Add stroke functionality to glyphs

README

@@ -1,7 +1,7 @@
 The Freetype font rasterizer in the Go programming language.
 
 To download and install from source:
-$ go get github.com/golang/freetype
+$ go get github.com/tdewolff/freetype
 
 It is an incomplete port:
   * It only supports TrueType fonts, and not Type 1 fonts nor bitmap fonts.

example/capjoin/main.go

@@ -5,7 +5,7 @@
 
 // +build example
 //
-// This build tag means that "go install github.com/golang/freetype/..."
+// This build tag means that "go install github.com/tdewolff/freetype/..."
 // doesn't install this example program. Use "go run main.go" to run it or "go
 // install -tags=example" to install it.
 
@@ -21,7 +21,7 @@ import (
 	"log"
 	"os"
 
-	"github.com/golang/freetype/raster"
+	"github.com/tdewolff/freetype/raster"
 	"golang.org/x/image/math/fixed"
 )
 

example/drawer/main.go

@@ -5,7 +5,7 @@
 
 // +build example
 //
-// This build tag means that "go install github.com/golang/freetype/..."
+// This build tag means that "go install github.com/tdewolff/freetype/..."
 // doesn't install this example program. Use "go run main.go" to run it or "go
 // install -tags=example" to install it.
 
@@ -24,7 +24,7 @@ import (
 	"math"
 	"os"
 
-	"github.com/golang/freetype/truetype"
+	"github.com/tdewolff/freetype/truetype"
 	"golang.org/x/image/font"
 	"golang.org/x/image/math/fixed"
 )

example/freetype/main.go

@@ -5,7 +5,7 @@
 
 // +build example
 //
-// This build tag means that "go install github.com/golang/freetype/..."
+// This build tag means that "go install github.com/tdewolff/freetype/..."
 // doesn't install this example program. Use "go run main.go" to run it or "go
 // install -tags=example" to install it.
 
@@ -23,7 +23,7 @@ import (
 	"log"
 	"os"
 
-	"github.com/golang/freetype"
+	"github.com/tdewolff/freetype"
 	"golang.org/x/image/font"
 )
 

example/gamma/main.go

@@ -5,7 +5,7 @@
 
 // +build example
 //
-// This build tag means that "go install github.com/golang/freetype/..."
+// This build tag means that "go install github.com/tdewolff/freetype/..."
 // doesn't install this example program. Use "go run main.go" to run it or "go
 // install -tags=example" to install it.
 
@@ -20,7 +20,7 @@ import (
 	"log"
 	"os"
 
-	"github.com/golang/freetype/raster"
+	"github.com/tdewolff/freetype/raster"
 	"golang.org/x/image/math/fixed"
 )
 

example/genbasicfont/main.go

@@ -5,7 +5,7 @@
 
 // +build example
 //
-// This build tag means that "go install github.com/golang/freetype/..."
+// This build tag means that "go install github.com/tdewolff/freetype/..."
 // doesn't install this example program. Use "go run main.go" to run it or "go
 // install -tags=example" to install it.
 
@@ -26,7 +26,7 @@ import (
 	"strings"
 	"unicode"
 
-	"github.com/golang/freetype/truetype"
+	"github.com/tdewolff/freetype/truetype"
 	"golang.org/x/image/font"
 	"golang.org/x/image/math/fixed"
 )

example/raster/main.go

@@ -5,7 +5,7 @@
 
 // +build example
 //
-// This build tag means that "go install github.com/golang/freetype/..."
+// This build tag means that "go install github.com/tdewolff/freetype/..."
 // doesn't install this example program. Use "go run main.go" to run it or "go
 // install -tags=example" to install it.
 
@@ -21,7 +21,7 @@ import (
 	"log"
 	"os"
 
-	"github.com/golang/freetype/raster"
+	"github.com/tdewolff/freetype/raster"
 	"golang.org/x/image/math/fixed"
 )
 

example/round/main.go

@@ -5,7 +5,7 @@
 
 // +build example
 //
-// This build tag means that "go install github.com/golang/freetype/..."
+// This build tag means that "go install github.com/tdewolff/freetype/..."
 // doesn't install this example program. Use "go run main.go" to run it or "go
 // install -tags=example" to install it.
 
