Re: [PATCH v2] ui/console: Pass placeholder surface to displays

[Akihiko Odaki <akihiko.odaki@gmail.com>]

2021年2月22日(月) 19:51 Gerd Hoffmann <kraxel@redhat.com>:
>
>   Hi,
>
> >  #define QEMU_ALLOCATED_FLAG     0x01
> > +#define QEMU_PLACEHOLDER_FLAG   0x02
>
> > +static inline int is_placeholder(DisplaySurface *surface)
> > +{
> > +    return surface->flags & QEMU_PLACEHOLDER_FLAG;
> > +}
>
> Interesting idea.  That approach makes sense too.
>
> > +        if (!placeholder) {
> > +            placeholder = qemu_create_message_surface(640, 480, placeholder_msg);
> > +            placeholder->flags |= QEMU_PLACEHOLDER_FLAG;
>
> I think we should set the placeholder flag in
> qemu_create_message_surface() because every surface created with that
> function is some kind if placeholder.
>
> Also when replacing an existing surface we should make the placeholder
> the same size, to avoid pointless ui window resizes.
>
> > -    if (!new_surface) {
> > +    if (is_placeholder(new_surface)) {
>
> We should check whenever this is the primary or a secondary window here
> and only destroy secondary windows.  qemu hiding all windows but
> continuing to run has great potential for user confusion ...
>
> > -    if (!new_surface) {
> > +    if (is_placeholder(new_surface)) {
>
> Same here.

The other surfaces created by qemu_create_message_surface() are not
considered as "placeholder" here, and have contents to be displayed.
Since no emulated devices give NULL to dpy_gfx_replace_surface for the
primary connection, it will never get the "placeholder", and its
window will be always shown.

Regards,
Akihiko Odaki

>
> take care,
>   Gerd
>