Cache keydown events while launching link hints.

Launching link hints can sometimes be slow.  For filtered hints, the
user already knows what to type - but must nevertheless wait until the
hints have been calculated and rendered.

Here, we cache intervening keydown events, and replay them once
hints-mode proper is launched.  This should make improve usability (in
the case of filtered hints).

Fixes #3050.

2 files changed, 21 insertions, 7 deletions

diff --git a/content_scripts/link_hints.coffee b/content_scripts/link_hints.coffee
index 849aa4c5..86cc4e4f 100644
--- a/content_scripts/link_hints.coffee
+++ b/content_scripts/link_hints.coffee
@@ -52,7 +52,7 @@ availableModes = [OPEN_IN_CURRENT_TAB, OPEN_IN_NEW_BG_TAB, OPEN_IN_NEW_FG_TAB, O
 HintCoordinator =
   onExit: []
   localHints: null
-  suppressKeyboardEvents: null
+  cacheAllKeydownEvents: null
 
   sendMessage: (messageType, request = {}) ->
     Frame.postMessage "linkHintsMessage", extend request, {messageType}
@@ -60,15 +60,15 @@ HintCoordinator =
   prepareToActivateMode: (mode, onExit) ->
     # We need to communicate with the background page (and other frames) to initiate link-hints mode.  To
     # prevent other Vimium commands from being triggered before link-hints mode is launched, we install a
-    # temporary mode to block keyboard events.
-    @suppressKeyboardEvents = suppressKeyboardEvents = new SuppressAllKeyboardEvents
+    # temporary mode to block (and cache) keyboard events.
+    @cacheAllKeydownEvents = cacheAllKeydownEvents = new CacheAllKeydownEvents
       name: "link-hints/suppress-keyboard-events"
       singleton: "link-hints-mode"
       indicator: "Collecting hints..."
       exitOnEscape: true
     # FIXME(smblott) Global link hints is currently insufficiently reliable.  If the mode above is left in
     # place, then Vimium blocks.  As a temporary measure, we install a timer to remove it.
-    Utils.setTimeout 1000, -> suppressKeyboardEvents.exit() if suppressKeyboardEvents?.modeIsActive
+    Utils.setTimeout 1000, -> cacheAllKeydownEvents.exit() if cacheAllKeydownEvents?.modeIsActive
     @onExit = [onExit]
     @sendMessage "prepareToActivateMode",
       modeIndex: availableModes.indexOf(mode), isVimiumHelpDialog: window.isVimiumHelpDialog
@@ -103,10 +103,13 @@ HintCoordinator =
     hintDescriptors = [].concat (hintDescriptors[fId] for fId in (fId for own fId of hintDescriptors).sort())...
     # Ensure that the document is ready and that the settings are loaded.
     DomUtils.documentReady => Settings.onLoaded =>
-      @suppressKeyboardEvents.exit() if @suppressKeyboardEvents?.modeIsActive
-      @suppressKeyboardEvents = null
+      @cacheAllKeydownEvents.exit() if @cacheAllKeydownEvents?.modeIsActive
       @onExit = [] unless frameId == originatingFrameId
       @linkHintsMode = new LinkHintsMode hintDescriptors, availableModes[modeIndex]
+      # Replay keydown events which we missed (but for filtered hints only).
+      @cacheAllKeydownEvents?.replayKeydownEvents() if Settings.get "filterLinkHints"
+      @cacheAllKeydownEvents = null
+      @linkHintsMode # Return this (for tests).
 
   # The following messages are exchanged between frames while link-hints mode is active.
   updateKeyState: (request) -> @linkHintsMode.updateKeyState request
diff --git a/content_scripts/mode.coffee b/content_scripts/mode.coffee
index a4a91c1f..8bdd6dd7 100644
--- a/content_scripts/mode.coffee
+++ b/content_scripts/mode.coffee
@@ -198,6 +198,17 @@ class SuppressAllKeyboardEvents extends Mode
       suppressAllKeyboardEvents: true
     super extend defaults, options
 
+class CacheAllKeydownEvents extends SuppressAllKeyboardEvents
+  constructor: (options = {}) ->
+    @keydownEvents = keydownEvents = []
+    defaults =
+      name: "cacheAllKeydownEvents"
+      keydown: (event) -> keydownEvents.push event
+    super extend defaults, options
+
+  replayKeydownEvents: ->
+    handlerStack.bubbleEvent "keydown", event for event in @keydownEvents
+
 root = exports ? (window.root ?= {})
-extend root, {Mode, SuppressAllKeyboardEvents}
+extend root, {Mode, SuppressAllKeyboardEvents, CacheAllKeydownEvents}
 extend window, root unless exports?