@@ -27,7 +27,7 @@ import (
 	"math"
 	"os"
 
-	"github.com/golang/freetype/raster"
+	"github.com/tdewolff/freetype/raster"
 	"golang.org/x/image/math/fixed"
 )
 

example/truetype/main.go

@@ -5,7 +5,7 @@
 
 // +build example
 //
-// This build tag means that "go install github.com/golang/freetype/..."
+// This build tag means that "go install github.com/tdewolff/freetype/..."
 // doesn't install this example program. Use "go run main.go" to run it or "go
 // install -tags=example" to install it.
 
@@ -17,7 +17,7 @@ import (
 	"io/ioutil"
 	"log"
 
-	"github.com/golang/freetype/truetype"
+	"github.com/tdewolff/freetype/truetype"
 	"golang.org/x/image/font"
 	"golang.org/x/image/math/fixed"
 )

freetype.go

@@ -6,15 +6,15 @@
 // The freetype package provides a convenient API to draw text onto an image.
 // Use the freetype/raster and freetype/truetype packages for lower level
 // control over rasterization and TrueType parsing.
-package freetype // import "github.com/golang/freetype"
+package freetype // import "github.com/tdewolff/freetype"
 
 import (
 	"errors"
 	"image"
 	"image/draw"
 
-	"github.com/golang/freetype/raster"
-	"github.com/golang/freetype/truetype"
+	"github.com/tdewolff/freetype/raster"
+	"github.com/tdewolff/freetype/truetype"
 	"golang.org/x/image/font"
 	"golang.org/x/image/math/fixed"
 )

raster/raster.go

@@ -13,7 +13,7 @@
 // the Freetype "smooth" module, and the Anti-Grain Geometry library. A
 // description of the area/coverage algorithm is at
 // http://projects.tuxee.net/cl-vectors/section-the-cl-aa-algorithm
-package raster // import "github.com/golang/freetype/raster"
+package raster // import "github.com/tdewolff/freetype/raster"
 
 import (
 	"strconv"

raster/stroke.go

@@ -438,12 +438,19 @@ func (k *stroker) stroke(q Path) {
 	if len(k.r) == 0 {
 		return
 	}
-	// TODO(nigeltao): if q is a closed curve then we should join the first and
-	// last segments instead of capping them.
-	k.cr.Cap(k.p, k.u, q.lastPoint(), pNeg(k.anorm))
+
+	closed := q.firstPoint() == q.lastPoint()
+	if !closed {
+		k.cr.Cap(k.p, k.u, q.lastPoint(), pNeg(k.anorm))
+	} else {
+		pivot := q.firstPoint()
+		k.jr.Join(k.p, &k.r, k.u, pivot, k.anorm, pivot.Sub(fixed.Point26_6{k.r[1], k.r[2]}))
+	}
 	addPathReversed(k.p, k.r)
-	pivot := q.firstPoint()
-	k.cr.Cap(k.p, k.u, pivot, pivot.Sub(fixed.Point26_6{k.r[1], k.r[2]}))
+	if !closed {
+		pivot := q.firstPoint()
+		k.cr.Cap(k.p, k.u, pivot, pivot.Sub(fixed.Point26_6{k.r[1], k.r[2]}))
+	}
 }
 
 // Stroke adds q stroked with the given width to p. The result is typically

truetype/face.go

@@ -9,7 +9,7 @@ import (
 	"image"
 	"math"
 
-	"github.com/golang/freetype/raster"
+	"github.com/tdewolff/freetype/raster"
 	"golang.org/x/image/font"
 	"golang.org/x/image/math/fixed"
 )
@@ -66,6 +66,11 @@ type Options struct {
 	//
 	// A zero value means to use 1 sub-pixel location.
 	SubPixelsY int
+
+	// Stroke is the number of pixels that the font glyphs are being stroked.
+	//
+	// A zero values means no stroke.
+	Stroke int
 }
 
