[gnome-builder/wip/gtk4-port] libide/sourceview: invalidate after monitor changes

[Christian Hergert <chergert src gnome org>]

commit c6a48b3ae9c9b94e7b30610dc3d7a0ae987c7e37
Author: Christian Hergert <chergert redhat com>
Date:   Wed Apr 6 15:03:50 2022 -0700

    libide/sourceview: invalidate after monitor changes
    
    The IdeBuffer:change-monitor can be used to determine when we've gotten
    changes from the underlying subsystem (git, etc) about line changes which
    need to be drawn in the gutter.
    
    This ensures that we use that to re-snapshot the gutter renderer with the
    updated changes.

 .../sourceview/ide-line-change-gutter-renderer.c   | 91 +++++++++++++++++-----
 1 file changed, 72 insertions(+), 19 deletions(-)
---
diff --git a/src/libide/sourceview/ide-line-change-gutter-renderer.c 
b/src/libide/sourceview/ide-line-change-gutter-renderer.c
index fe20cb61f..57954e11b 100644
--- a/src/libide/sourceview/ide-line-change-gutter-renderer.c
+++ b/src/libide/sourceview/ide-line-change-gutter-renderer.c
@@ -38,6 +38,10 @@ struct _IdeLineChangeGutterRenderer
 
   GtkSourceBuffer        *buffer;
   gulong                  buffer_notify_style_scheme;
+  gulong                  buffer_notify_change_monitor;
+
+  IdeBufferChangeMonitor *change_monitor;
+  gulong                  change_monitor_changed;
 
   struct {
     GdkRGBA add;
@@ -129,12 +133,19 @@ disconnect_buffer (IdeLineChangeGutterRenderer *self)
 {
   disconnect_style_scheme (self);
 
-  if (self->buffer && self->buffer_notify_style_scheme)
+  if (self->buffer)
     {
-      g_signal_handler_disconnect (self->buffer, self->buffer_notify_style_scheme);
-      self->buffer_notify_style_scheme = 0;
+      g_clear_signal_handler (&self->buffer_notify_style_scheme, self->buffer);
+      g_clear_signal_handler (&self->buffer_notify_change_monitor, self->buffer);
+
       g_clear_weak_pointer (&self->buffer);
     }
+
+  if (self->change_monitor)
+    {
+      g_clear_signal_handler (&self->change_monitor_changed, self->change_monitor);
+      g_clear_object (&self->change_monitor);
+    }
 }
 
 static void
@@ -170,20 +181,60 @@ notify_style_scheme_cb (GtkTextBuffer               *buffer,
   connect_style_scheme (self);
 }
 
+static void
+notify_change_monitor_cb (IdeBuffer                   *buffer,
+                          GParamSpec                  *pspec,
+                          IdeLineChangeGutterRenderer *self)
+{
+  IdeBufferChangeMonitor *change_monitor;
+
+  g_assert (IDE_IS_BUFFER (buffer));
+  g_assert (IDE_IS_LINE_CHANGE_GUTTER_RENDERER (self));
+
+  change_monitor = ide_buffer_get_change_monitor (buffer);
+
+  if (change_monitor == self->change_monitor)
+    return;
+
+  if (self->change_monitor)
+    g_clear_signal_handler (&self->change_monitor_changed, self->change_monitor);
+
+  g_set_object (&self->change_monitor, change_monitor);
+
+  if (self->change_monitor)
+    self->change_monitor_changed =
+      g_signal_connect_object (self->change_monitor,
+                               "changed",
+                               G_CALLBACK (gtk_widget_queue_draw),
+                               self,
+                               G_CONNECT_SWAPPED);
+}
+
 static void
 connect_buffer (IdeLineChangeGutterRenderer *self)
 {
-  GtkSourceBuffer *buffer = gtk_source_gutter_renderer_get_buffer (GTK_SOURCE_GUTTER_RENDERER (self));
+  GtkSourceBuffer *buffer;
 
-  if (buffer)
-    {
-      g_set_weak_pointer (&self->buffer, buffer);
-      self->buffer_notify_style_scheme = g_signal_connect (buffer,
-                                                           "notify::style-scheme",
-                                                           G_CALLBACK (notify_style_scheme_cb),
-                                                           self);
-      connect_style_scheme (self);
-    }
+  g_assert (IDE_IS_LINE_CHANGE_GUTTER_RENDERER (self));
+
+  buffer = gtk_source_gutter_renderer_get_buffer (GTK_SOURCE_GUTTER_RENDERER (self));
+  if (!IDE_IS_BUFFER (buffer))
+    return;
+
+  g_set_weak_pointer (&self->buffer, buffer);
+  self->buffer_notify_style_scheme =
+    g_signal_connect (buffer,
+                      "notify::style-scheme",
+                      G_CALLBACK (notify_style_scheme_cb),
+                      self);
+  self->buffer_notify_change_monitor =
+    g_signal_connect (buffer,
+                      "notify::change-monitor",
+                      G_CALLBACK (notify_change_monitor_cb),
+                      self);
+
+  connect_style_scheme (self);
+  notify_change_monitor_cb (IDE_BUFFER (buffer), NULL, self);
 }
 
 static void
@@ -220,21 +271,23 @@ ide_line_change_gutter_renderer_begin (GtkSourceGutterRenderer *renderer,
                                        GtkSourceGutterLines    *lines)
 {
   IdeLineChangeGutterRenderer *self = (IdeLineChangeGutterRenderer *)renderer;
-  IdeBufferChangeMonitor *monitor;
-  int first;
-  int last;
+  guint first;
+  guint last;
 
   g_assert (IDE_IS_LINE_CHANGE_GUTTER_RENDERER (self));
   g_assert (lines != NULL);
 
-  if (!IDE_IS_BUFFER (self->buffer) ||
-      !(monitor = ide_buffer_get_change_monitor (IDE_BUFFER (self->buffer))))
+  if (self->change_monitor == NULL)
     return;
 
   first = gtk_source_gutter_lines_get_first (lines);
   last = gtk_source_gutter_lines_get_last (lines);
 
-  ide_buffer_change_monitor_foreach_change (monitor, first, last, populate_changes_cb, lines);
+  ide_buffer_change_monitor_foreach_change (self->change_monitor,
+                                            first,
+                                            last,
+                                            populate_changes_cb,
+                                            lines);
 }
 
 static void