e71bf16d71
deviceScaleFactor pass-through to chromedp EmulateViewport; --scale 2 produces 2880x1800 PNGs for hidpi store galleries. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
113 lines
3.6 KiB
Go
113 lines
3.6 KiB
Go
// Package shot captures a PNG screenshot of a rendered CMS page using a
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// headless Chromium (chromedp / CDP). It is the image-capture half of the
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// `ninja theme screenshot` harness; dojo's Playwright runner only ingests
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// pass/fail JSON, so capture lives here.
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package shot
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import (
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"context"
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"fmt"
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"net/url"
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"strings"
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"time"
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"github.com/chromedp/cdproto/emulation"
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"github.com/chromedp/cdproto/network"
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"github.com/chromedp/chromedp"
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)
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// Options configures a single screenshot capture.
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type Options struct {
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URL string // full page URL to navigate to
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Width int // viewport width in px
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Height int // viewport height in px
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FullPage bool // capture the full scroll height, not just the viewport
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WaitSelector string // CSS selector to wait for before capturing (e.g. "section")
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Timeout time.Duration // overall navigation+capture timeout
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Mode string // "" (site default), "light" or "dark" — sets the bn-theme cookie + emulated prefers-color-scheme before navigation
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Scale float64 // device scale factor; 0 = 1.0. 2 captures retina PNGs (Width*2 × Height*2 px)
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}
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// PreviewURL composes the gallery-page URL with the render-only override.
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// host is the gallery site base (scheme+host), slug is the page path ("/"),
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// theme is the bare theme key written to ?preview_template.
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func PreviewURL(host, slug, theme string) string {
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host = strings.TrimRight(host, "/")
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if slug == "" {
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slug = "/"
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}
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if !strings.HasPrefix(slug, "/") {
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slug = "/" + slug
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}
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return fmt.Sprintf("%s%s?preview_template=%s", host, slug, url.QueryEscape(theme))
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}
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// Capture navigates to opts.URL in a headless Chromium and returns PNG bytes.
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func Capture(ctx context.Context, opts Options) ([]byte, error) {
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if opts.Width == 0 {
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opts.Width = 1440
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}
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if opts.Height == 0 {
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opts.Height = 900
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}
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if opts.Timeout == 0 {
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opts.Timeout = 30 * time.Second
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}
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allocCtx, cancelAlloc := chromedp.NewExecAllocator(ctx,
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append(chromedp.DefaultExecAllocatorOptions[:],
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chromedp.WindowSize(opts.Width, opts.Height),
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chromedp.Flag("headless", true),
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)...,
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)
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defer cancelAlloc()
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browserCtx, cancelBrowser := chromedp.NewContext(allocCtx)
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defer cancelBrowser()
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timeoutCtx, cancelTimeout := context.WithTimeout(browserCtx, opts.Timeout)
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defer cancelTimeout()
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var buf []byte
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viewport := []chromedp.EmulateViewportOption(nil)
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if opts.Scale > 0 {
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viewport = append(viewport, chromedp.EmulateScale(opts.Scale))
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}
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tasks := chromedp.Tasks{
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chromedp.EmulateViewport(int64(opts.Width), int64(opts.Height), viewport...),
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}
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if opts.Mode == "light" || opts.Mode == "dark" {
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u, err := url.Parse(opts.URL)
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if err != nil {
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return nil, fmt.Errorf("parse %s: %w", opts.URL, err)
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}
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host := u.Hostname()
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mode := opts.Mode
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tasks = append(tasks,
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chromedp.ActionFunc(func(ctx context.Context) error {
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return network.SetCookie("bn-theme", mode).
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WithDomain(host).WithPath("/").Do(ctx)
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}),
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emulation.SetEmulatedMedia().WithFeatures([]*emulation.MediaFeature{
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{Name: "prefers-color-scheme", Value: mode},
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}),
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)
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}
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tasks = append(tasks, chromedp.Navigate(opts.URL))
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if opts.WaitSelector != "" {
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tasks = append(tasks, chromedp.WaitVisible(opts.WaitSelector, chromedp.ByQuery))
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} else {
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tasks = append(tasks, chromedp.WaitReady("body", chromedp.ByQuery))
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}
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if opts.FullPage {
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tasks = append(tasks, chromedp.FullScreenshot(&buf, 90))
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} else {
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tasks = append(tasks, chromedp.CaptureScreenshot(&buf))
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}
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if err := chromedp.Run(timeoutCtx, tasks); err != nil {
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return nil, fmt.Errorf("capture %s: %w", opts.URL, err)
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}
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return buf, nil
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}
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