Add HiDPI xwayland + wlroots patches (#591)

.github/workflows/nix-build.yaml

@@ -5,6 +5,11 @@ jobs:
   nix:
     name: "Build Hyprland (Nix)"
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        package:
+        - default
+        - hyprland-no-hidpi
     steps:
     - name: Clone repository
       uses: actions/checkout@v3
@@ -22,4 +27,4 @@ jobs:
         name: hyprland
         authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
     - name: Build Hyprland with default settings
-      run: nix build --print-build-logs
+      run: nix build .#${{ matrix.package }} --print-build-logs

flake.nix

@@ -32,12 +32,15 @@
         version = mkDate (inputs.wlroots.lastModifiedDate or "19700101");
         src = inputs.wlroots;
       });
+
       hyprland = prev.callPackage ./nix/default.nix {
         stdenv = prev.gcc12Stdenv;
         version = "0.11.1beta" + "+date=" + (mkDate (self.lastModifiedDate or "19700101")) + "_" + (self.shortRev or "dirty");
         wlroots = wlroots-hyprland;
       };
       hyprland-debug = hyprland.override {debug = true;};
+      hyprland-no-hidpi = hyprland.override {hidpiXWayland = false;};
+
       waybar-hyprland = prev.waybar.overrideAttrs (oldAttrs: {
         mesonFlags = oldAttrs.mesonFlags ++ ["-Dexperimental=true"];
       });

nix/default.nix

@@ -2,6 +2,7 @@
   lib,
   stdenv,
   fetchFromGitHub,
+  fetchpatch,
   pkg-config,
   meson,
   ninja,
@@ -21,78 +22,88 @@
   xwayland,
   debug ? false,
   enableXWayland ? true,
+  hidpiXWayland ? true,
   legacyRenderer ? false,
   version ? "git",
-}:
+}: let
-stdenv.mkDerivation {
+  assertXWayland = lib.assertMsg (hidpiXWayland -> enableXWayland) ''
-  pname = "hyprland" + lib.optionalString debug "-debug";
+    Hyprland: cannot have hidpiXWayland when enableXWayland is false.
-  inherit version;
-
-  src = lib.cleanSourceWith {
-    filter = name: type: let
-      baseName = baseNameOf (toString name);
-    in
-      ! (
-        lib.hasSuffix ".nix" baseName
-      );
-    src = lib.cleanSource ../.;
-  };
-
-  nativeBuildInputs = [
-    meson
-    ninja
-    pkg-config
-  ];
-
-  outputs = [
-    "out"
-    "man"
-  ];
-
-  buildInputs =
-    [
-      git
-      libdrm
-      libinput
-      libxcb
-      libxkbcommon
-      mesa
-      pango
-      wayland
-      wayland-protocols
-      wayland-scanner
-      (wlroots.override {inherit enableXWayland;})
-      xcbutilwm
-    ]
-    ++ lib.optional enableXWayland xwayland;
-
-  mesonBuildType =
-    if debug
-    then "debug"
-    else "release";
-
-  mesonFlags = builtins.concatLists [
-    (lib.optional (!enableXWayland) "-Dxwayland=disabled")
-    (lib.optional legacyRenderer "-DLEGACY_RENDERER:STRING=true")
-  ];
-
-  patches = [
-    # make meson use the provided wlroots instead of the git submodule
-    ./meson-build.patch
-  ];
-
-  # Fix hardcoded paths to /usr installation
-  postPatch = ''
-    sed -i "s#/usr#$out#" src/render/OpenGL.cpp
   '';
+in
+  assert assertXWayland;
+    stdenv.mkDerivation {
+      pname = "hyprland" + lib.optionalString debug "-debug";
+      inherit version;
 
-  passthru.providedSessions = ["hyprland"];
+      src = lib.cleanSourceWith {
+        filter = name: type: let
+          baseName = baseNameOf (toString name);
+        in
+          ! (
+            lib.hasSuffix ".nix" baseName
+          );
+        src = lib.cleanSource ../.;
+      };
 
