freetype: re-organize the freetype/truetype package into smaller files.
No code changes, just a copy/paste. R=bradfitz CC=golang-dev http://codereview.appspot.com/6201052
This commit is contained in:
Nigel Tao
parent
eaa4846c62
commit
a16d1037a1
224
freetype/truetype/glyph.go
Normal file
224
freetype/truetype/glyph.go
Normal file
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@ -0,0 +1,224 @@
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// Copyright 2010 The Freetype-Go Authors. All rights reserved.
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// Use of this source code is governed by your choice of either the
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// FreeType License or the GNU General Public License version 2 (or
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// any later version), both of which can be found in the LICENSE file.
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package truetype
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// A Point is a co-ordinate pair plus whether it is ``on'' a contour or an
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// ``off'' control point.
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type Point struct {
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X, Y int16
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// The Flags' LSB means whether or not this Point is ``on'' the contour.
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// Other bits are reserved for internal use.
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Flags uint8
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}
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// A GlyphBuf holds a glyph's contours. A GlyphBuf can be re-used to load a
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// series of glyphs from a Font.
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type GlyphBuf struct {
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// The glyph's bounding box.
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B Bounds
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// Point contains all Points from all contours of the glyph.
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Point []Point
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// The length of End is the number of contours in the glyph. The i'th
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// contour consists of points Point[End[i-1]:End[i]], where End[-1]
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// is interpreted to mean zero.
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End []int
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}
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// Flags for decoding a glyph's contours. These flags are documented at
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// http://developer.apple.com/fonts/TTRefMan/RM06/Chap6glyf.html.
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const (
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flagOnCurve = 1 << iota
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flagXShortVector
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flagYShortVector
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flagRepeat
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flagPositiveXShortVector
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flagPositiveYShortVector
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)
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// The same flag bits (0x10 and 0x20) are overloaded to have two meanings,
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// dependent on the value of the flag{X,Y}ShortVector bits.
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const (
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flagThisXIsSame = flagPositiveXShortVector
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flagThisYIsSame = flagPositiveYShortVector
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)
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// decodeFlags decodes a glyph's run-length encoded flags,
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// and returns the remaining data.
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func (g *GlyphBuf) decodeFlags(d data, np0 int) data {
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for i := np0; i < len(g.Point); {
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c := d.u8()
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g.Point[i].Flags = c
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i++
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if c&flagRepeat != 0 {
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count := d.u8()
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for ; count > 0; count-- {
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g.Point[i].Flags = c
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i++
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}
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}
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}
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return d
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}
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// decodeCoords decodes a glyph's delta encoded co-ordinates.
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func (g *GlyphBuf) decodeCoords(d data, np0 int) {
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var x int16
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for i := np0; i < len(g.Point); i++ {
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f := g.Point[i].Flags
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if f&flagXShortVector != 0 {
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dx := int16(d.u8())
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if f&flagPositiveXShortVector == 0 {
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x -= dx
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} else {
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x += dx
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}
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} else if f&flagThisXIsSame == 0 {
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x += int16(d.u16())
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}
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g.Point[i].X = x
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}
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var y int16
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for i := np0; i < len(g.Point); i++ {
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f := g.Point[i].Flags
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if f&flagYShortVector != 0 {
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dy := int16(d.u8())
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if f&flagPositiveYShortVector == 0 {
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y -= dy
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} else {
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y += dy
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}
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} else if f&flagThisYIsSame == 0 {
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y += int16(d.u16())
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}
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g.Point[i].Y = y
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}
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}
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// Load loads a glyph's contours from a Font, overwriting any previously
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// loaded contours for this GlyphBuf.
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func (g *GlyphBuf) Load(f *Font, i Index) error {
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// Reset the GlyphBuf.
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g.B = Bounds{}
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g.Point = g.Point[0:0]
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g.End = g.End[0:0]
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return g.load(f, i, 0)
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}
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// loadCompound loads a glyph that is composed of other glyphs.
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func (g *GlyphBuf) loadCompound(f *Font, d data, recursion int) error {
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// Flags for decoding a compound glyph. These flags are documented at
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// http://developer.apple.com/fonts/TTRefMan/RM06/Chap6glyf.html.
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const (
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flagArg1And2AreWords = 1 << iota
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flagArgsAreXYValues
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flagRoundXYToGrid
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flagWeHaveAScale
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flagUnused
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flagMoreComponents
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flagWeHaveAnXAndYScale
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flagWeHaveATwoByTwo
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flagWeHaveInstructions
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flagUseMyMetrics
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flagOverlapCompound
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)
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for {
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flags := d.u16()
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component := d.u16()
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var dx, dy int16
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if flags&flagArg1And2AreWords != 0 {
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dx = int16(d.u16())
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dy = int16(d.u16())
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} else {
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dx = int16(int8(d.u8()))
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dy = int16(int8(d.u8()))
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}
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if flags&flagArgsAreXYValues == 0 {
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return UnsupportedError("compound glyph transform vector")
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}
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if flags&(flagWeHaveAScale|flagWeHaveAnXAndYScale|flagWeHaveATwoByTwo) != 0 {
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return UnsupportedError("compound glyph scale/transform")
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}
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b0, i0 := g.B, len(g.Point)
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g.load(f, Index(component), recursion+1)
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for i := i0; i < len(g.Point); i++ {
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g.Point[i].X += dx
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g.Point[i].Y += dy
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}
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if flags&flagUseMyMetrics == 0 {
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g.B = b0
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}
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if flags&flagMoreComponents == 0 {
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break
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}
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}
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return nil
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}
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// load appends a glyph's contours to this GlyphBuf.
