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ParseSVG: add linearGradient support, see #235
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@tdewolff
tdewolff committed Aug 24, 2023
1 parent 1fe37ad commit 8bc6ac4
Showing 1 changed file with 195 additions and 24 deletions.
219 changes: 195 additions & 24 deletions svg.go
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,8 @@ import (
"github.com/tdewolff/parse/v2/xml"
)

type svgDef func(Rect) interface{}

type elem struct {
tag string
id string
Expand Down Expand Up @@ -46,8 +48,10 @@ type svgParser struct {
stateStack []svgState
state svgState

cssRules []cssRule
fonts map[string]*FontFamily
cssRules []cssRule
activeDef svgDef
defs map[string]svgDef
fonts map[string]*FontFamily
}

func (svg *svgParser) init(width, height float64, viewbox [4]float64) {
Expand All @@ -61,6 +65,7 @@ func (svg *svgParser) init(width, height float64, viewbox [4]float64) {
}
svg.ctx.SetStrokeJoiner(MiterJoiner{BevelJoin, svgDefaultState.strokeMiterLimit})
svg.state = svgDefaultState
svg.defs = map[string]svgDef{}
svg.fonts = map[string]*FontFamily{}
}

Expand All @@ -75,6 +80,27 @@ func (svg *svgParser) pop() {
svg.ctx.Pop()
}

func (svg *svgParser) parseNumber(v string) float64 {
if len(v) == 0 {
return 0.0
}
percentage := v[len(v)-1] == '%'
if percentage {
v = v[:len(v)-1]
}
num, err := strconv.ParseFloat(v, 64)
if err != nil {
if svg.err == nil {
svg.err = parse.NewErrorLexer(svg.z, "bad number: %w: %s", err, v)
}
return 0.0
}
if percentage {
num /= 100.0
}
return num
}

func (svg *svgParser) parseDimension(v string, parent float64) float64 {
if len(v) == 0 {
return 0.0
Expand Down Expand Up @@ -133,14 +159,25 @@ func (svg *svgParser) parseColorComponent(v string) uint8 {
}

func (svg *svgParser) parsePaint(v string) Paint {
if strings.HasPrefix(v, "url(") && strings.HasSuffix(v, ")") {
if 8 < len(v) && v[5] == '#' {
id := v[6 : len(v)-2]
svg.activeDef = svg.defs[id]
return Paint{Color: Black}
}
}
return Paint{Color: svg.parseColor(v)}
}

func (svg *svgParser) parseColor(v string) color.RGBA {
if len(v) == 0 {
return Paint{Color: Black}
return Black
} else if v[0] == '#' {
return Paint{Color: Hex(v)}
return Hex(v)
}
v = strings.ToLower(v)
if col, ok := cssColors[v]; ok {
return Paint{Color: col}
return col
}
var col color.RGBA
if strings.HasPrefix(v, "rgb(") && strings.HasSuffix(v, ")") {
Expand All @@ -149,7 +186,7 @@ func (svg *svgParser) parsePaint(v string) Paint {
if svg.err == nil {
svg.err = parse.NewErrorLexer(svg.z, "bad rgb function: %s", v)
}
return Paint{Color: Black}
return Black
}
col.R = svg.parseColorComponent(comps[0])
col.G = svg.parseColorComponent(comps[1])
Expand All @@ -161,14 +198,16 @@ func (svg *svgParser) parsePaint(v string) Paint {
if svg.err == nil {
svg.err = parse.NewErrorLexer(svg.z, "bad rgba function: %s", v)
}
return Paint{Color: Black}
return Black
}
col.A = svg.parseColorComponent(comps[3])
col.R = uint8(float64(svg.parseColorComponent(comps[0]))*float64(col.A)/255.0 + 0.5)
col.G = uint8(float64(svg.parseColorComponent(comps[1]))*float64(col.A)/255.0 + 0.5)
col.B = uint8(float64(svg.parseColorComponent(comps[2]))*float64(col.A)/255.0 + 0.5)
} else {
col = Black
}
return Paint{Color: col}
return col
}

func (svg *svgParser) parsePoints(v string) []float64 {
Expand Down Expand Up @@ -250,6 +289,139 @@ func (svg *svgParser) parseTransform(v string) Matrix {
return m
}

func (svg *svgParser) parseAttributes(l *xml.Lexer) (xml.TokenType, []string, map[string]string) {
// get all attributes
var tt xml.TokenType
attrs := map[string]string{}
attrNames := []string{}
for {
// TODO: attribute errors point to wrong position
tt, _ = l.Next()
if tt != xml.AttributeToken {
break
}
val := l.AttrVal()
val = val[1 : len(val)-1]
attrNames = append(attrNames, string(l.Text()))
attrs[string(l.Text())] = string(val)
}
return tt, attrNames, attrs
}

func (svg *svgParser) parseSingleTag(l *xml.Lexer) (xml.TokenType, string, map[string]string) {
tt, data := l.Next()
if tt == xml.TextToken {
tt, data = l.Next()
}
if tt != xml.StartTagToken {
return tt, "", nil
}

tag := string(data[1:])
var attrs map[string]string
tt, _, attrs = svg.parseAttributes(l)
tt = svg.skipToEndTag(l, tt)
return tt, tag, attrs
}

