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svg.go
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svg.go
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package canvas
import (
"bytes"
"fmt"
"image/color"
"io"
"math"
"strconv"
"strings"
"github.com/tdewolff/parse/v2"
"github.com/tdewolff/parse/v2/css"
"github.com/tdewolff/parse/v2/xml"
"golang.org/x/net/html"
)
type svgDef func(string, *Canvas)
type svgElem struct {
tag string
id string
attrs map[string]string
}
type svgState struct {
strokeMiterLimit float64
textX float64
textY float64
textAnchor string
fontFamily string
fontSize float64
}
var svgDefaultState = svgState{
strokeMiterLimit: 4.0,
textAnchor: "start",
fontFamily: "serif",
fontSize: 16.0, // in px
}
type svgCanvas struct {
c *Canvas
ctx *Context
width, height, diagonal float64
}
type svgParser struct {
z *parse.Input
err error
svgCanvas
elemStack []svgElem
stateStack []svgState
state svgState
cssRules []cssRule // from <style>
defs map[string]svgDef
fonts map[string]*FontFamily
// active definitions for attributes
activeDefs map[string]svgDef
}
func (svg *svgParser) parseViewBox(attrWidth, attrHeight, attrViewBox string) (float64, float64, [4]float64) {
var err error
var viewbox [4]float64
var width, height float64
if attrViewBox != "" {
vals := strings.Split(attrViewBox, " ")
if len(vals) != 4 {
svg.err = parse.NewErrorLexer(svg.z, "bad viewBox")
} else {
for i := 0; i < 4; i++ {
viewbox[i], err = strconv.ParseFloat(vals[i], 64)
if err != nil && svg.err == nil {
svg.err = parse.NewErrorLexer(svg.z, "bad viewBox: %w", err)
}
}
}
}
if attrWidth != "" && !strings.HasSuffix(attrWidth, "%") {
width = svg.parseDimension(attrWidth, 1.0)
} else {
width = (viewbox[2] - viewbox[0]) * 25.4 / 96.0
}
if attrHeight != "" && !strings.HasSuffix(attrHeight, "%") {
height = svg.parseDimension(attrHeight, 1.0)
} else {
height = (viewbox[3] - viewbox[1]) * 25.4 / 96.0
}
return width, height, viewbox
}
func (svg *svgParser) init(width, height float64, viewbox [4]float64) {
svg.width, svg.height = width*96.0/25.4, height*96.0/25.4
svg.diagonal = math.Sqrt((svg.width*svg.width + svg.height*svg.height) / 2.0)
svg.c = New(width, height)
svg.ctx = NewContext(svg.c)
svg.ctx.SetCoordSystem(CartesianIV)
if 0.0 < (viewbox[2]-viewbox[0]) && 0.0 < (viewbox[3]-viewbox[1]) {
m := Identity.Scale(width/(viewbox[2]-viewbox[0]), height/(viewbox[3]-viewbox[1])).Translate(-viewbox[0], -viewbox[1])
svg.ctx.SetView(m)
}
svg.ctx.SetStrokeJoiner(MiterJoiner{BevelJoin, svgDefaultState.strokeMiterLimit})
svg.state = svgDefaultState
}
func (svg *svgParser) push(tag string, attrs map[string]string) {
svg.ctx.Push()
svg.stateStack = append(svg.stateStack, svg.state)
svg.elemStack = append(svg.elemStack, svgElem{tag, attrs["id"], attrs})
}
func (svg *svgParser) pop() {
if len(svg.stateStack) == 0 {
svg.err = parse.NewErrorLexer(svg.z, "invalid SVG")
return
}
svg.elemStack = svg.elemStack[:len(svg.elemStack)-1]
svg.state = svg.stateStack[len(svg.stateStack)-1]
svg.stateStack = svg.stateStack[:len(svg.stateStack)-1]
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
}
nn, _ := parse.Dimension([]byte(v))
num, err := strconv.ParseFloat(v[:nn], 64)
if err != nil {
