a3c53fdc3f
We can now hint the .notdef glyph from luxisr.ttf. Yay. R=bsiegert CC=golang-dev https://codereview.appspot.com/12829048
929 lines
22 KiB
Go
929 lines
22 KiB
Go
// Copyright 2012 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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// This file implements a Truetype bytecode interpreter.
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// The opcodes are described at https://developer.apple.com/fonts/TTRefMan/RM05/Chap5.html
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import (
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"errors"
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)
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// callStackEntry is a bytecode call stack entry.
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type callStackEntry struct {
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program []byte
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pc int
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loopCount int32
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}
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// Hinter implements bytecode hinting. Pass a Hinter to GlyphBuf.Load to hint
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// the resulting glyph. A Hinter can be re-used to hint a series of glyphs from
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// a Font.
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type Hinter struct {
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stack, store []int32
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// functions is a map from function number to bytecode.
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functions map[int32][]byte
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// g, font and scale are the glyph buffer, font and scale last used for
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// this Hinter. Changing the font will require running the new font's
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// fpgm bytecode. Changing either will require running the font's prep
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// bytecode.
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g *GlyphBuf
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font *Font
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scale int32
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// gs and defaultGS are the current and default graphics state. The
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// default graphics state is the global default graphics state after
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// the font's fpgm and prep programs have been run.
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gs, defaultGS graphicsState
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}
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// graphicsState is described at https://developer.apple.com/fonts/TTRefMan/RM04/Chap4.html
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type graphicsState struct {
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// Projection vector, freedom vector and dual projection vector.
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pv, fv, dv [2]f2dot14
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// Reference points and zone pointers.
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rp, zp [3]int32
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// Control Value / Single Width Cut-In.
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controlValueCutIn, singleWidthCutIn, singleWidth f26dot6
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// Delta base / shift.
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deltaBase, deltaShift int32
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// Minimum distance.
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minDist f26dot6
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// Loop count.
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loop int32
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// Rounding policy.
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roundPeriod, roundPhase, roundThreshold f26dot6
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// Auto-flip.
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autoFlip bool
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}
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var globalDefaultGS = graphicsState{
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pv: [2]f2dot14{0x4000, 0}, // Unit vector along the X axis.
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fv: [2]f2dot14{0x4000, 0},
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dv: [2]f2dot14{0x4000, 0},
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zp: [3]int32{1, 1, 1},
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controlValueCutIn: (17 << 6) / 16, // 17/16 as an f26dot6.
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deltaBase: 9,
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deltaShift: 3,
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minDist: 1 << 6, // 1 as an f26dot6.
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loop: 1,
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roundPeriod: 1 << 6, // 1 as an f26dot6.
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roundThreshold: 1 << 5, // 1/2 as an f26dot6.
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autoFlip: true,
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}
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func (h *Hinter) init(g *GlyphBuf, f *Font, scale int32) error {
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h.g = g
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rescale := h.scale != scale
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if h.font != f {
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h.font, rescale = f, true
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if h.functions == nil {
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h.functions = make(map[int32][]byte)
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} else {
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for k := range h.functions {
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delete(h.functions, k)
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}
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}
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if x := int(f.maxStackElements); x > len(h.stack) {
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x += 255
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x &^= 255
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h.stack = make([]int32, x)
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}
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if x := int(f.maxStorage); x > len(h.store) {
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x += 15
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x &^= 15
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h.store = make([]int32, x)
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}
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if len(f.fpgm) != 0 {
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if err := h.run(f.fpgm); err != nil {
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return err
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}
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}
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}
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if rescale {
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h.scale = scale
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h.defaultGS = globalDefaultGS
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if len(f.prep) != 0 {
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if err := h.run(f.prep); err != nil {
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return err
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}
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h.defaultGS = h.gs
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// The MS rasterizer doesn't allow the following graphics state
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// variables to be modified by the CVT program.
