High-DPI Fixes

Author: johnzhou721

winforms/src/toga_winforms/widgets/button.py

@@ -48,6 +48,16 @@ def set_icon(self, icon):
         else:
             self.native.Image = None
 
+    # Refreshing could change icon DPI, which means that the
+    # icon should be reassigned by the new scale.
+    def refresh(self):
+        super().refresh()
+        if self._icon:
+            self.native.Image = Bitmap(
+                self._icon._impl.bitmap,
+                Size(self.scale_in(32), self.scale_in(32)),
+            )
+
     def set_background_color(self, color):
         super().set_background_color(
             self._default_background_color if color in {None, TRANSPARENT} else color

winforms/tests_backend/widgets/button.py

@@ -20,6 +20,9 @@ def assert_no_icon(self):
     def assert_icon_size(self):
         icon = self.native.Image
         if icon:
-            assert (icon.Size.Width, icon.Size.Height) == (32, 32)
+            assert (icon.Size.Width, icon.Size.Height) == (
+                self.impl.scale_in(32),
+                self.impl.scale_in(32),
+            )
         else:
             pytest.fail("Icon does not exist")