if svg.err == nil {
svg.err = parse.NewErrorLexer(svg.z, "bad dimension: %w: %s", err, v)
}
return 0.0
}
dim := v[nn:]
switch strings.ToLower(dim) {
// lengths
case "cm":
return num * 10.0 * 96.0 / 25.4
case "mm":
return num * 96.0 / 25.4
case "q":
return num * 0.25 * 96.0 / 25.4
case "in":
return num * 96.0
case "pc":
return num * 96.0 / 6.0
case "pt":
return num * 96.0 / 72.0
case "", "px":
return num
// angles
case "deg":
return num
case "grad":
return num / 400.0 * 360.0
case "rad":
return num / math.Pi * 180.0
case "turn":
return num * 360.0
// other
case "%":
return num * parent / 100.0
}
if svg.err == nil {
svg.err = parse.NewErrorLexer(svg.z, "unknown dimension: %s", dim)
}
return 0.0
}
func (svg *svgParser) parseColorComponent(v string) uint8 {
v = strings.TrimSpace(v)
if len(v) == 0 {
return 0
} else if v[len(v)-1] == '%' {
num, err := strconv.ParseFloat(v[:len(v)-1], 64)
if err != nil && svg.err == nil {
svg.err = parse.NewErrorLexer(svg.z, "bad color component: %w: %s", err, v)
}
return uint8(num*255.0 + 0.5)
}
num, err := strconv.ParseUint(v, 10, 8)
if err != nil && svg.err == nil {
svg.err = parse.NewErrorLexer(svg.z, "bad color component: %w: %s", err, v)
}
return uint8(num)
}
func (svg *svgParser) parsePaint(v string) Paint {
if v == "none" {
return Paint{Color: Transparent}
}
return Paint{Color: svg.parseColor(v)}
}
func (svg *svgParser) parseColor(v string) color.RGBA {
if len(v) == 0 {
return Black
} else if v[0] == '#' {
return Hex(v)
}
v = strings.ToLower(v)
if col, ok := cssColors[v]; ok {
return col
}
var col color.RGBA
if strings.HasPrefix(v, "rgb(") && strings.HasSuffix(v, ")") {
comps := strings.Split(v[4:len(v)-1], ",")
if len(comps) != 3 {
if svg.err == nil {
svg.err = parse.NewErrorLexer(svg.z, "bad rgb function: %s", v)
}
return Black
}
col.R = svg.parseColorComponent(comps[0])
col.G = svg.parseColorComponent(comps[1])
col.B = svg.parseColorComponent(comps[2])
col.A = 255
} else if strings.HasPrefix(v, "rgba(") && strings.HasSuffix(v, ")") {
comps := strings.Split(v[5:len(v)-1], ",")
if len(comps) != 4 {
if svg.err == nil {
svg.err = parse.NewErrorLexer(svg.z, "bad rgba function: %s", v)
}
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 col
}
func (svg *svgParser) parsePoints(v string) []float64 {
v = strings.ReplaceAll(v, "\n", ",")
v = strings.ReplaceAll(v, "\t", ",")
v = strings.ReplaceAll(v, " ", ",")
vals := []float64{}
for _, item := range strings.Split(v, ",") {
if 0 < len(item) {
val, err := strconv.ParseFloat(item, 64)
if err != nil && svg.err == nil {
svg.err = parse.NewErrorLexer(svg.z, "bad number array: %w: %s", err, v)
}
vals = append(vals, val)
}
}
return vals
}
func (svg *svgParser) parseTransform(v string) Matrix {
i, j := 0, 0
m := Identity
var fun string
for i < len(v) {
if v[i] == '(' {
fun = strings.ToLower(strings.TrimSpace(v[j:i]))
j = i + 1
} else if v[i] == ')' {
d := svg.parsePoints(v[j:i])
switch fun {
case "matrix":
if len(d) != 6 {
svg.err = parse.NewErrorLexer(svg.z, "bad transform matrix")
} else {
m = m.Mul(Matrix{{d[0], d[2], d[4]}, {d[1], d[3], d[5]}})
}
case "translate":
if len(d) != 1 && len(d) != 2 {
svg.err = parse.NewErrorLexer(svg.z, "bad transform translate")
