WindowServer: Don't reallocate the cursor back bitmap all the time in HighDPI mode

It's in efficient, and it also meant we wouldn't reallocate a bigger
backing bitmap in a lowdpi->highdpi transition, leading to minor drawing
glitches after such a transition.

(Whoops!)

1 files changed, 3 insertions, 2 deletions

diff --git a/Userland/Services/WindowServer/Compositor.cpp b/Userland/Services/WindowServer/Compositor.cpp
index d93b163335..4bea8d81a8 100644
--- a/Userland/Services/WindowServer/Compositor.cpp
+++ b/Userland/Services/WindowServer/Compositor.cpp
@@ -802,8 +802,9 @@ void Compositor::draw_cursor(const Gfx::IntRect& cursor_rect)
 {
     auto& wm = WindowManager::the();
 
-    if (!m_cursor_back_bitmap || m_cursor_back_bitmap->size() != cursor_rect.size()) {
-        m_cursor_back_bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::RGB32, cursor_rect.size() * Screen::the().scale_factor());
+    auto physical_cursor_size = cursor_rect.size() * Screen::the().scale_factor();
+    if (!m_cursor_back_bitmap || m_cursor_back_bitmap->size() != physical_cursor_size) {
+        m_cursor_back_bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::RGB32, physical_cursor_size);
         m_cursor_back_painter = make<Gfx::Painter>(*m_cursor_back_bitmap);
     }