-  meta = with lib; {
+      nativeBuildInputs = [
-    homepage = "https://github.com/vaxerski/Hyprland";
+        meson
-    description = "A dynamic tiling Wayland compositor that doesn't sacrifice on its looks";
+        ninja
-    license = licenses.bsd3;
+        pkg-config
-    platforms = platforms.linux;
+      ];
-    mainProgram = "Hyprland";
+
-  };
+      outputs = [
-}
+        "out"
+        "man"
+      ];
+
+      buildInputs =
+        [
+          git
+          libdrm
+          libinput
+          libxcb
+          libxkbcommon
+          mesa
+          pango
+          wayland
+          wayland-protocols
+          wayland-scanner
+          (
+            if hidpiXWayland
+            then (import ./hidpi_wlroots.nix {inherit wlroots xwayland fetchpatch;})
+            else wlroots.override {inherit enableXWayland;}
+          )
+          xcbutilwm
+        ]
+        ++ lib.optional enableXWayland xwayland;
+
+      mesonBuildType =
+        if debug
+        then "debug"
+        else "release";
+
+      mesonFlags = builtins.concatLists [
+        (lib.optional (!enableXWayland) "-Dxwayland=disabled")
+        (lib.optional legacyRenderer "-DLEGACY_RENDERER:STRING=true")
+      ];
+
+      patches = [
+        # make meson use the provided wlroots instead of the git submodule
+        ./meson-build.patch
+      ];
+
+      # Fix hardcoded paths to /usr installation
+      postPatch = ''
+        sed -i "s#/usr#$out#" src/render/OpenGL.cpp
+      '';
+
+      passthru.providedSessions = ["hyprland"];
+
+      meta = with lib; {
+        homepage = "https://github.com/vaxerski/Hyprland";
+        description = "A dynamic tiling Wayland compositor that doesn't sacrifice on its looks";
+        license = licenses.bsd3;
+        platforms = platforms.linux;
+        mainProgram = "Hyprland";
+      };
+    }

nix/hidpi_wlroots.nix

@@ -0,0 +1,31 @@
+{
+  wlroots,
+  xwayland,
+  fetchpatch,
+}:
+(wlroots.overrideAttrs
+  (old: {
+    patches =
+      (old.patches or [])
+      ++ [
+        (fetchpatch {
+          url = "https://gitlab.freedesktop.org/lilydjwg/wlroots/-/commit/6c5ffcd1fee9e44780a6a8792f74ecfbe24a1ca7.diff";
+          sha256 = "sha256-Eo1pTa/PIiJsRZwIUnHGTIFFIedzODVf0ZeuXb0a3TQ=";
+        })
+        (fetchpatch {
+          url = "https://gitlab.freedesktop.org/wlroots/wlroots/-/commit/18595000f3a21502fd60bf213122859cc348f9af.diff";
+          sha256 = "sha256-jvfkAMh3gzkfuoRhB4E9T5X1Hu62wgUjj4tZkJm0mrI=";
+          revert = true;
+        })
+      ];
+  }))
+.override {
+  xwayland = xwayland.overrideAttrs (old: {
+    patches =
+      (old.patches or [])
+      ++ [
+        ./xwayland-vsync.patch
+        ./xwayland-hidpi.patch
+      ];
+  });
+}

nix/hm-module.nix

@@ -6,7 +6,8 @@ self: {
 }: let
   cfg = config.wayland.windowManager.hyprland;
   defaultHyprlandPackage = self.packages.${pkgs.system}.default.override {
-    enableXWayland = cfg.xwayland;
+    enableXWayland = cfg.xwayland.enable;
+    hidpiXWayland = cfg.xwayland.hidpi;
   };
 in {
   options.wayland.windowManager.hyprland = {
@@ -41,12 +42,21 @@ in {
         </itemizedlist>
       '';
     };
-    xwayland = lib.mkOption {
+    xwayland = {
-      type = lib.types.bool;
+      enable = lib.mkOption {
-      default = true;
+        type = lib.types.bool;
-      description = ''
+        default = true;
-        Enable xwayland.
+        description = ''
-      '';
+          Enable XWayland.
+        '';
+      };
+      hidpi = lib.mkOption {
+        type = lib.types.bool;
+        default = true;
+        description = ''
+          Enable HiDPI XWayland.
+        '';
+      };
     };
 
     extraConfig = lib.mkOption {
@@ -56,20 +66,28 @@ in {
         Extra configuration lines to add to ~/.config/hypr/hyprland.conf.
       '';
     };
+
+    imports = [
+      (
+        lib.mkRenamedOptionModule
+        ["wayland" "windowManager" "hyprland" "xwayland"]
+        ["wayland" "windowManager" "hyprland" "xwayland" "enable"]
+      )
+    ];
   };
 
   config = lib.mkIf cfg.enable {
     home.packages =
       lib.optional (cfg.package != null) cfg.package
-      ++ lib.optional cfg.xwayland pkgs.xwayland;
+      ++ lib.optional cfg.xwayland.enable pkgs.xwayland;
 