} else if len(d) == 1 {
m = m.Translate(d[0], 0.0)
} else {
m = m.Translate(d[0], d[1])
}
case "scale":
if len(d) != 1 && len(d) != 2 {
svg.err = parse.NewErrorLexer(svg.z, "bad transform scale")
} else if len(d) == 1 {
m = m.Scale(d[0], d[0])
} else {
m = m.Scale(d[0], d[1])
}
case "rotate":
if len(d) != 1 && len(d) != 3 {
svg.err = parse.NewErrorLexer(svg.z, "bad transform rotate")
} else if len(d) == 1 {
m = m.Rotate(d[0])
} else {
m = m.RotateAbout(d[0], d[1], d[2])
}
case "skewx":
if len(d) != 1 {
svg.err = parse.NewErrorLexer(svg.z, "bad transform skewX")
} else {
// TODO
}
case "skewy":
if len(d) != 1 {
svg.err = parse.NewErrorLexer(svg.z, "bad transform skewY")
} else {
// TODO
}
}
j = i + 1
}
i++
}
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()
if len(val) < 2 {
break
}
val = val[1 : len(val)-1]
attrNames = append(attrNames, string(l.Text()))
attrs[string(l.Text())] = string(val)
}
return tt, attrNames, attrs
}
type svgTag struct {
parent *svgTag
name string
attrNames []string
attrs map[string]string
content []*svgTag
}
func (svg *svgParser) parseTag(l *xml.Lexer) *svgTag {
var root, parent *svgTag
for {
tt, data := l.Next()
if tt == xml.ErrorToken {
if l.Err() != io.EOF {
svg.err = l.Err()
} else {
svg.err = parse.NewErrorLexer(svg.z, "unexpected end-of-file")
}
break
} else if tt == xml.StartTagToken {
var attrNames []string
var attrs map[string]string
name := string(data[1:])
tt, attrNames, attrs = svg.parseAttributes(l)
tag := &svgTag{
parent: parent,
name: name,
attrNames: attrNames,
attrs: attrs,
}
if parent == nil {
root = tag
} else {
parent.content = append(parent.content, tag)
}
if tt == xml.StartTagCloseVoidToken {
if parent == nil {
break
}
} else {
parent = tag
}
// Handle <style> being nested in <defs>. Adobe Illustrator
// does this, for example.
if name == "style" {
tt, data = l.Next()
if tt == xml.TextToken {
svg.parseStyle(data)
tt, data = l.Next()
} else {
svg.err = parse.NewErrorLexer(svg.z, "Bad style tag")
}
break
}
} else if tt == xml.EndTagToken {
if parent == nil {
break // when starting on an end tag
}
parent = parent.parent
if parent == nil {
break
}
}
}
return root
}
func (svg *svgParser) parseDefs(l *xml.Lexer) {
for {
tag := svg.parseTag(l)
if tag == nil {
break
}
id := tag.attrs["id"]
if id == "" {
continue
}
switch tag.name {
case "linearGradient":
if _, ok := tag.attrs["x2"]; !ok {
tag.attrs["x2"] = "100%"
}
x1p := strings.HasSuffix(tag.attrs["x1"], "%")
y1p := strings.HasSuffix(tag.attrs["y1"], "%")
x2p := strings.HasSuffix(tag.attrs["x2"], "%")
y2p := strings.HasSuffix(tag.attrs["y2"], "%")
x1 := svg.parseDimension(tag.attrs["x1"], 1.0)
x2 := svg.parseDimension(tag.attrs["x2"], 1.0)
y1 := svg.parseDimension(tag.attrs["y1"], 1.0)
y2 := svg.parseDimension(tag.attrs["y2"], 1.0)
stops := Stops{}
for _, tag := range tag.content {
if tag.name != "stop" {
continue
}
offset := svg.parseNumber(tag.attrs["offset"])
stopColor := svg.parseColor(tag.attrs["stop-color"])
if v, ok := tag.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(attr string, c *Canvas) {
layers := c.layers[c.zindex]
if len(layers) == 0 || layers[len(layers)-1].path == nil {
return
}
layer := &layers[len(layers)-1]
rect := layer.path.FastBounds()
