freetype/truetype: set the four phantom points, and adjust the glyph
points accordingly. Yes, it's a mess, but let's pass the tests first, and then refactor. R=bsiegert CC=golang-dev https://codereview.appspot.com/14419052
This commit is contained in:
Nigel Tao
parent
b76427be47
commit
ba07cbfbc8
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@ -55,8 +55,8 @@ const (
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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 []byte, offset int, np0 int) (offset1 int) {
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for i := np0; i < len(g.Point); {
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func (g *GlyphBuf) decodeFlags(d []byte, offset int, np0, np int) (offset1 int) {
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for i := np0; i < np; {
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c := uint32(d[offset])
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offset++
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g.Point[i].Flags = c
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@ -74,9 +74,9 @@ func (g *GlyphBuf) decodeFlags(d []byte, offset int, np0 int) (offset1 int) {
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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 []byte, offset int, np0 int) int {
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func (g *GlyphBuf) decodeCoords(d []byte, offset int, np0, np int) int {
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var x int16
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for i := np0; i < len(g.Point); i++ {
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for i := np0; i < np; 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[offset])
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@ -93,7 +93,7 @@ func (g *GlyphBuf) decodeCoords(d []byte, offset int, np0 int) int {
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g.Point[i].X = int32(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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for i := np0; i < np; 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[offset])
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@ -128,7 +128,7 @@ func (g *GlyphBuf) Load(f *Font, scale int32, i Index, h *Hinter) error {
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return err
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}
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}
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if err := g.load(f, scale, i, h, 0, 0, false, 0); err != nil {
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if _, err := g.load(f, scale, i, h, 0, 0, false, 0); err != nil {
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return err
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}
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g.B.XMin = f.scale(scale * g.B.XMin)
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@ -138,9 +138,16 @@ func (g *GlyphBuf) Load(f *Font, scale int32, i Index, h *Hinter) error {
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return nil
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}
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// TODO: all these extra parameters and return values for loadCompound and load
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// are awkward. We should clean this up once all the tests pass, when we can
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// refactor with confidence that we don't break anything.
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// loadCompound loads a glyph that is composed of other glyphs.
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//
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// metricsOverride is whether the sub-glyph overrides the super-glyph's
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// metrics. pp1x is the x co-ordinate of the 1st phantom point.
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func (g *GlyphBuf) loadCompound(f *Font, scale int32, h *Hinter, glyf []byte, offset int,
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dx, dy int32, recursion int) error {
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dx, dy int32, recursion int) (metricsOverride bool, pp1x int32, offset1 int, err 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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@ -171,29 +178,37 @@ func (g *GlyphBuf) loadCompound(f *Font, scale int32, h *Hinter, glyf []byte, of
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offset += 6
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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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return false, 0, 0, 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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return false, 0, 0, UnsupportedError("compound glyph scale/transform")
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}
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b0 := g.B
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g.load(f, scale, component, h, dx1, dy1, flags&flagRoundXYToGrid != 0, recursion+1)
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if flags&flagUseMyMetrics == 0 {
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g.B = b0
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b := g.B
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subPP1x, err := g.load(f, scale, component, h,
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dx1, dy1, flags&flagRoundXYToGrid != 0, recursion+1)
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if err != nil {
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return false, 0, 0, err
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}
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if flags&flagUseMyMetrics != 0 {
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metricsOverride, pp1x = true, subPP1x
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} else {
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g.B = b
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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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return metricsOverride, pp1x, offset, nil
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}
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// load appends a glyph's contours to this GlyphBuf.
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//
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// pp1x is the x co-ordinate of the 1st phantom point.
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func (g *GlyphBuf) load(f *Font, scale int32, i Index, h *Hinter,
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dx, dy int32, roundDxDy bool, recursion int) error {
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dx, dy int32, roundDxDy bool, recursion int) (pp1x int32, err error) {
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if recursion >= 4 {
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return UnsupportedError("excessive compound glyph recursion")
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return 0, 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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@ -205,79 +220,123 @@ func (g *GlyphBuf) load(f *Font, scale int32, i Index, h *Hinter,
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g1 = u32(f.loca, 4*int(i)+4)
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}
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if g0 == g1 {
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return nil
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return 0, nil
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}
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glyf := f.glyf[g0:g1]
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// Decode the contour end indices.
