Merge pull request #1486 from freakboy3742/winforms-tls

Explicitly define allowed Winforms TLS protocols.

src/winforms/toga_winforms/app.py

@@ -7,7 +7,15 @@
 from toga import Key
 from .keys import toga_to_winforms_key
 
-from .libs import Threading, WinForms, shcore, user32, win_version
+from .libs import (
+    SecurityProtocolType,
+    ServicePointManager,
+    Threading,
+    WinForms,
+    shcore,
+    user32,
+    win_version
+)
 from .libs.proactor import WinformsProactorEventLoop
 from .window import Window
 
@@ -69,6 +77,14 @@ def create(self):
         self.native.EnableVisualStyles()
         self.native.SetCompatibleTextRenderingDefault(False)
 
+        # Ensure that TLS1.2 and TLS1.3 are enabled for HTTPS connections.
+        # For some reason, some Windows installs have these protocols
+        # turned off by default. SSL3, TLS1.0 and TLS1.1 are *not* enabled
+        # as they are deprecated protocols and their use should *not* be
+        # encouraged.
+        ServicePointManager.SecurityProtocol |= SecurityProtocolType.Tls12
+        ServicePointManager.SecurityProtocol |= SecurityProtocolType.Tls13
+
         self.interface.commands.add(
             toga.Command(
                 lambda _: self.interface.about(),

src/winforms/toga_winforms/libs/__init__.py

@@ -20,6 +20,8 @@
     PointF,
     Rectangle,
     RectangleF,
+    SecurityProtocolType,
+    ServicePointManager,
     Single,
     Size,
     SolidBrush,

src/winforms/toga_winforms/libs/winforms.py

@@ -55,6 +55,7 @@
 
 from System.Threading.Tasks import Task, TaskScheduler  # noqa: F401, E402
 
+from System.Net import SecurityProtocolType, ServicePointManager  # noqa: F401, E402
 
 user32 = ctypes.windll.user32
 # shcore dll not exist on some Windows versions

src/winforms/toga_winforms/widgets/imageview.py

@@ -8,7 +8,7 @@ class ImageView(Widget):
     def create(self):
         self.native = WinForms.PictureBox()
         self.native.interface = self.interface
-        self.native.SizeMode = WinForms.PictureBoxSizeMode.StretchImage
+        self.native.SizeMode = WinForms.PictureBoxSizeMode.Zoom
 
     def set_image(self, image):
         # If an image already exists, ensure it is destroyed