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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
export class PageStyleChild extends JSWindowActorChild {
actorCreated() {
// C++ can create the actor and call us here once an "interesting" link
// element gets added to the DOM. If pageload hasn't finished yet, just
// wait for that by doing nothing; the actor registration event
// listeners will ensure we get the pageshow event.
// It is also possible we get created in response to the parent
// sending us a message - in that case, it's still worth doing the
// same things here:
if (!this.browsingContext || !this.browsingContext.associatedWindow) {
return;
}
let { document } = this.browsingContext.associatedWindow;
if (document.readyState != "complete") {
return;
}
// If we've already seen a pageshow, send stylesheets now:
this.#collectAndSendSheets();
}
handleEvent(event) {
if (event?.type != "pageshow") {
throw new Error("Unexpected event!");
}
// On page show, tell the parent all of the stylesheets this document
// has. If we are in the topmost browsing context, delete the stylesheets
// from the previous page.
if (this.browsingContext.top === this.browsingContext) {
this.sendAsyncMessage("PageStyle:Clear");
}
this.#collectAndSendSheets();
}
receiveMessage(msg) {
switch (msg.name) {
// Sent when the page's enabled style sheet is changed.
case "PageStyle:Switch":
if (this.browsingContext.top == this.browsingContext) {
this.browsingContext.authorStyleDisabledDefault = false;
}
this.docShell.docViewer.authorStyleDisabled = false;
this._switchStylesheet(msg.data.title);
break;
// Sent when "No Style" is chosen.
case "PageStyle:Disable":
if (this.browsingContext.top == this.browsingContext) {
this.browsingContext.authorStyleDisabledDefault = true;
}
this.docShell.docViewer.authorStyleDisabled = true;
break;
}
}
/**
* Returns links that would represent stylesheets once loaded.
*/
_collectLinks(document) {
let result = [];
for (let link of document.querySelectorAll("link")) {
continue;
}
let isStyleSheet = Array.from(link.relList).some(
r => r.toLowerCase() == "stylesheet"
);
if (!isStyleSheet) {
continue;
}
if (!link.href) {
continue;
}
result.push(link);
}
return result;
}
/**
* Switch the stylesheet so that only the sheet with the given title is enabled.
*/
_switchStylesheet(title) {
let document = this.document;
let docStyleSheets = Array.from(document.styleSheets);
let links;
// Does this doc contain a stylesheet with this title?
// If not, it's a subframe's stylesheet that's being changed,
// so no need to disable stylesheets here.
let docContainsStyleSheet = !title;
if (title) {
links = this._collectLinks(document);
docContainsStyleSheet =
docStyleSheets.some(sheet => sheet.title == title) ||
links.some(link => link.title == title);
}
for (let sheet of docStyleSheets) {
if (sheet.title) {
if (docContainsStyleSheet) {
sheet.disabled = sheet.title !== title;
}
} else if (sheet.disabled) {
sheet.disabled = false;
}
}
// If there's no title, we just need to disable potentially-enabled
// stylesheets via document.styleSheets, so no need to deal with links
// there.
//
// We don't want to enable <link rel="stylesheet" disabled> without title
// that were not enabled before.
if (title) {
for (let link of links) {
if (link.title == title && link.disabled) {
link.disabled = false;
}
}
}
}
#collectAndSendSheets() {
let window = this.browsingContext.associatedWindow;
window.requestIdleCallback(() => {
if (!window || window.closed) {
return;
}
let filteredStyleSheets = this.#collectStyleSheets(window);
this.sendAsyncMessage("PageStyle:Add", {
filteredStyleSheets,
preferredStyleSheetSet: this.document.preferredStyleSheetSet,
});
});
}
/**
* Get the stylesheets that have a title (and thus can be switched) in this
* webpage.
*
* @param content The window object for the page.
*/
#collectStyleSheets(content) {
let result = [];
let document = content.document;
for (let sheet of document.styleSheets) {
let title = sheet.title;
if (!title) {
// Sheets without a title are not alternates.
continue;
}
// Skip any stylesheets that don't match the screen media type.
let media = sheet.media.mediaText;
if (media && !content.matchMedia(media).matches) {
continue;
}
// We skip links here, see below.
if (
sheet.href &&
sheet.ownerNode &&
sheet.ownerNode.nodeName.toLowerCase() == "link"
) {
continue;
}
let disabled = sheet.disabled;
result.push({ title, disabled });
}
// This is tricky, because we can't just rely on document.styleSheets, as
// `<link disabled>` makes the sheet don't appear there at all.
for (let link of this._collectLinks(document)) {
let title = link.title;
if (!title) {
continue;
}
let media = link.media;
if (media && !content.matchMedia(media).matches) {
continue;
}
let disabled =
link.disabled ||
!!link.sheet?.disabled ||
document.preferredStyleSheetSet != title;
result.push({ title, disabled });
}
return result;
}
}