fix(button): use DPR for cached pixmap scale (#6255)

CHANGELOG.md

@@ -53,7 +53,7 @@
 - Dev: Simplified string literals to be a re-export of Qt functions. (#6175)
 - Dev: Fixed incorrect lua generation of static methods for typescript plugins. (#6190, #6223)
 - Dev: Merged top/bottom and left/right notebook layouts. (#6215)
-- Dev: Refactored `Button` and friends. (#6102)
+- Dev: Refactored `Button` and friends. (#6102, #6255)
 - Dev: `OnceFlag`'s internal flag is now atomic. (#6237)
 - Dev: Bumped clang-format requirement to 19. (#6236)
 

src/widgets/buttons/Button.cpp

@@ -306,9 +306,11 @@ void Button::paintButton(QPainter &painter)
 
     if (this->cachePixmap_)
     {
-        if (this->cachedPixmap_.size() != this->size())
+        if (this->cachedPixmap_.size() / this->devicePixelRatio() !=
+            this->size())
         {
-            this->cachedPixmap_ = QPixmap(this->size());
+            this->cachedPixmap_ =
+                QPixmap(this->size() * this->devicePixelRatio());
             this->cachedPixmap_.setDevicePixelRatio(this->devicePixelRatio());
             this->pixmapValid_ = false;
         }