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h.defaultGS.pv = globalDefaultGS.pv
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h.defaultGS.fv = globalDefaultGS.fv
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h.defaultGS.dv = globalDefaultGS.dv
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h.defaultGS.rp = globalDefaultGS.rp
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h.defaultGS.zp = globalDefaultGS.zp
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h.defaultGS.loop = globalDefaultGS.loop
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}
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}
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return nil
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}
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func (h *Hinter) run(program []byte) error {
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h.gs = h.defaultGS
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if len(program) > 50000 {
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return errors.New("truetype: hinting: too many instructions")
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}
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var (
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steps, pc, top int
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opcode uint8
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callStack [32]callStackEntry
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callStackTop int
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)
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for 0 <= pc && pc < len(program) {
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steps++
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if steps == 100000 {
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return errors.New("truetype: hinting: too many steps")
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}
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opcode = program[pc]
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if popCount[opcode] == q {
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return errors.New("truetype: hinting: unimplemented instruction")
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}
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if top < int(popCount[opcode]) {
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return errors.New("truetype: hinting: stack underflow")
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}
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switch opcode {
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case opSVTCA0:
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h.gs.pv = [2]f2dot14{0, 0x4000}
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h.gs.fv = [2]f2dot14{0, 0x4000}
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h.gs.dv = [2]f2dot14{0, 0x4000}
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case opSVTCA1:
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h.gs.pv = [2]f2dot14{0x4000, 0}
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h.gs.fv = [2]f2dot14{0x4000, 0}
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h.gs.dv = [2]f2dot14{0x4000, 0}
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case opSPVTCA0:
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h.gs.pv = [2]f2dot14{0, 0x4000}
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h.gs.dv = [2]f2dot14{0, 0x4000}
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case opSPVTCA1:
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h.gs.pv = [2]f2dot14{0x4000, 0}
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h.gs.dv = [2]f2dot14{0x4000, 0}
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case opSFVTCA0:
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h.gs.fv = [2]f2dot14{0, 0x4000}
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case opSFVTCA1:
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h.gs.fv = [2]f2dot14{0x4000, 0}
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case opSPVFS:
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top -= 2
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h.gs.pv[0] = f2dot14(h.stack[top+0])
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h.gs.pv[1] = f2dot14(h.stack[top+1])
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// TODO: normalize h.gs.pv ??
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// TODO: h.gs.dv = h.gs.pv ??
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case opSFVFS:
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top -= 2
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h.gs.fv[0] = f2dot14(h.stack[top+0])
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h.gs.fv[1] = f2dot14(h.stack[top+1])
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// TODO: normalize h.gs.fv ??
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case opGPV:
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if top+1 >= len(h.stack) {
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return errors.New("truetype: hinting: stack overflow")
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}
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h.stack[top+0] = int32(h.gs.pv[0])
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h.stack[top+1] = int32(h.gs.pv[1])
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top += 2
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case opGFV:
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if top+1 >= len(h.stack) {
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return errors.New("truetype: hinting: stack overflow")
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}
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h.stack[top+0] = int32(h.gs.fv[0])
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h.stack[top+1] = int32(h.gs.fv[1])
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top += 2
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case opSFVTPV:
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h.gs.fv = h.gs.pv
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case opSRP0, opSRP1, opSRP2:
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top--
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h.gs.rp[opcode-opSRP0] = h.stack[top]
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case opSZP0, opSZP1, opSZP2:
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top--
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h.gs.zp[opcode-opSZP0] = h.stack[top]
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case opSZPS:
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top--
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h.gs.zp[0] = h.stack[top]
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h.gs.zp[1] = h.stack[top]
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h.gs.zp[2] = h.stack[top]
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case opSLOOP:
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top--
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if h.stack[top] <= 0 {
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return errors.New("truetype: hinting: invalid data")
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}
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h.gs.loop = h.stack[top]
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case opRTG:
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h.gs.roundPeriod = 1 << 6
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h.gs.roundPhase = 0
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h.gs.roundThreshold = 1 << 5
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case opRTHG:
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h.gs.roundPeriod = 1 << 6
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h.gs.roundPhase = 1 << 5
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h.gs.roundThreshold = 1 << 5
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case opSMD:
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top--
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h.gs.minDist = f26dot6(h.stack[top])
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case opELSE:
