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cbGCUpdatesMgr

This class implements optimized logic for refreshing the areas of frame layout that actually need to be updated. It is used as the default updates manager by wxFrameLayout.

It is called 'Garbage Collecting' updates manager because its implementation tries to find out dependencies between bars, and to order them into a 'hierarchy'. This hierarchical sorting resembles the implementation of heap-garbage collectors, which resolve dependencies between references.

Example: there are situations where the order in which the user moves windows does matter.

  case 1)
     ------            ---
     | A     |             |B|
        ------     --->      | |
            ---               --- ------
            |B|                   | A  |
            | |                   ------
            ---
                        (future)
       (past)
Past/future positions of A and B windows completely overlap, i.e. depend on each other, and there is no solution for moving the windows without refreshing both of them -- we have a cyclic dependency here. The garbage collection algorithm will find this cyclic dependecy and will force refresh after movement.

  case 2)

     ------
     | A     |
        ------     --->
            ---
            |B|                              ------
            | |                              | A  |
            ---                              ------
                         ---
                         |B|
                         | |
                         ---

                        (future)
       (past)
In this case past/future positions do not overlap, so it is enough only to move windows without refreshing them. Garbage collection will 'notice' this.

There is also a third case, when overlapping is partial. In this case the refreshing can also be avoided by moving windows in the order of 'most-dependant' towards the 'least-dependent'. GC handles this automatically, by sorting windows by their dependency-level (or 'hierarchy').

See garbagec.h for more details of this method; garbagec.h/cpp implement sorting of generic dependencies and does not deal with graphical objects directly.

Summary: garbage collection improves performance when complex or large windows are moved around, by reducing the number of repaints. It also helps to avoid dirty non-client areas of moved windows in some special cases of 'overlapping anomalies'.

Derived from

cbSimpleUpdatesMgr

Include files

<wx/fl/gcupdatesmgr.h>

Data structures

Members

cbGCUpdatesMgr::cbGCUpdatesMgr
cbGCUpdatesMgr::AddItem
cbGCUpdatesMgr::DoRepositionItems
cbGCUpdatesMgr::OnStartChanges
cbGCUpdatesMgr::UpdateNow


cbGCUpdatesMgr::cbGCUpdatesMgr

cbGCUpdatesMgr()

Default constructor.

cbGCUpdatesMgr(wxFrameLayout* pPanel)

Constructor, taking a frame layout.


cbGCUpdatesMgr::AddItem

void AddItem(wxList& itemList, cbBarInfo* pBar, cbDockPane* pPane, wxRect& curBounds, wxRect& prevBounds)

Internal function for repositioning items.


cbGCUpdatesMgr::DoRepositionItems

void DoRepositionItems(wxList& items)

Internal function for repositioning items.


cbGCUpdatesMgr::OnStartChanges

void OnStartChanges()

Receives notifications from the frame layout.


cbGCUpdatesMgr::UpdateNow

void UpdateNow()

Refreshes the parts of the frame layout which need an update.