[gtksourceview] vim: use click gesture to constrain insert cursor

[Christian Hergert <chergert src gnome org>]

commit 8e5e496e5ccf0469c03b9e359b9a34f8f10aabd3
Author: Christian Hergert <chergert redhat com>
Date:   Thu Nov 18 13:36:03 2021 -0800

    vim: use click gesture to constrain insert cursor
    
    This is more reliable than responding to buffer changes. By doing it with
    release events we also avoid affecting other gestures too much.

 gtksourceview/vim/gtksourcevim.c | 77 +++++++++++++++++-----------------------
 1 file changed, 33 insertions(+), 44 deletions(-)
---
diff --git a/gtksourceview/vim/gtksourcevim.c b/gtksourceview/vim/gtksourcevim.c
index 51113ce1..4bfd78fe 100644
--- a/gtksourceview/vim/gtksourcevim.c
+++ b/gtksourceview/vim/gtksourcevim.c
@@ -21,7 +21,6 @@
 
 #include "config.h"
 
-#include "gtksourcebuffer.h"
 #include "gtksourceview.h"
 
 #include "gtksourcevim.h"
@@ -36,7 +35,7 @@ struct _GtkSourceVim
 {
        GtkSourceVimState  parent_instance;
        GString           *command_text;
-       GtkSourceBuffer   *buffer;
+       GtkGestureClick   *click;
        guint              constrain_insert_source;
        guint              in_handle_event : 1;
 };
@@ -141,9 +140,14 @@ constrain_insert_source (gpointer data)
        {
                GtkSourceVimState *visual;
 
-               /* Enter visual mode */
+               /* Try to emulate the selection as if it happened in Visual mode
+                * by first clearing the selection and then warp visual mode
+                * to where the insert cursor is now.
+                */
+               gtk_text_buffer_select_range (GTK_TEXT_BUFFER (buffer), &selection, &selection);
                visual = gtk_source_vim_visual_new (GTK_SOURCE_VIM_VISUAL_CHAR);
                gtk_source_vim_state_push (current, visual);
+               gtk_source_vim_visual_warp (GTK_SOURCE_VIM_VISUAL (visual), &iter);
                g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_COMMAND_TEXT]);
                g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_COMMAND_BAR_TEXT]);
        }
@@ -154,11 +158,9 @@ constrain_insert_source (gpointer data)
 }
 
 static void
-on_cursor_moved_cb (GtkSourceVim    *self,
-                    GtkSourceBuffer *buffer)
+queue_constrain (GtkSourceVim *self)
 {
        g_assert (GTK_SOURCE_IS_VIM (self));
-       g_assert (GTK_SOURCE_IS_BUFFER (buffer));
 
        if (self->in_handle_event)
                return;
@@ -170,45 +172,23 @@ on_cursor_moved_cb (GtkSourceVim    *self,
         */
        if (self->constrain_insert_source == 0)
        {
-               self->constrain_insert_source =
-                       g_timeout_add_full (G_PRIORITY_LOW, 35,
-                                           constrain_insert_source, self, NULL);
+               self->constrain_insert_source = g_idle_add (constrain_insert_source, self);
        }
 }
 
 static void
-on_notify_buffer_cb (GtkSourceVim  *self,
-                     GParamSpec    *pspec,
-                     GtkSourceView *view)
+on_click_released_cb (GtkSourceVim    *self,
+                      int              n_press,
+                      double           x,
+                      double           y,
+                      GtkGestureClick *click)
 {
-       GtkSourceBuffer *buffer;
-
        g_assert (GTK_SOURCE_IS_VIM (self));
-       g_assert (GTK_SOURCE_IS_VIEW (view));
-
-       buffer = GTK_SOURCE_BUFFER (gtk_text_view_get_buffer (GTK_TEXT_VIEW (view)));
-
-       if (self->buffer == buffer)
-               return;
-
-       if (self->buffer != NULL)
-       {
-               g_signal_handlers_disconnect_by_func (self->buffer,
-                                                     G_CALLBACK (on_cursor_moved_cb),
-                                                     self);
-               g_clear_object (&self->buffer);
-       }
-
-       g_set_object (&self->buffer, buffer);
+       g_assert (GTK_IS_GESTURE_CLICK (click));
 
-       if (buffer != NULL)
+       if (n_press == 1)
        {
-               g_signal_connect_object (buffer,
-                                        "cursor-moved",
-                                        G_CALLBACK (on_cursor_moved_cb),
-                                        self,
-                                        G_CONNECT_SWAPPED);
-               on_cursor_moved_cb (self, buffer);
+               queue_constrain (self);
        }
 }
 
@@ -225,12 +205,14 @@ gtk_source_vim_view_set (GtkSourceVimState *state)
        view = gtk_source_vim_state_get_view (state);
        gtk_source_vim_state_get_buffer (state, &iter, NULL);
 
-       g_signal_connect_object (view,
-                                "notify::buffer",
-                                G_CALLBACK (on_notify_buffer_cb),
-                                self,
-                                G_CONNECT_SWAPPED);
-       on_notify_buffer_cb (self, NULL, view);
+       self->click = GTK_GESTURE_CLICK (gtk_gesture_click_new ());
+       g_signal_connect_object (self->click,
+                                "released",
+                                G_CALLBACK (on_click_released_cb),
+                                self,
+                                G_CONNECT_SWAPPED);
+       gtk_widget_add_controller (GTK_WIDGET (view),
+                                  GTK_EVENT_CONTROLLER (self->click));
 
        gtk_source_vim_state_push_jump (state, &iter);
 
@@ -255,9 +237,16 @@ static void
 gtk_source_vim_dispose (GObject *object)
 {
        GtkSourceVim *self = (GtkSourceVim *)object;
+       GtkSourceView *view = gtk_source_vim_state_get_view (GTK_SOURCE_VIM_STATE (self));
+
+       if (view != NULL && self->click)
+       {
+               gtk_widget_remove_controller (GTK_WIDGET (view),
+                                             GTK_EVENT_CONTROLLER (self->click));
+               self->click = NULL;
+       }
 
        g_clear_handle_id (&self->constrain_insert_source, g_source_remove);
-       g_clear_object (&self->buffer);
 
        if (self->command_text != NULL)
        {