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
if attr == "fill" {
layer.style.Fill = Paint{Gradient: linearGradient}
} else if attr == "stroke" {
layer.style.Stroke = Paint{Gradient: linearGradient}
}
}
case "marker":
width, height, viewbox := svg.parseViewBox(tag.attrs["markerWidth"], tag.attrs["markerHeight"], tag.attrs["viewBox"])
if width == 0.0 {
width = 3.0
}
if height == 0.0 {
height = 3.0
}
units := tag.attrs["markerUnits"]
if units != "userSpaceOnUse" {
units = "strokeWidth"
}
var refx, refy float64
switch tag.attrs["refX"] {
case "left":
refx = 0.0
case "center":
refx = width / 2.0
case "right":
refx = width
default:
refx = svg.parseDimension(tag.attrs["refX"], 0.0)
}
switch tag.attrs["refY"] {
case "top":
refy = 0.0
case "center":
refy = height / 2.0
case "bottom":
refy = height
default:
refy = svg.parseDimension(tag.attrs["refY"], 0.0)
}
angle := 0.0
orient := tag.attrs["orient"]
if orient != "auto" && orient != "auto-start-reverse" {
angle = svg.parseDimension(tag.attrs["orient"], 0.0)
}
origSVGCanvas := svg.svgCanvas
svg.push(tag.name, tag.attrs)
svg.init(width, height, [4]float64{})
for _, tag := range tag.content {
svg.push(tag.name, tag.attrs)
props := []cssProperty{}
for _, key := range tag.attrNames {
props = append(props, cssProperty{key, tag.attrs[key]})
}
svg.setStyling(props)
svg.drawShape(tag.name, tag.attrs)
svg.pop()
}
marker := svg.c
svg.svgCanvas = origSVGCanvas
svg.pop()
svg.defs[id] = func(attr string, c *Canvas) {
layers := c.layers[c.zindex]
if len(layers) == 0 || layers[len(layers)-1].path == nil {
return
}
layer := layers[len(layers)-1]
path := layer.path
strokeWidth := layer.style.StrokeWidth
a := angle
coordPos := path.Coords()
coordDir := path.CoordDirections()
for i := range coordPos {
if attr == "marker-start" && i == 0 || attr == "marker-end" && i == len(coordPos)-1 || attr == "marker-mid" && i != 0 && i != len(coordPos)-1 {
pos, dir := coordPos[i], coordDir[i]
if orient == "auto" || orient == "auto-start-reverse" {
a = dir.Angle()
if orient == "auto-start-reverse" {
a += 180.0
}
}
view := Identity.ReflectYAbout(c.H/2.0).Mul(svg.ctx.View()).Translate(pos.X, pos.Y).Rotate(a * 180.0 / math.Pi)
if units == "strokeWidth" {
view = view.Scale(strokeWidth, strokeWidth)
}
f := height / (viewbox[3] - viewbox[1])
view = view.Translate(-refx*f, -refy*f).Scale(f, f).ReflectYAbout(height / 2.0)
marker.RenderViewTo(c, view)
}
}
}
}
}
}
func (svg *svgParser) parseStyle(b []byte) {
p := css.NewParser(parse.NewInputBytes(b), false)
selectors := []cssSelector{}
for {
gt, _, _ := p.Next()
if gt == css.ErrorGrammar {
break
} else if gt == css.BeginRulesetGrammar || gt == css.QualifiedRuleGrammar {
selector := cssSelector{}
node := cssSelectorNode{op: ' '}
vals := p.Values()
for i := 0; i < len(vals); i++ {
t := vals[i]
if t.TokenType == css.WhitespaceToken || t.TokenType == css.DelimToken && t.Data[0] == '>' {
selector = append(selector, node)
node = cssSelectorNode{op: ' '}
if t.TokenType == css.DelimToken {
node.op = '>'
}
} else if t.TokenType == css.IdentToken || t.TokenType == css.DelimToken && t.Data[0] == '*' {
node.typ = string(t.Data)
