winewayland.drv: Support compositor-side scaling.

Introduce a mechanism to select whether we should use application-side
or composidor-side scaling. This is controlled by the "HiDPIScaling"
global or per-app driver option, either "Application" (the default) or
"Compositor".

With application-side scaling, which is the default, the application has
access to the full/native resolution of the outputs, and needs to manage
scaling manually (e.g., by using the Wine DPI options).

With compositor-side scaling, the application has access only to the
scaled resolution of the outputs, and the compositor automatically
scales the provided buffers.

Signed-off-by: Alexandros Frantzis <alexandros.frantzis@collabora.com>

dlls/winewayland.drv/options.c

@@ -42,6 +42,7 @@
  */
 
 char *option_drm_device = NULL;
+enum wayland_hidpi_scaling option_hidpi_scaling = WAYLAND_HIDPI_SCALING_APPLICATION;
 BOOL option_use_system_cursors = TRUE;
 
 /***********************************************************************
@@ -95,6 +96,14 @@ void wayland_read_options_from_registry(void)
     if (!get_config_key(hkey, appkey, "DRMDevice", REG_SZ, buffer, sizeof(buffer)))
         option_drm_device = strdup(buffer);
 
+    if (!get_config_key(hkey, appkey, "HiDPIScaling", REG_SZ, buffer, sizeof(buffer)))
+    {
+        if (!strcasecmp(buffer, "Application"))
+            option_hidpi_scaling = WAYLAND_HIDPI_SCALING_APPLICATION;
+        else if (!strcasecmp(buffer, "Compositor"))
+            option_hidpi_scaling = WAYLAND_HIDPI_SCALING_COMPOSITOR;
+    }
+
     if (!get_config_key(hkey, appkey, "UseSystemCursors", REG_SZ, buffer, sizeof(buffer)))
         option_use_system_cursors = IS_OPTION_TRUE(buffer[0]);
 

dlls/winewayland.drv/wayland_output.c

@@ -274,6 +274,11 @@ static void wayland_output_list_update_physical_coords(struct wl_list *output_li
         cur->y = cur->logical_y;
     }
 
+    /* When compositor scaling is used, we treat logical coordinates as
+     * physical. */
+    if (option_hidpi_scaling == WAYLAND_HIDPI_SCALING_COMPOSITOR)
+        return;
+
     /* Sort and process the outputs from left to right. */
     cur_p = sorted_x = wayland_output_list_sorted(output_list, wayland_output_cmp_x);
     if (!sorted_x) return;
@@ -338,6 +343,15 @@ static void wayland_output_update_scale(struct wayland_output *output)
 {
     double inferred_scale = 0.0;
 
+    /* When compositor scaling is used, we ignore the output scale, to
+     * allow the the compositor to scale us. */
+    if (option_hidpi_scaling == WAYLAND_HIDPI_SCALING_COMPOSITOR)
+    {
+        output->scale = 1.0;
+        TRACE("using scale=%.2f to enable compositor scaling\n", output->scale);
+        return;
+    }
+
     if (output->logical_w != 0 && output->logical_h != 0 &&
         output->current_mode)
     {
@@ -369,6 +383,17 @@ static void wayland_output_done(struct wayland_output *output)
 
     TRACE("output->name=%s\n", output->name);
 
+    /* When compositor scaling is used, the current and only native mode
+     * corresponds to the logical width and height. */
+    if (option_hidpi_scaling == WAYLAND_HIDPI_SCALING_COMPOSITOR)
+    {
+        int32_t current_refresh =
+            output->current_mode ? output->current_mode->refresh : default_refresh;
+        wayland_output_clear_modes(output);
+        wayland_output_add_mode_all_bpp(output, output->logical_w, output->logical_h,
+                                        current_refresh, TRUE, TRUE);
+    }
+
     wayland_output_add_default_modes(output);
     wayland_output_list_update_physical_coords(&output->wayland->output_list);
     wayland_output_update_scale(output);
@@ -419,6 +444,12 @@ static void output_handle_mode(void *data, struct wl_output *wl_output,
 {
     struct wayland_output *output = data;
 
+    /* When compositor scaling is used, we don't use physical width/height
+     * for modes and the current mode will be set based on logical width
+     * and height (see wayland_output_done()). */
+    if (option_hidpi_scaling == WAYLAND_HIDPI_SCALING_COMPOSITOR)
+        return;
+
     /* Windows apps don't expect a zero refresh rate, so use a default value. */
     if (refresh == 0) refresh = default_refresh;
 

dlls/winewayland.drv/waylanddrv.h

@@ -59,6 +59,7 @@ extern struct wl_display *process_wl_display DECLSPEC_HIDDEN;
 extern struct gbm_device *process_gbm_device DECLSPEC_HIDDEN;
 extern const struct user_driver_funcs waylanddrv_funcs DECLSPEC_HIDDEN;
 extern char *option_drm_device DECLSPEC_HIDDEN;
+extern enum wayland_hidpi_scaling option_hidpi_scaling DECLSPEC_HIDDEN;
 extern BOOL option_use_system_cursors DECLSPEC_HIDDEN;
 
 /**********************************************************************
@@ -129,6 +130,12 @@ enum wayland_pointer_locked_reason
     WAYLAND_POINTER_LOCKED_REASON_CLIP = (1 << 1),
 };
 
+enum wayland_hidpi_scaling
+{
+    WAYLAND_HIDPI_SCALING_APPLICATION,
+    WAYLAND_HIDPI_SCALING_COMPOSITOR,
+};
+
 /**********************************************************************
  *          Definitions for wayland types
  */