ui/gtk: Consider scaling when propagating ui info

The ui width and height sent to guest is supposed to be in buffer
coordinate. Hence conversion is required.

If scaling (global window scale and zooming scale) is not respected in
non-free-scale mode, window size could keep changing because of the
existence of the iteration of the following steps:

1. In resize event or configure event, a size larger (or smaller) than
   the currently used one might be calculated due to not considering
   scaling.
2. On reception of the display size change event in guest, the guest
   might decide to do a mode setting and use the larger (or smaller)
   mode.
3. When the new guest scan-out command arrives, QEMU would request the
   window size to change to fit the new buffer size. This will trigger a
   resize event or a configure event, making us go back to step 1.

Signed-off-by: Weifeng Liu <weifeng.liu.z@gmail.com>
Message-ID: <20250511073337.876650-8-weifeng.liu.z@gmail.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
(cherry picked from commit a1b28f71f7ff0fcafbe0672b788e8e57ee4fe8f6)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/ui/gtk.c b/ui/gtk.c
index ea3f403b022d1166b767054b7a124a6b6f9d4dc3..2db10c46dad270c8e1cc14d91cbd828ae6e88c0b 100644 (file)
--- a/ui/gtk.c
+++ b/ui/gtk.c
@@ -772,8 +772,21 @@ static void gd_resize_event(GtkGLArea *area,
                             gint width, gint height, gpointer *opaque)
 {
     VirtualConsole *vc = (void *)opaque;
+    double pw = width, ph = height;
+    double sx = vc->gfx.scale_x, sy = vc->gfx.scale_y;
+    GdkWindow *window = gtk_widget_get_window(GTK_WIDGET(area));
+    const int gs = gdk_window_get_scale_factor(window);
 
-    gd_set_ui_size(vc, width, height);
+    if (!vc->s->free_scale && !vc->s->full_screen) {
+        pw /= sx;
+        ph /= sy;
+    }
+
+    /**
+     * width and height here are in pixel coordinate, so we must divide it
+     * by global window scale (gs)
+     */
+    gd_set_ui_size(vc, pw / gs, ph / gs);
 }
 
 #endif
@@ -1836,8 +1849,16 @@ static gboolean gd_configure(GtkWidget *widget,
                              GdkEventConfigure *cfg, gpointer opaque)
 {
     VirtualConsole *vc = opaque;
+    const double sx = vc->gfx.scale_x, sy = vc->gfx.scale_y;
+    double width = cfg->width, height = cfg->height;
+
+    if (!vc->s->free_scale && !vc->s->full_screen) {
+        width /= sx;
+        height /= sy;
+    }
+
+    gd_set_ui_size(vc, width, height);
 
-    gd_set_ui_size(vc, cfg->width, cfg->height);
     return FALSE;
 }