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1 ///////////////////////////////////////////////////////////////////////////////
2 // Name: wx/private/textmeasure.h
3 // Purpose: declaration of wxTextMeasure class
4 // Author: Manuel Martin
5 // Created: 2012-10-05
6 // RCS-ID: $Id:
7 // Copyright: (c) 1997-2012 wxWidgets team
8 // Licence: wxWindows licence
9 ///////////////////////////////////////////////////////////////////////////////
10
11 #ifndef _WX_PRIVATE_TEXTMEASURE_H_
12 #define _WX_PRIVATE_TEXTMEASURE_H_
13
14 class WXDLLIMPEXP_FWD_CORE wxDC;
15 class WXDLLIMPEXP_FWD_CORE wxFont;
16 class WXDLLIMPEXP_FWD_CORE wxWindow;
17
18 // ----------------------------------------------------------------------------
19 // wxTextMeasure: class used to measure text extent.
20 // ----------------------------------------------------------------------------
21
22 class wxTextMeasureBase
23 {
24 public:
25 // The first ctor argument must be non-NULL, i.e. each object of this class
26 // is associated with either a valid wxDC or a valid wxWindow. The font can
27 // be NULL to use the current DC/window font or can be specified explicitly.
28 wxTextMeasureBase(const wxDC *dc, const wxFont *theFont);
29 wxTextMeasureBase(const wxWindow *win, const wxFont *theFont);
30
31 // Even though this class is not supposed to be used polymorphically, give
32 // it a virtual dtor to avoid compiler warnings.
33 virtual ~wxTextMeasureBase() { }
34
35
36 // Return the extent of a single line string.
37 void GetTextExtent(const wxString& string,
38 wxCoord *width,
39 wxCoord *height,
40 wxCoord *descent = NULL,
41 wxCoord *externalLeading = NULL);
42
43 // The same for a multiline (with '\n') string.
44 void GetMultiLineTextExtent(const wxString& text,
45 wxCoord *width,
46 wxCoord *height,
47 wxCoord *heightOneLine = NULL);
48
49 // Find the dimensions of the largest string.
50 wxSize GetLargestStringExtent(size_t n, const wxString* strings);
51 wxSize GetLargestStringExtent(const wxArrayString& strings)
52 {
53 return GetLargestStringExtent(strings.size(), &strings[0]);
54 }
55
56 // Fill the array with the widths for each "0..N" substrings for N from 1
57 // to text.length().
58 //
59 // The scaleX argument is the horizontal scale used by wxDC and is only
60 // used in the generic implementation.
61 bool GetPartialTextExtents(const wxString& text,
62 wxArrayInt& widths,
63 double scaleX);
64
65
66 // These functions are called by our public methods before and after each
67 // call to DoGetTextExtent(). Derived classes may override them to prepare
68 // for -- possibly several -- subsequent calls to DoGetTextExtent().
69 //
70 // As these calls must be always paired, they're never called directly but
71 // only by our friend MeasuringGuard class.
72 //
73 // NB: They're public only to allow VC6 to compile this code, there doesn't
74 // seem to be any way to give MeasuringGuard access to them (FIXME-VC6)
75 virtual void BeginMeasuring() { }
76 virtual void EndMeasuring() { }
77
78 // This is another method which is only used by MeasuringGuard.
79 bool IsUsingDCImpl() const { return m_useDCImpl; }
80
81 protected:
82 // RAII wrapper for the two methods above.
83 class MeasuringGuard
84 {
85 public:
86 MeasuringGuard(wxTextMeasureBase& tm) : m_tm(tm)
87 {
88 // BeginMeasuring() should only be called if we have a native DC,
89 // so don't call it if we delegate to a DC of unknown type.
90 if ( !m_tm.IsUsingDCImpl() )
91 m_tm.BeginMeasuring();
92 }
93
94 ~MeasuringGuard()
95 {
96 if ( !m_tm.IsUsingDCImpl() )
97 m_tm.EndMeasuring();
98 }
99
100 private:
101 wxTextMeasureBase& m_tm;
102 };
103
104
105 // The main function of this class, to be implemented in platform-specific
106 // way used by all our public methods.
107 //
108 // The width and height pointers here are never NULL and the input string
109 // is not empty.
110 virtual void DoGetTextExtent(const wxString& string,
111 wxCoord *width,
112 wxCoord *height,
113 wxCoord *descent = NULL,
114 wxCoord *externalLeading = NULL) = 0;
115
116 // The real implementation of GetPartialTextExtents().
117 //
118 // On input, widths array contains text.length() zero elements and the text
119 // is guaranteed to be non-empty.
120 virtual bool DoGetPartialTextExtents(const wxString& text,
121 wxArrayInt& widths,
122 double scaleX) = 0;
123
124 // Call either DoGetTextExtent() or wxDC::GetTextExtent() depending on the
125 // value of m_useDCImpl.
126 //
127 // This must be always used instead of calling DoGetTextExtent() directly!
128 void CallGetTextExtent(const wxString& string,
129 wxCoord *width,
130 wxCoord *height,
131 wxCoord *descent = NULL,
132 wxCoord *externalLeading = NULL);
133
134 // Return a valid font: if one was given to us in the ctor, use this one,
135 // otherwise use the current font of the associated wxDC or wxWindow.
136 wxFont GetFont() const;
137
138
139 // Exactly one of m_dc and m_win is non-NULL for any given object of this
140 // class.
141 const wxDC* const m_dc;
142 const wxWindow* const m_win;
143
144 // If this is true, simply forward to wxDC::GetTextExtent() from our
145 // CallGetTextExtent() instead of calling our own DoGetTextExtent().
146 //
147 // We need this because our DoGetTextExtent() typically only works with
148 // native DCs, i.e. those having an HDC under Windows or using Pango under
149 // GTK+. However wxTextMeasure object can be constructed for any wxDC, not
150 // necessarily a native one and in this case we must call back into the DC
151 // implementation of text measuring itself.
152 bool m_useDCImpl;
153
154 // This one can be NULL or not.
155 const wxFont* const m_font;
156
157 wxDECLARE_NO_COPY_CLASS(wxTextMeasureBase);
158 };
159
160 // Include the platform dependant class declaration, if any.
161 #if defined(__WXGTK20__)
162 #include "wx/gtk/private/textmeasure.h"
163 #elif defined(__WXMSW__)
164 #include "wx/msw/private/textmeasure.h"
165 #else // no platform-specific implementation of wxTextMeasure yet
166 #include "wx/generic/private/textmeasure.h"
167
168 #define wxUSE_GENERIC_TEXTMEASURE 1
169 #endif
170
171 #ifndef wxUSE_GENERIC_TEXTMEASURE
172 #define wxUSE_GENERIC_TEXTMEASURE 0
173 #endif
174
175 #endif // _WX_PRIVATE_TEXTMEASURE_H_