Paul Davis
6019f06bdf
The idea now is that a scroll group item can be added to the canvas which will causes its children to scroll in either or both directions (horizontal or vertical). There are few complications: the position() of the ScrollGroup is ambiguous depending on whether you want it with scroll taken into account or not, so Item::canvas_position() was added, which defaults to the same value as Item::position() but is overridden by ScrollGroup to return the position independent of scrolling. This method is used when translating between item/canvas/window coordinate systems. Note that the basic idea is that we MOVE the scroll group when a scroll happens. This mirrors what happens in the GnomeCanvas, where Nick Mainsbridge came up with a great idea that allowed unification of the time bar and track canvases.
64 lines
1.6 KiB
C++
64 lines
1.6 KiB
C++
/*
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Copyright (C) 2014 Paul Davis
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <iostream>
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#include "canvas/scroll_group.h"
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using namespace std;
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using namespace ArdourCanvas;
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ScrollGroup::ScrollGroup (Group* parent, ScrollSensitivity s)
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: Group (parent)
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, _scroll_sensitivity (s)
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{
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}
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ScrollGroup::ScrollGroup (Group* parent, Duple position, ScrollSensitivity s)
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: Group (parent, position)
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, _scroll_sensitivity (s)
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{
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}
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void
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ScrollGroup::scroll_to (Duple const& d)
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{
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Duple base_pos (position().translate (_scroll_offset));
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if (_scroll_sensitivity & ScrollsHorizontally) {
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base_pos.x -= d.x;
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_scroll_offset.x = d.x;
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}
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if (_scroll_sensitivity & ScrollsVertically) {
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base_pos.y -= d.y;
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_scroll_offset.y = d.y;
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}
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set_position (base_pos);
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}
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Duple
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ScrollGroup::canvas_position() const
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{
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/* return the normal "base" position of this item
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rather its position as affected by any scroll
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offset.
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*/
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return _position.translate (_scroll_offset);
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}
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