From 290ae87c02abf5070422bb50af948402345ab4e1 Mon Sep 17 00:00:00 2001
From: Olivier Fourdan <ofourdan@redhat.com>
Date: Thu, 2 Nov 2023 11:05:55 +0100
Subject: [PATCH] xwayland: Update the scale based on enter/leave events

Recompute the window scale each time the window enters or leaves an
output.

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Reviewed-By: Kenny Levinsen <kl@kl.wtf>
Acked-by: Peter Hutterer <peter.hutterer@who-t.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1197>
---
 hw/xwayland/xwayland-window.c | 30 ++++++++++++++++++++++++++++--
 hw/xwayland/xwayland-window.h |  2 ++
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/hw/xwayland/xwayland-window.c b/hw/xwayland/xwayland-window.c
index b439c3a47..626a5d22d 100644
--- a/hw/xwayland/xwayland-window.c
+++ b/hw/xwayland/xwayland-window.c
@@ -794,6 +794,12 @@ static const struct xdg_surface_listener xdg_surface_listener = {
     xdg_surface_handle_configure,
 };
 
+static void
+xwl_window_update_surface_scale(struct xwl_window *xwl_window)
+{
+    xwl_window->surface_scale = xwl_window_get_max_output_scale(xwl_window);
+}
+
 static void
 xwl_window_enter_output(struct xwl_window *xwl_window, struct xwl_output *xwl_output)
 {
@@ -828,6 +834,22 @@ xwl_window_free_outputs(struct xwl_window *xwl_window)
     }
 }
 
+int
+xwl_window_get_max_output_scale(struct xwl_window *xwl_window)
+{
+    struct xwl_window_output *window_output;
+    struct xwl_output *xwl_output;
+    int scale = 1;
+
+    xorg_list_for_each_entry(window_output, &xwl_window->xwl_output_list, link) {
+        xwl_output = window_output->xwl_output;
+        if (xwl_output->scale > scale)
+            scale = xwl_output->scale;
+    }
+
+    return scale;
+}
+
 static void
 xwl_window_surface_enter(void *data,
                          struct wl_surface *wl_surface,
@@ -837,8 +859,10 @@ xwl_window_surface_enter(void *data,
     struct xwl_screen *xwl_screen = xwl_window->xwl_screen;
     struct xwl_output *xwl_output = xwl_output_from_wl_output(xwl_screen, wl_output);
 
-    if (xwl_output)
+    if (xwl_output) {
         xwl_window_enter_output(xwl_window, xwl_output);
+        xwl_window_update_surface_scale(xwl_window);
+    }
 
     if (xwl_window->wl_output != wl_output) {
         xwl_window->wl_output = wl_output;
@@ -857,8 +881,10 @@ xwl_window_surface_leave(void *data,
     struct xwl_screen *xwl_screen = xwl_window->xwl_screen;
     struct xwl_output *xwl_output = xwl_output_from_wl_output(xwl_screen, wl_output);
 
-    if (xwl_output)
+    if (xwl_output) {
         xwl_window_leave_output(xwl_window, xwl_output);
+        xwl_window_update_surface_scale(xwl_window);
+    }
 
     if (xwl_window->wl_output == wl_output)
         xwl_window->wl_output = NULL;
diff --git a/hw/xwayland/xwayland-window.h b/hw/xwayland/xwayland-window.h
index 0e45f08d2..03b4ad249 100644
--- a/hw/xwayland/xwayland-window.h
+++ b/hw/xwayland/xwayland-window.h
@@ -59,6 +59,7 @@ struct xwl_window {
     struct wl_surface *surface;
     struct wp_viewport *viewport;
     float viewport_scale_x, viewport_scale_y;
+    int surface_scale;
     struct xdg_surface *xdg_surface;
     struct xdg_toplevel *xdg_toplevel;
     WindowPtr window;
@@ -100,6 +101,7 @@ void xwl_window_set_window_pixmap(WindowPtr window, PixmapPtr pixmap);
 
 void xwl_window_leave_output(struct xwl_window *xwl_window,
                              struct xwl_output *xwl_output);
+int xwl_window_get_max_output_scale(struct xwl_window *xwl_window);
 Bool xwl_realize_window(WindowPtr window);
 Bool xwl_unrealize_window(WindowPtr window);
 Bool xwl_change_window_attributes(WindowPtr window, unsigned long mask);