From 3a1576f74c643b1873386ab0468e22c8b3a0d492 Mon Sep 17 00:00:00 2001
From: Maarten Bent <MaartenBent@users.noreply.github.com>
Date: Wed, 10 Mar 2021 23:46:24 +0100
Subject: [PATCH 1/2] Fix size of owner-drawn checkbox at non-standard DPI

Get the correct size from wxRendererNative instead of wxGetSystemMetrics.
Simplify positioning the button and label rectangles.

Closes #19095
---
 src/msw/control.cpp | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/src/msw/control.cpp b/src/msw/control.cpp
index 10bc8f0b4f..e111d272ca 100644
--- a/src/msw/control.cpp
+++ b/src/msw/control.cpp
@@ -542,34 +542,29 @@ bool wxMSWOwnerDrawnButtonBase::MSWDrawButton(WXDRAWITEMSTRUCT *item)
 
     // choose the values consistent with those used for native, non
     // owner-drawn, buttons
-    static const int MARGIN = 3;
-    int CXMENUCHECK = wxGetSystemMetrics(SM_CXMENUCHECK, m_win) + 1;
 
-    // the buttons were even bigger under Windows XP
-    if ( wxGetWinVersion() < wxWinVersion_6 )
-        CXMENUCHECK += 2;
+    const int spacing = m_win->FromDIP(3);
+    const wxSize cbSize = wxRendererNative::Get().GetCheckBoxSize(m_win, flags);
 
-    // The space between the button and the label
-    // is included in the button bitmap.
-    const int buttonSize = wxMin(CXMENUCHECK - MARGIN, m_win->GetSize().y);
+    const int buttonSize = wxMin(cbSize.y, m_win->GetSize().y);
     rectButton.top = rect.top + (rect.bottom - rect.top - buttonSize) / 2;
     rectButton.bottom = rectButton.top + buttonSize;
 
     const bool isRightAligned = m_win->HasFlag(wxALIGN_RIGHT);
     if ( isRightAligned )
     {
-        rectLabel.right = rect.right - CXMENUCHECK;
-        rectLabel.left = rect.left;
+        rectButton.right = rect.right;
+        rectButton.left = rectButton.right - buttonSize;
 
-        rectButton.left = rectLabel.right + ( CXMENUCHECK + MARGIN - buttonSize ) / 2;
-        rectButton.right = rectButton.left + buttonSize;
+        rectLabel.right = rectButton.left - spacing;
+        rectLabel.left = rect.left;
     }
     else // normal, left-aligned button
     {
-        rectButton.left = rect.left + ( CXMENUCHECK - MARGIN - buttonSize ) / 2;
+        rectButton.left = rect.left;
         rectButton.right = rectButton.left + buttonSize;
 
-        rectLabel.left = rect.left + CXMENUCHECK;
+        rectLabel.left = spacing + rectButton.right;
         rectLabel.right = rect.right;
     }
 

From 47047a608adb74e7190de5f6d4168074135e5cdb Mon Sep 17 00:00:00 2001
From: Maarten Bent <MaartenBent@users.noreply.github.com>
Date: Wed, 10 Mar 2021 23:46:50 +0100
Subject: [PATCH 2/2] Fix drawing undetermined state of owner-drawn checkbox

---
 src/msw/checkbox.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/msw/checkbox.cpp b/src/msw/checkbox.cpp
index d489201848..ac2784da74 100644
--- a/src/msw/checkbox.cpp
+++ b/src/msw/checkbox.cpp
@@ -247,11 +247,11 @@ int wxCheckBox::MSWGetButtonCheckedFlag() const
             return wxCONTROL_CHECKED;
 
         case wxCHK_UNDETERMINED:
-            return wxCONTROL_PRESSED;
+            return wxCONTROL_UNDETERMINED;
 
         case wxCHK_UNCHECKED:
             // no extra styles needed
-            return 0;
+            return wxCONTROL_NONE;
     }
 
     wxFAIL_MSG( wxT("unexpected Get3StateValue() return value") );