Re: [PATCH v2 3/3] ui: Fix gtk/gl when the scaled virtual console does not fit the window

[Marc-André Lureau]

Hi

On Wed, Dec 22, 2021 at 4:11 AM Alexander Orzechowski <orzechowski.alexander@gmail.com> wrote:

gtk/gl was incorrectly always rendering as if the 'Zoom to Fit' was
always checked even if it wasn't. This is now using logic closer
to what is being used for the existing cairo code paths.

Signed-off-by: Alexander Orzechowski <orzechowski.alexander@gmail.com>

This is definitely an improvement for me (on hidpi), but I have some questions and I don't have much interest in working on qemu GTK3 code.

(fwiw, I hope the future will be around the gtk4 widget I work on at https://gitlab.com/marcandre.lureau/qemu-display/)

The 2nd patch should come after this one imho, to avoid intermediary extra regressions.

---
 ui/gtk-gl-area.c | 34 +++++++++++++++++++++++++++++-----
 1 file changed, 29 insertions(+), 5 deletions(-)

diff --git a/ui/gtk-gl-area.c b/ui/gtk-gl-area.c
index 01e4e74ee3..f4f2dac882 100644
--- a/ui/gtk-gl-area.c
+++ b/ui/gtk-gl-area.c
@@ -41,16 +41,40 @@ void gd_gl_area_draw(VirtualConsole *vc)
 #ifdef CONFIG_GBM
     QemuDmaBuf *dmabuf = vc->gfx.guest_fb.dmabuf;
 #endif
+    GtkDisplayState *s = vc->s;
     int ww, wh, ws, y1, y2;
+    int mx, my;
+    int fbh, fbw;

     if (!vc->gfx.gls) {
         return;
     }

     gtk_gl_area_make_current(GTK_GL_AREA(vc->gfx.drawing_area));
+
+    fbw = surface_width(vc->gfx.ds);
+    fbh = surface_height(vc->gfx.ds);
+
     ws = gdk_window_get_scale_factor(gtk_widget_get_window(vc->gfx.drawing_area));
-    ww = gtk_widget_get_allocated_width(vc->gfx.drawing_area) * ws;
-    wh = gtk_widget_get_allocated_height(vc->gfx.drawing_area) * ws;
+    ww = gtk_widget_get_allocated_width(vc->gfx.drawing_area);
+    wh = gtk_widget_get_allocated_height(vc->gfx.drawing_area);
+
+    if (s->full_screen) {
+        vc->gfx.scale_x = (double)ww / fbw;
+        vc->gfx.scale_y = (double)wh / fbh;

Why not keep aspect-ratio in full-screen?

(and hopefully the pointer follows the same size logic, as well as the 2d/cairo & gtk-x11/egl code paths..)

+    } else if (s->free_scale) {
+        double sx, sy;
+
+        sx = (double)ww / fbw;
+        sy = (double)wh / fbh;
+
+        vc->gfx.scale_x = vc->gfx.scale_y = MIN(sx, sy);
+    }
+
+    fbw *= vc->gfx.scale_x * ws;
+    fbh *= vc->gfx.scale_y * ws;
+    mx = (ww * ws - fbw) / 2;
+    my = (wh * ws - fbh) / 2;

     if (vc->gfx.scanout_mode) {
         if (!vc->gfx.guest_fb.framebuffer) {
@@ -70,11 +94,11 @@ void gd_gl_area_draw(VirtualConsole *vc)
         glBindFramebuffer(GL_READ_FRAMEBUFFER, vc->gfx.guest_fb.framebuffer);
         /* GtkGLArea sets GL_DRAW_FRAMEBUFFER for us */

-        glViewport(0, 0, ww, wh);
+        glViewport(mx, my, fbw, fbh);
         y1 = vc->gfx.y0_top ? 0 : vc->gfx.h;
         y2 = vc->gfx.y0_top ? vc->gfx.h : 0;
         glBlitFramebuffer(0, y1, vc->gfx.w, y2,
-                          0, 0, ww, wh,
+                          mx, my, fbw + mx, fbh + my,
                           GL_COLOR_BUFFER_BIT, GL_NEAREST);
 #ifdef CONFIG_GBM
         if (dmabuf) {
@@ -98,7 +122,7 @@ void gd_gl_area_draw(VirtualConsole *vc)
         }
         gtk_gl_area_make_current(GTK_GL_AREA(vc->gfx.drawing_area));

-        surface_gl_setup_viewport(vc->gfx.gls, vc->gfx.ds, ww, wh);
+        glViewport(mx, my, fbw, fbh);

 We should be able to reuse and share the surface_gl_setup_viewport() logic, no?

--

Marc-André Lureau