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func (g *GlyphBuf) load(f *Font, i Index, recursion int) error {
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if recursion >= 4 {
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return UnsupportedError("excessive compound glyph recursion")
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}
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// Find the relevant slice of f.glyf.
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var g0, g1 uint32
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if f.locaOffsetFormat == locaOffsetFormatShort {
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d := data(f.loca[2*int(i):])
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g0 = 2 * uint32(d.u16())
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g1 = 2 * uint32(d.u16())
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} else {
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d := data(f.loca[4*int(i):])
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g0 = d.u32()
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g1 = d.u32()
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}
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if g0 == g1 {
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return nil
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}
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d := data(f.glyf[g0:g1])
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// Decode the contour end indices.
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ne := int(int16(d.u16()))
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g.B.XMin = int16(d.u16())
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g.B.YMin = int16(d.u16())
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g.B.XMax = int16(d.u16())
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g.B.YMax = int16(d.u16())
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if ne == -1 {
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return g.loadCompound(f, d, recursion)
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} else if ne < 0 {
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// http://developer.apple.com/fonts/TTRefMan/RM06/Chap6glyf.html says that
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// "the values -2, -3, and so forth, are reserved for future use."
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return UnsupportedError("negative number of contours")
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}
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ne0, np0 := len(g.End), len(g.Point)
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ne += ne0
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if ne <= cap(g.End) {
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g.End = g.End[0:ne]
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} else {
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g.End = make([]int, ne, ne*2)
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}
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for i := ne0; i < ne; i++ {
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g.End[i] = 1 + np0 + int(d.u16())
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}
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// Skip the TrueType hinting instructions.
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instrLen := int(d.u16())
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d.skip(instrLen)
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// Decode the points.
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np := int(g.End[ne-1])
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if np <= cap(g.Point) {
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g.Point = g.Point[0:np]
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} else {
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g.Point = make([]Point, np, np*2)
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}
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d = g.decodeFlags(d, np0)
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g.decodeCoords(d, np0)
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return nil
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}
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// NewGlyphBuf returns a newly allocated GlyphBuf.
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func NewGlyphBuf() *GlyphBuf {
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g := new(GlyphBuf)
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g.Point = make([]Point, 0, 256)
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g.End = make([]int, 0, 32)
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return g
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}
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@ -448,221 +448,3 @@ func parse(ttf []byte, offset int) (font *Font, err error) {
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font = f
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return
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}
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// A Point is a co-ordinate pair plus whether it is ``on'' a contour or an
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// ``off'' control point.
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type Point struct {
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X, Y int16
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// The Flags' LSB means whether or not this Point is ``on'' the contour.
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// Other bits are reserved for internal use.
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Flags uint8
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}
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// A GlyphBuf holds a glyph's contours. A GlyphBuf can be re-used to load a
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// series of glyphs from a Font.
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type GlyphBuf struct {
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// The glyph's bounding box.
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B Bounds
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// Point contains all Points from all contours of the glyph.
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Point []Point
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// The length of End is the number of contours in the glyph. The i'th
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// contour consists of points Point[End[i-1]:End[i]], where End[-1]
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// is interpreted to mean zero.
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End []int
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}
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// Flags for decoding a glyph's contours. These flags are documented at
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// http://developer.apple.com/fonts/TTRefMan/RM06/Chap6glyf.html.
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const (
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flagOnCurve = 1 << iota
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flagXShortVector
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flagYShortVector
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flagRepeat
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flagPositiveXShortVector
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flagPositiveYShortVector
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)
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// The same flag bits (0x10 and 0x20) are overloaded to have two meanings,
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// dependent on the value of the flag{X,Y}ShortVector bits.
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const (
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flagThisXIsSame = flagPositiveXShortVector
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flagThisYIsSame = flagPositiveYShortVector
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)
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// decodeFlags decodes a glyph's run-length encoded flags,
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// and returns the remaining data.
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func (g *GlyphBuf) decodeFlags(d data, np0 int) data {
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for i := np0; i < len(g.Point); {
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c := d.u8()
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g.Point[i].Flags = c
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i++
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if c&flagRepeat != 0 {
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count := d.u8()
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for ; count > 0; count-- {
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g.Point[i].Flags = c
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i++
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}
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}
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}
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return d
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}
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// decodeCoords decodes a glyph's delta encoded co-ordinates.
