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