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ne := int(int16(u16(glyf, 0)))
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g.B.XMin = int32(int16(u16(glyf, 2)))
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g.B.YMin = int32(int16(u16(glyf, 4)))
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g.B.XMax = int32(int16(u16(glyf, 6)))
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g.B.YMax = int32(int16(u16(glyf, 8)))
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b := Bounds{
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XMin: int32(int16(u16(glyf, 2))),
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YMin: int32(int16(u16(glyf, 4))),
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XMax: int32(int16(u16(glyf, 6))),
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YMax: int32(int16(u16(glyf, 8))),
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}
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offset := 10
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if ne == -1 {
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return g.loadCompound(f, scale, h, glyf, offset, dx, dy, 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[:ne]
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ne0, np0, np, metricsOverride, program := len(g.End), 0, 0, false, []byte(nil)
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if ne < 0 {
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if ne != -1 {
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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 0, UnsupportedError("negative number of contours")
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}
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var subPP1x int32
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metricsOverride, subPP1x, offset, err =
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g.loadCompound(f, scale, h, glyf, offset, dx, dy, recursion)
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if err != nil {
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return 0, err
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}
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if metricsOverride {
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pp1x = subPP1x
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}
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ne = ne0
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np0 = len(g.Point)
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np = np0
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// TODO: find the program, if present, for a compound glyph.
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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 + int(u16(glyf, offset))
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ne += ne0
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if ne <= cap(g.End) {
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g.End = g.End[: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 + int(u16(glyf, offset))
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offset += 2
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}
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np0 = len(g.Point)
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np = np0 + int(g.End[ne-1])
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// Note the TrueType hinting instructions.
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instrLen := int(u16(glyf, offset))
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offset += 2
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program = glyf[offset : offset+instrLen]
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offset += instrLen
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}
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// Note the TrueType hinting instructions.
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instrLen := int(u16(glyf, offset))
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offset += 2
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program := glyf[offset : offset+instrLen]
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offset += instrLen
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// Decode the points.
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np := int(g.End[ne-1]) + np0
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if np <= cap(g.Point) {
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g.Point = g.Point[:np]
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// Decode the points, including room for the phantom points.
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const nPhantomPoints = 4
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if np+nPhantomPoints <= cap(g.Point) {
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g.Point = g.Point[:np+nPhantomPoints]
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} else {
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p := g.Point
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g.Point = make([]Point, np, np*2)
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g.Point = make([]Point, np+nPhantomPoints, (np+nPhantomPoints)*2)
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copy(g.Point, p)
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}
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offset = g.decodeFlags(glyf, offset, np0)
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g.decodeCoords(glyf, offset, np0)
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offset = g.decodeFlags(glyf, offset, np0, np)
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g.decodeCoords(glyf, offset, np0, np)
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// Set the four phantom points. Freetype-Go uses only the first two,
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// but the hinting bytecode may expect four.
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g.B = b
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uhm := f.unscaledHMetric(i)
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g.Point[np+0] = Point{X: b.XMin - uhm.LeftSideBearing}
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g.Point[np+1] = Point{X: b.XMin - uhm.LeftSideBearing + uhm.AdvanceWidth}
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g.Point[np+2] = Point{}
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g.Point[np+3] = Point{}
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// Delta-adjust, scale and hint.
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if h != nil {
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g.InFontUnits = append(g.InFontUnits, g.Point[np0:np]...)
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for i := np0; i < np; i++ {
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g.InFontUnits = append(g.InFontUnits, g.Point[np0:np+nPhantomPoints]...)
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for i := np0; i < np+nPhantomPoints; i++ {
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g.InFontUnits[i].X += dx
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g.InFontUnits[i].Y += dy
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}
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}
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scaledDx := int32(0)
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if roundDxDy {
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dx = (f.scale(scale*dx) + 32) &^ 63
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dy = (f.scale(scale*dy) + 32) &^ 63
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for i := np0; i < np; i++ {
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for i := np0; i < np+nPhantomPoints; i++ {
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g.Point[i].X = dx + f.scale(scale*g.Point[i].X)
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g.Point[i].Y = dy + f.scale(scale*g.Point[i].Y)
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}
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scaledDx = dx
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} else {
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for i := np0; i < np; i++ {
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for i := np0; i < np+nPhantomPoints; i++ {
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g.Point[i].X = f.scale(scale * (g.Point[i].X + dx))
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g.Point[i].Y = f.scale(scale * (g.Point[i].Y + dy))
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}
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scaledDx = f.scale(scale * dx)
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}
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if h != nil {
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g.Unhinted = append(g.Unhinted, g.Point[np0:np]...)
