include/wx/vscroll.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        include/wx/vscroll.h
   3 // Purpose:     wxVScrolledWindow: generalization of wxScrolledWindow
   4 // Author:      Vadim Zeitlin
   5 // Modified by:
   6 // Created:     30.05.03
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) 2003 Vadim Zeitlin <vadim@wxwindows.org>
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 #ifndef _WX_VSCROLL_H_
  13 #define _WX_VSCROLL_H_
  14
  15 #include "wx/panel.h"           // base class
  16
  17 // ----------------------------------------------------------------------------
  18 // wxVScrolledWindow
  19 // ----------------------------------------------------------------------------
  20
  21 /*
  22    In the name of this class, "V" may stand for "variable" because it can be
  23    used for scrolling lines of variable heights; "virtual" because it is not
  24    necessary to know the heights of all lines in advance -- only those which
  25    are shown on the screen need to be measured; or, even, "vertical" because
  26    this class only supports scrolling in one direction currently (this could
  27    and probably will change in the future however).
  28
  29    In any case, this is a generalization of the wxScrolledWindow class which
  30    can be only used when all lines have the same height. It lacks some other
  31    wxScrolledWindow features however, notably it currently lacks support for
  32    horizontal scrolling; it can't scroll another window nor only a rectangle
  33    of the window and not its entire client area.
  34  */
  35 class WXDLLEXPORT wxVScrolledWindow : public wxPanel
  36 {
  37 public:
  38     // constructors and such
  39     // ---------------------
  40
  41     // default ctor, you must call Create() later
  42     wxVScrolledWindow() { Init(); }
  43
  44     // normal ctor, no need to call Create() after this one
  45     //
  46     // note that wxVSCROLL is always automatically added to our style, there is
  47     // no need to specify it explicitly
  48     wxVScrolledWindow(wxWindow *parent,
  49                       wxWindowID id = wxID_ANY,
  50                       const wxPoint& pos = wxDefaultPosition,
  51                       const wxSize& size = wxDefaultSize,
  52                       long style = 0,
  53                       const wxString& name = wxPanelNameStr)
  54     {
  55         Init();
  56
  57         (void)Create(parent, id, pos, size, style, name);
  58     }
  59
  60     // same as the previous ctor but returns status code: true if ok
  61     //
  62     // just as with the ctor above, wxVSCROLL style is always used, there is no
  63     // need to specify it
  64     bool Create(wxWindow *parent,
  65                 wxWindowID id,
  66                 const wxPoint& pos = wxDefaultPosition,
  67                 const wxSize& size = wxDefaultSize,
  68                 long style = 0,
  69                 const wxString& name = wxPanelNameStr)
  70     {
  71         return wxPanel::Create(parent, id, pos, size, style | wxVSCROLL, name);
  72     }
  73
  74
  75     // operations
  76     // ----------
  77
  78     // set the number of lines the window contains: the derived class must
  79     // provide the heights for all lines with indices up to the one given here
  80     // in its OnGetLineHeight()
  81     void SetLineCount(size_t count);
  82
  83     // scroll to the specified line: it will become the first visible line in
  84     // the window
  85     //
  86     // return true if we scrolled the window, false if nothing was done
  87     bool ScrollToLine(size_t line);
  88
  89     // scroll by the specified number of lines/pages
  90     virtual bool ScrollLines(int lines);
  91     virtual bool ScrollPages(int pages);
  92
  93
  94     // accessors
  95     // ---------
  96
  97     // get the number of lines this window contains (previously set by
  98     // SetLineCount())
  99     size_t GetLineCount() const { return m_lineMax; }
 100
 101     // get the first currently visible line
 102     size_t GetFirstVisibleLine() const { return m_lineFirst; }
 103
 104     // get the last currently visible line
 105     size_t GetLastVisibleLine() const { return m_lineFirst + m_nVisible - 1; }
 106
 107
 108 //protected:
 109     // this function must be overridden in the derived class and it should
 110     // return the height of the given line in pixels
 111     virtual wxCoord OnGetLineHeight(size_t n) const = 0;
 112
 113     // this function doesn't have to be overridden but it may be useful to do
 114     // it if calculating the lines heights is a relatively expensive operation
 115     // as it gives the user code a possibility to calculate several of them at
 116     // once
 117     //
 118     // OnGetLinesHint() is normally called just before OnGetLineHeight() but you
 119     // shouldn't rely on the latter being called for all lines in the interval
 120     // specified here. It is also possible that OnGetLineHeight() will be
 121     // called for the lines outside of this interval, so this is really just a
 122     // hint, not a promise.
 123     //
 124     // finally note that lineMin is inclusive, while lineMax is exclusive, as
 125     // usual
 126     virtual void OnGetLinesHint(size_t lineMin, size_t lineMax) const { }
 127
 128 protected:
 129     // the event handlers
 130     void OnSize(wxSizeEvent& event);
 131     void OnScroll(wxScrollWinEvent& event);
 132
 133     // find the index of the line we need to show at the top of the window such
 134     // that the last line shown is the given one
 135     size_t FindFirstFromBottom(size_t lineLast);
 136
 137     // get the total height of the lines between lineMin (inclusive) and
 138     // lineMax (exclusive)
 139     wxCoord GetLinesHeight(size_t lineMin, size_t lineMax) const;
 140
 141     // update the thumb size shown by the scrollbar
 142     void UpdateScrollbar();
 143
 144 private:
 145     // common part of all ctors
 146     void Init();
 147
 148
 149     // the total number of (logical) lines
 150     size_t m_lineMax;
 151
 152     // the total (estimated) height
 153     wxCoord m_heightTotal;
 154
 155     // the first currently visible line
 156     size_t m_lineFirst;
 157
 158     // the number of currently visible lines (including the last, possibly only
 159     // partly, visible one)
 160     size_t m_nVisible;
 161
 162
 163     DECLARE_EVENT_TABLE()
 164 };
 165
 166 #endif // _WX_VSCROLL_H_
 167