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opcode = 1
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goto ifelse
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case opJMPR:
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top--
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pc += int(h.stack[top])
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continue
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case opSCVTCI:
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top--
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h.gs.controlValueCutIn = f26dot6(h.stack[top])
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case opSSWCI:
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top--
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h.gs.singleWidthCutIn = f26dot6(h.stack[top])
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case opSSW:
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top--
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h.gs.singleWidth = f26dot6(h.stack[top])
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case opDUP:
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if top >= len(h.stack) {
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return errors.New("truetype: hinting: stack overflow")
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}
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h.stack[top] = h.stack[top-1]
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top++
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case opPOP:
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top--
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case opCLEAR:
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top = 0
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case opSWAP:
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h.stack[top-1], h.stack[top-2] = h.stack[top-2], h.stack[top-1]
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case opDEPTH:
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if top >= len(h.stack) {
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return errors.New("truetype: hinting: stack overflow")
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}
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h.stack[top] = int32(top)
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top++
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case opCINDEX, opMINDEX:
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x := int(h.stack[top-1])
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if x <= 0 || x >= top {
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return errors.New("truetype: hinting: invalid data")
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}
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h.stack[top-1] = h.stack[top-1-x]
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if opcode == opMINDEX {
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copy(h.stack[top-1-x:top-1], h.stack[top-x:top])
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top--
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}
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case opLOOPCALL, opCALL:
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if callStackTop >= len(callStack) {
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return errors.New("truetype: hinting: call stack overflow")
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}
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top--
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f, ok := h.functions[h.stack[top]]
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if !ok {
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return errors.New("truetype: hinting: undefined function")
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}
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callStack[callStackTop] = callStackEntry{program, pc, 1}
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if opcode == opLOOPCALL {
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top--
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if h.stack[top] == 0 {
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break
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}
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callStack[callStackTop].loopCount = h.stack[top]
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}
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callStackTop++
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program, pc = f, 0
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continue
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case opFDEF:
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// Save all bytecode up until the next ENDF.
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startPC := pc + 1
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fdefloop:
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for {
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pc++
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if pc >= len(program) {
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return errors.New("truetype: hinting: unbalanced FDEF")
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}
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switch program[pc] {
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case opFDEF:
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return errors.New("truetype: hinting: nested FDEF")
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case opENDF:
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top--
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h.functions[h.stack[top]] = program[startPC : pc+1]
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break fdefloop
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default:
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var ok bool
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pc, ok = skipInstructionPayload(program, pc)
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if !ok {
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return errors.New("truetype: hinting: unbalanced FDEF")
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}
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}
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}
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case opENDF:
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if callStackTop == 0 {
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return errors.New("truetype: hinting: call stack underflow")
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}
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callStackTop--
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callStack[callStackTop].loopCount--
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if callStack[callStackTop].loopCount != 0 {
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callStackTop++
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pc = 0
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continue
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}
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program, pc = callStack[callStackTop].program, callStack[callStackTop].pc
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case opMDAP0, opMDAP1:
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points := h.g.points(h.gs.zp[0])
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top--
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i := int(h.stack[top])
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if i < 0 || len(points) <= i {
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return errors.New("truetype: hinting: point out of range")
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}
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p := &points[i]
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distance := f26dot6(0)
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if opcode == opMDAP1 {
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distance = dotProduct(f26dot6(p.X), f26dot6(p.Y), h.gs.pv)
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// TODO: metrics compensation.