} else if t.TokenType == css.DelimToken && (t.Data[0] == '.' || t.Data[0] == '#') && i+1 < len(vals) && vals[i+1].TokenType == css.IdentToken {
if t.Data[0] == '#' {
node.attrs = append(node.attrs, cssAttrSelector{op: '=', attr: "id", val: string(vals[i+1].Data)})
} else {
node.attrs = append(node.attrs, cssAttrSelector{op: '~', attr: "class", val: string(vals[i+1].Data)})
}
i++
} else if t.TokenType == css.DelimToken && t.Data[0] == '[' && i+2 < len(vals) && vals[i+1].TokenType == css.IdentToken && vals[i+2].TokenType == css.DelimToken {
if vals[i+2].Data[0] == ']' {
node.attrs = append(node.attrs, cssAttrSelector{op: 0, attr: string(vals[i+1].Data)})
i += 2
} else if i+4 < len(vals) && vals[i+3].TokenType == css.IdentToken && vals[i+4].TokenType == css.DelimToken && vals[i+4].Data[0] == ']' {
node.attrs = append(node.attrs, cssAttrSelector{op: vals[i+2].Data[0], attr: string(vals[i+1].Data), val: string(vals[i+3].Data)})
i += 4
}
}
}
selector = append(selector, node)
selectors = append(selectors, selector)
}
if gt == css.BeginRulesetGrammar {
props := []cssProperty{}
for {
gt, _, data := p.Next()
if gt != css.DeclarationGrammar {
break
}
val := strings.Builder{}
for _, t := range p.Values() {
val.Write(t.Data)
}
props = append(props, cssProperty{string(data), val.String()})
}
svg.cssRules = append(svg.cssRules, cssRule{
selectors: selectors,
props: props,
})
selectors = selectors[:0:0]
}
}
}
func (svg *svgParser) parseStyleAttribute(style string) []cssProperty {
props := []cssProperty{}
p := css.NewParser(parse.NewInput(bytes.NewBufferString(style)), true)
for {
gt, _, data := p.Next()
if gt == css.ErrorGrammar {
break
} else if gt == css.DeclarationGrammar {
val := strings.Builder{}
for _, t := range p.Values() {
val.Write(t.Data)
}
props = append(props, cssProperty{string(data), val.String()})
}
}
return props
}
func (svg *svgParser) setStyling(props []cssProperty) {
// apply CSS from <style>
for _, rule := range svg.cssRules {
// TODO: this is in order of appearance, use selector specificity/precedence?
if rule.AppliesTo(svg.elemStack) {
for _, prop := range rule.props {
svg.setAttribute(prop.key, prop.val)
}
}
}
// apply attributes in order
for _, prop := range props {
if prop.key == "style" {
for _, styleProp := range svg.parseStyleAttribute(prop.val) {
svg.setAttribute(styleProp.key, styleProp.val)
}
} else {
svg.setAttribute(prop.key, prop.val)
}
}
}
func (svg *svgParser) parseUrlID(val string) string {
if strings.HasPrefix(val, "url(") && strings.HasSuffix(val, ")") {
if 6 < len(val) && (val[4] == '#' || val[5] == '#') {
id := val[6 : len(val)-2]
if val[4] == '#' {
id = val[5 : len(val)-1]
}
return id
}
}
return ""
}
func (svg *svgParser) setAttribute(key, val string) {
switch key {
case "fill":
if id := svg.parseUrlID(val); id != "" {
svg.activeDefs["fill"] = svg.defs[id]
} else {
svg.ctx.SetFill(svg.parsePaint(val))
}
case "stroke":
if id := svg.parseUrlID(val); id != "" {
svg.activeDefs["stroke"] = svg.defs[id]
} else {
svg.ctx.SetStroke(svg.parsePaint(val))
}
case "stroke-width":
svg.ctx.SetStrokeWidth(svg.parseDimension(val, svg.diagonal))
case "stroke-dashoffset":
svg.ctx.Style.DashOffset = svg.parseDimension(val, svg.diagonal)
case "stroke-dasharray":
if val == "none" {
svg.ctx.Style.Dashes = []float64{}
