cera/editor_example_test.go at main · timzifer/cera · GitHub

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package cera_test

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

	"github.com/timzifer/cera"
)

// A report with a cover page from another file, its last page deleted;
// its outline, form and the rest kept.
func ExampleDocument_Edit() {
	report, err := os.ReadFile("report.pdf")
	if err != nil {
		log.Fatal(err)
	}
	cover, err := os.ReadFile("cover.pdf")
	if err != nil {
		log.Fatal(err)
	}
	doc, err := cera.Open(report)
	if err != nil {
		log.Fatal(err)
	}
	src, err := cera.Open(cover)
	if err != nil {
		log.Fatal(err)
	}
	e := doc.Edit()
	if err := e.DeletePages(e.NumPages() - 1); err != nil {
		log.Fatal(err)
	}
	if err := e.ImportPages(0, src, cera.EditPage{Index: 0}); err != nil {
		log.Fatal(err)
	}
	f, err := os.Create("out.pdf")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()
	if err := e.Save(f); err != nil {
		log.Fatal(err)
	}
}

// A page number at the foot of every page, and a cover sheet in front.
func ExampleEditor_Draw() {
	data, err := os.ReadFile("in.pdf")
	if err != nil {
		log.Fatal(err)
	}
	doc, err := cera.Open(data)
	if err != nil {
		log.Fatal(err)
	}
	font, err := cera.StandardFont("Helvetica")
	if err != nil {
		log.Fatal(err)
	}
	e := doc.Edit()
	for i := range e.NumPages() {
		err := e.Draw(i, true, func(c *cera.Canvas) {
			w, h := c.Size()
			label := fmt.Sprintf("%d / %d", i+1, e.NumPages())
			c.DrawText(label, (w-font.Width(label, 9))/2, h-24, font, 9, color.Gray{Y: 90})
		})
		if err != nil {
			log.Fatal(err)
		}
	}
	if err := e.AddPage(0, 595, 842); err != nil {
		log.Fatal(err)
	}
	err = e.Draw(0, true, func(c *cera.Canvas) {
		c.DrawText("Annual report", 72, 200, font, 32, color.Black)
	})
	if err != nil {
		log.Fatal(err)
	}
	f, err := os.Create("out.pdf")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()
	if err := e.Save(f); err != nil {
		log.Fatal(err)
	}
}

// Pages 3 to 5 and page 1 of a file in a new one, the last turned to
// landscape.
func ExampleNewEditor() {
	data, err := os.ReadFile("in.pdf")
	if err != nil {
		log.Fatal(err)
	}
	doc, err := cera.Open(data)
	if err != nil {
		log.Fatal(err)
	}
	e := cera.NewEditor()
	err = e.ImportPages(0, doc,
		cera.EditPage{Index: 2}, cera.EditPage{Index: 3}, cera.EditPage{Index: 4},
		cera.EditPage{Index: 0, Rotate: 90})
	if err != nil {
		log.Fatal(err)
	}
	f, err := os.Create("out.pdf")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()
	if err := e.Save(f); err != nil {
		log.Fatal(err)
	}
}