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Copy pathpathdata.go
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Copy pathpathdata.go
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293 lines (269 loc) · 8.24 KB
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package svg
import (
strconvStdlib "strconv"
"github.com/tdewolff/minify/v2"
"github.com/tdewolff/parse/v2"
"github.com/tdewolff/parse/v2/strconv"
)
type PathData struct {
o *Minifier
x, y float64
x0, y0 float64
coords [][]byte
coordFloats []float64
state PathDataState
curBuffer []byte
altBuffer []byte
coordBuffer []byte
}
type PathDataState struct {
cmd byte
prevDigit bool
prevDigitIsInt bool
}
func NewPathData(o *Minifier) *PathData {
return &PathData{
o: o,
}
}
// ShortenPathData takes a full pathdata string and returns a shortened version. The original string is overwritten.
// It parses all commands (M, A, Z, ...) and coordinates (numbers) and calls copyInstruction for each command.
func (p *PathData) ShortenPathData(b []byte) []byte {
var cmd byte
p.x, p.y = 0.0, 0.0
p.coords = p.coords[:0]
p.coordFloats = p.coordFloats[:0]
p.state = PathDataState{}
j := 0
for i := 0; i < len(b); i++ {
c := b[i]
if c == ' ' || c == ',' || c == '\n' || c == '\r' || c == '\t' {
continue
} else if c >= 'A' && (cmd == 0 || cmd != c || c == 'M' || c == 'm') { // any command
if cmd != 0 {
j += p.copyInstruction(b[j:], cmd)
}
cmd = c
p.coords = p.coords[:0]
p.coordFloats = p.coordFloats[:0]
} else if n := parse.Number(b[i:]); n > 0 {
f, _ := strconv.ParseFloat(b[i : i+n])
p.coords = append(p.coords, b[i:i+n])
p.coordFloats = append(p.coordFloats, f)
i += n - 1
}
}
if cmd != 0 {
j += p.copyInstruction(b[j:], cmd)
}
return b[:j]
}
// copyInstruction copies pathdata of a single command, but may be comprised of multiple sets for that command. For example, L takes two coordinates, but this function may process 2*N coordinates. Lowercase commands are relative commands, where the coordinates are relative to the previous point. Uppercase commands have absolute coordinates.
// We update p.x and p.y (the current coordinates) according to the commands given. For each set of coordinates we call shortenCurPosInstruction and shortenAltPosInstruction. The former just minifies the coordinates, the latter will inverse the lowercase/uppercase of the command, and see if the coordinates get smaller due to that. The shortest is chosen and copied to `b`.
func (p *PathData) copyInstruction(b []byte, cmd byte) int {
n := len(p.coords)
if n == 0 {
if cmd == 'Z' || cmd == 'z' {
p.x = p.x0
p.y = p.y0
b[0] = 'z'
return 1
}
return 0
}
isRelCmd := cmd >= 'a'
// get new cursor coordinates
di := 0
if (cmd == 'M' || cmd == 'm' || cmd == 'L' || cmd == 'l' || cmd == 'T' || cmd == 't') && n%2 == 0 {
di = 2
// reprint M always, as the first pair is a move but subsequent pairs are L
if cmd == 'M' || cmd == 'm' {
p.state.cmd = byte(0)
}
} else if cmd == 'H' || cmd == 'h' || cmd == 'V' || cmd == 'v' {
di = 1
} else if (cmd == 'S' || cmd == 's' || cmd == 'Q' || cmd == 'q') && n%4 == 0 {
di = 4
} else if (cmd == 'C' || cmd == 'c') && n%6 == 0 {
di = 6
} else if (cmd == 'A' || cmd == 'a') && n%7 == 0 {
di = 7
} else {
return 0
}
j := 0
origCmd := cmd
ax, ay := 0.0, 0.0
for i := 0; i < n; i += di {
// subsequent coordinate pairs for M are really L
if i > 0 && (origCmd == 'M' || origCmd == 'm') {
origCmd = 'L' + (origCmd - 'M')
}
cmd = origCmd
coords := p.coords[i : i+di]
coordFloats := p.coordFloats[i : i+di]
if cmd == 'H' || cmd == 'h' {
ax = coordFloats[di-1]
if isRelCmd {
ay = 0
} else {
ay = p.y
}
} else if cmd == 'V' || cmd == 'v' {
if isRelCmd {
ax = 0
} else {
ax = p.x
}
ay = coordFloats[di-1]
} else {
ax = coordFloats[di-2]
ay = coordFloats[di-1]
}
// switch from L to H or V whenever possible
if cmd == 'L' || cmd == 'l' {
if isRelCmd {
if coordFloats[0] == 0 && coordFloats[1] == 0 {
continue
} else if coordFloats[0] == 0 {
cmd = 'v'
coords = coords[1:]
coordFloats = coordFloats[1:]
} else if coordFloats[1] == 0 {
cmd = 'h'
coords = coords[:1]
coordFloats = coordFloats[:1]
}
} else {
if coordFloats[0] == p.x && coordFloats[1] == p.y {
continue
} else if coordFloats[0] == p.x {
cmd = 'V'
coords = coords[1:]
coordFloats = coordFloats[1:]
} else if coordFloats[1] == p.y {
cmd = 'H'
coords = coords[:1]
coordFloats = coordFloats[:1]
}
}
}
// make a current and alternated path with absolute/relative altered
var curState, altState PathDataState
curState = p.shortenCurPosInstruction(cmd, coords)
if isRelCmd {
altState = p.shortenAltPosInstruction(cmd-'a'+'A', coordFloats, p.x, p.y)
} else {
altState = p.shortenAltPosInstruction(cmd-'A'+'a', coordFloats, -p.x, -p.y)
}
// choose shortest, relative or absolute path?
