Merge pull request #3037 from MirServer/fix-3036

[wayland platform] Less broken display on scaled hosts

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};
     }
 

src/platforms/wayland/displayclient.cpp

@@ -58,6 +58,7 @@ class mgw::DisplayClient::Output  :
 
     DisplayConfigurationOutput dcout;
     geom::Size output_size;
+    float host_scale{1.0f};
 
     wl_output* const output;
     DisplayClient* const owner;
@@ -280,7 +281,7 @@ void mgw::DisplayClient::Output::mode(uint32_t flags, int32_t width, int32_t hei
 
 void mgw::DisplayClient::Output::scale(int32_t factor)
 {
-    dcout.scale = factor;
+    host_scale = factor;
 }
 
 void mgw::DisplayClient::Output::done()
@@ -301,7 +302,7 @@ void mgw::DisplayClient::Output::done()
         xdg_toplevel_add_listener(shell_toplevel, &shell_toplevel_listener, this);
 
         xdg_toplevel_set_fullscreen(shell_toplevel, output);
-        wl_surface_set_buffer_scale(surface, round(dcout.scale));
+        wl_surface_set_buffer_scale(surface, round(host_scale));
         wl_surface_commit(surface);
 
         // After the next roundtrip the surface should be configured
@@ -325,9 +326,9 @@ void mgw::DisplayClient::Output::surface_configure(uint32_t serial)
     xdg_surface_ack_configure(shell_surface, serial);
     bool const size_is_changed = pending_toplevel_size && (
         !dcout.custom_logical_size || dcout.custom_logical_size.value() != pending_toplevel_size.value());
-    dcout.custom_logical_size = pending_toplevel_size.value();
+    dcout.custom_logical_size = host_scale*pending_toplevel_size.value();
     pending_toplevel_size.reset();
-    output_size = dcout.extents().size * dcout.scale;
+    output_size = dcout.extents().size;
     if (!has_initialized)
     {
         egl_window = wl_egl_window_create(surface, output_size.width.as_int(), output_size.height.as_int());
@@ -718,7 +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;
         }
     }

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;