Speed up key handling by adding modals.is_active().

The function modals.is_active() can see if modals are open
without having to look at the DOM.  This should make it snappier
to type in the compose box.  Even if the speedup is pretty minor,
not having to worry about jQuery slowness should make it easier
to diagnose future compose box issues.

The new function gets used in other places, too, where performance
isn't so much an issue.

frontend_tests/node_tests/hotkey.js

@@ -177,11 +177,11 @@ function stubbing(func_name_to_stub, test_function) {
     }
 
     _.each([return_true, return_false], function (is_settings_page) {
-        _.each([return_true, return_false], function (home_tab_obscured) {
+        _.each([return_true, return_false], function (is_active) {
             _.each([return_true, return_false], function (is_info_overlay) {
                 hotkey.is_settings_page = is_settings_page;
-                set_global('ui_state', {home_tab_obscured: home_tab_obscured,
-                                        is_info_overlay: is_info_overlay});
+                set_global('modals', {is_active: is_active});
+                set_global('ui_state', {is_info_overlay: is_info_overlay});
 
                 test_normal_typing();
             });

static/js/click_handlers.js

@@ -314,7 +314,7 @@ $(function () {
     });
 
     $(".brand").on('click', function (e) {
-        if (ui_state.home_tab_obscured()) {
+        if (modals.is_active()) {
             ui_util.change_tab_to('#home');
         } else {
             narrow.restore_home_state();

static/js/hotkey.js

@@ -456,7 +456,7 @@ exports.process_hotkey = function (e, hotkey) {
         return false;
     }
 
-    if (hotkey.message_view_only && ui_state.home_tab_obscured()) {
+    if (hotkey.message_view_only && modals.is_active()) {
         return false;
     }
 

static/js/modals.js

@@ -12,6 +12,10 @@ function reset_state() {
     open_modal_name = undefined;
 }
 
+exports.is_active = function () {
+    return !!open_modal_name;
+};
+
 exports.open_overlay = function (opts) {
     if (!opts.name || !opts.overlay || !opts.on_close) {
         blueslip.error('Programming error in open_modal');

static/js/narrow.js

@@ -461,7 +461,7 @@ exports.restore_home_state = function () {
     // If we click on the Home link from another nav pane, just go
     // back to the state you were in (possibly still narrowed) before
     // you left the Home pane.
-    if (!ui_state.home_tab_obscured()) {
+    if (!modals.is_active()) {
         exports.deactivate();
     }
     navigate.maybe_scroll_to_selected();

static/js/stream_list.js

@@ -427,7 +427,7 @@ $(function () {
         if (e.metaKey || e.ctrlKey) {
             return;
         }
-        if (ui_state.home_tab_obscured()) {
+        if (modals.is_active()) {
             ui_util.change_tab_to('#home');
         }
         var stream = $(e.target).parents('li').attr('data-name');
@@ -500,7 +500,7 @@ function maybe_select_stream(e) {
         var topStream = $('#stream_filters li.narrow-filter').first().data('name');
         if (topStream !== undefined) {
             // undefined if there are no results
-            if (ui_state.home_tab_obscured()) {
+            if (modals.is_active()) {
                 ui_util.change_tab_to('#home');
             }
             exports.clear_and_hide_search();

static/js/stream_muting.js

@@ -11,7 +11,7 @@ exports.update_in_home_view = function (sub, value) {
         var msg_offset;
         var saved_ypos;
         // Save our current scroll position
-        if (ui_state.home_tab_obscured()) {
+        if (modals.is_active()) {
             saved_ypos = message_viewport.scrollTop();
         } else if (home_msg_list === current_msg_list &&
                    current_msg_list.selected_row().offset() !== null) {
@@ -24,7 +24,7 @@ exports.update_in_home_view = function (sub, value) {
         message_util.add_messages(message_list.all.all_messages(), home_msg_list);
 
         // Ensure we're still at the same scroll position
-        if (ui_state.home_tab_obscured()) {
+        if (modals.is_active()) {
             message_viewport.scrollTop(saved_ypos);
         } else if (home_msg_list === current_msg_list) {
             // We pass use_closest to handle the case where the

static/js/topic_list.js

@@ -212,7 +212,7 @@ exports.set_click_handlers = function (callbacks) {
 
         // In a more componentized world, we would delegate some
         // of this stuff back up to our parents.
-        if (ui_state.home_tab_obscured()) {
+        if (modals.is_active()) {
             ui_util.change_tab_to('#home');
         }
 

static/js/tutorial.js

@@ -504,7 +504,7 @@ function welcome() {
 }
 
 exports.start = function () {
-    if (ui_state.home_tab_obscured()) {
+    if (modals.is_active()) {
         ui_util.change_tab_to('#home');
     }
     narrow.deactivate();

static/js/ui_init.js

@@ -68,7 +68,7 @@ $(function () {
     });
 
     message_viewport.message_pane.mousewheel(function (e, delta) {
-        if (!ui_state.home_tab_obscured()) {
+        if (!modals.is_active()) {
             // In the message view, we use a throttled mousewheel handler.
             throttled_mousewheelhandler(e, delta);
         }

static/js/ui_state.js

@@ -2,14 +2,6 @@ var ui_state = (function () {
 
 var exports = {};
 
-exports.home_tab_obscured = function () {
-    if ($('.overlay.show').length > 0) {
-        return 'modal';
-    }
-
-    return false;
-};
-
 exports.is_info_overlay = function () {
     return ($(".informational-overlays").hasClass("show"));
 };