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svg.go
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svg.go
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// Package svg minifies SVG1.1 following the specifications at http://www.w3.org/TR/SVG11/.
package svg
import (
"bytes"
"io"
"github.com/tdewolff/minify/v2"
"github.com/tdewolff/minify/v2/css"
minifyXML "github.com/tdewolff/minify/v2/xml"
"github.com/tdewolff/parse/v2"
"github.com/tdewolff/parse/v2/buffer"
"github.com/tdewolff/parse/v2/xml"
)
var (
voidBytes = []byte("/>")
isBytes = []byte("=")
spaceBytes = []byte(" ")
cdataEndBytes = []byte("]]>")
zeroBytes = []byte("0")
cssMimeBytes = []byte("text/css")
noneBytes = []byte("none")
urlBytes = []byte("url(")
)
////////////////////////////////////////////////////////////////
// Minifier is an SVG minifier.
type Minifier struct {
KeepComments bool
Precision int // number of significant digits
newPrecision int // precision for new numbers
}
// Minify minifies SVG data, it reads from r and writes to w.
func Minify(m *minify.M, w io.Writer, r io.Reader, params map[string]string) error {
return (&Minifier{}).Minify(m, w, r, params)
}
// Minify minifies SVG data, it reads from r and writes to w.
func (o *Minifier) Minify(m *minify.M, w io.Writer, r io.Reader, _ map[string]string) error {
o.newPrecision = o.Precision
if o.newPrecision <= 0 || 15 < o.newPrecision {
o.newPrecision = 15 // minimum number of digits a double can represent exactly
}
var tag Hash
defaultStyleType := cssMimeBytes
defaultStyleParams := map[string]string(nil)
defaultInlineStyleParams := map[string]string{"inline": "1"}
p := NewPathData(o)
minifyBuffer := buffer.NewWriter(make([]byte, 0, 64))
attrByteBuffer := make([]byte, 0, 64)
z := parse.NewInput(r)
defer z.Restore()
l := xml.NewLexer(z)
tb := NewTokenBuffer(z, l)
for {
t := *tb.Shift()
switch t.TokenType {
case xml.ErrorToken:
if _, err := w.Write(nil); err != nil {
return err
}
if l.Err() == io.EOF {
return nil
}
return l.Err()
case xml.CommentToken:
if o.KeepComments {
w.Write(t.Data)
}
case xml.DOCTYPEToken:
if len(t.Text) > 0 && t.Text[len(t.Text)-1] == ']' {
w.Write(t.Data)
}
case xml.TextToken:
t.Data = parse.ReplaceMultipleWhitespaceAndEntities(t.Data, minifyXML.EntitiesMap, nil)
t.Data = parse.TrimWhitespace(t.Data)
if tag == Style && len(t.Data) > 0 {
if err := m.MinifyMimetype(defaultStyleType, w, buffer.NewReader(t.Data), defaultStyleParams); err != nil {
if err != minify.ErrNotExist {
return minify.UpdateErrorPosition(err, z, t.Offset)
}
w.Write(t.Data)
}
} else {
w.Write(t.Data)
}
case xml.CDATAToken:
if tag == Style {
minifyBuffer.Reset()
if err := m.MinifyMimetype(defaultStyleType, minifyBuffer, buffer.NewReader(t.Text), defaultStyleParams); err == nil {
t.Data = append(t.Data[:9], minifyBuffer.Bytes()...)
t.Text = t.Data[9:]
t.Data = append(t.Data, cdataEndBytes...)
} else if err != minify.ErrNotExist {
return minify.UpdateErrorPosition(err, z, t.Offset)
}
}
var useText bool
if t.Text, useText = xml.EscapeCDATAVal(&attrByteBuffer, t.Text); useText {
t.Text = parse.ReplaceMultipleWhitespace(t.Text)
t.Text = parse.TrimWhitespace(t.Text)
w.Write(t.Text)
} else {
w.Write(t.Data)
}
case xml.StartTagPIToken:
for {
if t := *tb.Shift(); t.TokenType == xml.StartTagClosePIToken || t.TokenType == xml.ErrorToken {
break
}
}
case xml.StartTagToken:
tag = t.Hash
if tag == Metadata {
t.Data = nil
}
if t.Data == nil {
skipTag(tb)
} else {
w.Write(t.Data)
}
case xml.AttributeToken:
if t.Text == nil { // data is nil when attribute has been removed
continue
}
attr := t.Hash
val := t.AttrVal
if n, m := parse.Dimension(val); n+m == len(val) && attr != Version { // TODO: inefficient, temporary measure
val, _ = o.shortenDimension(val)
}
if attr == Xml_Space && bytes.Equal(val, []byte("preserve")) ||
tag == Svg && (attr == Version && bytes.Equal(val, []byte("1.1")) ||
attr == X && bytes.Equal(val, zeroBytes) ||
attr == Y && bytes.Equal(val, zeroBytes) ||
attr == PreserveAspectRatio && bytes.Equal(val, []byte("xMidYMid meet")) ||
attr == BaseProfile && bytes.Equal(val, noneBytes) ||
attr == ContentScriptType && bytes.Equal(val, []byte("application/ecmascript")) ||
attr == ContentStyleType && bytes.Equal(val, cssMimeBytes)) ||
tag == Style && attr == Type && bytes.Equal(val, cssMimeBytes) {
continue
}
w.Write(spaceBytes)
w.Write(t.Text)
w.Write(isBytes)
if tag == Svg && attr == ContentStyleType {
val = minify.Mediatype(val)
defaultStyleType = val
} else if attr == Style {
minifyBuffer.Reset()
if err := m.MinifyMimetype(defaultStyleType, minifyBuffer, buffer.NewReader(val), defaultInlineStyleParams); err == nil {
val = minifyBuffer.Bytes()
} else if err != minify.ErrNotExist {
return minify.UpdateErrorPosition(err, z, t.Offset)
}
} else if attr == D {
val = p.ShortenPathData(val)
} else if attr == ViewBox {
j := 0
newVal := val[:0]
for i := 0; i < 4; i++ {
if i != 0 {
if j >= len(val) || val[j] != ' ' && val[j] != ',' {
newVal = append(newVal, val[j:]...)