} else {
svg.ctx.Style.Dashes = svg.parsePoints(val)
}
case "stroke-linecap":
if val == "butt" {
svg.ctx.SetStrokeCapper(ButtCap)
} else if val == "round" {
svg.ctx.SetStrokeCapper(RoundCap)
} else if val == "square" {
svg.ctx.SetStrokeCapper(SquareCap)
}
case "stroke-linejoin":
if val == "arcs" {
svg.ctx.SetStrokeJoiner(ArcsJoin)
} else if val == "bevel" {
svg.ctx.SetStrokeJoiner(BevelJoin)
} else if val == "miter" {
svg.ctx.SetStrokeJoiner(MiterJoiner{BevelJoin, svg.state.strokeMiterLimit})
} else if val == "miter-clip" {
svg.ctx.SetStrokeJoiner(MiterJoiner{nil, svg.state.strokeMiterLimit})
} else if val == "round" {
svg.ctx.SetStrokeJoiner(RoundJoin)
}
case "stroke-miterlimit":
svg.state.strokeMiterLimit = svg.parseDimension(val, svg.diagonal)
if miter, ok := svg.ctx.StrokeJoiner.(MiterJoiner); ok {
miter.Limit = svg.state.strokeMiterLimit
}
case "transform":
m := svg.parseTransform(val)
svg.ctx.ComposeView(m)
case "text-anchor":
svg.state.textAnchor = val
case "font-family":
svg.state.fontFamily = val
case "font-size":
svg.state.fontSize = svg.parseDimension(val, svg.height)
case "marker-start":
if id := svg.parseUrlID(val); id != "" {
svg.activeDefs["marker-start"] = svg.defs[id]
}
case "marker-mid":
if id := svg.parseUrlID(val); id != "" {
svg.activeDefs["marker-mid"] = svg.defs[id]
}
case "marker-end":
if id := svg.parseUrlID(val); id != "" {
svg.activeDefs["marker-end"] = svg.defs[id]
}
}
}
func (svg *svgParser) getFontFace() *FontFace {
fontFamily, ok := svg.fonts[svg.state.fontFamily]
if !ok {
fontFamily = NewFontFamily(svg.state.fontFamily)
if err := fontFamily.LoadSystemFont(svg.state.fontFamily, FontRegular); err != nil {
panic(err)
}
svg.fonts[svg.state.fontFamily] = fontFamily
}
fontSize := svg.state.fontSize * ptPerMm
return fontFamily.Face(fontSize, svg.ctx.Style.Fill.Color)
}
func (svg *svgParser) drawShape(tag string, attrs map[string]string) {
switch tag {
case "circle":
cx := svg.parseDimension(attrs["cx"], svg.width)
cy := svg.parseDimension(attrs["cy"], svg.height)
r := svg.parseDimension(attrs["r"], svg.diagonal)
svg.ctx.DrawPath(cx, cy, Circle(r))
case "ellipse":
cx := svg.parseDimension(attrs["cx"], svg.width)
cy := svg.parseDimension(attrs["cy"], svg.height)
rx := svg.parseDimension(attrs["rx"], svg.width)
ry := svg.parseDimension(attrs["ry"], svg.height)
svg.ctx.DrawPath(cx, cy, Ellipse(rx, ry))
case "path":
p, err := ParseSVGPath(attrs["d"])
if err != nil && svg.err == nil {
svg.err = parse.NewErrorLexer(svg.z, "bad path: %w", err)
}
svg.ctx.DrawPath(0, 0, p)
case "polygon", "polyline":
points := svg.parsePoints(attrs["points"])
p := &Path{}
for i := 0; i+1 < len(points); i += 2 {
if i == 0 {
p.MoveTo(points[0], points[1])
} else {
p.LineTo(points[i], points[i+1])
}
}
if tag == "polygon" {
p.Close()
}
svg.ctx.DrawPath(0.0, 0.0, p)
case "line":
p := &Path{}
x1 := svg.parseDimension(attrs["x1"], svg.width)
y1 := svg.parseDimension(attrs["y1"], svg.height)
x2 := svg.parseDimension(attrs["x2"], svg.width)
y2 := svg.parseDimension(attrs["y2"], svg.height)
p.MoveTo(x1, y1)
p.LineTo(x2, y2)
svg.ctx.DrawPath(0.0, 0.0, p)
case "rect":
x := svg.parseDimension(attrs["x"], svg.width)
y := svg.parseDimension(attrs["y"], svg.height)