     xdg.configFile."hypr/hyprland.conf" = {
       text =
         (lib.optionalString cfg.systemdIntegration ''
-            exec-once=export XDG_SESSION_TYPE=wayland
+          exec-once=export XDG_SESSION_TYPE=wayland
-            exec-once=${pkgs.dbus}/bin/dbus-update-activation-environment --systemd DISPLAY WAYLAND_DISPLAY HYPRLAND_INSTANCE_SIGNATURE XDG_CURRENT_DESKTOP
+          exec-once=${pkgs.dbus}/bin/dbus-update-activation-environment --systemd DISPLAY WAYLAND_DISPLAY HYPRLAND_INSTANCE_SIGNATURE XDG_CURRENT_DESKTOP
-            exec-once=systemctl --user start hyprland-session.target
+          exec-once=systemctl --user start hyprland-session.target
-          '')
+        '')
         + cfg.extraConfig;
 
       onChange = let

nix/xwayland-hidpi.patch

@@ -0,0 +1,498 @@
+diff --git a/hw/xwayland/xwayland-cursor.c b/hw/xwayland/xwayland-cursor.c
+index c4457cc2a61b2103b47f996b51dbbe9eb87bd715..4a33e1f33e73c35c1691564ef4852e7501b02245 100644
+--- a/hw/xwayland/xwayland-cursor.c
++++ b/hw/xwayland/xwayland-cursor.c
+@@ -171,6 +171,8 @@ xwl_cursor_attach_pixmap(struct xwl_seat *xwl_seat,
+     }
+ 
+     wl_surface_attach(xwl_cursor->surface, buffer, 0, 0);
++    wl_surface_set_buffer_scale(xwl_cursor->surface,
++                                xwl_seat->xwl_screen->global_output_scale);
+     xwl_surface_damage(xwl_seat->xwl_screen, xwl_cursor->surface, 0, 0,
+                        xwl_seat->x_cursor->bits->width,
+                        xwl_seat->x_cursor->bits->height);
+@@ -190,6 +192,7 @@ xwl_cursor_attach_pixmap(struct xwl_seat *xwl_seat,
+ void
+ xwl_seat_set_cursor(struct xwl_seat *xwl_seat)
+ {
++    struct xwl_screen *xwl_screen = xwl_seat->xwl_screen;
+     struct xwl_cursor *xwl_cursor = &xwl_seat->cursor;
+     PixmapPtr pixmap;
+     CursorPtr cursor;
+@@ -220,8 +223,8 @@ xwl_seat_set_cursor(struct xwl_seat *xwl_seat)
+     wl_pointer_set_cursor(xwl_seat->wl_pointer,
+                           xwl_seat->pointer_enter_serial,
+                           xwl_cursor->surface,
+-                          xwl_seat->x_cursor->bits->xhot,
+-                          xwl_seat->x_cursor->bits->yhot);
++                          xwl_scale_to(xwl_screen, xwl_seat->x_cursor->bits->xhot),
++                          xwl_scale_to(xwl_screen, xwl_seat->x_cursor->bits->yhot));
+ 
+     xwl_cursor_attach_pixmap(xwl_seat, xwl_cursor, pixmap);
+ }
+@@ -230,6 +233,7 @@ void
+ xwl_tablet_tool_set_cursor(struct xwl_tablet_tool *xwl_tablet_tool)
+ {
+     struct xwl_seat *xwl_seat = xwl_tablet_tool->seat;
++    struct xwl_screen *xwl_screen = xwl_seat->xwl_screen;
+     struct xwl_cursor *xwl_cursor = &xwl_tablet_tool->cursor;
+     PixmapPtr pixmap;
+     CursorPtr cursor;
+@@ -258,9 +262,9 @@ xwl_tablet_tool_set_cursor(struct xwl_tablet_tool *xwl_tablet_tool)
+     zwp_tablet_tool_v2_set_cursor(xwl_tablet_tool->tool,
+                                   xwl_tablet_tool->proximity_in_serial,
+                                   xwl_cursor->surface,
+-                                  xwl_seat->x_cursor->bits->xhot,
+-                                  xwl_seat->x_cursor->bits->yhot);
+-
++                                  xwl_scale_to(xwl_screen, xwl_seat->x_cursor->bits->xhot),
++                                  xwl_scale_to(xwl_screen, xwl_seat->x_cursor->bits->yhot));
++    wl_surface_set_buffer_scale(xwl_cursor->surface, xwl_screen->global_output_scale);
+     xwl_cursor_attach_pixmap(xwl_seat, xwl_cursor, pixmap);
+ }
+ 
+diff --git a/hw/xwayland/xwayland-input.c b/hw/xwayland/xwayland-input.c
+index 26b3630c73b62514fe3ba7824371f79868e953f3..55cd8d466a55db03948abe93ffa03bf129b5e17a 100644
+--- a/hw/xwayland/xwayland-input.c
++++ b/hw/xwayland/xwayland-input.c
+@@ -412,8 +412,8 @@ pointer_handle_enter(void *data, struct wl_pointer *pointer,
