd ends a diffuse lighting filter primitive container Standard reference: http://www.w3.org/TR/SVG11/filters.html#feDiffuseLightingElement

 FeDisplacementMap(fs Filterspec, scale float64, xchannel, ychannel string, s ...string)

FeDisplacementMap specifies a feDisplacementMap filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#feDisplacementMapElement

 FeDistantLight(fs Filterspec, azimuth, elevation float64, s ...string)

FeDistantLight specifies a feDistantLight filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#feDistantLightElement

 FeFlood(fs Filterspec, color string, opacity float64, s ...string)

FeFlood specifies a flood filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#feFloodElement

FeFuncLinear(channel string, slope, intercept float64)

FeFuncLinear is the linear form of feFunc Standard reference: http://www.w3.org/TR/SVG11/filters.html#feComponentTransferElement

 FeFuncGamma(channel, amplitude, exponent, offset float64)

FeFuncGamma is the gamma curve form of feFunc Standard reference: http://www.w3.org/TR/SVG11/filters.html#feComponentTransferElement

FeFuncTable(channel string, tv []float64)

FeFuncGamma is the form of feFunc using a table of values Standard reference: http://www.w3.org/TR/SVG11/filters.html#feComponentTransferElement

FeFuncDiscrete(channel string, tv []float64)

FeFuncGamma is the form of feFunc using discrete values Standard reference: http://www.w3.org/TR/SVG11/filters.html#feComponentTransferElement

 FeGaussianBlur(fs Filterspec, stdx, stdy float64, s ...string)

FeGaussianBlur specifies a Gaussian Blur filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#feGaussianBlurElement

 FeImage(href string, result string, s ...string)

FeImage specifies a feImage filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#feImageElement

 FeMerge(nodes []string, s ...string)

FeMerge specifies a feMerge filter primitive, containing feMerge Element>s Standard reference: http://www.w3.org/TR/SVG11/filters.html#feMergeElement

 FeMorphology(fs Filterspec, operator string, xradius, yradius float64, s ...string)

FeMorphologyLight specifies a feMorphologyLight filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#feMorphologyElement

 FeOffset(fs Filterspec, dx, dy int, s ...string)

FeOffset specifies the feOffset filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#feOffsetElement

 FePointLight(x, y, z float64, s ...string)

FePointLight specifies a fePpointLight filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#fePointLightElement

 FeSpecularLighting(fs Filterspec, scale, constant float64, exponent int, color string, s ...string)

FeSpecularLighting specifies a specular lighting filter primitive, a container for light source elements, end with SpecularEnd()

 FeSpecEnd()

FeSpecularEnd ends a specular lighting filter primitive container Standard reference: http://www.w3.org/TR/SVG11/filters.html#feSpecularLightingElement

 FeSpotLight(fs Filterspec, x, y, z, px, py, pz float64, s ...string)

FeSpotLight specifies a feSpotLight filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#feSpotLightElement

 FeTile(fs Filterspec, in string, s ...string)

FeTile specifies the tile utility filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#feTileElement

 FeTurbulence(fs Filterspec, ftype string, bfx, bfy float64, octaves int, seed int64, stitch bool, s ...string)

FeTurbulence specifies a turbulence filter primitive Standard reference: http://www.w3.org/TR/SVG11/filters.html#feTurbulenceElement

Filter convenience functions (modeled on CSS filter effects)

Blur(p float64)

Blur function by standard deviation

Brightness(p float64)

Brightness function (0-100)

Grayscale()

Apply a grayscale filter to the image

HueRotate(a float64)

Rotate Hues (0-360 degrees)

Invert()

Invert the image's colors

Saturate(p float64)

Percent saturation, 0 is grayscale

Sepia()

Apply sepia tone

Utility

Grid(x int, y int, w int, h int, n int, s ...string)

draws a grid of straight lines starting at x,y, with a width w, and height h, and a size of n.

Credits

Thanks to Jonathan Wright for the io.Writer update.

There are issues with how Text() is generated, regarding both spacing and the use of style...at least when viewing in Chrome browser.

