Re: [Qemu-devel] [PATCH] gtk: Fix mouse offset in scaled gtk-gl display for VFIO/iGVT-g DMA Buf mode

[Gerd Hoffmann]

On Wed, Oct 31, 2018 at 06:24:56AM +0000, Chen Zhang wrote:
> The issue was reported as in https://bugs.launchpad.net/qemu/+bug/1793859
> 
> When an OpenGL accelerated GTK window is used for iGVT-g DMA Buf device,
> window scaling would cause guest cursor to move in undesirable velocity.
> 
> To fix this usability issue, the gtk mouse motion events was modified to
> scale the position of event to match the coordinates of the scaled GL
> surface.

Hmm, we already have logic in place to deal with that.  I suspect the
root cause is simply that the scale_{x,y} variables are not set properly
in egl mode.  Can you try the patch below?

thanks,
  Gerd

========================== [ cut here ] ===========================
>From ebecaab0102aca37a3101131c20f45576835b6b3 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kra...@redhat.com>
Date: Tue, 6 Nov 2018 13:18:39 +0100
Subject: [PATCH] try fix gtk egl cursor

---
 ui/gtk-egl.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/ui/gtk-egl.c b/ui/gtk-egl.c
index a77c25b490..5420c2362b 100644
--- a/ui/gtk-egl.c
+++ b/ui/gtk-egl.c
@@ -68,8 +68,15 @@ void gd_egl_draw(VirtualConsole *vc)
         return;
     }
 
+    window = gtk_widget_get_window(vc->gfx.drawing_area);
+    ww = gdk_window_get_width(window);
+    wh = gdk_window_get_height(window);
+
     if (vc->gfx.scanout_mode) {
         gd_egl_scanout_flush(&vc->gfx.dcl, 0, 0, vc->gfx.w, vc->gfx.h);
+
+        vc->gfx.scale_x = (double)ww / vc->gfx.w;
+        vc->gfx.scale_y = (double)wh / vc->gfx.h;
     } else {
         if (!vc->gfx.ds) {
             return;
@@ -77,13 +84,13 @@ void gd_egl_draw(VirtualConsole *vc)
         eglMakeCurrent(qemu_egl_display, vc->gfx.esurface,
                        vc->gfx.esurface, vc->gfx.ectx);
 
-        window = gtk_widget_get_window(vc->gfx.drawing_area);
-        ww = gdk_window_get_width(window);
-        wh = gdk_window_get_height(window);
         surface_gl_setup_viewport(vc->gfx.gls, vc->gfx.ds, ww, wh);
         surface_gl_render_texture(vc->gfx.gls, vc->gfx.ds);
 
         eglSwapBuffers(qemu_egl_display, vc->gfx.esurface);
+
+        vc->gfx.scale_x = (double)ww / surface_width(vc->gfx.ds);
+        vc->gfx.scale_y = (double)wh / surface_height(vc->gfx.ds);
     }
 }
 
@@ -232,8 +239,8 @@ void gd_egl_cursor_position(DisplayChangeListener *dcl,
 {
     VirtualConsole *vc = container_of(dcl, VirtualConsole, gfx.dcl);
 
-    vc->gfx.cursor_x = pos_x;
-    vc->gfx.cursor_y = pos_y;
+    vc->gfx.cursor_x = pos_x * vc->gfx.scale_x;
+    vc->gfx.cursor_y = pos_y * vc->gfx.scale_y;
 }
 
 void gd_egl_release_dmabuf(DisplayChangeListener *dcl,
-- 
2.9.3