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distance = h.round(distance) - distance
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}
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h.move(p, distance)
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h.gs.rp[0] = int32(i)
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h.gs.rp[1] = int32(i)
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case opALIGNRP:
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if top < int(h.gs.loop) {
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return errors.New("truetype: hinting: stack underflow")
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}
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i, points := int(h.gs.rp[0]), h.g.points(h.gs.zp[0])
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if i < 0 || len(points) <= i {
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return errors.New("truetype: hinting: point out of range")
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}
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ref := &points[i]
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points = h.g.points(h.gs.zp[1])
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for ; h.gs.loop != 0; h.gs.loop-- {
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top--
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i = int(h.stack[top])
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if i < 0 || len(points) <= i {
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return errors.New("truetype: hinting: point out of range")
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}
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p := &points[i]
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h.move(p, -dotProduct(f26dot6(p.X-ref.X), f26dot6(p.Y-ref.Y), h.gs.pv))
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}
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h.gs.loop = 1
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case opRTDG:
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h.gs.roundPeriod = 1 << 5
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h.gs.roundPhase = 0
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h.gs.roundThreshold = 1 << 4
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case opNPUSHB:
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opcode = 0
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goto push
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case opNPUSHW:
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opcode = 0x80
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goto push
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case opWS:
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top -= 2
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i := int(h.stack[top])
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if i < 0 || len(h.store) <= i {
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return errors.New("truetype: hinting: invalid data")
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}
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h.store[i] = h.stack[top+1]
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case opRS:
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i := int(h.stack[top-1])
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if i < 0 || len(h.store) <= i {
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return errors.New("truetype: hinting: invalid data")
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}
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h.stack[top-1] = h.store[i]
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case opMPPEM, opMPS:
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if top >= len(h.stack) {
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return errors.New("truetype: hinting: stack overflow")
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}
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// For MPS, point size should be irrelevant; we return the PPEM.
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h.stack[top] = h.scale >> 6
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top++
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case opFLIPON, opFLIPOFF:
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h.gs.autoFlip = opcode == opFLIPON
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case opDEBUG:
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// No-op.
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case opLT:
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top--
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h.stack[top-1] = bool2int32(h.stack[top-1] < h.stack[top])
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case opLTEQ:
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top--
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h.stack[top-1] = bool2int32(h.stack[top-1] <= h.stack[top])
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case opGT:
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top--
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h.stack[top-1] = bool2int32(h.stack[top-1] > h.stack[top])
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case opGTEQ:
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top--
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h.stack[top-1] = bool2int32(h.stack[top-1] >= h.stack[top])
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case opEQ:
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top--
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h.stack[top-1] = bool2int32(h.stack[top-1] == h.stack[top])
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case opNEQ:
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top--
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h.stack[top-1] = bool2int32(h.stack[top-1] != h.stack[top])
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case opODD, opEVEN:
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i := h.round(f26dot6(h.stack[top-1])) >> 6
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h.stack[top-1] = int32(i&1) ^ int32(opcode-opODD)
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case opIF:
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top--
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if h.stack[top] == 0 {
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opcode = 0
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goto ifelse
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}
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case opEIF:
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// No-op.
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case opAND:
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top--
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h.stack[top-1] = bool2int32(h.stack[top-1] != 0 && h.stack[top] != 0)
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case opOR:
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top--
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h.stack[top-1] = bool2int32(h.stack[top-1]|h.stack[top] != 0)
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case opNOT:
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h.stack[top-1] = bool2int32(h.stack[top-1] == 0)
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case opSDB:
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top--
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h.gs.deltaBase = h.stack[top]
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case opSDS:
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top--
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h.gs.deltaShift = h.stack[top]
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case opADD:
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top--
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h.stack[top-1] += h.stack[top]
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case opSUB:
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top--
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h.stack[top-1] -= h.stack[top]
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case opDIV:
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top--
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if h.stack[top] == 0 {
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return errors.New("truetype: hinting: division by zero")
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}
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h.stack[top-1] = int32(f26dot6(h.stack[top-1]).div(f26dot6(h.stack[top])))
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case opMUL:
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top--
|
|
h.stack[top-1] = int32(f26dot6(h.stack[top-1]).mul(f26dot6(h.stack[top])))
|
|
|
|
case opABS:
|
|
if h.stack[top-1] < 0 {
|
|
h.stack[top-1] = -h.stack[top-1]
|
|
}
|
|
|
|
case opNEG:
|
|
h.stack[top-1] = -h.stack[top-1]
|
|
|
|
case opFLOOR:
|
|
h.stack[top-1] &^= 63
|
|
|
|
case opCEILING:
|
|
h.stack[top-1] += 63
|
|
h.stack[top-1] &^= 63
|
|
|
|
case opROUND00, opROUND01, opROUND10, opROUND11:
|
|
// The four flavors of opROUND are equivalent. See the comment below on
|
|
// opNROUND for the rationale.
