Documentation
¶
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 ¶
package main
import (
"log"
"gonum.org/v1/plot"
"gonum.org/v1/plot/plotter"
"gonum.org/v1/plot/vg"
)
func main() {
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)
}
}
Output:
Example (EmbedFonts) ¶
package main
import (
"log"
"os"
lmit "github.com/go-fonts/latin-modern/lmroman10italic"
xfnt "golang.org/x/image/font"
"golang.org/x/image/font/opentype"
"gonum.org/v1/plot"
"gonum.org/v1/plot/font"
"gonum.org/v1/plot/plotter"
"gonum.org/v1/plot/vg"
"gonum.org/v1/plot/vg/draw"
"gonum.org/v1/plot/vg/vgsvg"
)
func main() {
// 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)
}
}
Output:
Example (StandardFonts) ¶
package main
import (
"log"
lreg "github.com/go-fonts/liberation/liberationserifregular"
"golang.org/x/image/font/opentype"
"gonum.org/v1/plot"
"gonum.org/v1/plot/font"
"gonum.org/v1/plot/plotter"
"gonum.org/v1/plot/vg"
)
func main() {
// 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)
}
}
Output:
Index ¶
- Constants
- func EmbedFonts(v bool) option
- func UseWH(w, h vg.Length) option
- type Canvas
- func (c *Canvas) DrawImage(rect vg.Rectangle, img image.Image)
- func (c *Canvas) Fill(path vg.Path)
- func (c *Canvas) FillString(font font.Face, pt vg.Point, str string)
- func (c *Canvas) Pop()
- func (c *Canvas) Push()
- func (c *Canvas) Rotate(rot float64)
- func (c *Canvas) Scale(x, y float64)
- func (c *Canvas) SetColor(clr color.Color)
- func (c *Canvas) SetLineDash(dashes []vg.Length, offs vg.Length)
- func (c *Canvas) SetLineWidth(w vg.Length)
- func (c *Canvas) Size() (w, h vg.Length)
- func (c *Canvas) Stroke(path vg.Path)
- func (c *Canvas) Translate(pt vg.Point)
- func (c *Canvas) WriteTo(w io.Writer) (int64, error)
Examples ¶
Constants ¶
const ( // DefaultWidth and DefaultHeight are the default canvas // dimensions. DefaultWidth = 4 * vg.Inch DefaultHeight = 4 * vg.Inch )
Variables ¶
This section is empty.
Functions ¶
func EmbedFonts ¶ added in v0.10.0
func EmbedFonts(v bool) option
EmbedFonts specifies whether fonts should be embedded inside the SVG canvas.
Types ¶
type Canvas ¶
type Canvas struct {
// contains filtered or unexported fields
}
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.
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) FillString ¶
FillString draws str at position pt using the specified font. Text passed to FillString is escaped with html.EscapeString.
Source Files