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This commit is contained in:
Laurent Le Goff 2015-04-30 18:06:25 +02:00
parent f6e1ada0f2
commit b14683a552
2 changed files with 81 additions and 45 deletions
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46
draw2dimg/ftgc.go
View file

@ -113,53 +113,9 @@ func (gc *GraphicContext) loadCurrentFont() (*truetype.Font, error) {
return font, nil
}
func fUnitsToFloat64(x int32) float64 {
scaled := x << 2
return float64(scaled/256) + float64(scaled%256)/256.0
}
// p is a truetype.Point measured in FUnits and positive Y going upwards.
// The returned value is the same thing measured in floating point and positive Y
// going downwards.
func pointToF64Point(p truetype.Point) (x, y float64) {
return fUnitsToFloat64(p.X), -fUnitsToFloat64(p.Y)
}
// drawContour draws the given closed contour at the given sub-pixel offset.
func (gc *GraphicContext) drawContour(ps []truetype.Point, dx, dy float64) {
if len(ps) == 0 {
return
}
startX, startY := pointToF64Point(ps[0])
gc.MoveTo(startX+dx, startY+dy)
q0X, q0Y, on0 := startX, startY, true
for _, p := range ps[1:] {
qX, qY := pointToF64Point(p)
on := p.Flags&0x01 != 0
if on {
if on0 {
gc.LineTo(qX+dx, qY+dy)
} else {
gc.QuadCurveTo(q0X+dx, q0Y+dy, qX+dx, qY+dy)
}
} else {
if on0 {
// No-op.
} else {
midX := (q0X + qX) / 2
midY := (q0Y + qY) / 2
gc.QuadCurveTo(q0X+dx, q0Y+dy, midX+dx, midY+dy)
}
}
q0X, q0Y, on0 = qX, qY, on
}
// Close the curve.
if on0 {
gc.LineTo(startX+dx, startY+dy)
} else {
gc.QuadCurveTo(q0X+dx, q0Y+dy, startX+dx, startY+dy)
}
}
func (gc *GraphicContext) drawGlyph(glyph truetype.Index, dx, dy float64) error {
if err := gc.glyphBuf.Load(gc.Current.Font, gc.Current.Scale, glyph, truetype.NoHinting); err != nil {
@ -167,7 +123,7 @@ func (gc *GraphicContext) drawGlyph(glyph truetype.Index, dx, dy float64) error
}
e0 := 0
for _, e1 := range gc.glyphBuf.End {
gc.drawContour(gc.glyphBuf.Point[e0:e1], dx, dy)
DrawContour(gc, gc.glyphBuf.Point[e0:e1], dx, dy)
e0 = e1
}
return nil

80
draw2dimg/text.go Normal file
View file

@ -0,0 +1,80 @@
package draw2dimg
import (
"code.google.com/p/freetype-go/freetype/truetype"
"github.com/llgcode/draw2d"
)
// drawContour draws the given closed contour at the given sub-pixel offset.
func DrawContour(path draw2d.PathBuilder, ps []truetype.Point, dx, dy float64) {
if len(ps) == 0 {
return
}
startX, startY := pointToF64Point(ps[0])
path.MoveTo(startX+dx, startY+dy)
q0X, q0Y, on0 := startX, startY, true
for _, p := range ps[1:] {
qX, qY := pointToF64Point(p)
on := p.Flags&0x01 != 0
if on {
if on0 {
path.LineTo(qX+dx, qY+dy)
} else {
path.QuadCurveTo(q0X+dx, q0Y+dy, qX+dx, qY+dy)
}
} else {
if on0 {
// No-op.
} else {
midX := (q0X + qX) / 2
midY := (q0Y + qY) / 2
path.QuadCurveTo(q0X+dx, q0Y+dy, midX+dx, midY+dy)
}
}
q0X, q0Y, on0 = qX, qY, on
}
// Close the curve.
if on0 {
path.LineTo(startX+dx, startY+dy)
} else {
path.QuadCurveTo(q0X+dx, q0Y+dy, startX+dx, startY+dy)
}
}
func pointToF64Point(p truetype.Point) (x, y float64) {
return fUnitsToFloat64(p.X), -fUnitsToFloat64(p.Y)
}
func fUnitsToFloat64(x int32) float64 {
scaled := x << 2
return float64(scaled/256) + float64(scaled%256)/256.0
}
// FontExtents contains font metric information.
type FontExtents struct {
// Ascent is the distance that the text
// extends above the baseline.
Ascent float64
// Descent is the distance that the text
// extends below the baseline. The descent
// is given as a negative value.
Descent float64
// Height is the distance from the lowest
// descending point to the highest ascending
// point.
Height float64
}
// TODO needs to read this https://developer.apple.com/fonts/TrueType-Reference-Manual/RM02/Chap2.html#intro
// Extents returns the FontExtents for a font.
func Extents(font *truetype.Font, size float64) FontExtents {
bounds := font.Bounds(font.FUnitsPerEm())
scale := size / float64(font.FUnitsPerEm())
return FontExtents{
Ascent: float64(bounds.YMax) * scale,
Descent: float64(bounds.YMin) * scale,
Height: float64(bounds.YMax-bounds.YMin) * scale,
}
}