// Text takes an image and, using the freetype package, writes text in the
// position specified on to the image. A color.Color, a font size and a font
// must also be specified.
// Finally, the (x, y) coordinate advanced by the text extents is returned.
//
// Note that the ParseFont helper function can be used to get a *truetype.Font
// value without having to import freetype-go directly.
//
// If you need more control over the 'context' used to draw text (like the DPI),
// then you'll need to ignore this convenience method and use your own.
func (im *Image) Text(x, y int, clr color.Color, fontSize float64,
font *truetype.Font, text string) (int, int, error) {
// Create a solid color image
textClr := image.NewUniform(clr)
// Set up the freetype context... mostly boiler plate
c := ftContext(font, fontSize)
c.SetClip(im.Bounds())
c.SetDst(im)
c.SetSrc(textClr)
// Now let's actually draw the text...
pt := freetype.Pt(x, y+int(c.PointToFix32(fontSize)>>8))
newpt, err := c.DrawString(text, pt)
if err != nil {
return 0, 0, err
}
return int(newpt.X / 256), int(newpt.Y / 256), nil
}
func main() {
flag.Parse()
// Read the font data.
fontBytes, err := ioutil.ReadFile(*fontfile)
if err != nil {
log.Println(err)
return
}
font, err := freetype.ParseFont(fontBytes)
if err != nil {
log.Println(err)
return
}
// Initialize the context.
fg, bg := image.Black, image.White
ruler := color.RGBA{0xdd, 0xdd, 0xdd, 0xff}
if *wonb {
fg, bg = image.White, image.Black
ruler = color.RGBA{0x22, 0x22, 0x22, 0xff}
}
rgba := image.NewRGBA(image.Rect(0, 0, 640, 480))
draw.Draw(rgba, rgba.Bounds(), bg, image.ZP, draw.Src)
c := freetype.NewContext()
c.SetDPI(*dpi)
c.SetFont(font)
c.SetFontSize(*size)
c.SetClip(rgba.Bounds())
c.SetDst(rgba)
c.SetSrc(fg)
// Draw the guidelines.
for i := 0; i < 200; i++ {
rgba.Set(10, 10+i, ruler)
rgba.Set(10+i, 10, ruler)
}
// Draw the text.
pt := freetype.Pt(10, 10+int(c.PointToFix32(*size)>>8))
for _, s := range text {
_, err = c.DrawString(s, pt)
if err != nil {
log.Println(err)
return
}
pt.Y += c.PointToFix32(*size * *spacing)
}
// Save that RGBA image to disk.
f, err := os.Create("out.png")
if err != nil {
log.Println(err)
os.Exit(1)
}
defer f.Close()
b := bufio.NewWriter(f)
err = png.Encode(b, rgba)
if err != nil {
log.Println(err)
os.Exit(1)
}
err = b.Flush()
if err != nil {
log.Println(err)
os.Exit(1)
}
fmt.Println("Wrote out.png OK.")
}