fonts

context.go

@@ -7,6 +7,8 @@ import (
 	"math"
 
 	"github.com/golang/freetype/raster"
+	"golang.org/x/image/font"
+	"golang.org/x/image/font/basicfont"
 	"golang.org/x/image/math/fixed"
 )
 
@@ -43,6 +45,7 @@ type Context struct {
 	capper    raster.Capper
 	joiner    raster.Joiner
 	fillRule  FillRule
+	fontFace  font.Face
 }
 
 func NewContext(width, height int) *Context {
@@ -54,6 +57,7 @@ func NewContext(width, height int) *Context {
 		color:     color.Transparent,
 		lineWidth: 1,
 		fillRule:  FillRuleWinding,
+		fontFace:  basicfont.Face7x13,
 	}
 }
 
@@ -181,6 +185,8 @@ func (dc *Context) Fill() {
 	dc.NewPath()
 }
 
+// Convenient Drawing Functions
+
 func (dc *Context) DrawLine(x1, y1, x2, y2 float64) {
 	dc.MoveTo(x1, y1)
 	dc.LineTo(x2, y2)
@@ -219,3 +225,33 @@ func (dc *Context) DrawArc(x, y, r, angle1, angle2 float64) {
 func (dc *Context) DrawCircle(x, y, r float64) {
 	dc.DrawEllipseArc(x, y, r, r, 0, 2*math.Pi)
 }
+
+// Text Functions
+
+func (dc *Context) SetFontFace(fontFace font.Face) {
+	dc.fontFace = fontFace
+}
+
+func (dc *Context) LoadFontFace(path string, size float64) {
+	dc.fontFace = loadFontFace(path, size)
+}
+
+func (dc *Context) DrawString(x, y float64, s string) {
+	d := &font.Drawer{
+		Dst:  dc.im,
+		Src:  image.NewUniform(dc.color),
+		Face: dc.fontFace,
+		Dot:  fp(x, y),
+	}
+	d.DrawString(s)
+}
+
+func (dc *Context) MeasureString(s string) float64 {
+	d := &font.Drawer{
+		Dst:  nil,
+		Src:  nil,
+		Face: dc.fontFace,
+	}
+	a := d.MeasureString(s)
+	return float64(a >> 6)
+}

examples/text.go

@@ -0,0 +1,15 @@
+package main
+
+import "github.com/fogleman/dd"
+
+func main() {
+	dc := dd.NewContext(1000, 1000)
+	dc.SetSourceRGB(1, 1, 1)
+	dc.Paint()
+	dc.SetSourceRGB(0, 0, 0)
+	dc.LoadFontFace("/Library/Fonts/Impact.ttf", 96)
+	s := "Hello, world!"
+	w := dc.MeasureString(s)
+	dc.DrawString(500-w/2, 500, s)
+	dc.WriteToPNG("out.png")
+}

util.go

@@ -3,8 +3,12 @@ package dd
 import (
 	"image"
 	"image/png"
+	"io/ioutil"
 	"os"
 
+	"github.com/golang/freetype/truetype"
+
+	"golang.org/x/image/font"
 	"golang.org/x/image/math/fixed"
 )
 
@@ -24,3 +28,19 @@ func fp(x, y float64) fixed.Point26_6 {
 func fi(x float64) fixed.Int26_6 {
 	return fixed.Int26_6(x * 64)
 }
+
+func loadFontFace(path string, size float64) font.Face {
+	fontBytes, err := ioutil.ReadFile(path)
+	if err != nil {
+		panic(err)
+	}
+	f, err := truetype.Parse(fontBytes)
+	if err != nil {
+		panic(err)
+	}
+	return truetype.NewFace(f, &truetype.Options{
+		Size:    size,
+		DPI:     96,
+		Hinting: font.HintingFull,
+	})
+}