+     DeviceIntPtr dev = get_pointer_device(xwl_seat);
+     DeviceIntPtr master;
+     int i;
+-    int sx = wl_fixed_to_int(sx_w);
+-    int sy = wl_fixed_to_int(sy_w);
++    int sx = wl_fixed_to_int(sx_w) * xwl_seat->xwl_screen->global_output_scale;
++    int sy = wl_fixed_to_int(sy_w) * xwl_seat->xwl_screen->global_output_scale;
+     int dx, dy;
+     ScreenPtr pScreen = xwl_seat->xwl_screen->screen;
+     ValuatorMask mask;
+@@ -592,13 +592,14 @@ pointer_handle_motion(void *data, struct wl_pointer *pointer,
+                       uint32_t time, wl_fixed_t sx_w, wl_fixed_t sy_w)
+ {
+     struct xwl_seat *xwl_seat = data;
++    int32_t scale = xwl_seat->xwl_screen->global_output_scale;
+ 
+     if (!xwl_seat->focus_window)
+         return;
+ 
+     xwl_seat->pending_pointer_event.has_absolute = TRUE;
+-    xwl_seat->pending_pointer_event.x = sx_w;
+-    xwl_seat->pending_pointer_event.y = sy_w;
++    xwl_seat->pending_pointer_event.x = sx_w * scale;
++    xwl_seat->pending_pointer_event.y = sy_w * scale;
+ 
+     if (wl_proxy_get_version((struct wl_proxy *) xwl_seat->wl_pointer) < 5)
+         dispatch_pointer_motion_event(xwl_seat);
+@@ -672,7 +673,8 @@ pointer_handle_axis(void *data, struct wl_pointer *pointer,
+         xorg_list_del(&pending->l);
+         free(pending);
+     } else {
+-        valuator_mask_set_double(&mask, index, wl_fixed_to_double(value) / divisor);
++        double scaled_value = wl_fixed_to_double(value);
++        valuator_mask_set_double(&mask, index, scaled_value / divisor);
+     }
+ 
+     QueuePointerEvents(get_pointer_device(xwl_seat),
+@@ -740,12 +742,13 @@ relative_pointer_handle_relative_motion(void *data,
+                                         wl_fixed_t dy_unaccelf)
+ {
+     struct xwl_seat *xwl_seat = data;
++    int32_t scale = xwl_seat->xwl_screen->global_output_scale;
+ 
+     xwl_seat->pending_pointer_event.has_relative = TRUE;
+-    xwl_seat->pending_pointer_event.dx = wl_fixed_to_double(dxf);
+-    xwl_seat->pending_pointer_event.dy = wl_fixed_to_double(dyf);
+-    xwl_seat->pending_pointer_event.dx_unaccel = wl_fixed_to_double(dx_unaccelf);
+-    xwl_seat->pending_pointer_event.dy_unaccel = wl_fixed_to_double(dy_unaccelf);
++    xwl_seat->pending_pointer_event.dx = wl_fixed_to_double(dxf) * scale;
++    xwl_seat->pending_pointer_event.dy = wl_fixed_to_double(dyf) * scale;
++    xwl_seat->pending_pointer_event.dx_unaccel = wl_fixed_to_double(dx_unaccelf) * scale;
++    xwl_seat->pending_pointer_event.dy_unaccel = wl_fixed_to_double(dy_unaccelf) * scale;
+ 
+     if (!xwl_seat->focus_window)
+         return;
+@@ -1057,8 +1060,8 @@ touch_handle_down(void *data, struct wl_touch *wl_touch,
+ 
+     xwl_touch->window = wl_surface_get_user_data(surface);
+     xwl_touch->id = id;
+-    xwl_touch->x = wl_fixed_to_int(sx_w);
+-    xwl_touch->y = wl_fixed_to_int(sy_w);
++    xwl_touch->x = wl_fixed_to_int(sx_w) * xwl_seat->xwl_screen->global_output_scale;
++    xwl_touch->y = wl_fixed_to_int(sy_w) * xwl_seat->xwl_screen->global_output_scale;
+     xorg_list_add(&xwl_touch->link_touch, &xwl_seat->touches);
+ 
+     xwl_touch_send_event(xwl_touch, xwl_seat, XI_TouchBegin);
+@@ -1094,8 +1097,8 @@ touch_handle_motion(void *data, struct wl_touch *wl_touch,
+     if (!xwl_touch)
+         return;
+ 
+-    xwl_touch->x = wl_fixed_to_int(sx_w);
+-    xwl_touch->y = wl_fixed_to_int(sy_w);
++    xwl_touch->x = wl_fixed_to_int(sx_w) * xwl_seat->xwl_screen->global_output_scale;;
++    xwl_touch->y = wl_fixed_to_int(sy_w) * xwl_seat->xwl_screen->global_output_scale;;
+     xwl_touch_send_event(xwl_touch, xwl_seat, XI_TouchUpdate);
+ }
+ 
+@@ -1726,8 +1729,8 @@ tablet_tool_motion(void *data, struct zwp_tablet_tool_v2 *tool,
+     struct xwl_tablet_tool *xwl_tablet_tool = data;
+     struct xwl_seat *xwl_seat = xwl_tablet_tool->seat;
