Gtk/Wayland: Support fractional scale.

gtk/CMakeLists.txt

@@ -140,7 +140,9 @@ if(USE_WAYLAND)
                         src/gtk_wayland_egl_context.h
                         src/gtk_wayland_surface.cpp
                         src/gtk_wayland_surface.h
-                        src/wayland-idle-inhibit-unstable-v1.c)
+                        src/wayland-idle-inhibit-unstable-v1.c
+                        src/viewporter-client-protocol.c
+                        src/fractional-scale-v1.c)
     list(APPEND ARGS ${WAYLAND_CFLAGS})
     list(APPEND LIBS ${WAYLAND_LIBRARIES})
 endif()

gtk/src/gtk_display_driver_vulkan.cpp

@@ -31,26 +31,29 @@ void S9xVulkanDisplayDriver::refresh()
     if (!context)
         return;
 
-    bool vsync_changed = context->swapchain->set_vsync(gui_config->sync_to_vblank);
+    context->swapchain->set_vsync(gui_config->sync_to_vblank);
+    int new_width, new_height;
 
-    auto new_width = drawing_area->get_width() * drawing_area->get_scale_factor();
-    auto new_height = drawing_area->get_height() * drawing_area->get_scale_factor();
-
-    if (new_width != current_width || new_height != current_height || vsync_changed)
-    {
 #ifdef GDK_WINDOWING_WAYLAND
     if (GDK_IS_WAYLAND_WINDOW(drawing_area->get_window()->gobj()))
     {
         wayland_surface->resize();
+        std::tie(new_width, new_height) = wayland_surface->get_size();
     }
+    else
 #endif
+    {
+        new_width = drawing_area->get_width() * drawing_area->get_scale_factor();
+        new_height = drawing_area->get_height() * drawing_area->get_scale_factor();
+    }
+
+    if (new_width != current_width || new_height != current_height)
+    {
         context->recreate_swapchain(new_width, new_height);
         context->wait_idle();
         current_width = new_width;
         current_height = new_height;
     }
-
-    context->swapchain->set_vsync(gui_config->sync_to_vblank);
 }
 
 int S9xVulkanDisplayDriver::init()

gtk/src/gtk_wayland_surface.cpp

@@ -6,10 +6,13 @@
 
 #include <stdio.h>
 #include <string.h>
+#include <wayland-util.h>
 
+#include "fractional-scale-v1.h"
 #include "gtk_s9x.h"
 #include "gtk_wayland_surface.h"
 #include "wayland-idle-inhibit-unstable-v1.h"
+#include "viewporter-client-protocol.h"
 
 static void wl_global(void *data,
                       struct wl_registry *wl_registry,
@@ -25,6 +28,10 @@ static void wl_global(void *data,
         wl->subcompositor = (struct wl_subcompositor *)wl_registry_bind(wl_registry, name, &wl_subcompositor_interface, 1);
     else if (!strcmp(interface, zwp_idle_inhibit_manager_v1_interface.name))
         wl->idle_inhibit_manager = (struct zwp_idle_inhibit_manager_v1 *)wl_registry_bind(wl_registry, name, &zwp_idle_inhibit_manager_v1_interface, 1);
+    else if (!strcmp(interface, wp_viewporter_interface.name))
+        wl->viewporter = (struct wp_viewporter *)wl_registry_bind(wl_registry, name, &wp_viewporter_interface, 1);
+    else if (!strcmp(interface, wp_fractional_scale_manager_v1_interface.name))
+        wl->fractional_scale_manager = (struct wp_fractional_scale_manager_v1 *)wl_registry_bind(wl_registry, name, &wp_fractional_scale_manager_v1_interface, 1);
 }
 
 static void wl_global_remove(void *data,
@@ -50,6 +57,11 @@ WaylandSurface::WaylandSurface()
     subsurface = nullptr;
     idle_inhibit_manager = nullptr;
     idle_inhibitor = nullptr;
+    viewporter = nullptr;
+    viewport = nullptr;
+    fractional_scale_manager = nullptr;
+    fractional_scale = nullptr;
+    actual_scale = 0.0;
 }
 
 WaylandSurface::~WaylandSurface()
@@ -68,8 +80,32 @@ WaylandSurface::~WaylandSurface()
 
     if (child)
         wl_surface_destroy(child);
+
+    if (viewporter)
+        wp_viewporter_destroy(viewporter);
+
+    if (viewport)
+        wp_viewport_destroy(viewport);
+
+    if (fractional_scale_manager)
+        wp_fractional_scale_manager_v1_destroy(fractional_scale_manager);
+
+    if (fractional_scale)
+        wp_fractional_scale_v1_destroy(fractional_scale);
 }
 
