From 5dd5cb88814c86919e18527229269e5d1bb82dbc Mon Sep 17 00:00:00 2001 From: Kurt Jung Date: Tue, 28 Jan 2014 15:35:50 -0500 Subject: Support for unstyled, path-only SVG images of the type generated by the jSignature web control. --- svgbasic.go | 210 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 210 insertions(+) create mode 100644 svgbasic.go (limited to 'svgbasic.go') diff --git a/svgbasic.go b/svgbasic.go new file mode 100644 index 0000000..4c58f95 --- /dev/null +++ b/svgbasic.go @@ -0,0 +1,210 @@ +/* + * Copyright (c) 2014 Kurt Jung (Gmail: kurt.w.jung) + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +package gofpdf + +import ( + "encoding/xml" + "fmt" + "io/ioutil" + "strconv" + "strings" +) + +var pathCmdSub *strings.Replacer + +func init() { + // Handle permitted constructions like "100L200,230" + pathCmdSub = strings.NewReplacer(",", " ", + "L", " L ", "l", " l ", + "C", " C ", "c", " c ", + "M", " M ", "m", " m ") +} + +// SvgBasicSegmentType describes a single curve or position segment +type SvgBasicSegmentType struct { + Cmd byte // See http://www.w3.org/TR/SVG/paths.html for path command structure + Arg [6]float64 +} + +func absolutizePath(segs []SvgBasicSegmentType) { + var x, y float64 + var segPtr *SvgBasicSegmentType + adjust := func(pos int, adjX, adjY float64) { + segPtr.Arg[pos] += adjX + segPtr.Arg[pos+1] += adjY + } + for j, seg := range segs { + segPtr = &segs[j] + if j == 0 && seg.Cmd == 'm' { + segPtr.Cmd = 'M' + } + switch segPtr.Cmd { + case 'M': + x = seg.Arg[0] + y = seg.Arg[1] + case 'm': + adjust(0, x, y) + segPtr.Cmd = 'M' + x = segPtr.Arg[0] + y = segPtr.Arg[1] + case 'L': + x = seg.Arg[0] + y = seg.Arg[1] + case 'l': + adjust(0, x, y) + segPtr.Cmd = 'L' + x = segPtr.Arg[0] + y = segPtr.Arg[1] + case 'C': + x = seg.Arg[4] + y = seg.Arg[5] + case 'c': + adjust(0, x, y) + adjust(2, x, y) + adjust(4, x, y) + segPtr.Cmd = 'C' + x = segPtr.Arg[4] + y = segPtr.Arg[5] + } + } +} + +func pathParse(pathStr string) (segs []SvgBasicSegmentType, err error) { + var seg SvgBasicSegmentType + var j, argJ, argCount, prevArgCount int + setup := func(n int) { + // It is not strictly necessary to clear arguments, but result may be clearer + // to caller + for j := 0; j < len(seg.Arg); j++ { + seg.Arg[j] = 0.0 + } + argJ = 0 + argCount = n + prevArgCount = n + } + var str string + var c byte + pathStr = pathCmdSub.Replace(pathStr) + strList := strings.Fields(pathStr) + count := len(strList) + for j = 0; j < count && err == nil; j++ { + str = strList[j] + if argCount == 0 { // Look for path command or argument continuation + c = str[0] + if c == '-' || (c >= '0' && c <= '9') { // More arguments + if j > 0 { + setup(prevArgCount) + // Repeat previous action + if seg.Cmd == 'M' { + seg.Cmd = 'L' + } else if seg.Cmd == 'm' { + seg.Cmd = 'l' + } + } else { + err = fmt.Errorf("expecting SVG path command at first position, got %s", str) + } + } + } + if err == nil { + if argCount == 0 { + seg.Cmd = str[0] + switch seg.Cmd { + case 'M', 'm': // Absolute/relative moveto: x, y + setup(2) + case 'C', 'c': // Absolute/relative Bézier curve: cx0, cy0, cx1, cy1, x1, y1 + setup(6) + case 'L', 'l': // Absolute/relative lineto: x, y + setup(2) + default: + err = fmt.Errorf("expecting SVG path command at position %d, got %s", j, str) + } + } else { + seg.Arg[argJ], err = strconv.ParseFloat(str, 64) + if err == nil { + argJ++ + argCount-- + if argCount == 0 { + segs = append(segs, seg) + } + } + } + } + } + if err == nil { + if argCount == 0 { + absolutizePath(segs) + } else { + err = fmt.Errorf("Expecting additional (%d) numeric arguments", argCount) + } + } + return +} + +// SvgBasicType aggregates the information needed to describe a multi-segment +// basic vector image +type SvgBasicType struct { + Wd, Ht float64 + Segments [][]SvgBasicSegmentType +} + +// SvgBasicParse parses a simple scalable vector graphics (SVG) buffer into a +// descriptor. Only a small subset of the SVG standard, in particular the path +// information generated by jSignature, is supported. The returned path data +// includes only the commands 'M' (absolute moveto: x, y), 'L' (absolute +// lineto: x, y), and 'C' (absolute cubic Bézier curve: cx0, cy0, cx1, cy1, +// x1,y1). +func SvgBasicParse(buf []byte) (sig SvgBasicType, err error) { + type pathType struct { + D string `xml:"d,attr"` + } + type srcType struct { + Wd float64 `xml:"width,attr"` + Ht float64 `xml:"height,attr"` + Paths []pathType `xml:"path"` + } + var src srcType + err = xml.Unmarshal(buf, &src) + if err == nil { + if src.Wd > 0 && src.Ht > 0 { + sig.Wd, sig.Ht = src.Wd, src.Ht + var segs []SvgBasicSegmentType + for _, path := range src.Paths { + if err == nil { + segs, err = pathParse(path.D) + if err == nil { + sig.Segments = append(sig.Segments, segs) + } + } + } + } else { + err = fmt.Errorf("Unacceptable values for basic SVG extent: %.2f x %.2f", + sig.Wd, sig.Ht) + } + } + return +} + +// SvgBasicParse parses a simple scalable vector graphics (SVG) file into a +// basic descriptor. See SvgBasicParse for additional comments. +func SvgBasicFileParse(svgFileStr string) (sig SvgBasicType, err error) { + var buf []byte + buf, err = ioutil.ReadFile(svgFileStr) + if err == nil { + sig, err = SvgBasicParse(buf) + } + return +} -- cgit v1.2.1-24-ge1ad