zcommand: Add /fluid-width and /fixed-width slash commands.

static/js/composebox_typeahead.js

@@ -380,6 +380,14 @@ exports.slash_commands = [
         text: i18n.t("/day (Toggle day mode)"),
         name: "day",
     },
+    {
+        text: i18n.t("/fixed-width (Toggle fixed width mode)"),
+        name: "fixed-width",
+    },
+    {
+        text: i18n.t("/fluid-width (Toggle fluid width mode)"),
+        name: "fluid-width",
+    },
     {
         text: i18n.t("/light (Toggle day mode)"),
         name: "light",

static/js/zcommand.js

@@ -90,6 +90,50 @@ exports.enter_night_mode = function () {
     });
 };
 
+exports.enter_fluid_mode = function () {
+    exports.send({
+        command: "/fluid-width",
+        on_success: function (data) {
+            scroll_bar.set_layout_width();
+            feedback_widget.show({
+                populate: function (container) {
+                    const rendered_msg = marked(data.msg).trim();
+                    container.html(rendered_msg);
+                },
+                on_undo: function () {
+                    exports.send({
+                        command: "/fixed-width",
+                    });
+                },
+                title_text: i18n.t("Fluid width mode"),
+                undo_button_text: i18n.t("Fixed width"),
+            });
+        },
+    });
+};
+
+exports.enter_fixed_mode = function () {
+    exports.send({
+        command: "/fixed-width",
+        on_success: function (data) {
+            scroll_bar.set_layout_width();
+            feedback_widget.show({
+                populate: function (container) {
+                    const rendered_msg = marked(data.msg).trim();
+                    container.html(rendered_msg);
+                },
+                on_undo: function () {
+                    exports.send({
+                        command: "/fluid-width",
+                    });
+                },
+                title_text: i18n.t("Fixed width mode"),
+                undo_button_text: i18n.t("Fluid width"),
+            });
+        },
+    });
+};
+
 exports.process = function (message_content) {
 
     const content = message_content.trim();
@@ -122,6 +166,16 @@ exports.process = function (message_content) {
         return true;
     }
 
+    if (content === '/fluid-width') {
+        exports.enter_fluid_mode();
+        return true;
+    }
+
+    if (content === '/fixed-width') {
+        exports.enter_fixed_mode();
+        return true;
+    }
+
     if (content === '/settings') {
         hashchange.go_to_location('settings/your-account');
         return true;

zerver/lib/zcommand.py

@@ -38,4 +38,18 @@ def process_zcommands(content: str, user_profile: UserProfile) -> Dict[str, Any]
                                             switch_command='night',
                                             setting='night_mode',
                                             setting_value=False))
+    elif command == 'fluid-width':
+        if user_profile.fluid_layout_width:
+            return dict(msg='You are still in fluid width mode.')
+        return dict(msg=change_mode_setting(command=command,
+                                            switch_command='fixed-width',
+                                            setting='fluid_layout_width',
+                                            setting_value=True))
+    elif command == 'fixed-width':
+        if not user_profile.fluid_layout_width:
+            return dict(msg='You are still in fixed width mode.')
+        return dict(msg=change_mode_setting(command=command,
+                                            switch_command='fluid-width',
+                                            setting='fluid_layout_width',
+                                            setting_value=False))
     raise JsonableError(_('No such command: %s') % (command,))

zerver/tests/test_zcommand.py

@@ -53,3 +53,33 @@ class ZcommandTest(ZulipTestCase):
         result = self.client_post("/json/zcommand", payload)
         self.assert_json_success(result)
         self.assertIn('still in day mode', result.json()['msg'])
+
+    def test_fluid_zcommand(self) -> None:
+        self.login("hamlet")
+        user = self.example_user("hamlet")
+        user.fluid_layout_width = False
+        user.save()
+
+        payload = dict(command="/fluid-width")
+        result = self.client_post("/json/zcommand", payload)
+        self.assert_json_success(result)
+        self.assert_in_response('Changed to fluid-width mode!', result)
+
+        result = self.client_post("/json/zcommand", payload)
+        self.assert_json_success(result)
+        self.assert_in_response('You are still in fluid width mode', result)
+
+    def test_fixed_zcommand(self) -> None:
+        self.login("hamlet")
+        user = self.example_user("hamlet")
+        user.fluid_layout_width = True
+        user.save()
+
+        payload = dict(command="/fixed-width")
+        result = self.client_post("/json/zcommand", payload)
+        self.assert_json_success(result)
+        self.assert_in_response('Changed to fixed-width mode!', result)
+
+        result = self.client_post("/json/zcommand", payload)
+        self.assert_json_success(result)
+        self.assert_in_response('You are still in fixed width mode', result)