Examples:

canvas.Text(300, 150, "Some Text", "font-size:48px;", `fill="#222222"`)
<text x="300" y="150" style="font-size:48px;"fill="#222222" >Some Text</text>

canvas.Text(300, 150, "Some Text", "font-size:48px;", "fill:white")
<text x="300" y="150" style="font-size:48px;" style="fill:white">Some Text</text>

In the first example, you can see that the fill attribute has no spacing before it which in Chrome, produces an attributes construct error message. Also, there is an unnecessary space before the closing >.

In the second example (after manually inserting that space before style) I get an Attribute style redefined message.

This is fixed very easily in endstyle(), which would also benefit from a little refactoring.

Units Of Measure (UOM) and Precision

It is not clear to me what the units are for the 'x' and 'y' coordinates. I would like to work with millimeters and have better precision than a one millimeter. Since all the functions seem to take []int instead of []float it is not possible to get better than whole number precision.

Is there any way to solve this problem? Thx...
Missing Translate with float parameters

In my pictures, I am seeing glitches which I think are due to the rounding of floating point numbers to ints because of the function Translate(x, y int). When nesting Scaling, Translation and Rotation operations, such rounding to ints will cause this effect. My workaround is to produce the transform(...) string myself.

Start method too strict for width and height parameters

One of the examples from http://www.w3.org/Graphics/SVG/IG/resources/svgprimer.html#SVG_web shows a use of viewboxes to stretch the svg to whatever its container is sized as, with width and height set to a percentage:

<svg xmlns="http://www.w3.org/2000/svg" width="100%" height="100%" viewBox="0 0 200 200">
<circle r="50" cx="100" cy="100"/>
</svg>

I made a few modifications to svgo to support this kind of Start:

// Startraw begins the SVG document with the width w and height h.
// Other attributes may be optionally added, for example viewbox or additional namespaces
// Standard Reference: http://www.w3.org/TR/SVG11/struct.html#SVGElement
func (svg *SVG) Startraw(w, h string, attrs ...string) {
    svg.printf(svginit, w, h)
    for _, v := range attrs {
        svg.printf("\n     %s", v)
    }
    svg.println(svgns)
}

Which is nearly identical to Start, but takes strings. svginit's width and height format verbs are changed to %v to accommodate. I'm not sure if this is a good fit for svgo, but some may find it useful.

Text() attribute styling/spacing
There are issues with how Text() is generated, regarding both spacing and the use of style...at least when viewing in Chrome browser.

Examples:

canvas.Text(300, 150, "Some Text", "font-size:48px;", `fill="#222222"`) <text x="300" y="150" style="font-size:48px;"fill="#222222" >Some Text</text> canvas.Text(300, 150, "Some Text", "font-size:48px;", "fill:white") <text x="300" y="150" style="font-size:48px;" style="fill:white">Some Text</text>

In the first example, you can see that the fill attribute has no spacing before it which in Chrome, produces an attributes construct error message. Also, there is an unnecessary space before the closing >.

In the second example (after manually inserting that space before style) I get an Attribute style redefined message.

This is fixed very easily in endstyle(), which would also benefit from a little refactoring.
Adds a way to set CSS styles on elements.

Hi,

I needed a way to add styling to elements, so I added this function. I finally got tired of the mess having a patch on your repo makes of vendoring, so am asking you to merge it upstream.

Thanks,
Adding Floating Point Precision

Added floating point precision by introducing an svg.FloatDecimals variable into the constructor (defaulting to 2, so it is backwards compatible), which allows you to modify the floating point precision at any point as you draw the SVG file. I have introduced new functions for the majority of the functionality which support floating points. For example: Circle(x int, y int, r int, s ...string) now has a sister function with the following stub CircleF(x float64, y float64, r float64, s ...string). Both can be used interchangeably in an SVG file.
Missing support

I'd be happy to write a small patch for it if you want.

