preview.h

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//----------------------------------------------------------------------------
// ObjectWindows
// Copyright (c) 1992, 1996 by Borland International, All Rights Reserved
//
/// \file
/// Definition of print preview classes
//----------------------------------------------------------------------------
 
#if !defined(OWL_PREVIEW_H)
#define OWL_PREVIEW_H
 
#include <owl/private/defs.h>
#if defined(BI_HAS_PRAGMA_ONCE)
# pragma once
#endif
 
#include <owl/window.h>
#include <owl/dc.h>
 
 
namespace owl {
 
#include <owl/preclass.h>
 
class _OWLCLASS TPrintout;
class _OWLCLASS TPrinter;
 
/// \addtogroup print
/// @{
/// \class TPreviewPage
// ~~~~~ ~~~~~~~~~~~~
/// TPreviewPage encapsulates a window which displays print-preview data.
/// It provides access to the basic information necessary to paint
/// print-preview data: i.e. the printer's DC.
//
/// TPreviewPage displays a page of a document in a print preview window. To obtain
/// the information needed to display the page, TPreviewPage interacts with
/// TPrintPreviewDC and TPrintout. Specifically, it creates a TPrintPreviewDC from
/// the window DC provided in Paint and passes that TPrintPreviewDC object to
/// TPrintout's SetPrintParams member function. The sample program PRINT.CPP
/// displays the following print preview window:
/// \image html bm243.BMP
//
class _OWLCLASS TPreviewPage : public TWindow {
  public:
    TPreviewPage(TWindow*   parent,
                 TPrintout& printout,
                 TPrintDC&  prndc,
                 TSize&     printExtent,
                 int        pagenum = 1);
 
    void         SetPageNumber(int newNum);
    int          GetPageNumber() const;
 
    // Overriden TWindow virtual
    //
    void Paint(TDC&, bool, TRect&) override;
 
  protected:
    void         EvSize(uint sizeType, const TSize& size);
 
  protected_data:
    int          PageNum;         ///< Page currently being previewed
    TSize        PrintExtent;     ///< Size of printer device (in pixels)
    TPrintout&   Printout;        ///< Printout which sends the output
    TPrintDC&    PrintDC;         ///< Device context of the printer
 
  DECLARE_RESPONSE_TABLE(TPreviewPage);
  DECLARE_CASTABLE;
};
 
//
/// \class TPreviewDCBase
// ~~~~~ ~~~~~~~~~~~~~~
/// TPreviewDCBase is the base class encapsulating a 'dual' device
/// context - i.e. a DC which is tied to the screen but responds as if it
/// were tied to a printer or some other device. A dual DC is schizophrenic
/// and maintains two personalities: Dr. Screen and Mr. Printer.
///
/// When querried about it's attributes, a 'dual' DC acts as a printer DC.
/// When requested to modify some attributes, a 'dual' DC acts as both a
/// printer DC and a screen DC.
/// When sent output, a 'dual' DC acts as a screen DC.
///
/// \note The TPreviewDCBase provides the basics of a 'dual' device context
///       object. However, this base object does not attempt to map the
///       screen DC to correspond to the attributes of the printer's device
///       context.
//
class _OWLCLASS TPreviewDCBase : public TPrintDC {
  public:
    TPreviewDCBase(TDC&         screen,
                   TPrintDC&    printdc);
 
    // Overriden to return printer's HDC
    //
    HDC           GetAttributeHDC() const;
 
  protected:
 
    /// DC of 'real' device (aka TargetDevice) whose output we're previewing
    //
    TPrintDC&     PrnDC;
};
 
