[gtksourceview] assistant: take visible rect coords and gutter into account

[Christian Hergert <chergert src gnome org>]

commit 261a91320a9a778a20660aa25484052dd43df0e1
Author: Christian Hergert <chergert redhat com>
Date:   Fri May 13 18:58:25 2022 -0700

    assistant: take visible rect coords and gutter into account
    
    Otherwise we'll only place things correctly on the first visible page.

 gtksourceview/gtksourceassistant.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
---
diff --git a/gtksourceview/gtksourceassistant.c b/gtksourceview/gtksourceassistant.c
index 0b5affb5..fba05e2e 100644
--- a/gtksourceview/gtksourceassistant.c
+++ b/gtksourceview/gtksourceassistant.c
@@ -103,6 +103,19 @@ _gtk_source_assistant_get_target_location (GtkSourceAssistant *assistant,
        GTK_SOURCE_ASSISTANT_GET_CLASS (assistant)->get_target_location (assistant, location);
 }
 
+static int
+get_gutter_width (GtkSourceView *view)
+{
+       GtkSourceGutter *left = gtk_source_view_get_gutter (view, GTK_TEXT_WINDOW_LEFT);
+
+       if (left != NULL)
+       {
+               return gtk_widget_get_width (GTK_WIDGET (left));
+       }
+
+       return 0;
+}
+
 static void
 _gtk_source_assistant_update_position (GtkSourceAssistant *assistant)
 {
@@ -119,9 +132,17 @@ _gtk_source_assistant_update_position (GtkSourceAssistant *assistant)
 
        if (GTK_SOURCE_IS_VIEW (parent))
        {
+               GdkRectangle visible_rect;
+
+               gtk_text_view_get_visible_rect (GTK_TEXT_VIEW (parent), &visible_rect);
+
                _gtk_source_assistant_get_offset (assistant, &x, &y);
                _gtk_source_assistant_get_target_location (assistant, &rect);
 
+               rect.x -= visible_rect.x;
+               rect.y -= visible_rect.y;
+               rect.x += get_gutter_width (GTK_SOURCE_VIEW (parent));
+
                gtk_popover_set_offset (GTK_POPOVER (assistant), x, y);
                gtk_popover_set_pointing_to (GTK_POPOVER (assistant), &rect);
        }