func (svg *svgParser) skipToEndTag(l *xml.Lexer, tt xml.TokenType) xml.TokenType {
// find close tag
if tt != xml.StartTagCloseToken {
return tt
}
level := 0
for {
tt, _ = l.Next()
if tt == xml.EndTagToken || tt == xml.StartTagCloseVoidToken {
if level == 0 {
break
}
level--
} else if tt == xml.StartTagToken {
level++
}
}
return tt
}

func (svg *svgParser) parseDefs(l *xml.Lexer) {
tt, data := l.Next()
for {
if tt == xml.EndTagToken {
break
} else if tt == xml.StartTagToken {
tag := string(data[1:])
var attrs map[string]string
tt, _, attrs = svg.parseAttributes(l)
id := attrs["id"]
if id == "" {
tt = svg.skipToEndTag(l, tt)
continue
}

switch tag {
case "linearGradient":
if tt != xml.StartTagCloseToken {
break
}

if _, ok := attrs["x2"]; !ok {
attrs["x2"] = "100%"
}
x1p := strings.HasSuffix(attrs["x1"], "%")
y1p := strings.HasSuffix(attrs["y1"], "%")
x2p := strings.HasSuffix(attrs["x2"], "%")
y2p := strings.HasSuffix(attrs["y2"], "%")
x1 := svg.parseDimension(attrs["x1"], 1.0)
x2 := svg.parseDimension(attrs["x2"], 1.0)
y1 := svg.parseDimension(attrs["y1"], 1.0)
y2 := svg.parseDimension(attrs["y2"], 1.0)

stops := Stops{}
for {
tt, tag, attrs = svg.parseSingleTag(l)
if tag != "stop" {
break
}
offset := svg.parseNumber(attrs["offset"])
stopColor := svg.parseColor(attrs["stop-color"])
if v, ok := attrs["stop-opacity"]; ok {
stopOpacity := svg.parseNumber(v)
stopColor.R = uint8(float64(stopColor.R) / float64(stopColor.A) * stopOpacity * 255.0)
stopColor.G = uint8(float64(stopColor.G) / float64(stopColor.A) * stopOpacity * 255.0)
stopColor.B = uint8(float64(stopColor.B) / float64(stopColor.A) * stopOpacity * 255.0)
stopColor.A = uint8(stopOpacity * 255.0)
}
stops.Add(offset, stopColor)
}
svg.defs[id] = func(rect Rect) interface{} {
x1t, y1t, x2t, y2t := x1, y1, x2, y2
if x1p {
x1t = (rect.X + rect.W*x1t) * 25.4 / 96.0
}
if y1p {
y1t = (rect.Y + rect.H*y1t) * 25.4 / 96.0
}
if x2p {
x2t = (rect.X + rect.W*x2t) * 25.4 / 96.0
}
if y2p {
y2t = (rect.Y + rect.H*y2t) * 25.4 / 96.0
}
linearGradient := NewLinearGradient(Point{x1t, y1t}, Point{x2t, y2t})
linearGradient.Stops = stops
return linearGradient
}
tt, data = l.Next()
default:
tt = svg.skipToEndTag(l, tt)
}
} else {
tt, data = l.Next()
}
}
}

func (svg *svgParser) parseStyle(b []byte) {
p := css.NewParser(parse.NewInputBytes(b), false)
for {
Expand Down Expand Up @@ -442,23 +614,10 @@ func ParseSVG(r io.Reader) (*Canvas, error) {
}
return svg.c, nil
case xml.StartTagToken:
// get all attributes
attrs := map[string]string{}
attrNames := []string{}
for {
// TODO: attribute errors point to wrong position
tt, _ = l.Next()
if tt != xml.AttributeToken {
break
}
val := l.AttrVal()
val = val[1 : len(val)-1]
attrNames = append(attrNames, string(l.Text()))
attrs[string(l.Text())] = string(val)
}
tag := string(data[1:])
tt, attrNames, attrs := svg.parseAttributes(l)

// handle SVG tag and create canvas
tag := string(data[1:])
if tag == "svg" && svg.c == nil {
var err error
var viewbox [4]float64
Expand Down Expand Up @@ -495,7 +654,7 @@ func ParseSVG(r io.Reader) (*Canvas, error) {
return svg.c, fmt.Errorf("expected SVG tag")
}

// handle style tag
// handle special tags
if tag == "style" {
tt, data = l.Next()
if tt == xml.TextToken {
Expand All @@ -505,6 +664,9 @@ func ParseSVG(r io.Reader) (*Canvas, error) {
return svg.c, fmt.Errorf("bad style tag")
}
break
} else if tag == "defs" {
svg.parseDefs(l)
break
}

// push new state
Expand Down Expand Up @@ -571,6 +733,15 @@ func ParseSVG(r io.Reader) (*Canvas, error) {
svg.state.textY = svg.parseDimension(attrs["y"], svg.height)
}

// TODO: fix linearGradient (ugly!)
if layers := svg.c.layers[svg.c.zindex]; 0 < len(layers) && layers[len(layers)-1].path != nil && svg.activeDef != nil {
bounds := layers[len(layers)-1].path.FastBounds()
def := svg.activeDef(bounds)
if linearGradient, ok := def.(*LinearGradient); ok {
layers[len(layers)-1].style.Fill = Paint{Gradient: linearGradient}
}
}

// tag is self-closing
if tt == xml.StartTagCloseVoidToken {
elemStack = elemStack[:len(elemStack)-1]
Expand Down

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