398 lines
9.7 KiB
Go
398 lines
9.7 KiB
Go
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// Copyright 2017 The oksvg Authors. All rights reserved.
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// created: 2/12/2017 by S.R.Wiley
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//
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// utils.go implements translation of an SVG2.0 path into a rasterx Path.
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package oksvg
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import (
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"errors"
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"log"
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"math"
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"unicode"
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"github.com/srwiley/rasterx"
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"golang.org/x/image/math/fixed"
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)
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type (
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// ErrorMode is the for setting how the parser reacts to unparsed elements
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ErrorMode uint8
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// PathCursor is used to parse SVG format path strings into a rasterx Path
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PathCursor struct {
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rasterx.Path
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placeX, placeY float64
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cntlPtX, cntlPtY float64
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pathStartX, pathStartY float64
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points []float64
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lastKey uint8
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ErrorMode ErrorMode
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inPath bool
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}
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)
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const (
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// IgnoreErrorMode skips un-parsed SVG elements.
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IgnoreErrorMode ErrorMode = iota
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// WarnErrorMode outputs a warning when an un-parsed SVG element is found.
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WarnErrorMode
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// StrictErrorMode causes an error when an un-parsed SVG element is found.
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StrictErrorMode
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)
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var (
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errParamMismatch = errors.New("param mismatch")
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errCommandUnknown = errors.New("unknown command")
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errZeroLengthID = errors.New("zero length id")
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)
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// ReadFloat reads a floating point value and adds it to the cursor's points slice.
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func (c *PathCursor) ReadFloat(numStr string) error {
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last := 0
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isFirst := true
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for i, n := range numStr {
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if n == '.' {
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if isFirst {
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isFirst = false
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continue
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}
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f, err := parseFloat(numStr[last:i], 64)
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if err != nil {
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return err
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}
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c.points = append(c.points, f)
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last = i
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}
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}
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f, err := parseFloat(numStr[last:], 64)
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if err != nil {
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return err
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}
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c.points = append(c.points, f)
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return nil
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}
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// GetPoints reads a set of floating point values from the SVG format number string,
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// and add them to the cursor's points slice.
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func (c *PathCursor) GetPoints(dataPoints string) error {
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lastIndex := -1
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c.points = c.points[0:0]
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lr := ' '
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for i, r := range dataPoints {
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if !unicode.IsNumber(r) && r != '.' && !(r == '-' && lr == 'e') && r != 'e' {
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if lastIndex != -1 {
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if err := c.ReadFloat(dataPoints[lastIndex:i]); err != nil {
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return err
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}
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}
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if r == '-' {
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lastIndex = i
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} else {
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lastIndex = -1
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}
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} else if lastIndex == -1 {
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lastIndex = i
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}
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lr = r
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}
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if lastIndex != -1 && lastIndex != len(dataPoints) {
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if err := c.ReadFloat(dataPoints[lastIndex:]); err != nil {
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return err
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}
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}
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return nil
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}
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// EllipseAt adds a path of an elipse centered at cx, cy of radius rx and ry
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// to the PathCursor
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func (c *PathCursor) EllipseAt(cx, cy, rx, ry float64) {
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c.placeX, c.placeY = cx+rx, cy
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c.points = c.points[0:0]
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c.points = append(c.points, rx, ry, 0.0, 1.0, 0.0, c.placeX, c.placeY)
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c.Path.Start(fixed.Point26_6{
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X: fixed.Int26_6(c.placeX * 64),
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Y: fixed.Int26_6(c.placeY * 64)})
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c.placeX, c.placeY = rasterx.AddArc(c.points, cx, cy, c.placeX, c.placeY, &c.Path)
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c.Path.Stop(true)
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}
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// AddArcFromA adds a path of an arc element to the cursor path to the PathCursor
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func (c *PathCursor) AddArcFromA(points []float64) {
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cx, cy := rasterx.FindEllipseCenter(&points[0], &points[1], points[2]*math.Pi/180, c.placeX,
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c.placeY, points[5], points[6], points[4] == 0, points[3] == 0)
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c.placeX, c.placeY = rasterx.AddArc(c.points, cx, cy, c.placeX, c.placeY, &c.Path)
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}
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// CompilePath translates the svgPath description string into a rasterx path.
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// All valid SVG path elements are interpreted to rasterx equivalents.
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// The resulting path element is stored in the PathCursor.
