Factor out text measurement from wxDC and wxWindow into wxTextMeasure.

Add a new private wxTextMeasure class implementing methods for measuring text
and move the often duplicated (but not always identically) code for doing the
same from wxDC and wxWindow into it.

Currently this class is only really implemented in wxMSW and wxGTK.

Also extend the test for text measuring functions and rename it to
MeasuringTextTestCase from MeasuringContextTestCase as it's not wxGC-specific
any more.

Closes #14705.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72699 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/private/textmeasure.h

@@ -0,0 +1,62 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        wx/msw/private/textmeasure.h
+// Purpose:     wxMSW-specific declaration of wxTextMeasure class
+// Author:      Manuel Martin
+// Created:     2012-10-05
+// Copyright:   (c) 1997-2012 wxWidgets team
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_MSW_PRIVATE_TEXTMEASURE_H_
+#define _WX_MSW_PRIVATE_TEXTMEASURE_H_
+
+#include "wx/msw/wrapwin.h"
+
+// ----------------------------------------------------------------------------
+// wxTextMeasure for MSW.
+// ----------------------------------------------------------------------------
+
+class wxTextMeasure : public wxTextMeasureBase
+{
+public:
+    wxTextMeasure(const wxDC *dc, const wxFont *font)
+        : wxTextMeasureBase(dc, font)
+    {
+        Init();
+    }
+    wxTextMeasure(const wxWindow *win, const wxFont *font)
+        : wxTextMeasureBase(win, font)
+    {
+        Init();
+    }
+
+protected:
+    void Init();
+
+    virtual void BeginMeasuring();
+    virtual void EndMeasuring();
+
+    virtual void DoGetTextExtent(const wxString& string,
+                               wxCoord *width,
+                               wxCoord *height,
+                               wxCoord *descent = NULL,
+                               wxCoord *externalLeading = NULL);
+
+    virtual bool DoGetPartialTextExtents(const wxString& text,
+                                         wxArrayInt& widths,
+                                         double scaleX);
+
+
+
+    // We use either the HDC of the provided wxDC or an HDC created for our
+    // window.
+    HDC m_hdc;
+
+    // If we change the font in BeginMeasuring(), we restore it to the old one
+    // in EndMeasuring().
+    HFONT m_hfontOld;
+
+    wxDECLARE_NO_COPY_CLASS(wxTextMeasure);
+};
+
+#endif // _WX_MSW_PRIVATE_TEXTMEASURE_H_