1 files changed, 215 insertions, 0 deletions
diff --git a/addon-sdk/source/lib/framescript/context-menu.js b/addon-sdk/source/lib/framescript/context-menu.js
new file mode 100644
index 000000000..3915b7cd8
--- /dev/null
+++ b/addon-sdk/source/lib/framescript/context-menu.js
@@ -0,0 +1,215 @@
+/* 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/. */
+"use strict";
+
+const { query, constant, cache } = require("sdk/lang/functional");
+const { pairs, each, map, object } = require("sdk/util/sequence");
+const { nodeToMessageManager } = require("./util");
+
+// Decorator function that takes `f` function and returns one that attempts
+// to run `f` with given arguments. In case of exception error is logged
+// and `fallback` is returned instead.
+const Try = (fn, fallback=null) => (...args) => {
+  try {
+    return fn(...args);
+  } catch(error) {
+    console.error(error);
+    return fallback;
+  }
+};
+
+// Decorator funciton that takes `f` function and returns one that returns
+// JSON cloned result of whatever `f` returns for given arguments.
+const JSONReturn = f => (...args) => JSON.parse(JSON.stringify(f(...args)));
+
+const Null = constant(null);
+
+// Table of readers mapped to field names they're going to be reading.
+const readers = Object.create(null);
+// Read function takes "contextmenu" event target `node` and returns table of
+// read field names mapped to appropriate values. Read uses above defined read
+// table to read data for all registered readers.
+const read = node =>
+  object(...map(([id, read]) => [id, read(node, id)], pairs(readers)));
+
+// Table of built-in readers, each takes a descriptor and returns a reader:
+// descriptor -> node -> JSON
+const parsers = Object.create(null)
+// Function takes a descriptor of the remotely defined reader and parsese it
+// to construct a local reader that's going to read out data from context menu
+// target.
+const parse = descriptor => {
+  const parser = parsers[descriptor.category];
+  if (!parser) {
+    console.error("Unknown reader descriptor was received", descriptor, `"${descriptor.category}"`);
+    return Null
+  }
+  return Try(parser(descriptor));
+}
+
+// TODO: Test how chrome's mediaType behaves to try and match it's behavior.
+const HTML_NS = "http://www.w3.org/1999/xhtml";
+const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+const SVG_NS = "http://www.w3.org/2000/svg";
+
+// Firefox always creates a HTMLVideoElement when loading an ogg file
+// directly. If the media is actually audio, be smarter and provide a
+// context menu with audio operations.
+// Source: https://github.com/mozilla/gecko-dev/blob/28c2fca3753c5371643843fc2f2f205146b083b7/browser/base/content/nsContextMenu.js#L632-L637
+const isVideoLoadingAudio = node =>
+  node.readyState >= node.HAVE_METADATA &&
+    (node.videoWidth == 0 || node.videoHeight == 0)
+
+const isVideo = node =>
+  node instanceof node.ownerDocument.defaultView.HTMLVideoElement &&
+  !isVideoLoadingAudio(node);
+
+const isAudio = node => {
+  const {HTMLVideoElement, HTMLAudioElement} = node.ownerDocument.defaultView;
+  return node instanceof HTMLAudioElement ? true :
+         node instanceof HTMLVideoElement ? isVideoLoadingAudio(node) :
+         false;
+};
+
+const isImage = ({namespaceURI, localName}) =>
+  namespaceURI === HTML_NS && localName === "img" ? true :
+  namespaceURI === XUL_NS && localName === "image" ? true :
+  namespaceURI === SVG_NS && localName === "image" ? true :
+  false;
+
+parsers["reader/MediaType()"] = constant(node =>
+  isImage(node) ? "image" :
+  isAudio(node) ? "audio" :
+  isVideo(node) ? "video" :
+  null);
+
+
+const readLink = node =>
+  node.namespaceURI === HTML_NS && node.localName === "a" ? node.href :
+  readLink(node.parentNode);
+
+parsers["reader/LinkURL()"] = constant(node =>
+  node.matches("a, a *") ? readLink(node) : null);
+
+// Reader that reads out `true` if "contextmenu" `event.target` matches
+// `descriptor.selector` and `false` if it does not.
+parsers["reader/SelectorMatch()"] = ({selector}) =>
+  node => node.matches(selector);
+
+// Accessing `selectionStart` and `selectionEnd` properties on non
+// editable input nodes throw exceptions, there for we need this util
+// function to guard us against them.