+     int32_t dx, dy;
+-    double sx = wl_fixed_to_double(x);
+-    double sy = wl_fixed_to_double(y);
++    double sx = wl_fixed_to_double(x) * xwl_seat->xwl_screen->global_output_scale;
++    double sy = wl_fixed_to_double(y) * xwl_seat->xwl_screen->global_output_scale;
+ 
+     if (!xwl_seat->tablet_focus_window)
+         return;
+@@ -2714,6 +2717,7 @@ xwl_pointer_warp_emulator_set_fake_pos(struct xwl_pointer_warp_emulator *warp_em
+                                        int x,
+                                        int y)
+ {
++    struct xwl_screen *xwl_screen;
+     struct zwp_locked_pointer_v1 *locked_pointer =
+         warp_emulator->locked_pointer;
+     WindowPtr window;
+@@ -2725,6 +2729,7 @@ xwl_pointer_warp_emulator_set_fake_pos(struct xwl_pointer_warp_emulator *warp_em
+     if (!warp_emulator->xwl_seat->focus_window)
+         return;
+ 
++    xwl_screen = warp_emulator->xwl_seat->xwl_screen;
+     window = warp_emulator->xwl_seat->focus_window->window;
+     if (x >= window->drawable.x ||
+         y >= window->drawable.y ||
+@@ -2733,8 +2738,8 @@ xwl_pointer_warp_emulator_set_fake_pos(struct xwl_pointer_warp_emulator *warp_em
+         sx = x - window->drawable.x;
+         sy = y - window->drawable.y;
+         zwp_locked_pointer_v1_set_cursor_position_hint(locked_pointer,
+-                                                       wl_fixed_from_int(sx),
+-                                                       wl_fixed_from_int(sy));
++                                                       wl_fixed_from_int(xwl_scale_to(xwl_screen, sx)),
++                                                       wl_fixed_from_int(xwl_scale_to(xwl_screen, sy)));
+         wl_surface_commit(warp_emulator->xwl_seat->focus_window->surface);
+     }
+ }
+diff --git a/hw/xwayland/xwayland-output.c b/hw/xwayland/xwayland-output.c
+index ef705bc01bf8c2d2f170cda9ba21ed8293f50559..b8f6cd51bd240ed5e16271eb4749db18868bea7b 100644
+--- a/hw/xwayland/xwayland-output.c
++++ b/hw/xwayland/xwayland-output.c
+@@ -191,6 +191,9 @@ update_screen_size(struct xwl_output *xwl_output, int width, int height)
+ {
+     struct xwl_screen *xwl_screen = xwl_output->xwl_screen;
+ 
++    width *= xwl_screen->global_output_scale;
++    height *= xwl_screen->global_output_scale;
++
+     if (xwl_screen->root_clip_mode == ROOT_CLIP_FULL)
+         SetRootClip(xwl_screen->screen, ROOT_CLIP_NONE);
+ 
+@@ -497,14 +500,15 @@ xwl_output_set_emulated_mode(struct xwl_output *xwl_output, ClientPtr client,
+     xwl_output_set_randr_emu_props(xwl_output->xwl_screen, client);
+ }
+ 
+-static void
+-apply_output_change(struct xwl_output *xwl_output)
++void
++xwl_output_apply_changes(struct xwl_output *xwl_output)
+ {
+     struct xwl_screen *xwl_screen = xwl_output->xwl_screen;
+     struct xwl_output *it;
+     int mode_width, mode_height, count;
+     int width = 0, height = 0, has_this_output = 0;
+     RRModePtr *randr_modes;
++    int32_t scale = xwl_screen->global_output_scale;
+ 
+     /* Clear out the "done" received flags */
+     xwl_output->wl_output_done = FALSE;
+@@ -523,10 +527,10 @@ apply_output_change(struct xwl_output *xwl_output)
+     }
+ 
+     /* Build a fresh modes array using the current refresh rate */
+-    randr_modes = output_get_rr_modes(xwl_output, mode_width, mode_height, &count);
++    randr_modes = output_get_rr_modes(xwl_output, mode_width * scale, mode_height * scale, &count);
+     RROutputSetModes(xwl_output->randr_output, randr_modes, count, 1);
+     RRCrtcNotify(xwl_output->randr_crtc, randr_modes[0],
+-                 xwl_output->x, xwl_output->y,
++                 xwl_output->x * scale, xwl_output->y * scale,
+                  xwl_output->rotation, NULL, 1, &xwl_output->randr_output);
