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

src/msw/textmeasure.cpp

@@ -0,0 +1,172 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        src/msw/textmeasure.cpp
+// Purpose:     wxTextMeasure implementation for wxMSW
+// Author:      Manuel Martin
+// Created:     2012-19-05
+// RCS-ID:
+// Copyright:
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+// ============================================================================
+// declarations
+// ============================================================================
+
+// ----------------------------------------------------------------------------
+// headers
+// ----------------------------------------------------------------------------
+
+// for compilers that support precompilation, includes "wx.h".
+#include "wx/wxprec.h"
+
+#ifdef __BORLANDC__
+    #pragma hdrstop
+#endif
+
+#include "wx/msw/private.h"
+#include "wx/msw/dc.h"
+
+#ifndef WX_PRECOMP
+    #include "wx/window.h"
+    #include "wx/font.h"
+#endif //WX_PRECOMP
+
+#include "wx/private/textmeasure.h"
+
+// ============================================================================
+// wxTextMeasure implementation
+// ============================================================================
+
+void wxTextMeasure::Init()
+{
+    m_hdc = NULL;
+    m_hfontOld = NULL;
+}
+
+void wxTextMeasure::BeginMeasuring()
+{
+    if ( m_dc )
+    {
+        m_hdc = m_dc->GetHDC();
+
+        // Non-native wxDC subclasses should override their DoGetTextExtent()
+        // and other methods.
+        wxASSERT_MSG( m_hdc, wxS("Must not be used with non-native wxDCs") );
+    }
+    else if ( m_win )
+    {
+        m_hdc = ::GetDC(GetHwndOf(m_win));
+    }
+
+    if ( m_font )
+        m_hfontOld = (HFONT)::SelectObject(m_hdc, GetHfontOf(*m_font));
+}
+
+void wxTextMeasure::EndMeasuring()
+{
+    if ( m_hfontOld )
+    {
+        ::SelectObject(m_hdc, m_hfontOld);
+        m_hfontOld = NULL;
+    }
+
+    if ( m_win )
+        ::ReleaseDC(GetHwndOf(m_win), m_hdc);
+    //else: our HDC belongs to m_dc, don't touch it
+
+    m_hdc = NULL;
+}
+
+// Notice we don't check here the font. It is supposed to be OK before the call.
+void wxTextMeasure::DoGetTextExtent(const wxString& string,
+                                       wxCoord *width,
+                                       wxCoord *height,
+                                       wxCoord *descent,
+                                       wxCoord *externalLeading)
+{
+    SIZE sizeRect;
+    const size_t len = string.length();
+    if ( !::GetTextExtentPoint32(m_hdc, string.t_str(), len, &sizeRect) )
+    {
+        wxLogLastError(wxT("GetTextExtentPoint32()"));
+    }
+
+#if !defined(_WIN32_WCE) || (_WIN32_WCE >= 400)
+    // the result computed by GetTextExtentPoint32() may be too small as it
+    // accounts for under/overhang of the first/last character while we want
+    // just the bounding rect for this string so adjust the width as needed
+    // (using API not available in 2002 SDKs of WinCE)
+    if ( len > 0 )
+    {
+        ABC widthABC;
+        const wxChar chFirst = *string.begin();
+        if ( ::GetCharABCWidths(m_hdc, chFirst, chFirst, &widthABC) )
+        {
+            if ( widthABC.abcA < 0 )
+                sizeRect.cx -= widthABC.abcA;
+
+            if ( len > 1 )
+            {
+                const wxChar chLast = *string.rbegin();
+                ::GetCharABCWidths(m_hdc, chLast, chLast, &widthABC);
+            }
+            //else: we already have the width of the last character
+
+            if ( widthABC.abcC < 0 )
+                sizeRect.cx -= widthABC.abcC;
+        }
+        //else: GetCharABCWidths() failed, not a TrueType font?
+    }
+#endif // !defined(_WIN32_WCE) || (_WIN32_WCE >= 400)
+
+    *width = sizeRect.cx;
+    *height = sizeRect.cy;
+
+    if ( descent || externalLeading )
+    {
+        TEXTMETRIC tm;
+        ::GetTextMetrics(m_hdc, &tm);
+        if ( descent )
+            *descent = tm.tmDescent;
+        if ( externalLeading )
+            *externalLeading = tm.tmExternalLeading;
+    }
+}
+
+bool wxTextMeasure::DoGetPartialTextExtents(const wxString& text,
+                                            wxArrayInt& widths,
+                                            double WXUNUSED(scaleX))
+{
+    static int maxLenText = -1;
+    static int maxWidth = -1;
+
+    if (maxLenText == -1)
+    {
+        // Win9x and WinNT+ have different limits
+        int version = wxGetOsVersion();
+        maxLenText = version == wxOS_WINDOWS_NT ? 65535 : 8192;
+        maxWidth =   version == wxOS_WINDOWS_NT ? INT_MAX : 32767;
+    }
+
+    int len = text.length();
+    if ( len > maxLenText )
+        len = maxLenText;
+
+    int fit = 0;
+    SIZE sz = {0,0};
+    if ( !::GetTextExtentExPoint(m_hdc,
+                                 text.t_str(), // string to check
+                                 len,
+                                 maxWidth,
+                                 &fit,         // [out] count of chars
+                                               // that will fit
+                                 &widths[0],   // array to fill
+                                 &sz) )
+    {
+        wxLogLastError(wxT("GetTextExtentExPoint"));
+
+        return false;
+    }
+
+    return true;
+}