From d0407f7c0ada76e1c03929799dde53977fa562a1 Mon Sep 17 00:00:00 2001
From: Alan Griffiths <alan@octopull.co.uk>
Date: Mon, 11 Sep 2023 14:21:59 +0100
Subject: [PATCH] Fix scaling of wayland platform pointer

---
 src/platforms/wayland/display.cpp       | 4 +++-
 src/platforms/wayland/displayclient.cpp | 4 +++-
 src/platforms/wayland/displayclient.h   | 3 ++-
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/platforms/wayland/display.cpp b/src/platforms/wayland/display.cpp
index 8d6c3d07395..eb70f9bbe3e 100644
--- a/src/platforms/wayland/display.cpp
+++ b/src/platforms/wayland/display.cpp
@@ -369,7 +369,9 @@ void mir::graphics::wayland::Display::pointer_motion(wl_pointer* pointer, uint32
 {
     {
         std::lock_guard lock{sink_mutex};
-        pointer_pos = geom::PointF{wl_fixed_to_double(x), wl_fixed_to_double(y)} + geom::DisplacementF{pointer_displacement};
+        auto const descaled_x = pointer_scale * wl_fixed_to_double(x);
+        auto const descaled_y = pointer_scale * wl_fixed_to_double(y);
+        pointer_pos = geom::PointF{descaled_x, descaled_y} + pointer_displacement;
         pointer_time = std::chrono::milliseconds{time};
     }
 
diff --git a/src/platforms/wayland/displayclient.cpp b/src/platforms/wayland/displayclient.cpp
index 7fcce539777..cb2e0cc74f7 100644
--- a/src/platforms/wayland/displayclient.cpp
+++ b/src/platforms/wayland/displayclient.cpp
@@ -719,7 +719,9 @@ void mgw::DisplayClient::pointer_enter(
     {
         if (surface == out.second->surface)
         {
-            pointer_displacement = out.second->dcout.top_left - geometry::Point{};
+            // Pointer events are displaced and scaled according to the surface
+            pointer_displacement = geom::DisplacementF{out.second->dcout.top_left - geometry::Point{}};
+            pointer_scale = out.second->host_scale;
             break;
         }
     }
diff --git a/src/platforms/wayland/displayclient.h b/src/platforms/wayland/displayclient.h
index f95c955d2f0..ca73bb3dd6b 100644
--- a/src/platforms/wayland/displayclient.h
+++ b/src/platforms/wayland/displayclient.h
@@ -159,8 +159,9 @@ class DisplayClient
     xkb_keymap* keyboard_map_ = nullptr;
     xkb_state* keyboard_state_ = nullptr;
     bool fake_pointer_frame = false;
-    geometry::Displacement pointer_displacement; // Position of current output
+    geometry::DisplacementF pointer_displacement; // Position of current output
     geometry::Displacement touch_displacement;   // Position of current output
+    float pointer_scale{1.0f};
 
     std::unique_ptr<wl_registry, decltype(&wl_registry_destroy)> registry;