if len(p.altBuffer) < len(p.curBuffer) {
j += copy(b[j:], p.altBuffer)
p.state = altState
} else {
j += copy(b[j:], p.curBuffer)
p.state = curState
}
if isRelCmd {
p.x += ax
p.y += ay
} else {
p.x = ax
p.y = ay
}
if i == 0 && (origCmd == 'M' || origCmd == 'm') {
p.x0 = p.x
p.y0 = p.y
}
}
return j
}
// shortenCurPosInstruction only minifies the coordinates.
func (p *PathData) shortenCurPosInstruction(cmd byte, coords [][]byte) PathDataState {
state := p.state
p.curBuffer = p.curBuffer[:0]
if cmd != state.cmd && !(state.cmd == 'M' && cmd == 'L' || state.cmd == 'm' && cmd == 'l') {
p.curBuffer = append(p.curBuffer, cmd)
state.cmd = cmd
state.prevDigit = false
state.prevDigitIsInt = false
}
for i, coord := range coords {
isFlag := false
// Arc has boolean flags that can only be 0 or 1. Setting isFlag prevents from adding a dot before a zero (instead of a space). However, when the dot already was there, the command is malformed and could make the path longer than before, introducing bugs.
if (cmd == 'A' || cmd == 'a') && (i%7 == 3 || i%7 == 4) && coord[0] != '.' {
isFlag = true
}
coord = minify.Number(coord, p.o.Decimals)
state.copyNumber(&p.curBuffer, coord, isFlag)
}
return state
}
// shortenAltPosInstruction toggles the command between absolute / relative coordinates and minifies the coordinates.
func (p *PathData) shortenAltPosInstruction(cmd byte, coordFloats []float64, x, y float64) PathDataState {
state := p.state
p.altBuffer = p.altBuffer[:0]
if cmd != state.cmd && !(state.cmd == 'M' && cmd == 'L' || state.cmd == 'm' && cmd == 'l') {
p.altBuffer = append(p.altBuffer, cmd)
state.cmd = cmd
state.prevDigit = false
state.prevDigitIsInt = false
}
for i, f := range coordFloats {
isFlag := false
if cmd == 'L' || cmd == 'l' || cmd == 'C' || cmd == 'c' || cmd == 'S' || cmd == 's' || cmd == 'Q' || cmd == 'q' || cmd == 'T' || cmd == 't' || cmd == 'M' || cmd == 'm' {
if i%2 == 0 {
f += x
} else {
f += y
}
} else if cmd == 'H' || cmd == 'h' {
f += x
} else if cmd == 'V' || cmd == 'v' {
f += y
} else if cmd == 'A' || cmd == 'a' {
if i%7 == 5 {
f += x
} else if i%7 == 6 {
f += y
} else if i%7 == 3 || i%7 == 4 {
isFlag = true
}
}
p.coordBuffer = strconvStdlib.AppendFloat(p.coordBuff
53A9
er[:0], f, 'g', -1, 64)
coord := minify.Number(p.coordBuffer, p.o.Decimals)
state.copyNumber(&p.altBuffer, coord, isFlag)
}
return state
}
// copyNumber will copy a number to the destination buffer, taking into account space or dot insertion to guarantee the shortest pathdata.
func (state *PathDataState) copyNumber(buffer *[]byte, coord []byte, isFlag bool) {
if state.prevDigit && (coord[0] >= '0' && coord[0] <= '9' || coord[0] == '.' && state.prevDigitIsInt) {
if coord[0] == '0' && !state.prevDigitIsInt {
if isFlag {
*buffer = append(*buffer, ' ', '0')
state.prevDigitIsInt = true
} else {
*buffer = append(*buffer, '.', '0') // aggresively add dot so subsequent numbers could drop leading space
// prevDigit stays true and prevDigitIsInt stays false
}
return
}
*buffer = append(*buffer, ' ')
}
state.prevDigit = true
state.prevDigitIsInt = true
if len(coord) > 2 && coord[len(coord)-2] == '0' && coord[len(coord)-1] == '0' {
coord[len(coord)-2] = 'e'
coord[len(coord)-1] = '2'
state.prevDigitIsInt = false
} else {
for _, c := range coord {
if c == '.' || c == 'e' || c == 'E' {
state.prevDigitIsInt = false
break
}
}
}
*buffer = append(*buffer, coord...)
}