+     /* RROutputSetModes takes ownership of the passed in modes, so we only
+      * have to free the pointer array.
+@@ -567,7 +571,7 @@ output_handle_done(void *data, struct wl_output *wl_output)
+      */
+     if (xwl_output->xdg_output_done || !xwl_output->xdg_output ||
+         zxdg_output_v1_get_version(xwl_output->xdg_output) >= 3)
+-        apply_output_change(xwl_output);
++        xwl_output_apply_changes(xwl_output);
+ }
+ 
+ static void
+@@ -610,7 +614,7 @@ xdg_output_handle_done(void *data, struct zxdg_output_v1 *xdg_output)
+     xwl_output->xdg_output_done = TRUE;
+     if (xwl_output->wl_output_done &&
+         zxdg_output_v1_get_version(xdg_output) < 3)
+-        apply_output_change(xwl_output);
++        xwl_output_apply_changes(xwl_output);
+ }
+ 
+ static void
+@@ -678,6 +682,8 @@ xwl_output_create(struct xwl_screen *xwl_screen, uint32_t id)
+     RROutputSetConnection(xwl_output->randr_output, RR_Connected);
+     RRTellChanged(xwl_screen->screen);
+ 
++    xwl_output->scale = 1;
++
+     /* We want the output to be in the list as soon as created so we can
+      * use it when binding to the xdg-output protocol...
+      */
+diff --git a/hw/xwayland/xwayland-output.h b/hw/xwayland/xwayland-output.h
+index 02b9831083e82a33d85d4404e39d00f06f6c56fd..ec089757f44178dcd7f9c48907f790ce1b2a2729 100644
+--- a/hw/xwayland/xwayland-output.h
++++ b/hw/xwayland/xwayland-output.h
+@@ -53,7 +53,7 @@ struct xwl_output {
+     struct wl_output *output;
+     struct zxdg_output_v1 *xdg_output;
+     uint32_t server_output_id;
+-    int32_t x, y, width, height, refresh;
++    int32_t x, y, width, height, refresh, scale;
+     Rotation rotation;
+     Bool wl_output_done;
+     Bool xdg_output_done;
+@@ -100,6 +100,8 @@ void xwl_output_set_emulated_mode(struct xwl_output *xwl_output,
+ void xwl_output_set_window_randr_emu_props(struct xwl_screen *xwl_screen,
+                                            WindowPtr window);
+ 
++void xwl_output_apply_changes(struct xwl_output *xwl_output);
++
+ void xwl_screen_init_xdg_output(struct xwl_screen *xwl_screen);
+ 
+ #endif /* XWAYLAND_OUTPUT_H */
+diff --git a/hw/xwayland/xwayland-present.c b/hw/xwayland/xwayland-present.c
+index c9cf8c2f569a319034e0789e7587414e50237065..5be0c208ca46b1a53a136885fdc8ab44251fe7ff 100644
+--- a/hw/xwayland/xwayland-present.c
++++ b/hw/xwayland/xwayland-present.c
+@@ -680,6 +680,8 @@ xwl_present_flip(WindowPtr present_window,
+ 
+     /* We can flip directly to the main surface (full screen window without clips) */
+     wl_surface_attach(xwl_window->surface, buffer, 0, 0);
++     wl_surface_set_buffer_scale(xwl_window->surface,
++                                 xwl_window->xwl_screen->global_output_scale);
+ 
+     if (!xwl_window->frame_callback)
+         xwl_window_create_frame_callback(xwl_window);
+diff --git a/hw/xwayland/xwayland-screen.c b/hw/xwayland/xwayland-screen.c
+index bb18e5c94fbc7134c801e4e1979e8184079d352e..4ec2de7d123dd36315df07a1e95b1f417925f0f8 100644
+--- a/hw/xwayland/xwayland-screen.c
++++ b/hw/xwayland/xwayland-screen.c
+@@ -51,6 +51,7 @@
+ #include "xwayland-pixmap.h"
+ #include "xwayland-present.h"
+ #include "xwayland-shm.h"
++#include "xwayland-window-buffers.h"
+ 
+ #ifdef MITSHM
+ #include "shmint.h"
+@@ -110,6 +111,12 @@ xwl_screen_has_resolution_change_emulation(struct xwl_screen *xwl_screen)
+     return xwl_screen->rootless && xwl_screen_has_viewport_support(xwl_screen);
+ }
+ 
++int
++xwl_scale_to(struct xwl_screen *xwl_screen, int value)
++{
++    return value / (double)xwl_screen->global_output_scale + 0.5;
++}
++
+ /* Return the output @ 0x0, falling back to the first output in the list */
+ struct xwl_output *
+ xwl_screen_get_first_output(struct xwl_screen *xwl_screen)
+@@ -127,6 +134,37 @@ xwl_screen_get_first_output(struct xwl_screen *xwl_screen)