 
//
/// \class TPrintPreviewDC
// ~~~~~ ~~~~~~~~~~~~~~~~
/// Derived from TPrintDC, TPrintPreviewDC maps printer device coordinates to
/// logical screen coordinates. It sets the extent of the view window and determines
/// the screen and printer font attributes. Many of TPrintPreviewDC's functions
/// override TDC's virtual functions.
///
/// TPrintPreviewDC is an enhanced 'TPreviewDCBase' where the attributes
/// of the screen DC are modified to corresponds [fairly] to those of the
/// printer.
///
/// For example, the screen DC's extent are modified to match those of the
/// printers. Similarly, the default font of the screen DC is computed to
/// correspond closely to the default font of the printer.
//
class _OWLCLASS TPrintPreviewDC : public TPreviewDCBase {
  public:
    TPrintPreviewDC(TDC&         screen,
                    TPrintDC&    printdc,
                    const TRect& client,
                    const TRect& clip);
   ~TPrintPreviewDC();
 
    // Override virtual TDC select & restore functions
    //
    void  SelectObject(const TFont& newFont);
    void  SelectStockObject(int index);
    void  RestoreFont();
    int   GetDeviceCaps(int index) const;
 
    // Dual DC synchronizing functions
    //
    virtual void SyncFont();
    virtual void ReScale();
    virtual void ReOrg();
 
    // Override virtual TDC color matching functions
    //
    TColor  SetBkColor(const TColor& color);
    TColor  SetTextColor(const TColor& color);
 
    // Override virtual TDC viewport & window mapping functions
    //
    int   SetMapMode(int mode);
    bool  SetViewportOrg(const TPoint& origin, TPoint * oldOrg=0);
    bool  OffsetViewportOrg(const TPoint& delta, TPoint * oldOrg=0);
 
    bool  SetViewportExt(const TSize& extent, TSize * oldExtent=0);
    bool  ScaleViewportExt(int xNum, int xDenom, int yNum, int yDenom,
                           TSize * oldExtent=0);
 
    bool  SetWindowExt(const TSize& extent, TSize * oldExtent=0);
    bool  ScaleWindowExt(int xNum, int xDenom, int yNum, int yDenom,
                         TSize * oldExtent=0);
 
    // Screen device point to Logical point conversions
    //
    bool  SDPtoLP(TPoint* points, int count = 1) const;
    bool  SDPtoLP(TRect& rect) const;
    bool  LPtoSDP(TPoint* points, int count = 1) const;
    bool  LPtoSDP(TRect& rect) const;
 
  protected_data:
    HFONT     PrnFont;              ///< Handle of current font in the printer dc
    TFont*    CurrentPreviewFont;   ///< Font object in PrnDC used during preview
};
/// @}
 
#include <owl/posclass.h>
 
 
// --------------------------------------------------------------------------
// Inline implementation
//
 
//
/// Converts each of the count points in the points array from screen device
/// points to logical points of the printer DC. Returns a nonzero value if the call
/// is successful; otherwise, returns 0.
//
inline bool
TPrintPreviewDC::SDPtoLP(TPoint* points, int count) const {
  PRECONDITION(::GetObjectType(static_cast<HDC>(Handle)) != 0);
  return ::DPtoLP(static_cast<HDC>(Handle), points, count);
}
 
//
/// Converts each of the points in the rect from screen device points to
/// logical points of the printer DC. Returns a nonzero value if the call is
/// successful; otherwise, returns 0.
//
inline bool
TPrintPreviewDC::SDPtoLP(TRect& rect) const {
  return SDPtoLP(rect, 2);
}
 
//
/// Converts each of the count points in the points array from logical
/// points of the printer DC to screen points. Returns a nonzero value if the call
/// is successful; otherwise, returns 0.
//
inline bool
TPrintPreviewDC::LPtoSDP(TPoint* points, int count) const {
  PRECONDITION(::GetObjectType(HDC(Handle)) != 0);
  return ::LPtoDP(HDC(Handle), points, count);
}
 
//
/// Converts each of the points in the rect from logical points of the
/// printer DC to screen device points. Returns a nonzero value if the call is
/// successful; otherwise, returns 0.
inline bool
TPrintPreviewDC::LPtoSDP(TRect& rect) const {
  return LPtoSDP(rect, 2);
}
 
//
/// Retrieves the index of the page currently being previewed (painted) on the
/// preview page window.
//
inline int
TPreviewPage::GetPageNumber() const {
  return PageNum;
}
 
} // OWL namespace
 
 
#endif  // OWL_PREVIEW_H