|
|
h.stack[top-1] = int32(h.round(f26dot6(h.stack[top-1])))
|
|
|
|
case opNROUND00, opNROUND01, opNROUND10, opNROUND11:
|
|
// No-op. The spec says to add one of four "compensations for the engine
|
|
// characteristics", to cater for things like "different dot-size printers".
|
|
// https://developer.apple.com/fonts/TTRefMan/RM02/Chap2.html#engine_compensation
|
|
// This code does not implement engine compensation, as we don't expect to
|
|
// be used to output on dot-matrix printers.
|
|
|
|
case opSROUND, opS45ROUND:
|
|
top--
|
|
switch (h.stack[top] >> 6) & 0x03 {
|
|
case 0:
|
|
h.gs.roundPeriod = 1 << 5
|
|
case 1, 3:
|
|
h.gs.roundPeriod = 1 << 6
|
|
case 2:
|
|
h.gs.roundPeriod = 1 << 7
|
|
}
|
|
if opcode == opS45ROUND {
|
|
// The spec says to multiply by √2, but the C Freetype code says 1/√2.
|
|
// We go with 1/√2.
|
|
h.gs.roundPeriod *= 46341
|
|
h.gs.roundPeriod /= 65536
|
|
}
|
|
h.gs.roundPhase = h.gs.roundPeriod * f26dot6((h.stack[top]>>4)&0x03) / 4
|
|
if x := h.stack[top] & 0x0f; x != 0 {
|
|
h.gs.roundThreshold = h.gs.roundPeriod * f26dot6(x-4) / 8
|
|
} else {
|
|
h.gs.roundThreshold = h.gs.roundPeriod - 1
|
|
}
|
|
|
|
case opJROT:
|
|
top -= 2
|
|
if h.stack[top+1] != 0 {
|
|
pc += int(h.stack[top])
|
|
continue
|
|
}
|
|
|
|
case opJROF:
|
|
top -= 2
|
|
if h.stack[top+1] == 0 {
|
|
pc += int(h.stack[top])
|
|
continue
|
|
}
|
|
|
|
case opROFF:
|
|
h.gs.roundPeriod = 0
|
|
h.gs.roundPhase = 0
|
|
h.gs.roundThreshold = 0
|
|
|
|
case opRUTG:
|
|
h.gs.roundPeriod = 1 << 6
|
|
h.gs.roundPhase = 0
|
|
h.gs.roundThreshold = 1<<6 - 1
|
|
|
|
case opRDTG:
|
|
h.gs.roundPeriod = 1 << 6
|
|
h.gs.roundPhase = 0
|
|
h.gs.roundThreshold = 0
|
|
|
|
case opSANGW, opAA:
|
|
// These ops are "anachronistic" and no longer used.
|
|
top--
|
|
|
|
case opSCANCTRL:
|
|
// We do not support dropout control, as we always rasterize grayscale glyphs.
|
|
top--
|
|
|
|
case opGETINFO:
|
|
res := int32(0)
|
|
if h.stack[top-1]&(1<<0) != 0 {
|
|
// Set the engine version. We hard-code this to 35, the same as
|
|
// the C freetype code, which says that "Version~35 corresponds
|
|
// to MS rasterizer v.1.7 as used e.g. in Windows~98".
|
|
res |= 35
|
|
}
|
|
if h.stack[top-1]&(1<<5) != 0 {
|
|
// Set that we support grayscale.
|
|
res |= 1 << 12
|
|
}
|
|
// We set no other bits, as we do not support rotated or stretched glyphs.
|
|
h.stack[top-1] = res
|
|
|
|
case opIDEF:
|
|
// IDEF is for ancient versions of the bytecode interpreter, and is no longer used.
