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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
14class WXDLLIMPEXP_FWD_CORE wxDC;
15class WXDLLIMPEXP_FWD_CORE wxFont;
16class WXDLLIMPEXP_FWD_CORE wxWindow;
17
18// ----------------------------------------------------------------------------
19// wxTextMeasure: class used to measure text extent.
20// ----------------------------------------------------------------------------
21
22class wxTextMeasureBase
23{
24public:
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
78protected:
79 // RAII wrapper for the two methods above.
80 class MeasuringGuard
81 {
82 public:
83 MeasuringGuard(wxTextMeasureBase& tm) : m_tm(tm)
84 {
85 m_tm.BeginMeasuring();
86 }
87
88 ~MeasuringGuard()
89 {
90 m_tm.EndMeasuring();
91 }
92
93 private:
94 wxTextMeasureBase& m_tm;
95 };
96
97
98 // The main function of this class, to be implemented in platform-specific
99 // way used by all our public methods.
100 //
101 // The width and height pointers here are never NULL and the input string
102 // is not empty.
103 virtual void DoGetTextExtent(const wxString& string,
104 wxCoord *width,
105 wxCoord *height,
106 wxCoord *descent = NULL,
107 wxCoord *externalLeading = NULL) = 0;
108
109 // The real implementation of GetPartialTextExtents().
110 //
111 // On input, widths array contains text.length() zero elements and the text
112 // is guaranteed to be non-empty.
113 virtual bool DoGetPartialTextExtents(const wxString& text,
114 wxArrayInt& widths,
115 double scaleX) = 0;
116
117 // Call either DoGetTextExtent() or wxDC::GetTextExtent() depending on the
118 // value of m_useDCImpl.
119 //
120 // This must be always used instead of calling DoGetTextExtent() directly!
121 void CallGetTextExtent(const wxString& string,
122 wxCoord *width,
123 wxCoord *height,
124 wxCoord *descent = NULL,
125 wxCoord *externalLeading = NULL);
126
127 // Return a valid font: if one was given to us in the ctor, use this one,
128 // otherwise use the current font of the associated wxDC or wxWindow.
129 wxFont GetFont() const;
130
131
132 // Exactly one of m_dc and m_win is non-NULL for any given object of this
133 // class.
134 const wxDC* const m_dc;
135 const wxWindow* const m_win;
136
137 // If this is true, simply forward to wxDC::GetTextExtent() from our
138 // CallGetTextExtent() instead of calling our own DoGetTextExtent().
139 //
140 // We need this because our DoGetTextExtent() typically only works with
141 // native DCs, i.e. those having an HDC under Windows or using Pango under
142 // GTK+. However wxTextMeasure object can be constructed for any wxDC, not
143 // necessarily a native one and in this case we must call back into the DC
144 // implementation of text measuring itself.
145 bool m_useDCImpl;
146
147 // This one can be NULL or not.
148 const wxFont* const m_font;
149
150 wxDECLARE_NO_COPY_CLASS(wxTextMeasureBase);
151};
152
153// Include the platform dependant class declaration, if any.
154#if defined(__WXGTK20__)
155 #include "wx/gtk/private/textmeasure.h"
156#elif defined(__WXMSW__)
157 #include "wx/msw/private/textmeasure.h"
158#else // no platform-specific implementation of wxTextMeasure yet
159 #include "wx/generic/private/textmeasure.h"
160
161 #define wxUSE_GENERIC_TEXTMEASURE 1
162#endif
163
164#ifndef wxUSE_GENERIC_TEXTMEASURE
165 #define wxUSE_GENERIC_TEXTMEASURE 0
166#endif
167
168#endif // _WX_PRIVATE_TEXTMEASURE_H_