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err := h.run(program, g.Point[np0:], g.Unhinted[np0:], g.InFontUnits[np0:], g.End[ne0:])
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if err != nil {
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return err
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g.Unhinted = append(g.Unhinted, g.Point[np0:np+nPhantomPoints]...)
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if program != nil {
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err := h.run(program, g.Point[np0:], g.Unhinted[np0:], g.InFontUnits[np0:], g.End[ne0:])
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if err != nil {
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return 0, err
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}
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}
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g.Unhinted = g.Unhinted[:np]
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g.InFontUnits = g.InFontUnits[:np]
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}
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if !metricsOverride {
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pp1x = g.Point[np].X - scaledDx
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}
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g.Point = g.Point[:np]
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if recursion == 0 && pp1x != 0 {
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for i := range g.Point {
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g.Point[i].X -= pp1x
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}
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}
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@ -288,7 +347,7 @@ func (g *GlyphBuf) load(f *Font, scale int32, i Index, h *Hinter,
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g.End[i] += np0
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}
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return nil
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return pp1x, nil
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}
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// NewGlyphBuf returns a newly allocated GlyphBuf.
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@ -96,9 +96,7 @@ var globalDefaultGS = graphicsState{
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}
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func resetTwilightPoints(f *Font, p []Point) []Point {
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// TODO: the C Freetype code uses n+4 for the 4 phantom points, but a
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// comment there says "(do we need this?)". Do we need to use n+4 here?
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if n := int(f.maxTwilightPoints); n <= cap(p) {
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if n := int(f.maxTwilightPoints) + 4; n <= cap(p) {
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p = p[:n]
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for i := range p {
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p[i] = Point{}
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@ -310,20 +310,29 @@ func (f *Font) Index(x rune) Index {
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return 0
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}
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// HMetric returns the horizontal metrics for the glyph with the given index.
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func (f *Font) HMetric(scale int32, i Index) (h HMetric) {
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// unscaledHMetric returns the unscaled horizontal metrics for the glyph with
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// the given index.
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func (f *Font) unscaledHMetric(i Index) (h HMetric) {
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j := int(i)
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if j >= f.nGlyph {
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return HMetric{}
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}
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if j >= f.nHMetric {
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p := 4 * (f.nHMetric - 1)
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h.AdvanceWidth = int32(u16(f.hmtx, p))
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h.LeftSideBearing = int32(int16(u16(f.hmtx, p+2*(j-f.nHMetric)+4)))
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} else {
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h.AdvanceWidth = int32(u16(f.hmtx, 4*j))
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h.LeftSideBearing = int32(int16(u16(f.hmtx, 4*j+2)))
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return HMetric{
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AdvanceWidth: int32(u16(f.hmtx, p)),
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LeftSideBearing: int32(int16(u16(f.hmtx, p+2*(j-f.nHMetric)+4))),
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}
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}
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return HMetric{
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AdvanceWidth: int32(u16(f.hmtx, 4*j)),
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LeftSideBearing: int32(int16(u16(f.hmtx, 4*j+2))),
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}
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}
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// HMetric returns the horizontal metrics for the glyph with the given index.
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func (f *Font) HMetric(scale int32, i Index) HMetric {
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h := f.unscaledHMetric(i)
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h.AdvanceWidth = f.scale(scale * h.AdvanceWidth)
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h.LeftSideBearing = f.scale(scale * h.LeftSideBearing)
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return h
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@ -85,10 +85,9 @@ var scalingTestCases = []struct {
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{"luxisr", 12, -1},
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// TODO: uncomment the fonts below, once they get past Parse and
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// GlyphBuf.Load, and the unhinted values match C Freetype.
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//{"x-arial-bold", 11, 0},
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{"x-arial-bold", 11, 0},
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//{"x-deja-vu-sans-oblique", 17, 0},
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//{"x-droid-sans-japanese", 9, 0},
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//{"x-inconsolata", 10, 0},
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//{"x-times-new-roman", 13, 0},
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}
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