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refactor(chromium): drop paint-callback polyfill now that chromedp is pinned

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This commit is contained in:
Julien Neuhart
2026-04-30 14:05:03 +02:00
parent ace379a92c
commit 45b9f32351
3 changed files with 2 additions and 145 deletions
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pkg/modules/chromium/browser.go
-2
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@@ -317,7 +317,6 @@ func (b *chromiumBrowser) pdf(ctx context.Context, logger *slog.Logger, url, out
disableJavaScriptActionFunc(logger, b.arguments.disableJavaScript),
setCookiesActionFunc(logger, options.Cookies),
userAgentOverride(logger, options.UserAgent),
injectPaintCallbacksPolyfillActionFunc(logger),
navigateActionFunc(logger, url, options.SkipNetworkIdleEvent, options.SkipNetworkAlmostIdleEvent),
hideDefaultWhiteBackgroundActionFunc(logger, options.OmitBackground, options.PrintBackground),
forceExactColorsActionFunc(logger, options.PrintBackground),
@@ -344,7 +343,6 @@ func (b *chromiumBrowser) screenshot(ctx context.Context, logger *slog.Logger, u
disableJavaScriptActionFunc(logger, b.arguments.disableJavaScript),
setCookiesActionFunc(logger, options.Cookies),
userAgentOverride(logger, options.UserAgent),
injectPaintCallbacksPolyfillActionFunc(logger),
navigateActionFunc(logger, url, options.SkipNetworkIdleEvent, options.SkipNetworkAlmostIdleEvent),
hideDefaultWhiteBackgroundActionFunc(logger, options.OmitBackground, true),
forceExactColorsActionFunc(logger, true),
pkg/modules/chromium/paint_polyfill.go
-141
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@@ -1,141 +0,0 @@
package chromium
import (
"context"
"fmt"
"log/slog"
"github.com/chromedp/cdproto/page"
"github.com/chromedp/chromedp"
)
// paintCallbacksPolyfill is a JavaScript shim installed before any user
// script runs. Replaces requestAnimationFrame, cancelAnimationFrame,
// ResizeObserver, and IntersectionObserver with timer-backed
// implementations. Headless Chromium's print-emulation pipeline does
// not tick the compositor refresh driver between the load event and
// the Page.printToPDF call, which leaves the native callback queues
// stalled and breaks charting libraries (visx, ApexCharts) that rely
// on rAF-gated measurement. The polyfill exposes the same APIs with
// timer semantics so user-scheduled callbacks fire in print mode and
// the rendered output matches a live browser. See
// https://github.com/gotenberg/gotenberg/issues/1535.
const paintCallbacksPolyfill = `
(function () {
var nextHandle = 0;
var pending = new Map();
window.requestAnimationFrame = function (callback) {
var handle = ++nextHandle;
pending.set(handle, setTimeout(function () {
pending.delete(handle);
callback(performance.now());
}, 16));
return handle;
};
window.cancelAnimationFrame = function (handle) {
clearTimeout(pending.get(handle));
pending.delete(handle);
};
function PollingResizeObserver(callback) {
this._callback = callback;
this._observed = [];
this._timer = null;
}
PollingResizeObserver.prototype.observe = function (el) {
var entry = { target: el, lastW: -1, lastH: -1 };
this._observed.push(entry);
if (!this._timer) {
var self = this;
this._timer = setInterval(function () { self._tick(); }, 100);
}
this._tick();
};
PollingResizeObserver.prototype.unobserve = function (el) {
this._observed = this._observed.filter(function (e) { return e.target !== el; });
if (this._observed.length === 0 && this._timer) {
clearInterval(this._timer);
this._timer = null;
}
};
PollingResizeObserver.prototype.disconnect = function () {
this._observed = [];
if (this._timer) {
clearInterval(this._timer);
this._timer = null;
}
};
