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86 lines
2.5 KiB
86 lines
2.5 KiB
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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
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/*
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Rosegarden
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A MIDI and audio sequencer and musical notation editor.
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This program is Copyright 2000-2008
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Guillaume Laurent <glaurent@telegraph-road.org>,
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Chris Cannam <cannam@all-day-breakfast.com>,
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Richard Bown <richard.bown@ferventsoftware.com>
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The moral rights of Guillaume Laurent, Chris Cannam, and Richard
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Bown to claim authorship of this work have been asserted.
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Other copyrights also apply to some parts of this work. Please
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see the AUTHORS file and individual file headers for details.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version. See the file
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COPYING included with this distribution for more information.
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*/
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#ifndef _RG_CANVASITEMGC_H_
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#define _RG_CANVASITEMGC_H_
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#include <vector>
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class TQCanvasItem;
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namespace Rosegarden
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{
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/**
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* A pseudo GC in which CanvasItems whose ownership isn't clear cut
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* can be put for periodical removal.
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*
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* This is especially for SegmentItems which can put their repeat
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* rectangles when they're being deleted.
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*
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* The problem this solves is a classic ownership/double deletion
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* case. The SegmentCanvas deletes all its items on destruction. But
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* the SegmentItems have an auxiliary "repeat rectangle" which is a
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* TQCanvasRectangle, that needs to be deleted when the SegmentItem is
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* itself deleted.
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*
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* However, if the SegmentItem deletes its repeat rectangle, then when
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* the SegmentCanvas destruction occurs, the SegmentCanvas dtor will
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* get a list of all its children (TQCanvas::allItems()), containing
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* both SegmentItems and their repeat rectangles. Deleting a
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* SegmentItem will delete its repeat rectangle, which will still be
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* present in the all children list which the SegmentCanvas dtor is
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* iterating over.
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*
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* So a solution is simply to push to-be-deleted repeat rectangles on
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* this GC, which should be processed on canvas updates, for instance.
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*
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*/
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class CanvasItemGC
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{
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public:
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/// mark the given item for GC
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static void mark(TQCanvasItem*);
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/// GC all marked items
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static void gc();
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/// Forget all marked items - don't delete them
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static void flush();
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protected:
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static std::vector<TQCanvasItem*> m_garbage;
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};
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}
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#endif
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