|
|
return errors.New("truetype: hinting: unsupported IDEF instruction")
|
|
|
|
case opROLL:
|
|
h.stack[top-1], h.stack[top-3], h.stack[top-2] =
|
|
h.stack[top-3], h.stack[top-2], h.stack[top-1]
|
|
|
|
case opMAX:
|
|
top--
|
|
if h.stack[top-1] < h.stack[top] {
|
|
h.stack[top-1] = h.stack[top]
|
|
}
|
|
|
|
case opMIN:
|
|
top--
|
|
if h.stack[top-1] > h.stack[top] {
|
|
h.stack[top-1] = h.stack[top]
|
|
}
|
|
|
|
case opSCANTYPE:
|
|
// We do not support dropout control, as we always rasterize grayscale glyphs.
|
|
top--
|
|
|
|
case opPUSHB000, opPUSHB001, opPUSHB010, opPUSHB011,
|
|
opPUSHB100, opPUSHB101, opPUSHB110, opPUSHB111:
|
|
|
|
opcode -= opPUSHB000 - 1
|
|
goto push
|
|
|
|
case opPUSHW000, opPUSHW001, opPUSHW010, opPUSHW011,
|
|
opPUSHW100, opPUSHW101, opPUSHW110, opPUSHW111:
|
|
|
|
opcode -= opPUSHW000 - 1
|
|
opcode += 0x80
|
|
goto push
|
|
|
|
case opMDRP00000, opMDRP00001, opMDRP00010, opMDRP00011,
|
|
opMDRP00100, opMDRP00101, opMDRP00110, opMDRP00111,
|
|
opMDRP01000, opMDRP01001, opMDRP01010, opMDRP01011,
|
|
opMDRP01100, opMDRP01101, opMDRP01110, opMDRP01111,
|
|
opMDRP10000, opMDRP10001, opMDRP10010, opMDRP10011,
|
|
opMDRP10100, opMDRP10101, opMDRP10110, opMDRP10111,
|
|
opMDRP11000, opMDRP11001, opMDRP11010, opMDRP11011,
|
|
opMDRP11100, opMDRP11101, opMDRP11110, opMDRP11111:
|
|
|
|
i, points := int(h.gs.rp[0]), h.g.points(h.gs.zp[0])
|
|
if i < 0 || len(points) <= i {
|
|
return errors.New("truetype: hinting: point out of range")
|
|
}
|
|
ref := &points[i]
|
|
top--
|
|
i = int(h.stack[top])
|
|
points = h.g.points(h.gs.zp[1])
|
|
if i < 0 || len(points) <= i {
|
|
return errors.New("truetype: hinting: point out of range")
|
|
}
|
|
p := &points[i]
|
|
|
|
origDist := f26dot6(0)
|
|
if h.gs.zp[0] == 0 && h.gs.zp[1] == 0 {
|
|
p0 := &h.g.Unhinted[i]
|
|
p1 := &h.g.Unhinted[h.gs.rp[0]]
|
|
origDist = dotProduct(f26dot6(p0.X-p1.X), f26dot6(p0.Y-p1.Y), h.gs.dv)
|
|
} else {
|
|
p0 := &h.g.InFontUnits[i]
|
|
p1 := &h.g.InFontUnits[h.gs.rp[0]]
|
|
origDist = dotProduct(f26dot6(p0.X-p1.X), f26dot6(p0.Y-p1.Y), h.gs.dv)
|
|
origDist = f26dot6(h.font.scale(h.scale * int32(origDist)))
|
|
}
|
|
|
|
// Single-width cut-in test.
|
|
if x := (origDist - h.gs.singleWidth).abs(); x < h.gs.singleWidthCutIn {
|
|
if origDist >= 0 {
|
|
origDist = h.gs.singleWidthCutIn
|
|
} else {
|
|
origDist = -h.gs.singleWidthCutIn
|
|
}
|
|
}
|
|
|
|
// Rounding bit.
|
|
// TODO: metrics compensation.
|
|
distance := origDist
|
|
if opcode&0x04 != 0 {
|
|
distance = h.round(origDist)
|
|
}
|
|
|
|
// Minimum distance bit.