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func (c *PathCursor) CompilePath(svgPath string) error {
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c.init()
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lastIndex := -1
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for i, v := range svgPath {
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if unicode.IsLetter(v) && v != 'e' {
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if lastIndex != -1 {
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if err := c.addSeg(svgPath[lastIndex:i]); err != nil {
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return err
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}
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}
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lastIndex = i
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}
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}
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if lastIndex != -1 {
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if err := c.addSeg(svgPath[lastIndex:]); err != nil {
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return err
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}
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}
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return nil
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}
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func reflect(px, py, rx, ry float64) (x, y float64) {
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return px*2 - rx, py*2 - ry
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}
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func (c *PathCursor) valsToAbs(last float64) {
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for i := 0; i < len(c.points); i++ {
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last += c.points[i]
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c.points[i] = last
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}
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}
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func (c *PathCursor) pointsToAbs(sz int) {
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lastX := c.placeX
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lastY := c.placeY
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for j := 0; j < len(c.points); j += sz {
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for i := 0; i < sz; i += 2 {
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c.points[i+j] += lastX
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c.points[i+1+j] += lastY
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}
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lastX = c.points[(j+sz)-2]
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lastY = c.points[(j+sz)-1]
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}
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}
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func (c *PathCursor) hasSetsOrMore(sz int, rel bool) bool {
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if !(len(c.points) >= sz && len(c.points)%sz == 0) {
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return false
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}
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if rel {
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c.pointsToAbs(sz)
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}
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return true
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}
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func (c *PathCursor) reflectControlQuad() {
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switch c.lastKey {
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case 'q', 'Q', 'T', 't':
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c.cntlPtX, c.cntlPtY = reflect(c.placeX, c.placeY, c.cntlPtX, c.cntlPtY)
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default:
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c.cntlPtX, c.cntlPtY = c.placeX, c.placeY
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}
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}
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func (c *PathCursor) reflectControlCube() {
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switch c.lastKey {
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case 'c', 'C', 's', 'S':
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c.cntlPtX, c.cntlPtY = reflect(c.placeX, c.placeY, c.cntlPtX, c.cntlPtY)
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default:
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c.cntlPtX, c.cntlPtY = c.placeX, c.placeY
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}
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}
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// addSeg decodes an SVG seqment string into equivalent raster path commands saved
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// in the cursor's Path
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func (c *PathCursor) addSeg(segString string) error {
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// Parse the string describing the numeric points in SVG format
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if err := c.GetPoints(segString[1:]); err != nil {
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return err
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}
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l := len(c.points)
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k := segString[0]
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rel := false
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switch k {
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case 'z':
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fallthrough
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case 'Z':
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if len(c.points) != 0 {
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return errParamMismatch
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}
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if c.inPath {
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c.Path.Stop(true)
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c.placeX = c.pathStartX
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c.placeY = c.pathStartY
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c.inPath = false
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}
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case 'm':
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rel = true
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fallthrough
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case 'M':
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if !c.hasSetsOrMore(2, rel) {
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return errParamMismatch
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}
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c.pathStartX, c.pathStartY = c.points[0], c.points[1]
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c.inPath = true
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c.Path.Start(fixed.Point26_6{X: fixed.Int26_6((c.pathStartX) * 64), Y: fixed.Int26_6((c.pathStartY) * 64)})
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for i := 2; i < l-1; i += 2 {
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c.Path.Line(fixed.Point26_6{
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X: fixed.Int26_6((c.points[i]) * 64),
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Y: fixed.Int26_6((c.points[i+1]) * 64)})
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}
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c.placeX = c.points[l-2]
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c.placeY = c.points[l-1]
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case 'l':
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rel = true
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fallthrough
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case 'L':
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if !c.hasSetsOrMore(2, rel) {
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return errParamMismatch
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}
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for i := 0; i < l-1; i += 2 {
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c.Path.Line(fixed.Point26_6{
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X: fixed.Int26_6((c.points[i]) * 64),
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Y: fixed.Int26_6((c.points[i+1]) * 64)})
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}
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c.placeX = c.points[l-2]
