support fractional scale (#2042)

wl_compositor v6 requires this.

https://gitlab.freedesktop.org/wayland/wayland/-/commit/9afab91d212164b56c7eefd234c798fc59ae3fd8

src/api/wayfire/nonstd/wlroots-full.hpp

@@ -134,6 +134,7 @@ extern "C"
 #include <wlr/types/wlr_relative_pointer_v1.h>
 #include <wlr/types/wlr_text_input_v3.h>
 #include <wlr/types/wlr_primary_selection_v1.h>
+#include <wlr/types/wlr_fractional_scale_v1.h>
 
 // Activation plugin
 #include <wlr/types/wlr_xdg_activation_v1.h>

src/core/core.cpp

@@ -191,6 +191,8 @@ void wf::compositor_core_impl_t::init()
     protocols.foreign_v2 = wlr_xdg_foreign_v2_create(display,
         protocols.foreign_registry);
 
+    wlr_fractional_scale_manager_v1_create(display, 1);
+
     this->bindings = std::make_unique<bindings_repository_t>();
     image_io::init();
     OpenGL::init();

src/view/wlr-surface-node.cpp

@@ -252,6 +252,7 @@ class wf::scene::wlr_surface_node_t::wlr_surface_render_instance_t : public rend
             if (self->surface)
             {
                 wlr_surface_send_enter(self->surface, visible_on->handle);
+                wlr_fractional_scale_v1_notify_scale(self->surface, visible_on->handle->scale);
             }
         }