/
mermaid.go
85 lines (73 loc) · 2.14 KB
/
mermaid.go
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package mermaid_go
import (
"context"
_ "embed"
"errors"
"fmt"
"github.com/chromedp/cdproto/dom"
"github.com/chromedp/cdproto/runtime"
"github.com/chromedp/chromedp"
)
//go:embed mermaid.min.js
var SOURCE_MERMAID string
var DEFAULT_PAGE = `data:text/html,<!DOCTYPE html>
<html lang="en">
<head><meta charset="utf-8"></head>
<body></body>
</html>`
var ERR_MERMAID_NOT_READY = errors.New("mermaid.js initial failed")
type BoxModel = dom.BoxModel
type RenderEngine struct {
ctx context.Context
cancel context.CancelFunc
}
func NewRenderEngine(ctx context.Context, statements ...string) (*RenderEngine, error) {
ctx, cancel := chromedp.NewContext(ctx)
var (
lib_ready *runtime.RemoteObject
)
actions := []chromedp.Action{
chromedp.Navigate(DEFAULT_PAGE),
chromedp.Evaluate(SOURCE_MERMAID, &lib_ready),
}
for _, stmt := range statements {
actions = append(actions, chromedp.Evaluate(stmt, nil))
}
err := chromedp.Run(ctx, actions...)
if err == nil && lib_ready.ObjectID != "" {
err = ERR_MERMAID_NOT_READY
}
return &RenderEngine{
ctx: ctx,
cancel: cancel,
}, err
}
func (r *RenderEngine) Render(content string) (string, error) {
var (
result string
)
err := chromedp.Run(r.ctx,
chromedp.Evaluate(fmt.Sprintf("mermaid.render('mermaid', `%s`).then(({ svg }) => { return svg; });", content), &result, func(p *runtime.EvaluateParams) *runtime.EvaluateParams {
return p.WithAwaitPromise(true)
}),
)
return result, err
}
func (r *RenderEngine) RenderAsScaledPng(content string, scale float64) ([]byte, *BoxModel, error) {
var (
result_in_bytes []byte
model *dom.BoxModel
)
err := chromedp.Run(r.ctx,
chromedp.Evaluate(fmt.Sprintf("mermaid.render('mermaid', `%s`).then(({ svg }) => { document.body.innerHTML = svg; });", content), nil),
chromedp.ScreenshotScale("#mermaid", scale, &result_in_bytes, chromedp.ByID),
chromedp.Dimensions("#mermaid", &model, chromedp.ByID),
)
return result_in_bytes, interface{}(model).(*BoxModel), err
}
func (r *RenderEngine) RenderAsPng(content string) ([]byte, *BoxModel, error) {
return r.RenderAsScaledPng(content, 1.0)
}
func (r *RenderEngine) Cancel() {
r.cancel()
}