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func (g *GlyphBuf) decodeCoords(d data, np0 int) {
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var x int16
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for i := np0; i < len(g.Point); i++ {
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f := g.Point[i].Flags
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if f&flagXShortVector != 0 {
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dx := int16(d.u8())
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if f&flagPositiveXShortVector == 0 {
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x -= dx
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} else {
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x += dx
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}
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} else if f&flagThisXIsSame == 0 {
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x += int16(d.u16())
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}
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g.Point[i].X = x
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}
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var y int16
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for i := np0; i < len(g.Point); i++ {
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f := g.Point[i].Flags
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if f&flagYShortVector != 0 {
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dy := int16(d.u8())
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if f&flagPositiveYShortVector == 0 {
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y -= dy
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} else {
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y += dy
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}
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} else if f&flagThisYIsSame == 0 {
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y += int16(d.u16())
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}
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g.Point[i].Y = y
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}
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}
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// Load loads a glyph's contours from a Font, overwriting any previously
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// loaded contours for this GlyphBuf.
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func (g *GlyphBuf) Load(f *Font, i Index) error {
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// Reset the GlyphBuf.
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g.B = Bounds{}
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g.Point = g.Point[0:0]
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g.End = g.End[0:0]
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return g.load(f, i, 0)
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}
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// loadCompound loads a glyph that is composed of other glyphs.
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func (g *GlyphBuf) loadCompound(f *Font, d data, recursion int) error {
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// Flags for decoding a compound glyph. These flags are documented at
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// http://developer.apple.com/fonts/TTRefMan/RM06/Chap6glyf.html.
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const (
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flagArg1And2AreWords = 1 << iota
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flagArgsAreXYValues
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flagRoundXYToGrid
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flagWeHaveAScale
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flagUnused
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flagMoreComponents
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flagWeHaveAnXAndYScale
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flagWeHaveATwoByTwo
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flagWeHaveInstructions
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flagUseMyMetrics
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flagOverlapCompound
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)
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for {
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flags := d.u16()
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component := d.u16()
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var dx, dy int16
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if flags&flagArg1And2AreWords != 0 {
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dx = int16(d.u16())
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dy = int16(d.u16())
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} else {
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dx = int16(int8(d.u8()))
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dy = int16(int8(d.u8()))
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}
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if flags&flagArgsAreXYValues == 0 {
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return UnsupportedError("compound glyph transform vector")
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}
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if flags&(flagWeHaveAScale|flagWeHaveAnXAndYScale|flagWeHaveATwoByTwo) != 0 {
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return UnsupportedError("compound glyph scale/transform")
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}
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b0, i0 := g.B, len(g.Point)
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g.load(f, Index(component), recursion+1)
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for i := i0; i < len(g.Point); i++ {
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g.Point[i].X += dx
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g.Point[i].Y += dy
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}
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if flags&flagUseMyMetrics == 0 {
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g.B = b0
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}
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if flags&flagMoreComponents == 0 {
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break
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}
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}
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return nil
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}
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// load appends a glyph's contours to this GlyphBuf.
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func (g *GlyphBuf) load(f *Font, i Index, recursion int) error {
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if recursion >= 4 {
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return UnsupportedError("excessive compound glyph recursion")
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}
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// Find the relevant slice of f.glyf.
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var g0, g1 uint32
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if f.locaOffsetFormat == locaOffsetFormatShort {
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d := data(f.loca[2*int(i):])
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g0 = 2 * uint32(d.u16())
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g1 = 2 * uint32(d.u16())
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} else {
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d := data(f.loca[4*int(i):])
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g0 = d.u32()
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g1 = d.u32()
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}
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if g0 == g1 {
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return nil
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}
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d := data(f.glyf[g0:g1])
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// Decode the contour end indices.
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ne := int(int16(d.u16()))
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g.B.XMin = int16(d.u16())
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g.B.YMin = int16(d.u16())
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g.B.XMax = int16(d.u16())
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g.B.YMax = int16(d.u16())
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if ne == -1 {
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return g.loadCompound(f, d, recursion)
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} else if ne < 0 {
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// http://developer.apple.com/fonts/TTRefMan/RM06/Chap6glyf.html says that
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// "the values -2, -3, and so forth, are reserved for future use."
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return UnsupportedError("negative number of contours")
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}
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ne0, np0 := len(g.End), len(g.Point)
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ne += ne0
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if ne <= cap(g.End) {
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g.End = g.End[0:ne]
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} else {
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g.End = make([]int, ne, ne*2)
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}
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for i := ne0; i < ne; i++ {
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g.End[i] = 1 + np0 + int(d.u16())
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}
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// Skip the TrueType hinting instructions.
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instrLen := int(d.u16())
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d.skip(instrLen)
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// Decode the points.
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np := int(g.End[ne-1])
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if np <= cap(g.Point) {
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g.Point = g.Point[0:np]
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} else {
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g.Point = make([]Point, np, np*2)
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}
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d = g.decodeFlags(d, np0)
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g.decodeCoords(d, np0)
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return nil
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}
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// NewGlyphBuf returns a newly allocated GlyphBuf.
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func NewGlyphBuf() *GlyphBuf {
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g := new(GlyphBuf)
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g.Point = make([]Point, 0, 256)
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g.End = make([]int, 0, 32)
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return g
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}
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