[polari] main: Add GTK4 polyfill

[Marge Bot <marge-bot src gnome org>]

commit cf0854d24c0c3b9b0bf9a724184dbcc8a79c1325
Author: Florian Müllner <fmuellner gnome org>
Date:   Fri Oct 9 21:45:49 2020 +0200

    main: Add GTK4 polyfill
    
    Some of the GTK4 changes are easy to implement as polyfill, so we
    can port to them before doing the actual switch to the new version.
    
    Part-of: <https://gitlab.gnome.org/GNOME/polari/-/merge_requests/228>

 src/gtkShim.js  | 177 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.js     |   3 +
 src/meson.build |   1 +
 3 files changed, 181 insertions(+)
---
diff --git a/src/gtkShim.js b/src/gtkShim.js
new file mode 100644
index 00000000..fedb8e47
--- /dev/null
+++ b/src/gtkShim.js
@@ -0,0 +1,177 @@
+import GLib from 'gi://GLib';
+import Graphene from 'gi://Graphene';
+import Pango from 'gi://Pango';
+
+import gi from 'gi';
+
+/* eslint brace-style: ["error", "1tbs", { "allowSingleLine": true }] */
+/* eslint-disable no-invalid-this */
+
+/** @returns {void} */
+export function init() {
+    let Gtk, Gdk;
+
+    try {
+        Gtk = gi.require('Gtk', '3.0');
+        Gdk = gi.require('Gdk', '3.0');
+    } catch (e) {
+        // assume we are already on GTK4
+        return;
+    }
+
+    Gtk.show_uri_full = function (window, uri, timestamp, cancellable, callback) {
+        GLib.idle_add(GLib.PRIORITY_DEFAULT, () => {
+            callback(window, { uri, timestamp });
+            return GLib.SOURCE_REMOVE;
+        });
+    };
+    Gtk.show_uri_full_finish = function (window, result) {
+        const { uri, timestamp } = result;
+        return Gtk.show_uri_on_window(window, uri, timestamp);
+    };
+
+    Gtk.EventController.prototype.get_current_event = function () {
+        return Gtk.get_current_event();
+    };
+    Gtk.EventControllerKey.prototype.forward = function (widget) {
+        widget.event(Gtk.get_current_event());
+    };
+    Gtk.GestureClick = Gtk.GestureMultiPress;
+
+    Gtk.Widget.prototype.add_css_class = function (cssClass) {
+        this.get_style_context().add_class(cssClass);
+    };
+    Gtk.Widget.prototype.remove_css_class = function (cssClass) {
+        this.get_style_context().remove_class(cssClass);
+    };
+
+    Gtk.StyleContext.add_provider_for_display = function (dsp, ...args) {
+        this.add_provider_for_screen(dsp.get_default_screen(), ...args);
+    };
+
+    Gtk.AccessibleProperty = { LABEL: 4 };
+    Gtk.Widget.prototype.update_property = function (props, values) {
+        const label = values[props.findIndex(p => p === 4)];
+        if (label)
+            this.get_accessible().set_name(label);
+    };
+
+    Gtk.Widget.prototype.get_root = Gtk.Widget.prototype.get_toplevel;
+
+    Gtk.Widget.prototype.measure = function (orientation) {
+        if (orientation === Gtk.Orientation.HORIZONTAL)
+            return this.get_preferred_width();
+        else
+            return this.get_preferred_height();
+    };
+
+    Gtk.Widget.prototype[Symbol.iterator] = function* () {
+        const children = this.get_children();
+        for (const c of children)
+            yield c;
+    };
+    Gtk.Widget.prototype.get_first_child = function () {
+        const [child] = this;
+        return child ?? null;
+    };
+    Gtk.Widget.prototype.get_clipboard = function () {
+        return Gtk.Clipboard.get_default(this.get_display());
+    };
+    Gtk.Clipboard.prototype.set = function (text) {
+        this.set_text(text, -1);
+    };
+
+    /* Widget-specific container-method replacements */
+    Gtk.Box.prototype.append = Gtk.Container.prototype.add;
+    Gtk.ListBox.prototype.append = Gtk.Container.prototype.add;
+
+    function setChild(child) {
+        if (child)
+            this.add(child);
+        else if ((child = this.get_first_child()))