|
|
if opcode&0x08 != 0 {
|
|
if origDist >= 0 {
|
|
if distance < h.gs.minDist {
|
|
distance = h.gs.minDist
|
|
}
|
|
} else {
|
|
if distance > -h.gs.minDist {
|
|
distance = -h.gs.minDist
|
|
}
|
|
}
|
|
}
|
|
|
|
// Set-RP0 bit.
|
|
if opcode&0x10 != 0 {
|
|
h.gs.rp[0] = int32(i)
|
|
}
|
|
h.gs.rp[1] = h.gs.rp[0]
|
|
h.gs.rp[2] = int32(i)
|
|
|
|
// Move the point.
|
|
origDist = dotProduct(f26dot6(p.X-ref.X), f26dot6(p.Y-ref.Y), h.gs.pv)
|
|
h.move(p, distance-origDist)
|
|
|
|
default:
|
|
return errors.New("truetype: hinting: unrecognized instruction")
|
|
}
|
|
pc++
|
|
continue
|
|
|
|
ifelse:
|
|
// Skip past bytecode until the next ELSE (if opcode == 0) or the
|
|
// next EIF (for all opcodes). Opcode == 0 means that we have come
|
|
// from an IF. Opcode == 1 means that we have come from an ELSE.
|
|
{
|
|
ifelseloop:
|
|
for depth := 0; ; {
|
|
pc++
|
|
if pc >= len(program) {
|
|
return errors.New("truetype: hinting: unbalanced IF or ELSE")
|
|
}
|
|
switch program[pc] {
|
|
case opIF:
|
|
depth++
|
|
case opELSE:
|
|
if depth == 0 && opcode == 0 {
|
|
break ifelseloop
|
|
}
|
|
case opEIF:
|
|
depth--
|
|
if depth < 0 {
|
|
break ifelseloop
|
|
}
|
|
default:
|
|
var ok bool
|
|
pc, ok = skipInstructionPayload(program, pc)
|
|
if !ok {
|
|
return errors.New("truetype: hinting: unbalanced IF or ELSE")
|
|
}
|
|
}
|
|
}
|
|
pc++
|
|
continue
|
|
}
|
|
|
|
push:
|
|
// Push n elements from the program to the stack, where n is the low 7 bits of
|
|
// opcode. If the low 7 bits are zero, then n is the next byte from the program.
|
|
// The high bit being 0 means that the elements are zero-extended bytes.
|
|
// The high bit being 1 means that the elements are sign-extended words.
|
|
{
|
|
width := 1
|
|
if opcode&0x80 != 0 {
|
|
opcode &^= 0x80
|
|
width = 2
|
|
}
|
|
if opcode == 0 {
|
|
pc++
|
|
if pc >= len(program) {
|
|
return errors.New("truetype: hinting: insufficient data")
|
|
}
|
|
opcode = program[pc]
|
|
}
|
|
pc++
|
|
if top+int(opcode) > len(h.stack) {
|
|
return errors.New("truetype: hinting: stack overflow")
|
|
}
|
|
if pc+width*int(opcode) > len(program) {
|
|
return errors.New("truetype: hinting: insufficient data")
|
|
}
|
|
for ; opcode > 0; opcode-- {
|
|
if width == 1 {
|
|
h.stack[top] = int32(program[pc])
|
|
} else {
|
|
h.stack[top] = int32(int8(program[pc]))<<8 | int32(program[pc+1])
|
|
}
|
|
top++
|
|
pc += width
|
|
}
|
|
continue
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (h *Hinter) move(p *Point, distance f26dot6) {
|
|
if h.gs.fv[0] == 0 {
|
|
p.Y += int32(distance)
|
|
p.Flags |= flagTouchedY
|
|
return
|
|
}
|
|
if h.gs.fv[1] == 0 {
|
|
p.X += int32(distance)
|
|
p.Flags |= flagTouchedX
|
|
return
|
|
}
|
|
fvx := int64(h.gs.fv[0])
|
|
fvy := int64(h.gs.fv[1])
|
|
pvx := int64(h.gs.pv[0])
|
|
pvy := int64(h.gs.pv[1])
|
|
fvDotPv := (fvx*pvx + fvy*pvy) >> 14
|
|
p.X += int32(int64(distance) * fvx / fvDotPv)
|
|
p.Y += int32(int64(distance) * fvy / fvDotPv)
|
|
p.Flags |= flagTouchedX | flagTouchedY
|
|
}
|
|
|
|
// skipInstructionPayload increments pc by the extra data that follows a
|
|
// variable length PUSHB or PUSHW instruction.