+     return xorg_list_first_entry(&xwl_screen->output_list, struct xwl_output, link);
+ }
+ 
++static void
++xwl_screen_set_global_scale_from_property(struct xwl_screen *screen,
++                                          PropertyPtr prop)
++{
++    CARD32 *propdata;
++
++    if (prop->type != XA_CARDINAL || prop->format != 32 || prop->size != 1) {
++        // TODO: handle warnings more cleanly.
++        LogMessageVerb(X_WARNING, 0, "Bad value for property %s.\n",
++                        NameForAtom(prop->propertyName));
++        return;
++    }
++
++    propdata = prop->data;
++    xwl_screen_set_global_scale(screen, propdata[0]);
++}
++
++static void
++xwl_screen_update_property(struct xwl_screen *screen,
++                           PropertyStateRec *propstate)
++{
++    switch (propstate->state) {
++    case PropertyNewValue:
++        xwl_screen_set_global_scale_from_property(screen, propstate->prop);
++        break;
++    case PropertyDelete:
++        xwl_screen_set_global_scale(screen, 1);
++        break;
++    }
++}
++
+ static void
+ xwl_property_callback(CallbackListPtr *pcbl, void *closure,
+                       void *calldata)
+@@ -134,19 +172,24 @@ xwl_property_callback(CallbackListPtr *pcbl, void *closure,
+     ScreenPtr screen = closure;
+     PropertyStateRec *rec = calldata;
+     struct xwl_screen *xwl_screen;
+-    struct xwl_window *xwl_window;
+ 
+     if (rec->win->drawable.pScreen != screen)
+         return;
+ 
+-    xwl_window = xwl_window_get(rec->win);
+-    if (!xwl_window)
+-        return;
+-
+     xwl_screen = xwl_screen_get(screen);
+ 
+-    if (rec->prop->propertyName == xwl_screen->allow_commits_prop)
++    if (rec->prop->propertyName == xwl_screen->allow_commits_prop) {
++        struct xwl_window *xwl_window;
++
++        xwl_window = xwl_window_get(rec->win);
++        if (!xwl_window)
++            return;
++
+         xwl_window_update_property(xwl_window, rec);
++    }
++    else if (rec->prop->propertyName == xwl_screen->global_output_scale_prop) {
++        xwl_screen_update_property(xwl_screen, rec);
++    }
+ }
+ 
+ Bool
+@@ -521,8 +564,14 @@ void xwl_surface_damage(struct xwl_screen *xwl_screen,
+ {
+     if (wl_surface_get_version(surface) >= WL_SURFACE_DAMAGE_BUFFER_SINCE_VERSION)
+         wl_surface_damage_buffer(surface, x, y, width, height);
+-    else
++    else {
++        x = xwl_scale_to(xwl_screen, x);
++        y = xwl_scale_to(xwl_screen, y);
++        width = xwl_scale_to(xwl_screen, width);
++        height = xwl_scale_to(xwl_screen, height);
++
+         wl_surface_damage(surface, x, y, width, height);
++    }
+ }
+ 
+ void
+@@ -538,10 +587,34 @@ xwl_screen_roundtrip(struct xwl_screen *xwl_screen)
+         xwl_give_up("could not connect to wayland server\n");
+ }
+ 
++void
++xwl_screen_set_global_scale(struct xwl_screen *xwl_screen, int32_t scale)
++{
++    struct xwl_output *it;
++    struct xwl_window *xwl_window;
++
++    xwl_screen->global_output_scale = scale;
++
++    /* change randr resolutions and positions */
++    xorg_list_for_each_entry(it, &xwl_screen->output_list, link) {
++        xwl_output_apply_changes(it);
++    }
++
++    if (!xwl_screen->rootless && xwl_screen->screen->root) {
++        /* Clear all the buffers, so that they'll be remade with the new sizes
++         * (this doesn't occur automatically because as far as Xorg is
++         *  concerned, the window's size is the same) */
++        xorg_list_for_each_entry(xwl_window, &xwl_screen->window_list, link_window) {
++            xwl_window_buffers_recycle(xwl_window);
++        }
++    }
++}
++
+ Bool
+ xwl_screen_init(ScreenPtr pScreen, int argc, char **argv)
+ {
+     static const char allow_commits[] = "_XWAYLAND_ALLOW_COMMITS";
++    static const char global_output_scale[] = "_XWAYLAND_GLOBAL_OUTPUT_SCALE";
