display: Set useful values for MIN_DISPLAY_{WIDTH, HEIGHT}

Nowadays the value for MIN_DISPLAY_{WIDTH,HEIGHT} is 50. This arbitrary
value doesn't bring any benefit, doesn't provide a useful size for a
desktop to be usable and can actually trigger some undefined behavior
when reaching resolutions that are lower than the ones provided by the
video drivers (as in rhbz#1296878).

In order to avoid these issues and provide a minimum resolution that can
still be useful for our users, let's use the same values for minimum
width and height used by the linux QXL drivers (320x200).

This also requires us to adjust the minimum requested widget size when
zoom is enabled so that we don't accidentally request a size smaller
than the driver can support.

Related: rhbz#1296878
Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>

2 files changed, 20 insertions, 17 deletions

diff --git a/src/virt-viewer-display.c b/src/virt-viewer-display.c
index 036b713..a16181f 100644
--- a/src/virt-viewer-display.c
+++ b/src/virt-viewer-display.c
@@ -116,7 +116,7 @@ virt_viewer_display_class_init(VirtViewerDisplayClass *class)
                                                      "Desktop width",
                                                      MIN_DISPLAY_WIDTH,
                                                      G_MAXINT32,
-                                                     100,
+                                                     MIN_DISPLAY_WIDTH,
                                                      G_PARAM_READWRITE));
 
     g_object_class_install_property(object_class,
@@ -126,7 +126,7 @@ virt_viewer_display_class_init(VirtViewerDisplayClass *class)
                                                      "Desktop height",
                                                      MIN_DISPLAY_HEIGHT,
                                                      G_MAXINT32,
-                                                     100,
+                                                     MIN_DISPLAY_HEIGHT,
                                                      G_PARAM_READWRITE));
 
     g_object_class_install_property(object_class,
@@ -274,8 +274,8 @@ virt_viewer_display_init(VirtViewerDisplay *display)
 
     display->priv = VIRT_VIEWER_DISPLAY_GET_PRIVATE(display);
 
-    display->priv->desktopWidth = 100;
-    display->priv->desktopHeight = 100;
+    display->priv->desktopWidth = MIN_DISPLAY_WIDTH;
+    display->priv->desktopHeight = MIN_DISPLAY_HEIGHT;
     display->priv->zoom_level = NORMAL_ZOOM_LEVEL;
     display->priv->zoom = TRUE;
 #if !GTK_CHECK_VERSION(3, 0, 0)
@@ -425,8 +425,8 @@ virt_viewer_display_size_request(GtkWidget *widget,
     if (priv->dirty || !priv->size_request_once) {
         virt_viewer_display_get_preferred_size(display, requisition);
     } else {
-        requisition->width = MIN_DISPLAY_WIDTH;
-        requisition->height = MIN_DISPLAY_HEIGHT;
+        requisition->width = MIN_DISPLAY_WIDTH * priv->zoom_level / (double) NORMAL_ZOOM_LEVEL;
+        requisition->height = MIN_DISPLAY_HEIGHT * priv->zoom_level / (double) NORMAL_ZOOM_LEVEL;
     }
 
     priv->size_request_once = TRUE;
@@ -460,14 +460,16 @@ static void virt_viewer_display_get_preferred_width(GtkWidget *widget,
     VirtViewerDisplayPrivate *priv = display->priv;
     int border_width = gtk_container_get_border_width(GTK_CONTAINER(widget));
 
-    *minwidth = MIN_DISPLAY_WIDTH + 2 * border_width;
 
     if (priv->zoom) {
-        *defwidth = round(priv->desktopWidth * priv->zoom_level / (double) NORMAL_ZOOM_LEVEL) +
-                    2 * border_width;
+        *defwidth = round(priv->desktopWidth * priv->zoom_level / (double) NORMAL_ZOOM_LEVEL);
+        *minwidth = round(MIN_DISPLAY_WIDTH * priv->zoom_level / (double) NORMAL_ZOOM_LEVEL);
     } else {
-        *defwidth = priv->desktopWidth + 2 * border_width;
+        *defwidth = priv->desktopWidth;
+        *minwidth = MIN_DISPLAY_WIDTH;
     }
+    *defwidth += 2 * border_width;
+    *minwidth += 2 * border_width;
 }
 
 
@@ -479,14 +481,15 @@ static void virt_viewer_display_get_preferred_height(GtkWidget *widget,
     VirtViewerDisplayPrivate *priv = display->priv;
     int border_height = gtk_container_get_border_width(GTK_CONTAINER(widget));
 
-    *minheight = MIN_DISPLAY_HEIGHT + 2 * border_height;
-
     if (priv->zoom) {
-        *defheight = round(priv->desktopHeight * priv->zoom_level / (double) NORMAL_ZOOM_LEVEL) +
-                    2 * border_height;
+        *defheight = round(priv->desktopHeight * priv->zoom_level / (double) NORMAL_ZOOM_LEVEL);
+        *minheight = round(MIN_DISPLAY_HEIGHT * priv->zoom_level / (double) NORMAL_ZOOM_LEVEL);
     } else {
-        *defheight = priv->desktopHeight + 2 * border_height;
+        *defheight = priv->desktopHeight;
+        *minheight = MIN_DISPLAY_HEIGHT;
     }
+    *defheight += 2 * border_height;
+    *minheight += 2 * border_height;
 }
 #endif
 
diff --git a/src/virt-viewer-display.h b/src/virt-viewer-display.h
index a899bb4..a279697 100644
--- a/src/virt-viewer-display.h
+++ b/src/virt-viewer-display.h
@@ -29,8 +29,8 @@
 
 G_BEGIN_DECLS
 
-#define MIN_DISPLAY_WIDTH 50
-#define MIN_DISPLAY_HEIGHT 50
+#define MIN_DISPLAY_WIDTH 320
+#define MIN_DISPLAY_HEIGHT 200
 
 #define VIRT_VIEWER_TYPE_DISPLAY virt_viewer_display_get_type()