Examples:

http://www.carto.net/svg/samples/patterns.shtml

Also missing a generic way to append content for things not yet supported by svgo. For instance exposing the printf() method, or something like func Tag(tagName string, s ... string) and TagEnd(tagName string)

cheers
Add ScaleXY for uneven scales

Hi,

this adds a wrapper for things like s.Gtransform("scale(0.5, 1)")

Please, let me know if I need to add something to this pull request.

Thanks, Ivan

Requesting support for tspan

Thanks for the useful library, one thing I found missing (and had to hack together myself) was support for tspan - as I was trying to center text with mixed styling.

This is what I ended up with in non-method form (the _svg functions are my replicas of the svgo private methods)

func startText(canvas *svg.SVG, x int, y int, s ...string) {
	_svg_printf(canvas, `<text %s %s`, _svg_loc(x, y), _svg_endstyle(s, ">"))
}

func addText(canvas *svg.SVG, t string, s ...string) {
	if len(s) == 0 {
		xml.Escape(canvas.Writer, []byte(t))
		return
	}
	_svg_printf(canvas, `<tspan %s`, _svg_endstyle(s, ">"))
	xml.Escape(canvas.Writer, []byte(t))
	_svg_printf(canvas, "</tspan>")
}

func endText(canvas *svg.SVG) {
	_svg_println(canvas, "</text>")
}

there is no support for embedding SVGs

It is not uncommon to want to embed SVG data inside an SVG. For example, see this PR: https://github.com/juju/jujusvg/pull/8/files In that PR, some SVGs have been produced by our design team, and we want to use them as part of the higher level SVG generation. We have manually translated them to svgo code, but that's obviously not ideal. I've considered making a little parser to parse the SVG and emit svgo calls, but that's not ideal - we're really just translating one format to itself.

Perhaps a "RawSVG" call might work here - it could perhaps do some XML processing (strip off the outer element) or perhaps just write the exact bytes given.
Support embedded style

SVGo is nice, however, for my use, I cannot find support for embedded CSS.

The closest thing I can find is SVG.Script(), I guess we should have SVG.Style(), that add a CSS section inside a DEF section: supporting CSS is also part of SVG 1.1 spec.
Add method for rotation around the center

func (svg *SVG) RotateCenter(r float64, x, y int) { svg.Gtransform(rotateCenter(r, x, y)) }

func rotateCenter(r float64, x, y int) string { return fmt.Sprintf(rotate(%g %d %d), r, x, y) }
feat: add embed.go example

This commit adds the embed.go example, which focuses on demonstrating how to embed an svg within another. The example adds a title and a red border around the svg file provided via the -f argument.

Closes #57.
Support importing a svg into the SVG object
Would be really cool if we could get functionality that allowed us to take an already existing svg (a file, for example) and import it into svgo and modify it!

This would be really helpful when working with large preexisting svgs and adding dynamic content on top of it :)

Here how I envision it to be used:

buf, err := os.OpenFile("my.svg") if err != nil { return err } canvas, err := svg.Import(buf, os.Stdout) if err != nil { return err } canvas.DoAwesomeThings(...) // ... canvas.End() // my.svg with awesome things done to it printed to stdout

Go Language Library for SVG generation

SVGo: A Go library for SVG generation

Supported SVG elements and functions

Shapes, lines, text

Paths

Image and Gradients

Transforms

Animation

Filter Effects

Metadata elements

Building and Usage

Graphics Sketching with SVGo and svgplay

SVGo Papers and presentations

Tutorial Video

Package contents

Functions and types

Structure, Scripting, Metadata, Transformation and Links

Shapes

Paths

Lines

Image and Text

Color

Gradients

Animation

Filter Effects

Filter convenience functions (modeled on CSS filter effects)

Utility

Credits

Owner

Anthony Starks

Comments

Units Of Measure (UOM) and Precision

Missing Translate with float parameters

Start method too strict for width and height parameters

Text() attribute styling/spacing

Adds a way to set CSS styles on elements.

Adding Floating Point Precision

Missing support

Add ScaleXY for uneven scales

Requesting support for tspan

there is no support for embedding SVGs

Support embedded style

Add method for rotation around the center

feat: add embed.go example

Support importing a svg into the SVG object

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