svg.go

     1  // Copyright 2014 Google Inc. All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package driver
    16  
    17  import (
    18  	"regexp"
    19  	"strings"
    20  
    21  	"github.com/google/pprof/third_party/svgpan"
    22  )
    23  
    24  var (
    25  	viewBox  = regexp.MustCompile(`<svg\s*width="[^"]+"\s*height="[^"]+"\s*viewBox="[^"]+"`)
    26  	graphID  = regexp.MustCompile(`<g id="graph\d"`)
    27  	svgClose = regexp.MustCompile(`</svg>`)
    28  )
    29  
    30  // massageSVG enhances the SVG output from DOT to provide better
    31  // panning inside a web browser. It uses the svgpan library, which is
    32  // embedded into the svgpan.JSSource variable.
    33  func massageSVG(svg string) string {
    34  	// Work around for dot bug which misses quoting some ampersands,
    35  	// resulting on unparsable SVG.
    36  	svg = strings.Replace(svg, "&;", "&amp;;", -1)
    37  
    38  	// Dot's SVG output is
    39  	//
    40  	//    <svg width="___" height="___"
    41  	//     viewBox="___" xmlns=...>
    42  	//    <g id="graph0" transform="...">
    43  	//    ...
    44  	//    </g>
    45  	//    </svg>
    46  	//
    47  	// Change it to
    48  	//
    49  	//    <svg width="100%" height="100%"
    50  	//     xmlns=...>
    51  
    52  	//    <script type="text/ecmascript"><![CDATA[` ..$(svgpan.JSSource)... `]]></script>`
    53  	//    <g id="viewport" transform="translate(0,0)">
    54  	//    <g id="graph0" transform="...">
    55  	//    ...
    56  	//    </g>
    57  	//    </g>
    58  	//    </svg>
    59  
    60  	if loc := viewBox.FindStringIndex(svg); loc != nil {
    61  		svg = svg[:loc[0]] +
    62  			`<svg width="100%" height="100%"` +
    63  			svg[loc[1]:]
    64  	}
    65  
    66  	if loc := graphID.FindStringIndex(svg); loc != nil {
    67  		svg = svg[:loc[0]] +
    68  			`<script type="text/ecmascript"><![CDATA[` + svgpan.JSSource + `]]></script>` +
    69  			`<g id="viewport" transform="scale(0.5,0.5) translate(0,0)">` +
    70  			svg[loc[0]:]
    71  	}
    72  
    73  	if loc := svgClose.FindStringIndex(svg); loc != nil {
    74  		svg = svg[:loc[0]] +
    75  			`</g>` +
    76  			svg[loc[0]:]
    77  	}
    78  
    79  	return svg
    80  }
    81
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