Documentation
¶
Overview ¶
Package text provides types and functions to parse, format and render text.
Index ¶
Examples ¶
Constants ¶
View Source
const ( PosLeft = -1 PosBottom = -1 PosCenter = 0 PosTop = +1 PosRight = +1 )
Position specifies the text position.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Handler ¶ added in v0.9.0
type Handler interface {
// Cache returns the cache of fonts used by the text handler.
Cache() *font.Cache
// Extents returns the Extents of a font.
Extents(fnt font.Font) font.Extents
// Lines splits a given block of text into separate lines.
Lines(txt string) []string
// Box returns the bounding box of the given non-multiline text where:
// - width is the horizontal space from the origin.
// - height is the vertical space above the baseline.
// - depth is the vertical space below the baseline, a positive number.
Box(txt string, fnt font.Font) (width, height, depth vg.Length)
// Draw renders the given text with the provided style and position
// on the canvas.
Draw(c vg.Canvas, txt string, sty Style, pt vg.Point)
}
Handler parses, formats and renders text.
type Latex ¶
type Latex struct {
// Fonts is the cache of font faces used by this text handler.
Fonts *font.Cache
// DPI is the dot-per-inch controlling the font resolution used by LaTeX.
// If zero, the resolution defaults to 72.
DPI float64
}
Latex parses, formats and renders LaTeX.
Example ¶
package main
import (
"image/color"
"log"
"math"
"gonum.org/v1/plot"
"gonum.org/v1/plot/font"
"gonum.org/v1/plot/font/liberation"
"gonum.org/v1/plot/plotter"
"gonum.org/v1/plot/text"
"gonum.org/v1/plot/vg"
"gonum.org/v1/plot/vg/draw"
)
func main() {
fonts := font.NewCache(liberation.Collection())
plot.DefaultTextHandler = text.Latex{
Fonts: fonts,
}
p := plot.New()
p.Title.Text = `$f(x) = \sqrt{\alpha x \Gamma}$`
p.X.Label.Text = `$\frac{\sqrt{x}}{2\pi\Gamma\gamma}$`
p.Y.Label.Text = `$\beta$`
p.X.Min = -1
p.X.Max = +1
p.Y.Min = -1
p.Y.Max = +1
labels, err := plotter.NewLabels(plotter.XYLabels{
XYs: []plotter.XY{
{X: +0.0, Y: +0.0},
{X: -0.9, Y: -0.9},
{X: +0.6, Y: +0.0},
{X: +0.5, Y: -0.9},
},
Labels: []string{
`$\frac{\sqrt{x}}{2\pi\Gamma\gamma}$`,
`$LaTeX$`,
"plain",
`$\frac{\sqrt{x}}{2\beta}$`,
},
})
if err != nil {
log.Fatalf("could not create labels: %+v", err)
}
labels.TextStyle[0].Font.Size = 24
labels.TextStyle[0].Color = color.RGBA{B: 255, A: 255}
labels.TextStyle[0].XAlign = draw.XCenter
labels.TextStyle[0].YAlign = draw.YCenter
labels.TextStyle[1].Font.Size = 24
labels.TextStyle[1].Color = color.RGBA{R: 255, A: 255}
labels.TextStyle[1].Rotation = math.Pi / 4
labels.TextStyle[2].Font.Size = 24
labels.TextStyle[2].Rotation = math.Pi / 4
labels.TextStyle[2].YAlign = draw.YCenter
labels.TextStyle[2].Handler = &text.Plain{Fonts: fonts}
labels.TextStyle[3].Font.Size = 24
labels.TextStyle[3].Rotation = math.Pi / 2
p.Add(labels)
p.Add(plotter.NewGlyphBoxes())
p.Add(plotter.NewGrid())
err = p.Save(10*vg.Centimeter, 5*vg.Centimeter, "testdata/latex.png")
if err != nil {
log.Fatalf("could not save plot: %+v", err)
}
}
Output:
func (Latex) Box ¶
Box returns the bounding box of the given non-multiline text where:
- width is the horizontal space from the origin.
- height is the vertical space above the baseline.
- depth is the vertical space below the baseline, a positive number.
type Plain ¶
Plain is a text/plain handler.
func (Plain) Box ¶ added in v0.9.0
Box returns the bounding box of the given non-multiline text where:
- width is the horizontal space from the origin.
- height is the vertical space above the baseline.
- depth is the vertical space below the baseline, a positive number.
func (Plain) Draw ¶ added in v0.9.0
Draw renders the given text with the provided style and position on the canvas.
type Style ¶ added in v0.9.0
type Style struct {
// Color is the text color.
Color color.Color
// Font is the font description.
Font font.Font
// Rotation is the text rotation in radians, performed around the axis
// defined by XAlign and YAlign.
Rotation float64
// XAlign and YAlign specify the alignment of the text.
XAlign XAlignment
YAlign YAlignment
// Handler parses and formats text according to a given
// dialect (Markdown, LaTeX, plain, ...)
// The default is a plain text handler.
Handler Handler
}
Style describes what text will look like.
func (Style) FontExtents ¶ added in v0.9.0
FontExtents returns the extents of this Style's font.
func (Style) Height ¶ added in v0.9.0
Height returns the height of the text when using the given font before any text rotation is applied.
type XAlignment ¶ added in v0.9.0
type XAlignment float64
XAlignment specifies text alignment in the X direction. Three preset options are available, but an arbitrary alignment can also be specified using XAlignment(desired number).
const ( // XLeft aligns the left edge of the text with the specified location. XLeft XAlignment = 0 // XCenter aligns the horizontal center of the text with the specified location. XCenter XAlignment = -0.5 // XRight aligns the right edge of the text with the specified location. XRight XAlignment = -1 )
type YAlignment ¶ added in v0.9.0
type YAlignment float64
YAlignment specifies text alignment in the Y direction. Three preset options are available, but an arbitrary alignment can also be specified using YAlignment(desired number).
const ( // YTop aligns the top of of the text with the specified location. YTop YAlignment = -1 // YCenter aligns the vertical center of the text with the specified location. YCenter YAlignment = -0.5 // YBottom aligns the bottom of the text with the specified location. YBottom YAlignment = 0 )
Source Files
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