width := svg.parseDimension(attrs["width"], svg.width)
height := svg.parseDimension(attrs["height"], svg.height)
if attrs["rx"] == "" && attrs["ry"] == "" {
svg.ctx.DrawPath(x, y, Rectangle(width, height))
} else {
// TODO: handle both rx and ry
var r float64
if attrs["ry"] == "" {
r = svg.parseDimension(attrs["rx"], svg.width)
} else {
r = svg.parseDimension(attrs["ry"], svg.height)
}
svg.ctx.DrawPath(x, y, RoundedRectangle(width, height, r))
}
case "text":
svg.state.textX = svg.parseDimension(attrs["x"], svg.width)
svg.state.textY = svg.parseDimension(attrs["y"], svg.height)
}
}
func ParseSVG(r io.Reader) (*Canvas, error) {
z := parse.NewInput(r)
defer z.Restore()
l := xml.NewLexer(z)
svg := svgParser{
z: z,
defs: map[string]svgDef{},
fonts: map[string]*FontFamily{},
activeDefs: map[string]svgDef{},
}
for {
tt, data := l.Next()
switch tt {
case xml.ErrorToken:
if l.Err() != io.EOF {
return svg.c, l.Err()
} else if svg.err != nil {
return svg.c, svg.err
} else if svg.c == nil {
return svg.c, fmt.Errorf("expected SVG tag")
}
if svg.c.W == 0.0 || svg.c.H == 0.0 {
svg.c.Fit(0.0)
}
return svg.c, nil
case xml.StartTagToken:
tag := string(data[1:])
tt, attrNames, attrs := svg.parseAttributes(l)
// handle SVG tag and create canvas
if tag == "svg" && svg.c == nil {
width, height, viewbox := svg.parseViewBox(attrs["width"], attrs["height"], attrs["viewBox"])
svg.init(width, height, viewbox)
} else if tag != "svg" && svg.c == nil {
return svg.c, fmt.Errorf("expected SVG tag")
}
// handle special tags
if tag == "style" {
tt, data = l.Next()
if tt == xml.TextToken {
svg.parseStyle(data)
tt, data = l.Next() // end token
} else {
return svg.c, fmt.Errorf("bad style tag")
}
break
} else if tag == "defs" {
if tt != xml.StartTagCloseVoidToken {
svg.parseDefs(l)
}
break
}
// push new state
svg.push(tag, attrs)
// set styling and presentation attributes
props := []cssProperty{}
for _, key := range attrNames {
props = append(props, cssProperty{key, attrs[key]})
}
svg.setStyling(props)
// draw shapes such as circles, paths, etc.
svg.drawShape(tag, attrs)
// set linearGradient, markers, etc.
// these defs depend on the shape or size of the path
for attr, applyDef := range svg.activeDefs {
if applyDef != nil {
applyDef(attr, svg.c)
}
svg.activeDefs[attr] = nil
}
// tag is self-closing
if tt == xml.StartTagCloseVoidToken {
svg.pop()
}
case xml.TextToken:
if 0 < len(svg.elemStack) {
tag := svg.elemStack[len(svg.elemStack)-1].tag
if tag == "text" {
textAlign := Left
if svg.state.textAnchor == "middle" {
textAlign = Center
} else if svg.state.textAnchor == "end" {
textAlign = Right
}
t := html.UnescapeString(string(data))
text := NewTextLine(svg.getFontFace(), t, textAlign)
svg.ctx.DrawText(svg.state.textX, svg.state.textY, text)
}
}
case xml.EndTagToken:
svg.pop()
}
}
}
type cssAttrSelector struct {
op byte // empty, =, ~, |
attr string
val string
}
func (sel cssAttrSelector) AppliesTo(elem svgElem) bool {
switch sel.op {
case 0:
_, ok := elem.attrs[sel.attr]
return ok
case '=':
return elem.attrs[sel.attr] == sel.val
case '~':
vals := strings.Split(elem.attrs[sel.attr], " ")
for _, val := range vals {
if val != "" && val == sel.val {
return true
}
}