+            this.remove(child);
+    }
+    Gtk.Revealer.prototype.set_child = setChild;
+    Gtk.Frame.prototype.set_child = setChild;
+    Gtk.ScrolledWindow.prototype.set_child = setChild;
+    Gtk.ListBoxRow.prototype.set_child = setChild;
+    Gtk.Overlay.prototype.set_child = setChild;
+    Gtk.Popover.prototype.set_child = setChild;
+
+    /* Other widget-specific replacements */
+    Gtk.Entry.prototype.get_delegate = function () {
+        return this;
+    };
+    Gtk.Entry.prototype.compute_cursor_extents = function (pos) {
+        const index = this.text_index_to_layout_index(pos);
+        const wordPos = this.get_layout().index_to_pos(index);
+        const [offX, offY_] = this.get_layout_offsets();
+        const extents = new Graphene.Rect();
+        extents.init(offX + wordPos.x / Pango.SCALE, 0, 0, 1);
+        return [extents, extents];
+    };
+    Gtk.Entry.prototype.compute_bounds = function () {
+        return [true, new Graphene.Rect()];
+    };
+    Gtk.Popover.prototype.get_parent = Gtk.Popover.prototype.get_relative_to;
+    Gtk.Popover.prototype.set_parent = Gtk.Popover.prototype.set_relative_to;
+    Gtk.Popover.prototype.unparent = function () {
+        this.relative_to = null;
+    };
+
+    Gtk.PopoverMenu.prototype.set_menu_model = function (menu) {
+        this.bind_model(menu, null);
+    };
+
+    Gtk.TextView.prototype.set_cursor_from_name = function (name) {
+        const cursor = Gdk.Cursor.new_from_name(this.get_display(), name);
+        this.get_window(Gtk.TextWindowType.TEXT).set_cursor(cursor);
+    };
+
+    Gtk.ListStore.prototype.insert_with_values = Gtk.ListStore.prototype.insert_with_valuesv;
+
+    /* Properties */
+    injectProperty(Gtk.Popover.prototype, 'autohide',
+        function () { return this.modal; },
+        function (value) { this.modal = value; });
+
+    injectProperty(Gtk.Spinner.prototype, 'spinning',
+        function () { return this.active; },
+        function (value) { this.active = value; });
+
+    injectProperty(Gtk.Button.prototype, 'has_frame',
+        function () { return this.relief !== Gtk.ReliefStyle.NONE; },
+        function (value) {
+            this.relief = value
+                ? Gtk.ReliefStyle.NORMAL : Gtk.ReliefStyle.NONE;
+        });
+
+    injectProperty(Gtk.ScrolledWindow.prototype, 'has_frame',
+        function () { return this.shadow_type !== Gtk.ShadowType.NONE; },
+        function (value) {
+            this.shadow_type = value
+                ? Gtk.ShadowType.ETCHED_IN : Gtk.ShadowType.NONE;
+        });
+}
+
+/**
+ * @param {prototype} prototype to be patched
+ * @param {string} name - property name
+ * @param {Function} get - getter funcition
+ * @param {Function} set - setter funcition
+ * @returns {void}
+ */
+function injectProperty(prototype, name, get, set) {
+    Object.defineProperty(prototype, name, { get, set });
+
+    const realInit = prototype._init;
+    prototype._init = function (params = {}) {
+        const injected = params[name];
+        delete params[name];
+
+        realInit.call(this, params);
+
+        if (injected !== undefined)
+            this[name] = injected;
+    };
+}
diff --git a/src/main.js b/src/main.js
index bf2cf104..0af2b10f 100755
--- a/src/main.js
+++ b/src/main.js
@@ -35,6 +35,9 @@ if (!pkg.checkSymbol('Soup', '3.0'))
 
 import Application from './application.js';
 
+import * as GtkShim from './gtkShim.js';
+GtkShim.init();
+
 let application = new Application();
 if (GLib.getenv('POLARI_PERSIST'))
     application.hold();
diff --git a/src/meson.build b/src/meson.build
index 275d9eda..164c272c 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -12,6 +12,7 @@ js_sources = [
   'chatView.js',
   'connections.js',
   'entryArea.js',
+  'gtkShim.js',
   'initialSetup.js',
   'ircParser.js',
   'joinDialog.js',