src/msw/textmeasure.cpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/msw/textmeasure.cpp
   3 // Purpose:     wxTextMeasure implementation for wxMSW
   4 // Author:      Manuel Martin
   5 // Created:     2012-10-05
   6 // Copyright:   (c) 1997-2012 wxWidgets team
   7 // Licence:     wxWindows licence
   8 ///////////////////////////////////////////////////////////////////////////////
   9
  10 // ============================================================================
  11 // declarations
  12 // ============================================================================
  13
  14 // ----------------------------------------------------------------------------
  15 // headers
  16 // ----------------------------------------------------------------------------
  17
  18 // for compilers that support precompilation, includes "wx.h".
  19 #include "wx/wxprec.h"
  20
  21 #ifdef __BORLANDC__
  22     #pragma hdrstop
  23 #endif
  24
  25 #include "wx/msw/private.h"
  26
  27 #ifndef WX_PRECOMP
  28     #include "wx/window.h"
  29     #include "wx/font.h"
  30 #endif //WX_PRECOMP
  31
  32 #include "wx/private/textmeasure.h"
  33
  34 #include "wx/msw/dc.h"
  35
  36 // ============================================================================
  37 // wxTextMeasure implementation
  38 // ============================================================================
  39
  40 void wxTextMeasure::Init()
  41 {
  42     m_hdc = NULL;
  43     m_hfontOld = NULL;
  44
  45     if ( m_dc )
  46     {
  47         wxClassInfo* const ci = m_dc->GetImpl()->GetClassInfo();
  48
  49         if ( ci->IsKindOf(wxCLASSINFO(wxMSWDCImpl)))
  50         {
  51             m_useDCImpl = false;
  52         }
  53     }
  54 }
  55
  56 void wxTextMeasure::BeginMeasuring()
  57 {
  58     if ( m_dc )
  59     {
  60         m_hdc = m_dc->GetHDC();
  61
  62         // Non-native wxDC subclasses should override their DoGetTextExtent()
  63         // and other methods.
  64         wxASSERT_MSG( m_hdc, wxS("Must not be used with non-native wxDCs") );
  65     }
  66     else if ( m_win )
  67     {
  68         m_hdc = ::GetDC(GetHwndOf(m_win));
  69     }
  70
  71     // We need to set the font if it's explicitly specified, of course, but
  72     // also if we're associated with a window because the window HDC created
  73     // above has the default font selected into it and not the font of the
  74     // window.
  75     if ( m_font || m_win )
  76         m_hfontOld = (HFONT)::SelectObject(m_hdc, GetHfontOf(GetFont()));
  77 }
  78
  79 void wxTextMeasure::EndMeasuring()
  80 {
  81     if ( m_hfontOld )
  82     {
  83         ::SelectObject(m_hdc, m_hfontOld);
  84         m_hfontOld = NULL;
  85     }
  86
  87     if ( m_win )
  88         ::ReleaseDC(GetHwndOf(m_win), m_hdc);
  89     //else: our HDC belongs to m_dc, don't touch it
  90
  91     m_hdc = NULL;
  92 }
  93
  94 // Notice we don't check here the font. It is supposed to be OK before the call.
  95 void wxTextMeasure::DoGetTextExtent(const wxString& string,
  96                                        wxCoord *width,
  97                                        wxCoord *height,
  98                                        wxCoord *descent,
  99                                        wxCoord *externalLeading)
 100 {
 101     SIZE sizeRect;
 102     const size_t len = string.length();
 103     if ( !::GetTextExtentPoint32(m_hdc, string.t_str(), len, &sizeRect) )
 104     {
 105         wxLogLastError(wxT("GetTextExtentPoint32()"));
 106     }
 107
 108 #if !defined(_WIN32_WCE) || (_WIN32_WCE >= 400)
 109     // the result computed by GetTextExtentPoint32() may be too small as it
 110     // accounts for under/overhang of the first/last character while we want
 111     // just the bounding rect for this string so adjust the width as needed
 112     // (using API not available in 2002 SDKs of WinCE)
 113     if ( len > 0 )
 114     {
 115         ABC widthABC;
 116         const wxChar chFirst = *string.begin();
 117         if ( ::GetCharABCWidths(m_hdc, chFirst, chFirst, &widthABC) )
 118         {
 119             if ( widthABC.abcA < 0 )
 120                 sizeRect.cx -= widthABC.abcA;
 121
 122             if ( len > 1 )
 123             {
 124                 const wxChar chLast = *string.rbegin();
 125                 ::GetCharABCWidths(m_hdc, chLast, chLast, &widthABC);
 126             }
 127             //else: we already have the width of the last character
 128
 129             if ( widthABC.abcC < 0 )
 130                 sizeRect.cx -= widthABC.abcC;
 131         }
 132         //else: GetCharABCWidths() failed, not a TrueType font?
 133     }
 134 #endif // !defined(_WIN32_WCE) || (_WIN32_WCE >= 400)
 135
 136     *width = sizeRect.cx;
 137     *height = sizeRect.cy;
 138
 139     if ( descent || externalLeading )
 140     {
 141         TEXTMETRIC tm;
 142         ::GetTextMetrics(m_hdc, &tm);
 143         if ( descent )
 144             *descent = tm.tmDescent;
 145         if ( externalLeading )
 146             *externalLeading = tm.tmExternalLeading;
 147     }
 148 }
 149
 150 bool wxTextMeasure::DoGetPartialTextExtents(const wxString& text,
 151                                             wxArrayInt& widths,
 152                                             double scaleX)
 153 {
 154     if ( !m_hdc )
 155         return wxTextMeasureBase::DoGetPartialTextExtents(text, widths, scaleX);
 156
 157     static int maxLenText = -1;
 158     static int maxWidth = -1;
 159
 160     if (maxLenText == -1)
 161     {
 162         // Win9x and WinNT+ have different limits
 163         int version = wxGetOsVersion();
 164         maxLenText = version == wxOS_WINDOWS_NT ? 65535 : 8192;
 165         maxWidth =   version == wxOS_WINDOWS_NT ? INT_MAX : 32767;
 166     }
 167
 168     int len = text.length();
 169     if ( len > maxLenText )
 170         len = maxLenText;
 171
 172     int fit = 0;
 173     SIZE sz = {0,0};
 174     if ( !::GetTextExtentExPoint(m_hdc,
 175                                  text.t_str(), // string to check
 176                                  len,
 177                                  maxWidth,
 178                                  &fit,         // [out] count of chars
 179                                                // that will fit
 180                                  &widths[0],   // array to fill
 181                                  &sz) )
 182     {
 183         wxLogLastError(wxT("GetTextExtentExPoint"));
 184
 185         return false;
 186     }
 187
 188     return true;
 189 }