vgpdf

Documentation

Overview

Package vgpdf implements the vg.Canvas interface using gofpdf (github.com/phpdave11/gofpdf).

Example (EmbedFonts)

Example_embedFonts shows how one can embed (or not) fonts inside a PDF plot.

package main

import (
	"log"
	"os"

	"gonum.org/v1/plot"
	"gonum.org/v1/plot/plotter"
	"gonum.org/v1/plot/vg/draw"
	"gonum.org/v1/plot/vg/vgpdf"
)

func main() {
	p := plot.New()

	pts := plotter.XYs{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 1, Y: 0}, {X: 1, Y: 1}}
	line, err := plotter.NewLine(pts)
	if err != nil {
		log.Fatalf("could not create line: %v", err)
	}
	p.Add(line)
	p.X.Label.Text = "X axis"
	p.Y.Label.Text = "Y axis"

	c := vgpdf.New(100, 100)

	// enable/disable embedding fonts
	c.EmbedFonts(true)
	p.Draw(draw.New(c))

	f, err := os.Create("testdata/enable-embedded-fonts.pdf")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

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

	err = f.Close()
	if err != nil {
		log.Fatalf("could not save canvas: %v", err)
	}
}

Example (Multipage)

Example_multipage shows how one can create a PDF with multiple pages.

package main

import (
	"fmt"
	"image/color"
	"log"
	"os"

	"gonum.org/v1/plot"
	"gonum.org/v1/plot/plotter"
	"gonum.org/v1/plot/vg"
	"gonum.org/v1/plot/vg/draw"
	"gonum.org/v1/plot/vg/vgpdf"
)

func main() {
	c := vgpdf.New(5*vg.Centimeter, 5*vg.Centimeter)

	for i, col := range []color.RGBA{{B: 255, A: 255}, {R: 255, A: 255}} {
		if i > 0 {
			// Add a new page.
			c.NextPage()
		}

		p := plot.New()

		pts := plotter.XYs{{X: 0, Y: 0}, {X: 0, Y: 1}, {X: 1, Y: 0}, {X: 1, Y: 1}}
		line, err := plotter.NewLine(pts)
		if err != nil {
			log.Fatalf("could not create line: %v", err)
		}
		line.Color = col
		p.Add(line)
		p.Title.Text = fmt.Sprintf("Plot %d", i+1)
		p.X.Label.Text = "X axis"
		p.Y.Label.Text = "Y axis"

		// Write plot to page.
		p.Draw(draw.New(c))
	}

	f, err := os.Create("testdata/multipage.pdf")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

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

	err = f.Close()
	if err != nil {
		log.Fatalf("could not save canvas: %v", err)
	}
}

Index

• Constants
• type Canvas
  • func New(w, h vg.Length) *Canvas
  • func (c *Canvas) DPI() float64
  • func (c *Canvas) DrawImage(rect vg.Rectangle, img image.Image)
  • func (c *Canvas) EmbedFonts(v bool) bool
  • func (c *Canvas) Fill(p vg.Path)
  • func (c *Canvas) FillString(fnt font.Face, pt vg.Point, str string)
  • func (c *Canvas) NextPage()
  • func (c *Canvas) Pop()
  • func (c *Canvas) Push()
  • func (c *Canvas) Rotate(r float64)
  • func (c *Canvas) Scale(x float64, 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(p vg.Path)
  • func (c *Canvas) Translate(pt vg.Point)
  • func (c *Canvas) WriteTo(w io.Writer) (int64, error)

Examples

• Package (EmbedFonts)
• Package (Multipage)

Constants

const DPI = 72

DPI is the nominal resolution of drawing in PDF.

Types

type Canvas

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

Canvas implements the vg.Canvas interface, drawing to a PDF.

func New

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

New creates a new PDF Canvas.

func (*Canvas) DPI

func (c *Canvas) DPI() float64

func (*Canvas) DrawImage

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

DrawImage implements the vg.Canvas.DrawImage method.

func (*Canvas) EmbedFonts

func (c *Canvas) EmbedFonts(v bool) bool

EmbedFonts specifies whether the resulting PDF canvas should embed the fonts or not. EmbedFonts returns the previous value before modification.

func (*Canvas) Fill

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

func (*Canvas) FillString

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

func (*Canvas) NextPage

func (c *Canvas) NextPage()

NextPage creates a new page in the final PDF document. The new page is the new current page. Modifications applied to the canvas will only be applied to that new page.

func (*Canvas) Pop

func (c *Canvas) Pop()

func (*Canvas) Push

func (c *Canvas) Push()

func (*Canvas) Rotate

func (c *Canvas) Rotate(r float64)

func (*Canvas) Scale

func (c *Canvas) Scale(x float64, 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(p 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. After calling Write, the canvas is closed and may no longer be used for drawing.