include/wx/cocoa/private/scrollview.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/cocoa/private/scrollview.h
   3 // Purpose:     wxWindowCocoaScrollView
   4 // Author:      David Elliott
   5 // Modified by:
   6 // Created:     2008/02/14
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) 2003- David Elliott
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 #ifndef _WX_COCOA_SCROLLVIEW_H__
  13 #define _WX_COCOA_SCROLLVIEW_H__
  14
  15 @class NSScroller;
  16
  17 // ========================================================================
  18 // wxWindowCocoaScrollView
  19 // ========================================================================
  20 class wxWindowCocoaScrollView: protected wxCocoaNSView
  21 {
  22     wxDECLARE_NO_COPY_CLASS(wxWindowCocoaScrollView);
  23 public:
  24     wxWindowCocoaScrollView(wxWindow *owner);
  25     virtual ~wxWindowCocoaScrollView();
  26     inline WX_NSScrollView GetNSScrollView() { return m_cocoaNSScrollView; }
  27     void ClientSizeToSize(int &width, int &height);
  28     void DoGetClientSize(int *x, int *y) const;
  29     void Encapsulate();
  30     void Unencapsulate();
  31
  32     // wxWindow calls this to do the work.  Note that we don't have the refresh parameter
  33     // because wxWindow handles that itself.
  34     void SetScrollbar(int orientation, int position, int thumbSize, int range);
  35     int GetScrollPos(wxOrientation orient);
  36     void SetScrollPos(wxOrientation orient, int position);
  37     int GetScrollRange(wxOrientation orient);
  38     int GetScrollThumb(wxOrientation orient);
  39     void ScrollWindow(int dx, int dy, const wxRect*);
  40     void UpdateSizes();
  41
  42     void _wx_doScroller(NSScroller *sender);
  43
  44 protected:
  45     wxWindowCocoa *m_owner;
  46     WX_NSScrollView m_cocoaNSScrollView;
  47     virtual void Cocoa_FrameChanged(void);
  48     virtual void Cocoa_synthesizeMouseMoved(void) {}
  49     /*!
  50         Flag as to whether we're scrolling for a native view or a custom
  51         wxWindow.  This controls the scrolling behaviour.  When providing
  52         scrolling for a native view we don't catch scroller action messages
  53         and thus don't send scroll events and we don't actually scroll the
  54         window when the application calls ScrollWindow.
  55
  56         When providing scrolling for a custom wxWindow, we make the NSScroller
  57         send their action messages to us which we in turn package as wx window
  58         scrolling events.  At this point, the window will not physically be
  59         scrolled.  The application will most likely handle the event by calling
  60         ScrollWindow which will do the real scrolling.  On the other hand,
  61         the application may instead not call ScrollWindow until some threshold
  62         is reached.  This causes the window to only scroll in steps which is
  63         what, for instance, wxScrolledWindow does.
  64      */
  65     bool m_isNativeView;
  66     /*!
  67         The range as the application code wishes to see it.  That is, the
  68         range from the last SetScrollbar call for the appropriate dimension.
  69         The horizontal dimension is the first [0] element and the vertical
  70         dimension the second [1] element.
  71
  72         In wxMSW, a SCROLLINFO with nMin=0 and nMax=range-1 is used which
  73         gives exactly range possible positions so long as nPage (which is
  74         the thumb size) is less than or equal to 1.
  75      */
  76     int m_scrollRange[2];
  77     /*!
  78         The thumb size is intended to reflect the size of the visible portion
  79         of the scrolled document.  As the document size increases, the thumb
  80         visible thumb size decreases.  As document size decreases, the visible
  81         thumb size increases.  However, the thumb size on wx is defined in
  82         terms of scroll units (which are effectively defined by the scroll
  83         range) and so increasing the number of scroll units to reflect increased
  84         document size will have the effect of decreasing the visible thumb
  85         size even though the number doesn't change.
  86
  87         It's also important to note that subtracting the thumb size from the
  88         full range gives you the real range that can be used.  Microsoft
  89         defines nPos (the current scrolling position) to be within the range
  90         from nMin to nMax - max(nPage - 1, 0).  We know that wxMSW code always
  91         sets nMin = 0 and nMax = range -1.  So let's algebraically reduce the
  92         definition of the maximum allowed position:
  93
  94         Begin:
  95         = nMax - max(nPage - 1, 0)
  96         Substitute (range - 1) for nMax and thumbSize for nPage:
  97         = range - 1 - max(thumbSize - 1, 0)
  98         Add one inside the max conditional and subtract one outside of it:
  99         = range - 1 - (max(thumbSize - 1 + 1, 1) - 1)
 100         Reduce some constants:
 101         = range - 1 - (max(thumbSize, 1) - 1)
 102         Distribute the negative across the parenthesis:
 103         = range - 1 - max(thumbSize, 1) + 1
 104         Reduce the constants:
 105         = range - max(thumbSize, 1)
 106
 107         Also keep in mind that thumbSize may never be greater than range but
 108         can be equal to it.  Thus for the smallest possible thumbSize there
 109         are exactly range possible scroll positions (numbered from 0 to
 110         range - 1) and for the largest possible thumbSize there is exactly
 111         one possible scroll position (numbered 0).
 112      */
 113     int m_scrollThumb[2];
 114
 115     /*!
 116         The origin of the virtual coordinate space expressed in terms of client
 117         coordinates.  Starts at (0,0) and each call to ScrollWindow accumulates
 118         into it.  Thus if the user scrolls the window right (thus causing the
 119         contents to move left with respect to the client origin, the
 120         application code (typically wxScrolledWindow) will be called with
 121         dx of -something, for example -20.  This is added to m_virtualOrigin
 122         and thus m_virtualOrigin will be (-20,0) in this example.
 123      */
 124     wxPoint m_virtualOrigin;
 125 private:
 126     wxWindowCocoaScrollView();
 127 };
 128
 129 #endif //ndef _WX_COCOA_SCROLLVIEW_H__