kern_test.go

package gopdf

import (
	"errors"
	"fmt"
	"log"
	"testing"
)

func TestKern01(t *testing.T) {
	Wo, err := kern01("test/res/times.ttf", "times", 'W', 'o')
	if err != nil {
		t.Error(err)
		return
	}

	if Wo != -80 {
		t.Error(fmt.Sprintf("Wo must be -80 (but %d)", Wo))
		//return
	}

	Wi, err := kern01("test/res/times.ttf", "times", 'W', 'i')
	if err != nil {
		t.Error(err)
		return
	}

	if Wi != -40 {
		t.Error(fmt.Sprintf("Wi must be -40 (but %d)", Wi))
		//return
	}

}

func kern01(font string, prefix string, leftRune rune, rightRune rune) (int, error) {

	pdf := GoPdf{}
	pdf.Start(Config{Unit: Unit_PT, PageSize: Rect{W: 595.28, H: 841.89}}) //595.28, 841.89 = A4
	pdf.AddPage()
	err := pdf.AddTTFFontWithOption(prefix, font, TtfOption{
		UseKerning: true,
	})
	if err != nil {
		log.Print(err.Error())
		return 0, err
	}

	err = pdf.SetFont(prefix, "", 50)
	if err != nil {
		log.Print(err.Error())
		return 0, err
	}

	gindexleftRune, err := pdf.curr.Font_ISubset.CharCodeToGlyphIndex(leftRune)
	if err != nil {
		return 0, err
	}

	gindexrightRune, err := pdf.curr.Font_ISubset.CharCodeToGlyphIndex(rightRune)
	if err != nil {
		return 0, err
	}
	//fmt.Printf("gindexleftRune = %d  gindexrightRune=%d \n", gindexleftRune, gindexrightRune)
	kernTb := pdf.curr.Font_ISubset.ttfp.Kern()

	//fmt.Printf("UnitsPerEm = %d\n", pdf.Curr.Font_ISubset.ttfp.UnitsPerEm())

	//fmt.Printf("len =%d\n", len(kernTb.Kerning))
	for left, kval := range kernTb.Kerning {
		if left == gindexleftRune {
			for right, val := range kval {
				if right == gindexrightRune {
					//fmt.Printf("left=%d right= %d  val=%d\n", left, right, val)
					valPdfUnit := convertTTFUnit2PDFUnit(int(val), int(pdf.curr.Font_ISubset.ttfp.UnitsPerEm()))
					return valPdfUnit, nil
				}
			}
			break
		}
	}

	return 0, errors.New("not found")
}