Use properties for can-zoom-in and -out

This simplifies the logic required to enable zoom actions for
consumers of the view.

Backported from https://gitlab.gnome.org/GNOME/evince/-/commit/bbfbf913

2 files changed, 79 insertions, 3 deletions

diff --git a/libview/ev-view-private.h b/libview/ev-view-private.h
index e9515723..98891965 100644
--- a/libview/ev-view-private.h
+++ b/libview/ev-view-private.h
@@ -165,6 +165,8 @@ struct _EvView {
 	gint spacing;
 
 	gboolean loading;
+	gboolean can_zoom_in;
+	gboolean can_zoom_out;
 	gboolean continuous;
 	gboolean dual_even_left;
 	gboolean fullscreen;
diff --git a/libview/ev-view.c b/libview/ev-view.c
index 17a1e18c..68ca0970 100644
--- a/libview/ev-view.c
+++ b/libview/ev-view.c
@@ -73,7 +73,9 @@ enum {
 	PROP_HADJUSTMENT,
 	PROP_VADJUSTMENT,
 	PROP_HSCROLL_POLICY,
-	PROP_VSCROLL_POLICY
+	PROP_VSCROLL_POLICY,
+	PROP_CAN_ZOOM_IN,
+	PROP_CAN_ZOOM_OUT
 };
 
 static guint signals[N_SIGNALS] = { 0 };
@@ -5988,6 +5990,12 @@ ev_view_get_property (GObject     *object,
 	case PROP_IS_LOADING:
 		g_value_set_boolean (value, view->loading);
 		break;
+	case PROP_CAN_ZOOM_IN:
+		g_value_set_boolean (value, view->can_zoom_in);
+		break;
+	case PROP_CAN_ZOOM_OUT:
+		g_value_set_boolean (value, view->can_zoom_out);
+		break;
 	case PROP_HADJUSTMENT:
 		g_value_set_object (value, view->hadjustment);
 		break;
@@ -6263,6 +6271,23 @@ ev_view_class_init (EvViewClass *class)
 							       G_PARAM_READABLE |
 							       G_PARAM_STATIC_STRINGS));
 
+	g_object_class_install_property (object_class,
+					 PROP_CAN_ZOOM_IN,
+					 g_param_spec_boolean ("can-zoom-in",
+							       "Can Zoom In",
+							       "Whether the view can be zoomed in further",
+							       TRUE,
+							       G_PARAM_READABLE |
+							       G_PARAM_STATIC_STRINGS));
+	g_object_class_install_property (object_class,
+					 PROP_CAN_ZOOM_OUT,
+					 g_param_spec_boolean ("can-zoom-out",
+							       "Can Zoom Out",
+							       "Whether the view can be zoomed out further",
+							       TRUE,
+							       G_PARAM_READABLE |
+							       G_PARAM_STATIC_STRINGS));
+
 	/* Scrollable interface */
 	g_object_class_override_property (object_class, PROP_HADJUSTMENT, "hadjustment");
 	g_object_class_override_property (object_class, PROP_VADJUSTMENT, "vadjustment");
@@ -6871,6 +6896,31 @@ ev_view_sizing_mode_changed_cb (EvDocumentModel *model,
 }
 
 static void
+update_can_zoom (EvView *view)
+{
+	gdouble min_scale;
+	gdouble max_scale;
+	gboolean can_zoom_in;
+	gboolean can_zoom_out;
+
+	min_scale = ev_document_model_get_min_scale (view->model);
+	max_scale = ev_document_model_get_max_scale (view->model);
+
+	can_zoom_in = (view->scale * ZOOM_IN_FACTOR) <= max_scale;
+	can_zoom_out = (view->scale * ZOOM_OUT_FACTOR) > min_scale;
+
+	if (can_zoom_in != view->can_zoom_in) {
+		view->can_zoom_in = can_zoom_in;
+		g_object_notify (G_OBJECT (view), "can-zoom-in");
+	}
+
+	if (can_zoom_out != view->can_zoom_out) {
+		view->can_zoom_out = can_zoom_out;
+		g_object_notify (G_OBJECT (view), "can-zoom-out");
+	}
+}
+
+static void
 ev_view_page_layout_changed_cb (EvDocumentModel *model,
 				GParamSpec      *pspec,
 				EvView          *view)
@@ -6903,6 +6953,24 @@ ev_view_scale_changed_cb (EvDocumentModel *model,
 	view->pending_resize = TRUE;
 	if (view->sizing_mode == EV_SIZING_FREE)
 		gtk_widget_queue_resize (GTK_WIDGET (view));
+
+	update_can_zoom (view);
+}
+
+static void
+ev_view_min_scale_changed_cb (EvDocumentModel *model,
+			      GParamSpec      *pspec,
+			      EvView          *view)
+{
+	update_can_zoom (view);
+}
+
+static void
+ev_view_max_scale_changed_cb (EvDocumentModel *model,
+			      GParamSpec      *pspec,
+			      EvView          *view)
+{
+	update_can_zoom (view);
 }
 
 static void
@@ -6986,6 +7054,12 @@ ev_view_set_model (EvView          *view,
 	g_signal_connect (view->model, "notify::scale",
 			  G_CALLBACK (ev_view_scale_changed_cb),
 			  view);
+	g_signal_connect (view->model, "notify::min-scale",
+			  G_CALLBACK (ev_view_min_scale_changed_cb),
+			  view);
+	g_signal_connect (view->model, "notify::max-scale",
+			  G_CALLBACK (ev_view_max_scale_changed_cb),
+			  view);
 	g_signal_connect (view->model, "notify::continuous",
 			  G_CALLBACK (ev_view_continuous_changed_cb),
 			  view);
@@ -7028,13 +7102,13 @@ ev_view_reload (EvView *view)
 gboolean
 ev_view_can_zoom_in (EvView *view)
 {
-	return view->scale * ZOOM_IN_FACTOR <= ev_document_model_get_max_scale (view->model);
+	return view->can_zoom_in;
 }
 
 gboolean
 ev_view_can_zoom_out (EvView *view)
 {
-	return view->scale * ZOOM_OUT_FACTOR >= ev_document_model_get_min_scale (view->model);
+	return view->can_zoom_out;
 }
 
 void