82 lines
1.8 KiB
Go
82 lines
1.8 KiB
Go
package d2latex
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import (
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_ "embed"
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"fmt"
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"math"
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"regexp"
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"strconv"
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"github.com/dop251/goja"
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"oss.terrastruct.com/util-go/xdefer"
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)
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var pxPerEx = 8
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//go:embed polyfills.js
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var polyfillsJS string
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//go:embed setup.js
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var setupJS string
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//go:embed mathjax.js
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var mathjaxJS string
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// Matches this
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// <svg style="background: white;" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="563" height="326" viewBox="-100 -100 563 326"><style type="text/css">
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var svgRe = regexp.MustCompile(`<svg[^>]+width="([0-9\.]+)ex" height="([0-9\.]+)ex"[^>]+>`)
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func Render(s string) (_ string, err error) {
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defer xdefer.Errorf(&err, "latex failed to parse")
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vm := goja.New()
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if _, err := vm.RunString(polyfillsJS); err != nil {
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return "", err
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}
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if _, err := vm.RunString(mathjaxJS); err != nil {
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return "", err
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}
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if _, err := vm.RunString(setupJS); err != nil {
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return "", err
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}
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val, err := vm.RunString(fmt.Sprintf(`adaptor.innerHTML(html.convert(`+"`"+"%s`"+`, {
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em: %d,
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ex: %d,
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}))`, s, pxPerEx*2, pxPerEx))
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if err != nil {
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return "", err
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}
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return val.String(), nil
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}
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func Measure(s string) (width, height int, err error) {
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defer xdefer.Errorf(&err, "latex failed to parse")
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svg, err := Render(s)
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if err != nil {
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return 0, 0, err
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}
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dims := svgRe.FindAllStringSubmatch(svg, -1)
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if len(dims) != 1 || len(dims[0]) != 3 {
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return 0, 0, fmt.Errorf("svg parsing failed for latex: %v", svg)
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}
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wEx := dims[0][1]
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hEx := dims[0][2]
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wf, err := strconv.ParseFloat(wEx, 64)
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if err != nil {
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return 0, 0, fmt.Errorf("svg parsing failed for latex: %v", svg)
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}
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hf, err := strconv.ParseFloat(hEx, 64)
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if err != nil {
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return 0, 0, fmt.Errorf("svg parsing failed for latex: %v", svg)
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}
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return int(math.Ceil(wf * float64(pxPerEx))), int(math.Ceil(hf * float64(pxPerEx))), nil
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}
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