break
}
newVal = append(newVal, ' ')
j++
}
if dim, n := o.shortenDimension(val[j:]); n > 0 {
newVal = append(newVal, dim...)
j += n
} else {
newVal = append(newVal, val[j:]...)
break
}
}
val = newVal
} else if colorAttrMap[attr] && len(val) > 0 && (len(val) < 5 || !parse.EqualFold(val[:4], urlBytes)) {
parse.ToLower(val)
if val[0] == '#' {
if name, ok := css.ShortenColorHex[string(val)]; ok {
val = name
} else if len(val) == 7 && val[1] == val[2] && val[3] == val[4] && val[5] == val[6] {
val[2] = val[3]
val[3] = val[5]
val = val[:4]
}
} else if hex, ok := css.ShortenColorName[css.ToHash(val)]; ok {
val = hex
// } else if len(val) > 5 && bytes.Equal(val[:4], []byte("rgb(")) && val[len(val)-1] == ')' {
// TODO: handle rgb(x, y, z) and hsl(x, y, z)
}
}
// prefer single or double quotes depending on what occurs more often in value
val = xml.EscapeAttrVal(&attrByteBuffer, val)
w.Write(val)
case xml.StartTagCloseToken:
next := tb.Peek(0)
skipExtra := false
if next.TokenType == xml.TextToken && parse.IsAllWhitespace(next.Data) {
next = tb.Peek(1)
skipExtra = true
}
if next.TokenType == xml.EndTagToken {
// collapse empty tags to single void tag
tb.Shift()
if skipExtra {
tb.Shift()
}
w.Write(voidBytes)
} else {
w.Write(t.Data)
}
if tag == ForeignObject {
printTag(w, tb, tag)
}
case xml.StartTagCloseVoidToken:
tag = 0
w.Write(t.Data)
case xml.EndTagToken:
tag = 0
if len(t.Data) > 3+len(t.Text) {
t.Data[2+len(t.Text)] = '>'
t.Data = t.Data[:3+len(t.Text)]
}
w.Write(t.Data)
}
}
}
func (o *Minifier) shortenDimension(b []byte) ([]byte, int) {
if n, m := parse.Dimension(b); n > 0 {
unit := b[n : n+m]
b = minify.Number(b[:n], o.Precision)
if len(b) != 1 || b[0] != '0' {
if m == 2 && unit[0] == 'p' && unit[1] == 'x' {
unit = nil
} else if m > 1 { // only percentage is length 1
parse.ToLower(unit)
}
b = append(b, unit...)
}
return b, n + m
}
return b, 0
}
////////////////////////////////////////////////////////////////
func printTag(w io.Writer, tb *TokenBuffer, tag Hash) {
level := 0
inStartTag := false
for {
t := *tb.Peek(0)
switch t.TokenType {
case xml.ErrorToken:
return
case xml.StartTagToken:
inStartTag = t.Hash == tag
if t.Hash == tag {
level++
}
case xml.StartTagCloseVoidToken:
if inStartTag {
if level == 0 {
return
}
level--
}
case xml.EndTagToken:
if t.Hash == tag {
if level == 0 {
return
}
level--
}
}
w.Write(t.Data)
tb.Shift()
}
}
func skipTag(tb *TokenBuffer) {
level := 0
for {
if t := *tb.Shift(); t.TokenType == xml.ErrorToken {
break
} else if t.TokenType == xml.EndTagToken || t.TokenType == xml.StartTagCloseVoidToken {
if level == 0 {
break
}
level--
} else if t.TokenType == xml.StartTagToken {
level++
}
}
}