PollingResizeObserver.prototype._tick = function () {
var changed = [];
for (var i = 0; i < this._observed.length; i++) {
var e = this._observed[i];
var w = e.target.offsetWidth;
var h = e.target.offsetHeight;
if (w !== e.lastW || h !== e.lastH) {
e.lastW = w;
e.lastH = h;
changed.push({
target: e.target,
contentRect: { width: w, height: h, top: 0, left: 0, right: w, bottom: h, x: 0, y: 0 },
borderBoxSize: [{ inlineSize: w, blockSize: h }],
contentBoxSize: [{ inlineSize: w, blockSize: h }],
devicePixelContentBoxSize: [{ inlineSize: w, blockSize: h }],
});
}
}
if (changed.length > 0) {
try { this._callback(changed, this); } catch (err) { console.error(err); }
}
};
window.ResizeObserver = PollingResizeObserver;
function ImmediateIntersectionObserver(callback) {
this._callback = callback;
this._observed = [];
}
ImmediateIntersectionObserver.prototype.observe = function (el) {
this._observed.push(el);
var self = this;
setTimeout(function () {
var rect = el.getBoundingClientRect();
var entry = {
target: el,
isIntersecting: true,
intersectionRatio: 1,
boundingClientRect: rect,
intersectionRect: rect,
rootBounds: null,
time: performance.now(),
};
try { self._callback([entry], self); } catch (err) { console.error(err); }
}, 0);
};
ImmediateIntersectionObserver.prototype.unobserve = function (el) {
this._observed = this._observed.filter(function (x) { return x !== el; });
};
ImmediateIntersectionObserver.prototype.disconnect = function () {
this._observed = [];
};
ImmediateIntersectionObserver.prototype.takeRecords = function () { return []; };
window.IntersectionObserver = ImmediateIntersectionObserver;
})();
`
// injectPaintCallbacksPolyfillActionFunc installs the
// [paintCallbacksPolyfill] via [page.AddScriptToEvaluateOnNewDocument]
// before any user script runs. Runs on every conversion: Chromium's
// headless-print pipeline does not fire the native rAF,
// ResizeObserver, and IntersectionObserver, so the timer-backed
// replacements fire the user's callbacks when the page relies on them
// and have no effect otherwise.
func injectPaintCallbacksPolyfillActionFunc(logger *slog.Logger) chromedp.ActionFunc {
return func(ctx context.Context) error {
logger.DebugContext(ctx, "inject paint-callbacks polyfill")
_, err := page.AddScriptToEvaluateOnNewDocument(paintCallbacksPolyfill).Do(ctx)
if err != nil {
return fmt.Errorf("inject paint-callbacks polyfill: %w", err)
}
return nil
}
}
test/integration/features/chromium_convert_html.feature
+2 -2
View File
@@ -195,7 +195,7 @@ Feature: /forms/chromium/convert/html
Wait delay > 2 seconds or expression window globalVar === 'ready' returns true.
"""
Scenario: POST /forms/chromium/convert/html (paint-callback polyfill fires rAF / ResizeObserver / IntersectionObserver with waitForExpression)
Scenario: POST /forms/chromium/convert/html (rAF / ResizeObserver / IntersectionObserver fire with waitForExpression)
Given I have a default Gotenberg container
When I make a "POST" request to Gotenberg at the "/forms/chromium/convert/html" endpoint with the following form data and header(s):
| files | testdata/paint-callbacks-html/index.html | file |
@@ -219,7 +219,7 @@ Feature: /forms/chromium/convert/html
io-fired
"""
Scenario: POST /forms/chromium/convert/html (paint-callback polyfill fires rAF / ResizeObserver / IntersectionObserver with waitDelay and emulatedMediaType=print)
Scenario: POST /forms/chromium/convert/html (rAF / ResizeObserver / IntersectionObserver fire with waitDelay and emulatedMediaType=print)
Given I have a default Gotenberg container
When I make a "POST" request to Gotenberg at the "/forms/chromium/convert/html" endpoint with the following form data and header(s):
| files | testdata/paint-callbacks-html/index.html | file |