+     struct xwl_screen *xwl_screen;
+     Pixel red_mask, blue_mask, green_mask;
+     int ret, bpc, green_bpc, i;
+@@ -573,6 +646,7 @@ xwl_screen_init(ScreenPtr pScreen, int argc, char **argv)
+ #ifdef XWL_HAS_GLAMOR
+     xwl_screen->glamor = 1;
+ #endif
++    xwl_screen->global_output_scale = 1;
+ 
+     for (i = 1; i < argc; i++) {
+         if (strcmp(argv[i], "-rootless") == 0) {
+@@ -743,6 +817,12 @@ xwl_screen_init(ScreenPtr pScreen, int argc, char **argv)
+     if (xwl_screen->allow_commits_prop == BAD_RESOURCE)
+         return FALSE;
+ 
++    xwl_screen->global_output_scale_prop = MakeAtom(global_output_scale,
++                                                    strlen(global_output_scale),
++                                                    TRUE);
++    if (xwl_screen->global_output_scale_prop == BAD_RESOURCE)
++        return FALSE;
++
+     AddCallback(&PropertyStateCallback, xwl_property_callback, pScreen);
+ 
+     xwl_screen_roundtrip(xwl_screen);
+diff --git a/hw/xwayland/xwayland-screen.h b/hw/xwayland/xwayland-screen.h
+index b965dddd7f964b1d100bbb9d10da1c35ab39810e..7446829d098fbe235e605084a016daff1a8eaea2 100644
+--- a/hw/xwayland/xwayland-screen.h
++++ b/hw/xwayland/xwayland-screen.h
+@@ -72,6 +72,8 @@ struct xwl_screen {
+     struct xorg_list damage_window_list;
+     struct xorg_list window_list;
+ 
++    int32_t global_output_scale;
++
+     int wayland_fd;
+     struct wl_display *display;
+     struct wl_registry *registry;
+@@ -107,6 +109,7 @@ struct xwl_screen {
+     struct glamor_context *glamor_ctx;
+ 
+     Atom allow_commits_prop;
++    Atom global_output_scale_prop;
+ 
+     /* The preferred GLVND vendor. If NULL, "mesa" is assumed. */
+     const char *glvnd_vendor;
+@@ -134,5 +137,7 @@ void xwl_screen_roundtrip (struct xwl_screen *xwl_screen);
+ void xwl_surface_damage(struct xwl_screen *xwl_screen,
+                         struct wl_surface *surface,
+                         int32_t x, int32_t y, int32_t width, int32_t height);
++int xwl_scale_to(struct xwl_screen *xwl_screen, int value);
++void xwl_screen_set_global_scale(struct xwl_screen *xwl_screen, int32_t scale);
+ 
+ #endif /* XWAYLAND_SCREEN_H */
+diff --git a/hw/xwayland/xwayland-window.c b/hw/xwayland/xwayland-window.c
+index 00f161eda084e335ac07471a2198176d75d9fcf0..ed3903853f0dab1dad390cd8429639541546157d 100644
+--- a/hw/xwayland/xwayland-window.c
++++ b/hw/xwayland/xwayland-window.c
+@@ -470,7 +470,8 @@ ensure_surface_for_window(WindowPtr window)
+         }
+ 
+         wl_region_add(region, 0, 0,
+-                      window->drawable.width, window->drawable.height);
++                      xwl_scale_to(xwl_screen, window->drawable.width),
++                      xwl_scale_to(xwl_screen, window->drawable.height));
+         wl_surface_set_opaque_region(xwl_window->surface, region);
+         wl_region_destroy(region);
+     }
+@@ -820,6 +821,7 @@ xwl_window_post_damage(struct xwl_window *xwl_window)
+ #endif
+ 
+     wl_surface_attach(xwl_window->surface, buffer, 0, 0);
++    wl_surface_set_buffer_scale(xwl_window->surface, xwl_screen->global_output_scale);
+ 
+     /* Arbitrary limit to try to avoid flooding the Wayland
+      * connection. If we flood it too much anyway, this could
+

nix/xwayland-vsync.patch

@@ -0,0 +1,12 @@
+--- a/hw/xwayland/xwayland-present.c
++++ b/hw/xwayland/xwayland-present.c
+@@ -824,7 +824,8 @@
+         dixDestroyPixmap(vblank->pixmap, vblank->pixmap->drawable.id);
+         vblank->pixmap = NULL;
+
+-        if (xwl_present_queue_vblank(screen, window, vblank->crtc,
++        if (vblank->target_msc > crtc_msc &&
++            xwl_present_queue_vblank(screen, window, vblank->crtc,
+                                      vblank->event_id, crtc_msc + 1)
+             == Success)
+             return;