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Package vgsvg

import "gonum.org/v1/plot/vg/vgsvg"
Overview
Index
Examples

Overview ▾

Package vgsvg uses svgo (github.com/ajstarks/svgo) as a backend for vg.

By default, gonum/plot uses the Liberation fonts. When embedding was not requested during plot creation, it may happen that the generated SVG plot may not display well if the Liberation fonts are not available to the program displaying the SVG plot. See gonum.org/v1/plot/vg/vgsvg#Example_standardFonts for how to work around this issue.

Alternatively, users may want to install the Liberation fonts on their system:

▾ Example

Code:

p := plot.New()
p.Title.Text = "Scatter plot"
p.X.Label.Text = "X"
p.Y.Label.Text = "Y"

scatter, err := plotter.NewScatter(plotter.XYs{{X: 1, Y: 1}, {X: 0, Y: 1}, {X: 0, Y: 0}})
if err != nil {
    log.Fatalf("could not create scatter: %v", err)
}
p.Add(scatter)

err = p.Save(5*vg.Centimeter, 5*vg.Centimeter, "testdata/scatter.svg")
if err != nil {
    log.Fatalf("could not save SVG plot: %v", err)
}

▾ Example (EmbedFonts)

Code:

// Use Latin-Modern fonts.
cmi10 := font.Font{Typeface: "Latin-Modern", Style: xfnt.StyleItalic}
fnt, err := opentype.Parse(lmit.TTF)
if err != nil {
    log.Fatalf("could not parse Latin-Modern fonts: %+v", err)
}

font.DefaultCache.Add([]font.Face{{
    Font: cmi10,
    Face: fnt,
}})
plot.DefaultFont = cmi10

p := plot.New()
p.Title.Text = "Scatter plot"
p.X.Label.Text = "x-Axis"
p.Y.Label.Text = "y-Axis"

scatter, err := plotter.NewScatter(plotter.XYs{{X: 1, Y: 1}, {X: 0, Y: 1}, {X: 0, Y: 0}})
if err != nil {
    log.Fatalf("could not create scatter: %v", err)
}
p.Add(scatter)

c := vgsvg.NewWith(
    vgsvg.UseWH(5*vg.Centimeter, 5*vg.Centimeter),
    vgsvg.EmbedFonts(true),
)
p.Draw(draw.New(c))

f, err := os.Create("testdata/embed_fonts.svg")
if err != nil {
    log.Fatalf("could not create output SVG file: %+v", err)
}
defer f.Close()

_, err = c.WriteTo(f)
if err != nil {
    log.Fatalf("could not write output SVG plot: %+v", err)
}

err = f.Close()
if err != nil {
    log.Fatalf("could not close output SVG file: %v", err)
}

▾ Example (StandardFonts)

Code:

// Use standard fonts.
tms := font.Font{Typeface: "Times"}
fnt, err := opentype.Parse(lreg.TTF)
if err != nil {
    log.Fatalf("could not parse Times fonts: %+v", err)
}

font.DefaultCache.Add([]font.Face{{
    Font: tms,
    Face: fnt,
}})
plot.DefaultFont = tms

p := plot.New()
p.Title.Text = "Scatter plot"
p.X.Label.Text = "x-Axis"
p.Y.Label.Text = "y-Axis"

scatter, err := plotter.NewScatter(plotter.XYs{{X: 1, Y: 1}, {X: 0, Y: 1}, {X: 0, Y: 0}})
if err != nil {
    log.Fatalf("could not create scatter: %v", err)
}
p.Add(scatter)

err = p.Save(5*vg.Centimeter, 5*vg.Centimeter, "testdata/standard_fonts.svg")
if err != nil {
    log.Fatalf("could not save SVG plot: %+v", err)
}

Constants

const (
    // DefaultWidth and DefaultHeight are the default canvas
    // dimensions.
    DefaultWidth  = 4 * vg.Inch
    DefaultHeight = 4 * vg.Inch
)

func EmbedFonts 

func EmbedFonts(v bool) option

EmbedFonts specifies whether fonts should be embedded inside the SVG canvas.

func UseWH 

func UseWH(w, h vg.Length) option

UseWH specifies the width and height of the canvas.

type Canvas

Canvas implements the vg.Canvas interface, drawing to a SVG document.

By default, fonts used by the canvas are not embedded in the produced SVG document. This results in smaller but less portable SVG plots. Users wanting completely portable SVG documents should create SVG canvases with the EmbedFonts function. 

type Canvas struct {
    // contains filtered or unexported fields
}

func New 

func New(w, h vg.Length) *Canvas

New returns a new image canvas.

func NewWith 

func NewWith(opts ...option) *Canvas

NewWith returns a new image canvas created according to the specified options. The currently accepted options is UseWH. If size is not specified, the default is used.

func (*Canvas) DrawImage 

func (c *Canvas) DrawImage(rect vg.Rectangle, img image.Image)

DrawImage implements the vg.Canvas.DrawImage method.

func (*Canvas) Fill 

func (c *Canvas) Fill(path vg.Path)

func (*Canvas) FillString 

func (c *Canvas) FillString(font font.Face, pt vg.Point, str string)

FillString draws str at position pt using the specified font. Text passed to FillString is escaped with html.EscapeString.

func (*Canvas) Pop 

func (c *Canvas) Pop()

func (*Canvas) Push 

func (c *Canvas) Push()

func (*Canvas) Rotate 

func (c *Canvas) Rotate(rot float64)

func (*Canvas) Scale 

func (c *Canvas) Scale(x, y float64)

func (*Canvas) SetColor 

func (c *Canvas) SetColor(clr color.Color)

func (*Canvas) SetLineDash 

func (c *Canvas) SetLineDash(dashes []vg.Length, offs vg.Length)

func (*Canvas) SetLineWidth 

func (c *Canvas) SetLineWidth(w vg.Length)

func (*Canvas) Size 

func (c *Canvas) Size() (w, h vg.Length)

func (*Canvas) Stroke 

func (c *Canvas) Stroke(path vg.Path)

func (*Canvas) Translate 

func (c *Canvas) Translate(pt vg.Point)

func (*Canvas) WriteTo 

func (c *Canvas) WriteTo(w io.Writer) (int64, error)

WriteTo writes the canvas to an io.Writer.