Fix WinForms Icon Button Size Handling

changes/4051.bugfix.1.md

@@ -0,0 +1 @@
+WinForms buttons with icons will now reliably scale to 32x32px icon size, regardless of the size of the original icon image.

changes/4051.bugfix.2.md

@@ -0,0 +1 @@
+`Screen.as_image` now properly accounts for HiDPI scaling on Winforms.

examples/button/button/app.py

@@ -70,6 +70,7 @@ def startup(self):
         button9 = toga.Button(
             icon=toga.Icon("resources/star"),
         )
+        print("WIDTH", button9._impl.native.Image.Width, button9._impl.scale_in(32))
 
         # Add components for the second row of the outer box
         inner_box2 = toga.Box(

testbed/tests/widgets/test_button.py

@@ -62,7 +62,7 @@ async def test_icon(widget, probe):
     probe.assert_no_icon()
     initial_height = probe.height
 
-    # Set an icon
+    # Set an icon. The icon image is bigger than 32x32, so it should be scaled
     widget.icon = "resources/icons/red"
     await probe.redraw("Button is now an icon button")
 

winforms/src/toga_winforms/screens.py

@@ -65,11 +65,17 @@ def get_size(self) -> Size:
         return Size(self.scale_out(bounds.Width), self.scale_out(bounds.Height))
 
     def get_image_data(self):
-        bitmap = Bitmap(*self.get_size())
+        bitmap = Bitmap(
+            self.scale_in(self.get_size()[0]), self.scale_in(self.get_size()[1])
+        )
         graphics = Graphics.FromImage(bitmap)
-        source_point = Point(*self.get_origin())
+        source_point = Point(
+            self.scale_in(self.get_origin()[0]), self.scale_in(self.get_origin()[1])
+        )
         destination_point = Point(0, 0)
-        copy_size = WinSize(*self.get_size())
+        copy_size = WinSize(
+            self.scale_in(self.get_size()[0]), self.scale_in(self.get_size()[1])
+        )
         graphics.CopyFromScreen(source_point, destination_point, copy_size)
         stream = MemoryStream()
         bitmap.Save(stream, Imaging.ImageFormat.Png)

winforms/src/toga_winforms/widgets/button.py

@@ -1,6 +1,7 @@
 from decimal import ROUND_UP
 
 import System.Windows.Forms as WinForms
+from System.Drawing import Bitmap, Size
 from travertino.size import at_least
 
 from toga.colors import TRANSPARENT
@@ -40,10 +41,23 @@ def get_icon(self):
     def set_icon(self, icon):
         self._icon = icon
         if icon:
-            self.native.Image = icon._impl.native.ToBitmap()
+            self.native.Image = Bitmap(
+                icon._impl.bitmap,
+                Size(self.scale_in(32), self.scale_in(32)),
+            )
         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")