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package text
import (
"log"
"sync"
"image"
"image/color"
"image/draw"
"golang.org/x/image/font"
"golang.org/x/image/font/gofont/goregular"
"golang.org/x/image/font/opentype"
"golang.org/x/image/math/fixed"
)
var (
FONT = goregular.TTF
FONT_SIZE = 15
DPI = 72
PAD = 3
)
var face *concurrentFace
func init() {
fnt, err := opentype.Parse(FONT)
if err != nil {
log.Fatal(err)
}
fce, err := opentype.NewFace(fnt, &opentype.FaceOptions{
Size: float64(FONT_SIZE),
DPI: float64(DPI),
})
if err != nil {
log.Fatal(err)
}
face = &concurrentFace{sync.Mutex{}, fce}
}
type Align int
const (
ALIGN_LEFT Align = iota
ALIGN_RIGHT
)
func Size(text string) image.Point {
bounds := textBounds(text, font.Drawer{Face: face})
return image.Point{bounds.Max.X - bounds.Min.X + 2*PAD, bounds.Max.Y - bounds.Min.Y + 2*PAD}
}
func Draw(text string, dst draw.Image, r image.Rectangle, fg, bg color.Color, align Align) {
drawer := font.Drawer{
Src: &image.Uniform{fg},
Face: face,
Dot: fixed.P(0, 0),
}
// background
draw.Draw(dst, r, &image.Uniform{bg}, image.ZP, draw.Src)
// text image
bounds := textBounds(text, drawer)
textImg := image.NewRGBA(bounds)
draw.Draw(textImg, bounds, &image.Uniform{bg}, image.ZP, draw.Src)
drawer.Dst = textImg
drawer.DrawString(text)
leftCentre := image.Pt(bounds.Min.X, (bounds.Min.Y+bounds.Max.Y)/2)
var target image.Point
switch align {
case ALIGN_LEFT:
target = image.Pt(r.Min.X+PAD, (r.Min.Y+r.Max.Y)/2)
case ALIGN_RIGHT:
target = image.Pt(r.Max.X-bounds.Max.X-PAD, (r.Min.Y+r.Max.Y)/2)
}
delta := target.Sub(leftCentre)
draw.Draw(dst, bounds.Add(delta).Intersect(r), textImg, bounds.Min, draw.Src)
}
func textBounds(text string, drawer font.Drawer) image.Rectangle {
b, _ := drawer.BoundString(text)
return image.Rect(
b.Min.X.Floor(),
b.Min.Y.Floor(),
b.Max.X.Ceil(),
b.Max.Y.Ceil(),
)
}
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