codeview.go

package codeview

import (
	"bytes"
	_ "embed"
	"github.com/golang/freetype/truetype"
	"github.com/llgcode/draw2d"
	"github.com/llgcode/draw2d/draw2dimg"
	"github.com/llgcode/draw2d/draw2dkit"
	"image"
	"image/png"
	"math"
)

var (
	//go:embed assets/font.ttf
	fontBytes []byte

	logo        []byte = nil
	projectName        = ""
	theme              = DefaultTheme()
)

// SetProjectName sets the project name to be used.
func SetProjectName(name string) {
	projectName = name
}

// SetLogo sets the logo image to be used.
func SetLogo(png []byte) {
	logo = png
}

// SetTheme sets the theme to be used.
func SetTheme(t Theme) {
	theme = t
}

func _render(text Text, title string, scale float64) (image.Image, error) {
	width := math.Floor(802 * scale)
	height := math.Floor(528 * scale)

	dest := image.NewRGBA(image.Rect(0, 0, int(width), int(height)))

	pad := 25 * scale
	fontSize := 18 * scale
	lineHeight := 28 * scale
	logoY := 22 * scale

	innerX := pad + (18 * scale)
	innerY := innerX + fontSize + (60 * scale)

	gc := draw2dimg.NewGraphicContext(dest)

	gc.SetFillColor(theme.Background)
	draw2dkit.Rectangle(gc, 0, 0, width, height)

	gc.Fill()

	gc.SetFillColor(theme.Foreground)
	draw2dkit.Rectangle(gc, pad, pad+(60*scale), width-pad, height-pad)

	gc.Fill()

	logoImg, err := png.Decode(bytes.NewReader(logo))
	if err != nil {
		return nil, err
	}

	gc.Save()

	w := float64(logoImg.Bounds().Dx())
	sc := (48 / w) * scale

	gc.Translate(pad, logoY)
	gc.Scale(sc, sc)
	gc.DrawImage(logoImg)

	gc.Restore()

	font, err := truetype.Parse(fontBytes)
	if err != nil {
		return nil, err
	}

	fontData := draw2d.FontData{
		Name:   "ComicCode",
		Family: draw2d.FontFamilyMono,
		Style:  draw2d.FontStyleNormal,
	}

	draw2d.RegisterFont(fontData, font)

	gc.SetFontData(fontData)

	gc.SetFillColor(theme.Default)
	gc.SetFontSize(24 * scale)

	gc.FillStringAt(title, pad+(48+16)*scale, logoY+(38*scale))

	gc.SetFontSize(fontSize)

	for i, line := range text.Lines {
		y := innerY + float64(i)*lineHeight
		x := innerX

		for _, token := range line {
			gc.SetFillColor(token.GetColor(theme))
			x += gc.FillStringAt(token.Text, x, y)
		}
	}

	return dest, nil
}