[virt-tools-list] [PATCH virt-viewer] virt-viewer-window: Change zoom of the display only when it is possible

[Pavel Grunt]

Do not allow to zoom out if it is not possible due to the width of
the top menu. It avoids emitting size allocation events that will
change the display resolution of the spice guest.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1206460
---
 src/virt-viewer-window.c | 46 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 44 insertions(+), 2 deletions(-)

diff --git a/src/virt-viewer-window.c b/src/virt-viewer-window.c
index d668f74..205a09a 100644
--- a/src/virt-viewer-window.c
+++ b/src/virt-viewer-window.c
@@ -67,6 +67,8 @@ static void virt_viewer_window_disable_modifiers(VirtViewerWindow *self);
 static void virt_viewer_window_resize(VirtViewerWindow *self, gboolean keep_win_size);
 static void virt_viewer_window_toolbar_setup(VirtViewerWindow *self);
 static GtkMenu* virt_viewer_window_get_keycombo_menu(VirtViewerWindow *self);
+static void virt_viewer_window_get_minimal_dimensions(VirtViewerWindow *self, guint *width, guint *height);
+static gboolean virt_viewer_window_can_zoom_out(VirtViewerWindow *self);
 
 G_DEFINE_TYPE (VirtViewerWindow, virt_viewer_window, G_TYPE_OBJECT)
 
@@ -366,14 +368,16 @@ G_MODULE_EXPORT void
 virt_viewer_window_menu_view_zoom_out(GtkWidget *menu G_GNUC_UNUSED,
                                       VirtViewerWindow *self)
 {
-    virt_viewer_window_set_zoom_level(self, self->priv->zoomlevel - 10);
+    if (virt_viewer_window_can_zoom_out(self))
+        virt_viewer_window_set_zoom_level(self, self->priv->zoomlevel - 10);
 }
 
 G_MODULE_EXPORT void
 virt_viewer_window_menu_view_zoom_in(GtkWidget *menu G_GNUC_UNUSED,
                                      VirtViewerWindow *self)
 {
-    virt_viewer_window_set_zoom_level(self, self->priv->zoomlevel + 10);
+    if (self->priv->zoomlevel < MAX_ZOOM_LEVEL)
+        virt_viewer_window_set_zoom_level(self, self->priv->zoomlevel + 10);
 }
 
 G_MODULE_EXPORT void
@@ -1467,6 +1471,44 @@ virt_viewer_window_set_kiosk(VirtViewerWindow *self, gboolean enabled)
         g_debug("disabling kiosk not implemented yet");
 }
 
+static void
+virt_viewer_window_get_minimal_dimensions(VirtViewerWindow *self,
+                                          guint *width,
+                                          guint *height)
+{
+    GtkRequisition req;
+    GtkWidget *top_menu;
+    g_return_if_fail(VIRT_VIEWER_IS_WINDOW(self));
+    g_return_if_fail(width != NULL);
+    g_return_if_fail(height != NULL);
+
+    top_menu = GTK_WIDGET(gtk_builder_get_object(virt_viewer_window_get_builder(self), "top-menu"));
+#if !GTK_CHECK_VERSION(3, 0, 0)
+    gtk_widget_get_child_requisition(top_menu, &req);
+#else
+    gtk_widget_get_preferred_size(top_menu, &req, NULL);
+#endif
+    *height = 50;
+    *width = req.width;
+}
+
+static gboolean
+virt_viewer_window_can_zoom_out(VirtViewerWindow *self)
+{
+    double zoom_level;
+    guint min_width = 0, min_height = 0, act_width = 0, act_height = 0;
+
+    g_return_val_if_fail(VIRT_VIEWER_IS_WINDOW(self), FALSE);
+    if (self->priv->zoomlevel <= MIN_ZOOM_LEVEL || self->priv->display == NULL)
+        return FALSE;
+
+    virt_viewer_window_get_minimal_dimensions(self, &min_width, &min_height);
+    virt_viewer_display_get_desktop_size(virt_viewer_window_get_display(self), &act_width, &act_height);
+    zoom_level = (self->priv->zoomlevel - 10) / 100.0;
+
+    return zoom_level * act_width >= min_width && zoom_level *act_height >= min_height;
+}
+
 /*
  * Local variables:
  *  c-indent-level: 4
-- 
2.3.4