ui/console: Add placeholder flag to message surface

The surfaces created with former qemu_create_message_surface
did not display the content from the guest and always contained
simple messages describing the reason.

A display backend may want to hide the window showing such a
surface. This change renames the function to
qemu_create_placeholder_surface, and adds "placeholder" flag; the
display can check the flag to decide to do anything special like
hiding the window.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Message-Id: <20210225101316.83940-1-akihiko.odaki@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hw/display/vhost-user-gpu.c

@@ -194,8 +194,8 @@ vhost_user_gpu_handle_display(VhostUserGPU *g, VhostUserGpuMsg *msg)
         con = s->con;
 
         if (m->scanout_id == 0 && m->width == 0) {
-            s->ds = qemu_create_message_surface(640, 480,
-                                                "Guest disabled display.");
+            s->ds = qemu_create_placeholder_surface(640, 480,
+                                                    "Guest disabled display.");
             dpy_gfx_replace_surface(con, s->ds);
         } else {
             s->ds = qemu_create_displaysurface(m->width, m->height);

hw/display/virtio-gpu.c

@@ -338,9 +338,9 @@ static void virtio_gpu_disable_scanout(VirtIOGPU *g, int scanout_id)
 
     if (scanout_id == 0) {
         /* primary head */
-        ds = qemu_create_message_surface(scanout->width  ?: 640,
-                                         scanout->height ?: 480,
-                                         "Guest disabled display.");
+        ds = qemu_create_placeholder_surface(scanout->width  ?: 640,
+                                             scanout->height ?: 480,
+                                             "Guest disabled display.");
     }
     dpy_gfx_replace_surface(scanout->con, ds);
     scanout->resource_id = 0;

include/ui/console.h

@@ -106,6 +106,7 @@ struct QemuConsoleClass {
 };
 
 #define QEMU_ALLOCATED_FLAG     0x01
+#define QEMU_PLACEHOLDER_FLAG   0x02
 
 typedef struct DisplaySurface {
     pixman_format_code_t format;
@@ -259,8 +260,8 @@ DisplaySurface *qemu_create_displaysurface_from(int width, int height,
                                                 pixman_format_code_t format,
                                                 int linesize, uint8_t *data);
 DisplaySurface *qemu_create_displaysurface_pixman(pixman_image_t *image);
-DisplaySurface *qemu_create_message_surface(int w, int h,
-                                            const char *msg);
+DisplaySurface *qemu_create_placeholder_surface(int w, int h,
+                                                const char *msg);
 PixelFormat qemu_default_pixelformat(int bpp);
 
 DisplaySurface *qemu_create_displaysurface(int width, int height);
@@ -281,6 +282,11 @@ static inline int is_buffer_shared(DisplaySurface *surface)
     return !(surface->flags & QEMU_ALLOCATED_FLAG);
 }
 
+static inline int is_placeholder(DisplaySurface *surface)
+{
+    return surface->flags & QEMU_PLACEHOLDER_FLAG;
+}
+
 void register_displaychangelistener(DisplayChangeListener *dcl);
 void update_displaychangelistener(DisplayChangeListener *dcl,
                                   uint64_t interval);

ui/console.c

@@ -1436,8 +1436,8 @@ DisplaySurface *qemu_create_displaysurface_pixman(pixman_image_t *image)
     return surface;
 }
 
-DisplaySurface *qemu_create_message_surface(int w, int h,
-                                            const char *msg)
+DisplaySurface *qemu_create_placeholder_surface(int w, int h,
+                                                const char *msg)
 {
     DisplaySurface *surface = qemu_create_displaysurface(w, h);
     pixman_color_t bg = color_table_rgb[0][QEMU_COLOR_BLACK];
@@ -1454,6 +1454,7 @@ DisplaySurface *qemu_create_message_surface(int w, int h,
                                  x+i, y, FONT_WIDTH, FONT_HEIGHT);
         qemu_pixman_image_unref(glyph);
     }
+    surface->flags |= QEMU_PLACEHOLDER_FLAG;
     return surface;
 }
 
@@ -1550,7 +1551,7 @@ void register_displaychangelistener(DisplayChangeListener *dcl)
             dcl->ops->dpy_gfx_switch(dcl, con->surface);
         } else {
             if (!dummy) {
-                dummy = qemu_create_message_surface(640, 480, nodev);
+                dummy = qemu_create_placeholder_surface(640, 480, nodev);
             }
             dcl->ops->dpy_gfx_switch(dcl, dummy);
         }
@@ -1998,7 +1999,7 @@ QemuConsole *graphic_console_init(DeviceState *dev, uint32_t head,
                                  &error_abort);
     }
 
-    surface = qemu_create_message_surface(width, height, noinit);
+    surface = qemu_create_placeholder_surface(width, height, noinit);
     dpy_gfx_replace_surface(s, surface);
     return s;
 }
@@ -2027,7 +2028,7 @@ void graphic_console_close(QemuConsole *con)
     if (con->gl) {
         dpy_gl_scanout_disable(con);
     }
-    surface = qemu_create_message_surface(width, height, unplugged);
+    surface = qemu_create_placeholder_surface(width, height, unplugged);
     dpy_gfx_replace_surface(con, surface);
 }
 

ui/vnc.c

@@ -799,7 +799,7 @@ static void vnc_dpy_switch(DisplayChangeListener *dcl,
 
     if (surface == NULL) {
         if (placeholder == NULL) {
-            placeholder = qemu_create_message_surface(640, 480, placeholder_msg);
+            placeholder = qemu_create_placeholder_surface(640, 480, placeholder_msg);
         }
         surface = placeholder;
     }