1 files changed, 82 insertions, 0 deletions
diff --git a/dom/manifest/ManifestIcons.sys.mjs b/dom/manifest/ManifestIcons.sys.mjs
new file mode 100644
index 0000000000..9994c40d55
--- /dev/null
+++ b/dom/manifest/ManifestIcons.sys.mjs
@@ -0,0 +1,82 @@
+/* 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
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+export var ManifestIcons = {
+  async browserFetchIcon(aBrowser, manifest, iconSize) {
+    const msgKey = "DOM:WebManifest:fetchIcon";
+
+    const actor =
+      aBrowser.browsingContext.currentWindowGlobal.getActor("ManifestMessages");
+    const reply = await actor.sendQuery(msgKey, { manifest, iconSize });
+    if (!reply.success) {
+      throw reply.result;
+    }
+    return reply.result;
+  },
+
+  async contentFetchIcon(aWindow, manifest, iconSize) {
+    return getIcon(aWindow, toIconArray(manifest.icons), iconSize);
+  },
+};
+
+function parseIconSize(size) {
+  if (size === "any" || size === "") {
+    // We want icons without size specified to sorted
+    // as the largest available icons
+    return Number.MAX_SAFE_INTEGER;
+  }
+  // 100x100 will parse as 100
+  return parseInt(size, 10);
+}
+
+// Create an array of icons sorted by their size
+function toIconArray(icons) {
+  const iconBySize = [];
+  icons.forEach(icon => {
+    const sizes = "sizes" in icon ? icon.sizes : "";
+    sizes.forEach(size => {
+      iconBySize.push({ src: icon.src, size: parseIconSize(size) });
+    });
+  });
+  return iconBySize.sort((a, b) => a.size - b.size);
+}
+
+async function getIcon(aWindow, icons, expectedSize) {
+  if (!icons.length) {
+    throw new Error("Could not find valid icon");
+  }
+  // We start trying the smallest icon that is larger than the requested
+  // size and go up to the largest icon if they fail, if all those fail
+  // go back down to the smallest
+  let index = icons.findIndex(icon => icon.size >= expectedSize);
+  if (index === -1) {
+    index = icons.length - 1;
+  }
+
+  return fetchIcon(aWindow, icons[index].src).catch(err => {
+    // Remove all icons with the failed source, the same source
+    // may have been used for multiple sizes
+    icons = icons.filter(x => x.src !== icons[index].src);
+    return getIcon(aWindow, icons, expectedSize);
+  });
+}
+
+async function fetchIcon(aWindow, src) {
+  const iconURL = new aWindow.URL(src, aWindow.location);
+  // If this is already a data URL then no need to load it again.
+  if (iconURL.protocol === "data:") {
+    return iconURL.href;
+  }
+
+  const request = new aWindow.Request(iconURL, { mode: "cors" });
+  request.overrideContentPolicyType(Ci.nsIContentPolicy.TYPE_IMAGE);
+  const response = await aWindow.fetch(request);
+  const blob = await response.blob();
+  return new Promise((resolve, reject) => {
+    const reader = new FileReader();
+    reader.onloadend = () => resolve(reader.result);
+    reader.onerror = reject;
+    reader.readAsDataURL(blob);
+  });
+}