support multiline labels in wxCheckBox (#9495)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@54008 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/private/button.h

@@ -0,0 +1,46 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        msw/private/button.h
+// Purpose:     helper functions used with native BUTTON control
+// Author:      Vadim Zeitlin
+// Created:     2008-06-07
+// RCS-ID:      $Id$
+// Copyright:   (c) 2008 Vadim Zeitlin <vadim@wxwidgets.org>
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_MSW_PRIVATE_BUTTON_H_
+#define _WX_MSW_PRIVATE_BUTTON_H_
+
+namespace wxMSWButton
+{
+
+// returns BS_MULTILINE if the label contains new lines or 0 otherwise
+inline int GetMultilineStyle(const wxString& label)
+{
+    return label.find(_T('\n')) == wxString::npos ? 0 : BS_MULTILINE;
+}
+
+// update the style of the specified HWND to include or exclude BS_MULTILINE
+// depending on whether the label contains the new lines
+inline void UpdateMultilineStyle(HWND hwnd, const wxString& label)
+{
+    // update BS_MULTILINE style depending on the new label (resetting it
+    // doesn't seem to do anything very useful but it shouldn't hurt and we do
+    // have to set it whenever the label becomes multi line as otherwise it
+    // wouldn't be shown correctly as we don't use BS_MULTILINE when creating
+    // the control unless it already has new lines in its label)
+    long styleOld = ::GetWindowLong(hwnd, GWL_STYLE),
+         styleNew;
+    if ( label.find(_T('\n')) != wxString::npos )
+        styleNew = styleOld | BS_MULTILINE;
+    else
+        styleNew = styleOld & ~BS_MULTILINE;
+
+    if ( styleNew != styleOld )
+        ::SetWindowLong(hwnd, GWL_STYLE, styleNew);
+}
+
+} // namespace wxMSWButton
+
+#endif // _WX_MSW_PRIVATE_BUTTON_H_
+