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///////////////////////////////////////////////////////////////////////////////
// Name: wx/private/textmeasure.h
// Purpose: declaration of wxTextMeasure class
// Author: Manuel Martin
// Created: 2012-10-05
// Copyright: (c) 1997-2012 wxWidgets team
// Licence: wxWindows licence
///////////////////////////////////////////////////////////////////////////////
#ifndef _WX_PRIVATE_TEXTMEASURE_H_
#define _WX_PRIVATE_TEXTMEASURE_H_
class WXDLLIMPEXP_FWD_CORE wxDC;
class WXDLLIMPEXP_FWD_CORE wxFont;
class WXDLLIMPEXP_FWD_CORE wxWindow;
// ----------------------------------------------------------------------------
// wxTextMeasure: class used to measure text extent.
// ----------------------------------------------------------------------------
class wxTextMeasureBase
{
public:
// The first ctor argument must be non-NULL, i.e. each object of this class
// is associated with either a valid wxDC or a valid wxWindow. The font can
// be NULL to use the current DC/window font or can be specified explicitly.
wxTextMeasureBase(const wxDC *dc, const wxFont *theFont);
wxTextMeasureBase(const wxWindow *win, const wxFont *theFont);
// Even though this class is not supposed to be used polymorphically, give
// it a virtual dtor to avoid compiler warnings.
virtual ~wxTextMeasureBase() { }
// Return the extent of a single line string.
void GetTextExtent(const wxString& string,
wxCoord *width,
wxCoord *height,
wxCoord *descent = NULL,
wxCoord *externalLeading = NULL);
// The same for a multiline (with '\n') string.
void GetMultiLineTextExtent(const wxString& text,
wxCoord *width,
wxCoord *height,
wxCoord *heightOneLine = NULL);
// Find the dimensions of the largest string.
wxSize GetLargestStringExtent(size_t n, const wxString* strings);
wxSize GetLargestStringExtent(const wxArrayString& strings)
{
return GetLargestStringExtent(strings.size(), &strings[0]);
}
// Fill the array with the widths for each "0..N" substrings for N from 1
// to text.length().
//
// The scaleX argument is the horizontal scale used by wxDC and is only
// used in the generic implementation.
bool GetPartialTextExtents(const wxString& text,
wxArrayInt& widths,
double scaleX);
// These functions are called by our public methods before and after each
// call to DoGetTextExtent(). Derived classes may override them to prepare
// for -- possibly several -- subsequent calls to DoGetTextExtent().
//
// As these calls must be always paired, they're never called directly but
// only by our friend MeasuringGuard class.
//
// NB: They're public only to allow VC6 to compile this code, there doesn't
// seem to be any way to give MeasuringGuard access to them (FIXME-VC6)
virtual void BeginMeasuring() { }
virtual void EndMeasuring() { }
// This is another method which is only used by MeasuringGuard.
bool IsUsingDCImpl() const { return m_useDCImpl; }
protected:
// RAII wrapper for the two methods above.
class MeasuringGuard
{
public:
MeasuringGuard(wxTextMeasureBase& tm) : m_tm(tm)
{
// BeginMeasuring() should only be called if we have a native DC,
// so don't call it if we delegate to a DC of unknown type.
if ( !m_tm.IsUsingDCImpl() )
m_tm.BeginMeasuring();
}
~MeasuringGuard()
{
if ( !m_tm.IsUsingDCImpl() )
m_tm.EndMeasuring();
}
private:
wxTextMeasureBase& m_tm;
};
// The main function of this class, to be implemented in platform-specific
// way used by all our public methods.
//
// The width and height pointers here are never NULL and the input string
// is not empty.
virtual void DoGetTextExtent(const wxString& string,
wxCoord *width,
wxCoord *height,
wxCoord *descent = NULL,
wxCoord *externalLeading = NULL) = 0;
// The real implementation of GetPartialTextExtents().
//
// On input, widths array contains text.length() zero elements and the text
// is guaranteed to be non-empty.
virtual bool DoGetPartialTextExtents(const wxString& text,
wxArrayInt& widths,
double scaleX) = 0;
// Call either DoGetTextExtent() or wxDC::GetTextExtent() depending on the
// value of m_useDCImpl.
//
// This must be always used instead of calling DoGetTextExtent() directly!
void CallGetTextExtent(const wxString& string,
wxCoord *width,
wxCoord *height,
wxCoord *descent = NULL,
wxCoord *externalLeading = NULL);
// Return a valid font: if one was given to us in the ctor, use this one,
// otherwise use the current font of the associated wxDC or wxWindow.
wxFont GetFont() const;
// Exactly one of m_dc and m_win is non-NULL for any given object of this
// class.
const wxDC* const m_dc;
const wxWindow* const m_win;
// If this is true, simply forward to wxDC::GetTextExtent() from our
// CallGetTextExtent() instead of calling our own DoGetTextExtent().
//
// We need this because our DoGetTextExtent() typically only works with
// native DCs, i.e. those having an HDC under Windows or using Pango under
// GTK+. However wxTextMeasure object can be constructed for any wxDC, not
// necessarily a native one and in this case we must call back into the DC
// implementation of text measuring itself.
bool m_useDCImpl;
// This one can be NULL or not.
const wxFont* const m_font;
wxDECLARE_NO_COPY_CLASS(wxTextMeasureBase);
};
// Include the platform dependent class declaration, if any.
#if defined(__WXGTK20__)
#include "wx/gtk/private/textmeasure.h"
#elif defined(__WXMSW__)
#include "wx/msw/private/textmeasure.h"
#else // no platform-specific implementation of wxTextMeasure yet
#include "wx/generic/private/textmeasure.h"
#define wxUSE_GENERIC_TEXTMEASURE 1
#endif
#ifndef wxUSE_GENERIC_TEXTMEASURE
#define wxUSE_GENERIC_TEXTMEASURE 0
#endif
#endif // _WX_PRIVATE_TEXTMEASURE_H_
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