contrib/include/wx/fl/gcupdatesmgr.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        gcupdatesmgr.h
   3 // Purpose:     Header for cbGCUpdatesMgr class.
   4 // Author:      Aleksandras Gluchovas
   5 // Modified by:
   6 // Created:     19/10/98
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) Aleksandras Gluchovas
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 #ifndef __GCUPDATESMGR_G__
  13 #define __GCUPDATESMGR_G__
  14
  15 #include "wx/fl/controlbar.h"
  16 #include "wx/fl/updatesmgr.h"
  17
  18 #include "wx/fl/garbagec.h"
  19
  20 /*
  21 This class implements optimized logic for refreshing
  22 the areas of frame layout that actually need to be updated.
  23 It is used as the default updates manager by wxFrameLayout.
  24
  25 It is called 'Garbage Collecting' updates manager because
  26 its implementation tries to find out dependencies between bars,
  27 and to order them into a 'hierarchy'. This hierarchical sorting resembles
  28 the implementation of heap-garbage collectors, which resolve
  29 dependencies between references.
  30
  31 Example: there are situations where the order in which the user
  32 moves windows does matter.
  33
  34 \begin{verbatim}
  35   case 1)
  36      ------            ---
  37      | A     |             |B|
  38         ------     --->      | |
  39             ---               --- ------
  40             |B|                   | A  |
  41             | |                   ------
  42             ---
  43                         (future)
  44        (past)
  45 \end{verbatim}
  46
  47 Past/future positions of A and B windows completely overlap, i.e.
  48 depend on each other, and there is no solution for
  49 moving the windows without refreshing both of them
  50 -- we have a cyclic dependency here. The garbage collection algorithm will
  51 find this cyclic dependecy and will force refresh after movement.
  52
  53 \begin{verbatim}
  54   case 2)
  55
  56      ------
  57      | A     |
  58         ------     --->
  59             ---
  60             |B|                              ------
  61             | |                              | A  |
  62             ---                              ------
  63                          ---
  64                          |B|
  65                          | |
  66                          ---
  67
  68                         (future)
  69        (past)
  70 \end{verbatim}
  71
  72 In this case past/future positions do not overlap, so
  73 it is enough only to move windows without refreshing them.
  74 Garbage collection will 'notice' this.
  75
  76 There is also a third case, when overlapping is partial.
  77 In this case the refreshing can also be avoided by
  78 moving windows in the order of 'most-dependant' towards the
  79 'least-dependent'. GC handles this automatically, by
  80 sorting windows by their dependency-level (or 'hierarchy').
  81
  82 See garbagec.h for more details of this method; garbagec.h/cpp
  83 implement sorting of generic dependencies and does not deal
  84 with graphical objects directly.
  85
  86 Summary: garbage collection improves performance when complex or large
  87 windows are moved around, by reducing the number of repaints. It also helps
  88 to avoid dirty non-client areas of moved windows
  89 in some special cases of 'overlapping anomalies'.
  90 */
  91
  92 class WXDLLIMPEXP_FL cbGCUpdatesMgr : public cbSimpleUpdatesMgr
  93 {
  94     DECLARE_DYNAMIC_CLASS( cbGCUpdatesMgr )
  95 protected:
  96
  97     GarbageCollector mGC;
  98
  99         // Internal function for repositioning items.
 100     void DoRepositionItems( wxList& items );
 101
 102         // Internal function for repositioning items.
 103     void AddItem( wxList&     itemList,
 104                   cbBarInfo*  pBar,
 105                   cbDockPane* pPane,
 106                   wxRect&     curBounds,
 107                   wxRect&     prevBounds );
 108
 109 public:
 110
 111         // Default constructor.
 112     cbGCUpdatesMgr(void) {}
 113
 114         // Constructor, taking a frame layout.
 115     cbGCUpdatesMgr( wxFrameLayout* pPanel );
 116
 117         // Receives notifications from the frame layout.
 118     virtual void OnStartChanges();
 119
 120         // Refreshes the parts of the frame layout which need an update.
 121     virtual void UpdateNow();
 122 };
 123
 124 #endif /* __GCUPDATESMGR_G__ */
 125