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svg.go
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svg.go
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// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package svg provides tools related to handling of SVG files
package svg
import (
"bytes"
"regexp"
"strings"
)
var (
viewBox = regexp.MustCompile(`<svg\s*width="[^"]+"\s*height="[^"]+"\s*viewBox="[^"]+"`)
graphId = regexp.MustCompile(`<g id="graph\d"`)
svgClose = regexp.MustCompile(`</svg>`)
)
// Massage enhances the SVG output from DOT to provide bettern
// panning inside a web browser. It uses the SVGPan library, which is
// accessed through the svgPan URL.
func Massage(in bytes.Buffer, svgPan string) string {
svg := string(in.Bytes())
// Work around for dot bug which misses quoting some ampersands,
// resulting on unparsable SVG.
svg = strings.Replace(svg, "&;", "&;", -1)
if svgPan == "" {
return svg
}
//Dot's SVG output is
//
// <svg width="___" height="___"
// viewBox="___" xmlns=...>
// <g id="graph0" transform="...">
// ...
// </g>
// </svg>
//
// Change it to
//
// <svg width="100%" height="100%"
// xmlns=...>
// <script xlink:href=" ...$svgpan.. "/>
// <g id="viewport" transform="translate(0,0)">
// <g id="graph0" transform="...">
// ...
// </g>
// </g>
// </svg>
if loc := viewBox.FindStringIndex(svg); loc != nil {
svg = svg[:loc[0]] +
`<svg width="100%" height="100%"` +
svg[loc[1]:]
}
if loc := graphId.FindStringIndex(svg); loc != nil {
svg = svg[:loc[0]] +
`<script xlink:href="` + svgPan + `"/>` +
`<g id="viewport" transform="scale(0.5,0.5) translate(0,0)">` +
svg[loc[0]:]
}
if loc := svgClose.FindStringIndex(svg); loc != nil {
svg = svg[:loc[0]] +
`</g>` +
svg[loc[0]:]
}
return svg
}