|
|
func skipInstructionPayload(program []byte, pc int) (newPC int, ok bool) {
|
|
switch program[pc] {
|
|
case opNPUSHB:
|
|
pc++
|
|
if pc >= len(program) {
|
|
return 0, false
|
|
}
|
|
pc += int(program[pc])
|
|
case opNPUSHW:
|
|
pc++
|
|
if pc >= len(program) {
|
|
return 0, false
|
|
}
|
|
pc += 2 * int(program[pc])
|
|
case opPUSHB000, opPUSHB001, opPUSHB010, opPUSHB011,
|
|
opPUSHB100, opPUSHB101, opPUSHB110, opPUSHB111:
|
|
pc += int(program[pc] - (opPUSHB000 - 1))
|
|
case opPUSHW000, opPUSHW001, opPUSHW010, opPUSHW011,
|
|
opPUSHW100, opPUSHW101, opPUSHW110, opPUSHW111:
|
|
pc += 2 * int(program[pc]-(opPUSHW000-1))
|
|
}
|
|
return pc, true
|
|
}
|
|
|
|
// f2dot14 is a 2.14 fixed point number.
|
|
type f2dot14 int16
|
|
|
|
// f26dot6 is a 26.6 fixed point number.
|
|
type f26dot6 int32
|
|
|
|
// abs returns abs(x) in 26.6 fixed point arithmetic.
|
|
func (x f26dot6) abs() f26dot6 {
|
|
if x < 0 {
|
|
return -x
|
|
}
|
|
return x
|
|
}
|
|
|
|
// div returns x/y in 26.6 fixed point arithmetic.
|
|
func (x f26dot6) div(y f26dot6) f26dot6 {
|
|
return f26dot6((int64(x) << 6) / int64(y))
|
|
}
|
|
|
|
// mul returns x*y in 26.6 fixed point arithmetic.
|
|
func (x f26dot6) mul(y f26dot6) f26dot6 {
|
|
return f26dot6(int64(x) * int64(y) >> 6)
|
|
}
|
|
|
|
func dotProduct(x, y f26dot6, q [2]f2dot14) f26dot6 {
|
|
px := int64(x)
|
|
py := int64(y)
|
|
qx := int64(q[0])
|
|
qy := int64(q[1])
|
|
return f26dot6((px*qx + py*qy) >> 14)
|
|
}
|
|
|
|
// round rounds the given number. The rounding algorithm is described at
|
|
// https://developer.apple.com/fonts/TTRefMan/RM02/Chap2.html#rounding
|
|
func (h *Hinter) round(x f26dot6) f26dot6 {
|
|
if h.gs.roundPeriod == 0 {
|
|
return x
|
|
}
|
|
neg := x < 0
|
|
x -= h.gs.roundPhase
|
|
x += h.gs.roundThreshold
|
|
if x >= 0 {
|
|
x = (x / h.gs.roundPeriod) * h.gs.roundPeriod
|
|
} else {
|
|
x -= h.gs.roundPeriod
|
|
x += 1
|
|
x = (x / h.gs.roundPeriod) * h.gs.roundPeriod
|
|
}
|
|
x += h.gs.roundPhase
|
|
if neg {
|
|
if x >= 0 {
|
|
x = h.gs.roundPhase - h.gs.roundPeriod
|
|
}
|
|
} else if x < 0 {
|
|
x = h.gs.roundPhase
|
|
}
|
|
return x
|
|
}
|
|
|
|
func bool2int32(b bool) int32 {
|
|
if b {
|
|
return 1
|
|
}
|
|
return 0
|
|
}
|