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c.placeY = c.points[l-1]
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case 'v':
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c.valsToAbs(c.placeY)
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fallthrough
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case 'V':
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if !c.hasSetsOrMore(1, false) {
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return errParamMismatch
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}
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for _, p := range c.points {
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c.Path.Line(fixed.Point26_6{
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X: fixed.Int26_6((c.placeX) * 64),
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Y: fixed.Int26_6((p) * 64)})
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}
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c.placeY = c.points[l-1]
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case 'h':
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c.valsToAbs(c.placeX)
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fallthrough
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case 'H':
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if !c.hasSetsOrMore(1, false) {
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return errParamMismatch
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}
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for _, p := range c.points {
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c.Path.Line(fixed.Point26_6{
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X: fixed.Int26_6((p) * 64),
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Y: fixed.Int26_6((c.placeY) * 64)})
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}
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c.placeX = c.points[l-1]
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case 'q':
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rel = true
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fallthrough
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case 'Q':
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if !c.hasSetsOrMore(4, rel) {
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return errParamMismatch
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}
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for i := 0; i < l-3; i += 4 {
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c.Path.QuadBezier(
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fixed.Point26_6{
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X: fixed.Int26_6((c.points[i]) * 64),
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Y: fixed.Int26_6((c.points[i+1]) * 64)},
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fixed.Point26_6{
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X: fixed.Int26_6((c.points[i+2]) * 64),
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Y: fixed.Int26_6((c.points[i+3]) * 64)})
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}
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c.cntlPtX, c.cntlPtY = c.points[l-4], c.points[l-3]
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c.placeX = c.points[l-2]
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c.placeY = c.points[l-1]
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case 't':
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rel = true
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fallthrough
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case 'T':
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if !c.hasSetsOrMore(2, rel) {
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return errParamMismatch
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}
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for i := 0; i < l-1; i += 2 {
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c.reflectControlQuad()
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c.Path.QuadBezier(
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fixed.Point26_6{
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X: fixed.Int26_6((c.cntlPtX) * 64),
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Y: fixed.Int26_6((c.cntlPtY) * 64)},
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fixed.Point26_6{
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X: fixed.Int26_6((c.points[i]) * 64),
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Y: fixed.Int26_6((c.points[i+1]) * 64)})
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c.lastKey = k
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c.placeX = c.points[i]
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c.placeY = c.points[i+1]
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}
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case 'c':
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rel = true
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fallthrough
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case 'C':
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if !c.hasSetsOrMore(6, rel) {
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return errParamMismatch
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}
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for i := 0; i < l-5; i += 6 {
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c.Path.CubeBezier(
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fixed.Point26_6{
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X: fixed.Int26_6((c.points[i]) * 64),
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Y: fixed.Int26_6((c.points[i+1]) * 64)},
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fixed.Point26_6{
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X: fixed.Int26_6((c.points[i+2]) * 64),
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Y: fixed.Int26_6((c.points[i+3]) * 64)},
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fixed.Point26_6{
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X: fixed.Int26_6((c.points[i+4]) * 64),
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Y: fixed.Int26_6((c.points[i+5]) * 64)})
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}
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c.cntlPtX, c.cntlPtY = c.points[l-4], c.points[l-3]
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c.placeX = c.points[l-2]
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c.placeY = c.points[l-1]
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case 's':
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rel = true
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fallthrough
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case 'S':
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if !c.hasSetsOrMore(4, rel) {
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return errParamMismatch
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}
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for i := 0; i < l-3; i += 4 {
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c.reflectControlCube()
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c.Path.CubeBezier(fixed.Point26_6{
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X: fixed.Int26_6((c.cntlPtX) * 64), Y: fixed.Int26_6((c.cntlPtY) * 64)},
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fixed.Point26_6{
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X: fixed.Int26_6((c.points[i]) * 64), Y: fixed.Int26_6((c.points[i+1]) * 64)},
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fixed.Point26_6{
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|
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X: fixed.Int26_6((c.points[i+2]) * 64), Y: fixed.Int26_6((c.points[i+3]) * 64)})
|
||
|
|
c.lastKey = k
|
||
|
|
c.cntlPtX, c.cntlPtY = c.points[i], c.points[i+1]
|
||
|
|
c.placeX = c.points[i+2]
|
||
|
|
c.placeY = c.points[i+3]
|
||
|
|
}
|
||
|
|
case 'a', 'A':
|
||
|
|
if !c.hasSetsOrMore(7, false) {
|
||
|
|
return errParamMismatch
|
||
|
|
}
|
||
|
|
for i := 0; i < l-6; i += 7 {
|
||
|
|
if k == 'a' {
|
||
|
|
c.points[i+5] += c.placeX
|
||
|
|
c.points[i+6] += c.placeY
|
||
|
|
}
|
||
|
|
c.AddArcFromA(c.points[i:])
|
||
|
|
}
|
||
|
|
default:
|
||
|
|
if c.ErrorMode == StrictErrorMode {
|
||
|
|
return errCommandUnknown
|
||
|
|
}
|
||
|
|
if c.ErrorMode == WarnErrorMode {
|
||
|
|
log.Println("Ignoring svg command " + string(k))
|
||
|
|
}
|
||
|
|
}
|
||
|
|
// So we know how to extend some segment types
|
||
|
|
c.lastKey = k
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
func (c *PathCursor) init() {
|
||
|
|
c.placeX = 0.0
|
||
|
|
c.placeY = 0.0
|
||
|
|
c.points = c.points[0:0]
|
||
|
|
c.lastKey = ' '
|
||
|
|
c.Path.Clear()
|
||
|
|
c.inPath = false
|
||
|
|
}
|