[gthumb] accel button: added a change-value signal to confirm shortcut is valid

[Paolo Bacchilega <paobac src gnome org>]

commit 110f10a041864b13052d77291586709887d0abf3
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Sat Nov 16 10:08:25 2019 +0100

    accel button: added a change-value signal to confirm shortcut is valid

 gthumb/gth-accel-button.c | 51 +++++++++++++++++++++++++++++++++++++++++++----
 gthumb/gth-accel-button.h |  5 ++++-
 gthumb/gth-marshal.list   |  1 +
 3 files changed, 52 insertions(+), 5 deletions(-)
---
diff --git a/gthumb/gth-accel-button.c b/gthumb/gth-accel-button.c
index 1542d857..62b4fd2f 100644
--- a/gthumb/gth-accel-button.c
+++ b/gthumb/gth-accel-button.c
@@ -25,6 +25,7 @@
 #include <gtk/gtk.h>
 #include "gth-accel-button.h"
 #include "gth-accel-dialog.h"
+#include "gth-marshal.h"
 #include "gtk-utils.h"
 
 
@@ -37,6 +38,7 @@ enum {
 
 /* Signals */
 enum {
+       CHANGE_VALUE,
        CHANGED,
        LAST_SIGNAL
 };
@@ -117,6 +119,18 @@ gth_accel_button_get_property (GObject    *object,
 }
 
 
+static gboolean
+gth_accel_button_real_change_value (GthAccelButton  *accel_button,
+                                   guint            keycode,
+                                   GdkModifierType  modifiers)
+{
+       if (gth_accel_button_set_accelerator (accel_button, keycode, modifiers))
+               return GDK_EVENT_PROPAGATE;
+       else
+               return GDK_EVENT_STOP;
+}
+
+
 static void
 gth_accel_button_class_init (GthAccelButtonClass *klass)
 {
@@ -127,6 +141,8 @@ gth_accel_button_class_init (GthAccelButtonClass *klass)
        object_class->get_property = gth_accel_button_get_property;
        object_class->finalize = gth_accel_button_finalize;
 
+       klass->change_value = gth_accel_button_real_change_value;
+
        /* properties */
 
        g_object_class_install_property (object_class,
@@ -149,6 +165,17 @@ gth_accel_button_class_init (GthAccelButtonClass *klass)
 
        /* signals */
 
+       gth_accel_button_signals[CHANGE_VALUE] =
+               g_signal_new ("change-value",
+                             G_TYPE_FROM_CLASS (klass),
+                             G_SIGNAL_RUN_LAST,
+                             G_STRUCT_OFFSET (GthAccelButtonClass, change_value),
+                             g_signal_accumulator_true_handled, NULL,
+                             gth_marshal_BOOLEAN__UINT_ENUM,
+                             G_TYPE_BOOLEAN,
+                             2,
+                             G_TYPE_UINT,
+                             GDK_TYPE_MODIFIER_TYPE);
        gth_accel_button_signals[CHANGED] =
                 g_signal_new ("changed",
                               G_TYPE_FROM_CLASS (klass),
@@ -175,7 +202,22 @@ _update_label (GthAccelButton *self)
 }
 
 
-#define _RESPONSE_RESET 10
+static gboolean
+change_value (GthAccelButton  *accel_button,
+             guint            keycode,
+             GdkModifierType  modifiers)
+{
+       gboolean result = GDK_EVENT_PROPAGATE;
+
+       g_signal_emit (accel_button,
+                      gth_accel_button_signals[CHANGE_VALUE],
+                      0,
+                      keycode,
+                      modifiers,
+                      &result);
+
+       return result == GDK_EVENT_PROPAGATE;
+}
 
 
 static void
@@ -190,14 +232,14 @@ accel_dialog_response_cb (GtkDialog *dialog,
        switch (response_id) {
        case GTK_RESPONSE_OK:
                if (gth_accel_dialog_get_accel (GTH_ACCEL_DIALOG (dialog), &keycode, &modifiers))
-                       gth_accel_button_set_accelerator (accel_button, keycode, modifiers);
-               gtk_widget_destroy (GTK_WIDGET (dialog));
+                       if (change_value (accel_button, keycode, modifiers))
+                               gtk_widget_destroy (GTK_WIDGET (dialog));
                break;
        case GTK_RESPONSE_CANCEL:
                gtk_widget_destroy (GTK_WIDGET (dialog));
                break;
        case GTH_ACCEL_BUTTON_RESPONSE_DELETE:
-               gth_accel_button_set_accelerator (accel_button, 0, 0);
+               change_value (accel_button, 0, 0);
                gtk_widget_destroy (GTK_WIDGET (dialog));
                break;
        }
@@ -259,6 +301,7 @@ gth_accel_button_set_accelerator (GthAccelButton  *self,
        self->priv->modifiers = modifiers;
 
        _update_label (self);
+       g_signal_emit (self, gth_accel_button_signals[CHANGED], 0);
 
        return self->priv->valid;
 }
diff --git a/gthumb/gth-accel-button.h b/gthumb/gth-accel-button.h
index 8d1fc63e..f14f13c2 100644
--- a/gthumb/gth-accel-button.h
+++ b/gthumb/gth-accel-button.h
@@ -47,7 +47,10 @@ struct _GthAccelButtonClass {
 
        /*< signals >*/
 
-       void (*changed) (GthAccelButton *accel_button);
+       gboolean (*change_value)        (GthAccelButton  *accel_button,
+                                        guint            keycode,
+                                        GdkModifierType  modifiers);
+       void     (*changed)             (GthAccelButton  *accel_button);
 };
 
 GType         gth_accel_button_get_type            (void) G_GNUC_CONST;
diff --git a/gthumb/gth-marshal.list b/gthumb/gth-marshal.list
index 8c873a22..2d24ea94 100644
--- a/gthumb/gth-marshal.list
+++ b/gthumb/gth-marshal.list
@@ -1,5 +1,6 @@
 BOOLEAN:ENUM, ENUM
 BOOLEAN:VOID
+BOOLEAN:UINT, ENUM
 VOID:BOOLEAN, POINTER
 VOID:BOXED, BOXED
 VOID:ENUM, ENUM