From 7de85d7470da8a0e612332fc976338836d1dc11f Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Sun, 24 May 2020 22:43:50 +0200
Subject: [PATCH] Restore correct best width of wxDatePickerCtrl in MSW

This partially reverts the changes of a98d8448fa (Fix size of
wxDateTimePickerCtrl after DPI change, 2019-01-13) to still use
DTM_GETIDEALSIZE, even if it returns wrong height value after a DPI
change, because it still computes the best width more precisely than we
do and using our code could result in the date being partially truncated
when using some date formats.
---
 src/msw/datetimectrl.cpp | 36 +++++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/src/msw/datetimectrl.cpp b/src/msw/datetimectrl.cpp
index 604c2dcf0c..35bee5252c 100644
--- a/src/msw/datetimectrl.cpp
+++ b/src/msw/datetimectrl.cpp
@@ -112,11 +112,6 @@ wxDateTime wxDateTimePickerCtrl::GetValue() const
 
 wxSize wxDateTimePickerCtrl::DoGetBestSize() const
 {
-    // Do not use DateTime_GetIdealSize / DTM_GETIDEALSIZE. It returns
-    // incorrect sizes after the DPI of the window has changed. For every DPI
-    // change, the returned size is 4 pixels higher, even if the DPI is
-    // lowered.
-
     wxClientDC dc(const_cast<wxDateTimePickerCtrl *>(this));
 
     // Use the same native format as the underlying native control.
@@ -134,16 +129,35 @@ wxSize wxDateTimePickerCtrl::DoGetBestSize() const
 
     wxSize size = dc.GetTextExtent(s);
 
-    // Account for the drop-down arrow or spin arrows.
-    size.x += wxSystemSettings::GetMetric(wxSYS_HSCROLL_ARROW_X, m_parent);
+    // We can ask the control itself to compute its ideal size, but we only use
+    // it for the horizontal component: the vertical size is not computed
+    // correctly after the DPI of the window has changed because for every DPI
+    // change, the returned size is 4 pixels higher, even if the DPI is
+    // lowered, so we always need to compute it ourselves below.
+    //
+    // Also work around https://bugs.winehq.org/show_bug.cgi?id=44680 by
+    // checking for the return value: even if all "real" MSW systems do support
+    // this message, Wine does not, even when it's configured to return Vista
+    // or later version to the application, and returns FALSE for it.
+    SIZE idealSize;
+    if ( wxGetWinVersion() >= wxWinVersion_Vista
+            && ::SendMessage(m_hWnd, DTM_GETIDEALSIZE, 0, (LPARAM)&idealSize) )
+    {
+        size.x = idealSize.cx;
+    }
+    else // Adjust the size ourselves.
+    {
+        // Account for the drop-down arrow or spin arrows.
+        size.x += wxSystemSettings::GetMetric(wxSYS_HSCROLL_ARROW_X, m_parent);
+
+        // We need to account for the checkbox, if we have one.
+        if ( MSWAllowsNone() )
+            size.x += 3 * GetCharWidth();
+    }
 
     int scrollY = wxSystemSettings::GetMetric(wxSYS_HSCROLL_ARROW_Y, m_parent);
     size.y = wxMax(size.y, scrollY);
 
-    // We need to account for the checkbox, if we have one.
-    if ( MSWAllowsNone() )
-        size.x += 3 * GetCharWidth();
-
     // In any case, adjust the height to be the same as for the text controls.
     size.y = EDIT_HEIGHT_FROM_CHAR_HEIGHT(size.y);