+const getInputSelection = node => {
+  try {
+    if ("selectionStart" in node && "selectionEnd" in node) {
+      const {selectionStart, selectionEnd} = node;
+      return {selectionStart, selectionEnd}
+    }
+  }
+  catch(_) {}
+
+  return null;
+}
+
+// Selection reader does not really cares about descriptor so it is
+// a constant function returning selection reader. Selection reader
+// returns string of the selected text or `null` if there is no selection.
+parsers["reader/Selection()"] = constant(node => {
+  const selection = node.ownerDocument.getSelection();
+  if (!selection.isCollapsed) {
+    return selection.toString();
+  }
+  // If target node is editable (text, input, textarea, etc..) document does
+  // not really handles selections there. There for we fallback to checking
+  // `selectionStart` `selectionEnd` properties and if they are present we
+  // extract selections manually from the `node.value`.
+  else {
+    const selection = getInputSelection(node);
+    const isSelected = selection &&
+                       Number.isInteger(selection.selectionStart) &&
+                       Number.isInteger(selection.selectionEnd) &&
+                       selection.selectionStart !== selection.selectionEnd;
+    return  isSelected ? node.value.substring(selection.selectionStart,
+                                              selection.selectionEnd) :
+            null;
+  }
+});
+
+// Query reader just reads out properties from the node, so we just use `query`
+// utility function.
+parsers["reader/Query()"] = ({path}) => JSONReturn(query(path));
+// Attribute reader just reads attribute of the event target node.
+parsers["reader/Attribute()"] = ({name}) => node => node.getAttribute(name);
+
+// Extractor reader defines generates a reader out of serialized function, who's
+// return value is JSON cloned. Note: We do know source will evaluate to function
+// as that's what we serialized on the other end, it's also ok if generated function
+// is going to throw as registered readers are wrapped in try catch to avoid breakting
+// unrelated readers.
+parsers["reader/Extractor()"] = ({source}) =>
+  JSONReturn(new Function("return (" + source + ")")());
+
+// If the context-menu target node or any of its ancestors is one of these,
+// Firefox uses a tailored context menu, and so the page context doesn't apply.
+// There for `reader/isPage()` will read `false` in that case otherwise it's going
+// to read `true`.
+const nonPageElements = ["a", "applet", "area", "button", "canvas", "object",
+                         "embed", "img", "input", "map", "video", "audio", "menu",
+                         "option", "select", "textarea", "[contenteditable=true]"];
+const nonPageSelector = nonPageElements.
+                          concat(nonPageElements.map(tag => `${tag} *`)).
+                          join(", ");
+
+// Note: isPageContext implementation could have actually used SelectorMatch reader,
+// but old implementation was also checked for collapsed selection there for to keep
+// the behavior same we end up implementing a new reader.
+parsers["reader/isPage()"] = constant(node =>
+  node.ownerDocument.defaultView.getSelection().isCollapsed &&
+  !node.matches(nonPageSelector));
+
+// Reads `true` if node is in an iframe otherwise returns true.
+parsers["reader/isFrame()"] = constant(node =>
+  !!node.ownerDocument.defaultView.frameElement);
+
+parsers["reader/isEditable()"] = constant(node => {
+  const selection = getInputSelection(node);
+  return selection ? !node.readOnly && !node.disabled : node.isContentEditable;
+});
+
+
+// TODO: Add some reader to read out tab id.
+
+const onReadersUpdate = message => {
+  each(([id, descriptor]) => {
+    if (descriptor) {
+      readers[id] = parse(descriptor);
+    }
+    else {
+      delete readers[id];
+    }
+  }, pairs(message.data));
+};
+exports.onReadersUpdate = onReadersUpdate;
+
+
+const onContextMenu = event => {
+  if (!event.defaultPrevented) {
+    const manager = nodeToMessageManager(event.target);
+    manager.sendSyncMessage("sdk/context-menu/read", read(event.target), readers);
+  }
+};
+exports.onContextMenu = onContextMenu;
+
+
+const onContentFrame = (frame) => {
+  // Listen for contextmenu events in on this frame.
+  frame.addEventListener("contextmenu", onContextMenu);
+  // Listen to registered reader changes and update registry.
+  frame.addMessageListener("sdk/context-menu/readers", onReadersUpdate);
+
+  // Request table of readers (if this is loaded in a new process some table
+  // changes may be missed, this is way to sync up).
+  frame.sendAsyncMessage("sdk/context-menu/readers?");
+};
+exports.onContentFrame = onContentFrame;