 func (o *Options) size() float64 {
@@ -182,6 +187,7 @@ func NewFace(f *Font, opts *Options) font.Face {
 		hinting:    opts.hinting(),
 		scale:      fixed.Int26_6(0.5 + (opts.size() * opts.dpi() * 64 / 72)),
 		glyphCache: make([]glyphCacheEntry, opts.glyphCacheEntries()),
+		stroke:     fixed.I(opts.Stroke * 2),
 	}
 	a.subPixelX, a.subPixelBiasX, a.subPixelMaskX = opts.subPixelsX()
 	a.subPixelY, a.subPixelBiasY, a.subPixelMaskY = opts.subPixelsY()
@@ -207,6 +213,10 @@ func NewFace(f *Font, opts *Options) font.Face {
 	a.r.SetBounds(a.maxw, a.maxh)
 	a.p = facePainter{a}
 
+	if a.stroke != 0 {
+		a.r.UseNonZeroWinding = true
+	}
+
 	return a
 }
 
@@ -220,6 +230,7 @@ type face struct {
 	subPixelY     uint32
 	subPixelBiasY fixed.Int26_6
 	subPixelMaskY fixed.Int26_6
+	stroke        fixed.Int26_6
 	masks         *image.Alpha
 	glyphCache    []glyphCacheEntry
 	r             raster.Rasterizer
@@ -329,6 +340,10 @@ func (a *face) GlyphBounds(r rune) (bounds fixed.Rectangle26_6, advance fixed.In
 	if xmin > xmax || ymin > ymax {
 		return fixed.Rectangle26_6{}, 0, false
 	}
+	xmin -= a.stroke
+	ymin -= a.stroke
+	xmax += a.stroke
+	ymax += a.stroke
 	return fixed.Rectangle26_6{
 		Min: fixed.Point26_6{
 			X: xmin,
@@ -364,6 +379,10 @@ func (a *face) rasterize(index Index, fx, fy fixed.Int26_6) (v glyphCacheVal, ok
 	if xmin > xmax || ymin > ymax {
 		return glyphCacheVal{}, false
 	}
+	xmin -= int(a.stroke) >> 6
+	ymin -= int(a.stroke) >> 6
+	xmax += int(a.stroke) >> 6
+	ymax += int(a.stroke) >> 6
 	// A TrueType's glyph's nodes can have negative co-ordinates, but the
 	// rasterizer clips anything left of x=0 or above y=0. xmin and ymin are
 	// the pixel offsets, based on the font's FUnit metrics, that let a
@@ -434,7 +453,8 @@ func (a *face) drawContour(ps []Point, dx, dy fixed.Int26_6) {
 			others = ps
 		}
 	}
-	a.r.Start(start)
+	path := raster.Path{}
+	path.Start(start)
 	q0, on0 := start, true
 	for _, p := range others {
 		q := fixed.Point26_6{
@@ -444,9 +464,9 @@ func (a *face) drawContour(ps []Point, dx, dy fixed.Int26_6) {
 		on := p.Flags&0x01 != 0
 		if on {
 			if on0 {
-				a.r.Add1(q)
+				path.Add1(q)
 			} else {
-				a.r.Add2(q0, q)
+				path.Add2(q0, q)
 			}
 		} else {
 			if on0 {
@@ -456,16 +476,22 @@ func (a *face) drawContour(ps []Point, dx, dy fixed.Int26_6) {
 					X: (q0.X + q.X) / 2,
 					Y: (q0.Y + q.Y) / 2,
 				}
-				a.r.Add2(q0, mid)
+				path.Add2(q0, mid)
 			}
 		}
 		q0, on0 = q, on
 	}
 	// Close the curve.
 	if on0 {
-		a.r.Add1(start)
+		path.Add1(start)
+	} else {
+		path.Add2(q0, start)
+	}
+
+	if a.stroke == 0 {
+		a.r.AddPath(path)
 	} else {
-		a.r.Add2(q0, start)
+		a.r.AddStroke(path, a.stroke, raster.RoundCapper, raster.RoundJoiner)
 	}
 }
 

truetype/truetype.go

@@ -15,7 +15,7 @@
 //
 // To measure a TrueType font in ideal FUnit space, use scale equal to
 // font.FUnitsPerEm().
-package truetype // import "github.com/golang/freetype/truetype"
+package truetype // import "github.com/tdewolff/freetype/truetype"
 
 import (
 	"fmt"