1 files changed, 74 insertions, 0 deletions
diff --git a/gui/widget/text.go b/gui/widget/text.go
new file mode 100644
index 0000000..cb66a0a
--- /dev/null
+++ b/gui/widget/text.go
@@ -0,0 +1,74 @@
+package widget
+
+import (
+	"log"
+	"sync"
+
+	"image"
+	"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  float64 = 15
+	DPI        float64 = 72
+	BG_COLOR           = image.White
+	TEXT_COLOR         = image.Black
+)
+
+var face *concurrentFace
+
+func init() {
+	fnt, err := opentype.Parse(FONT)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fce, err := opentype.NewFace(fnt, &opentype.FaceOptions{
+		Size: FONT_SIZE,
+		DPI:  DPI,
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+	face = &concurrentFace{sync.Mutex{}, fce}
+}
+
+func drawText(text []byte, dst draw.Image, r image.Rectangle) {
+	drawer := font.Drawer{
+		Src:  TEXT_COLOR,
+		Face: face,
+		Dot:  fixed.P(0, 0),
+	}
+
+	bounds := textBounds(text, drawer)
+
+	// background
+	draw.Draw(dst, r, BG_COLOR, image.ZP, draw.Src)
+
+	// text image
+	textImg := image.NewRGBA(bounds)
+	draw.Draw(textImg, bounds, BG_COLOR, image.ZP, draw.Src)
+	drawer.Dst = textImg
+	drawer.DrawBytes(text)
+
+	// draw text image over background
+	left := image.Pt(bounds.Min.X, (bounds.Min.Y+bounds.Max.Y)/2)
+	target := image.Pt(r.Min.X, (r.Min.Y+r.Max.Y)/2)
+	delta := target.Sub(left)
+	draw.Draw(dst, bounds.Add(delta).Intersect(r), drawer.Dst, bounds.Min, draw.Src)
+}
+
+func textBounds(text []byte, drawer font.Drawer) image.Rectangle {
+	b, _ := drawer.BoundBytes(text)
+	return image.Rect(
+		b.Min.X.Floor(),
+		b.Min.Y.Floor(),
+		b.Max.X.Ceil(),
+		b.Max.Y.Ceil(),
+	)
+}