+static void preferred_scale(void *data,
+                            struct wp_fractional_scale_v1 *wp_fractional_scale_v1,
+                            uint32_t scale)
+{
+    ((WaylandSurface *)data)->actual_scale = scale / 120.0;
+}
+
+wp_fractional_scale_v1_listener fractional_scale_v1_listener =
+{
+    preferred_scale
+};
+
 bool WaylandSurface::attach(GtkWidget *widget)
 {
     GdkWindow *window = gtk_widget_get_window(widget);
@@ -79,6 +115,7 @@ bool WaylandSurface::attach(GtkWidget *widget)
 
     gdk_window = window;
     gdk_window_get_geometry(gdk_window, &x, &y, &width, &height);
+    gdk_scale = gdk_window_get_scale_factor(gdk_window);
 
     display = gdk_wayland_display_get_wl_display(gdk_window_get_display(gdk_window));
     parent = gdk_wayland_window_get_wl_surface(gdk_window);
@@ -98,22 +135,47 @@ bool WaylandSurface::attach(GtkWidget *widget)
     wl_subsurface_set_desync(subsurface);
     wl_subsurface_set_position(subsurface, x, y);
 
+    if (fractional_scale_manager)
+    {
+        fractional_scale = wp_fractional_scale_manager_v1_get_fractional_scale(fractional_scale_manager, child);
+        wp_fractional_scale_v1_add_listener(fractional_scale, &fractional_scale_v1_listener, this);
+    }
+
     if (idle_inhibit_manager && gui_config->prevent_screensaver)
     {
         printf("Inhibiting screensaver.\n");
         zwp_idle_inhibit_manager_v1_create_inhibitor(idle_inhibit_manager, child);
     }
 
-    auto scale = gdk_window_get_scale_factor(window);
-    wl_surface_set_buffer_scale(child, scale);
-
     return true;
 }
 
+std::tuple<int, int> WaylandSurface::get_size()
+{
+    gdk_window_get_geometry(gdk_window, &x, &y, &width, &height);
+
+    if (actual_scale == 0.0)
+    {
+        gdk_scale = gdk_window_get_scale_factor(gdk_window);
+
+        return { width * gdk_scale, height * gdk_scale };
+    }
+
+    return { width * actual_scale, height * actual_scale };
+}
+
 void WaylandSurface::resize()
 {
-    gdk_window_get_geometry(gdk_window, &x, &y, &width, &height);
-    auto scale = gdk_window_get_scale_factor(gdk_window);
+    int w, h; std::tie(w, h) = get_size();
     wl_subsurface_set_position(subsurface, x, y);
-    wl_surface_set_buffer_scale(child, scale);
+
+    if (!viewport)
+        viewport = wp_viewporter_get_viewport(viewporter, child);
+
+    wp_viewport_set_source(viewport,
+        wl_fixed_from_int(0), wl_fixed_from_int(0),
+        wl_fixed_from_int(w), wl_fixed_from_int(h));
+    wp_viewport_set_destination(viewport, width, height);
+
+    wl_surface_commit(child);
 }

gtk/src/gtk_wayland_surface.h

@@ -7,6 +7,8 @@
 #pragma once
 
 #include "gtk_compat.h"
+#include "viewporter-client-protocol.h"
+#include "fractional-scale-v1.h"
 
 class WaylandSurface
 {
@@ -15,6 +17,7 @@ class WaylandSurface
     ~WaylandSurface();
     bool attach(GtkWidget *widget);
     void resize();
+    std::tuple<int, int> get_size();
 
     GdkWindow *gdk_window;
 
@@ -32,7 +35,15 @@ class WaylandSurface
     int y;
     int width;
     int height;
+    int gdk_scale;
+    double actual_scale;
 
     struct zwp_idle_inhibit_manager_v1 *idle_inhibit_manager;
     struct zwp_idle_inhibitor_v1 *idle_inhibitor;
+
+    struct wp_viewporter *viewporter;
+    struct wp_viewport *viewport;
+
+    struct wp_fractional_scale_manager_v1 *fractional_scale_manager;
+    struct wp_fractional_scale_v1 *fractional_scale;
 };