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* \file grid-snapper.cpp
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* \brief Snapping things to grids.
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* Lauris Kaplinski <lauris@kaplinski.com>
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* Frank Felfe <innerspace@iname.com>
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* Carl Hetherington <inkscape@carlh.net>
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* Copyright (C) 1999-2002 Authors
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* Released under GNU GPL, read the file 'COPYING' for more information
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#include "sp-namedview.h"
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#include "display/canvas-grid.h"
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* \return x rounded to the nearest multiple of c1 plus c0.
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* If c1==0 (and c0 is finite), then returns +/-inf. This makes grid spacing of zero
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* mean "ignore the grid in this dimention". We're currently discussing "good" semantics
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* for guide/grid snapping.
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/* FIXME: move this somewhere else, perhaps */
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static double round_to_nearest_multiple_plus(double x, double const c1, double const c0)
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return floor((x - c0) / c1 + .5) * c1 + c0;
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Inkscape::GridSnapper::GridSnapper(SPNamedView const *nv, NR::Coord const d) : LineSnapper(nv, d)
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Inkscape::LineSnapper::LineList Inkscape::GridSnapper::_getSnapLines(NR::Point const &p) const
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if ( NULL == _named_view ) {
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SPCGrid *griditem = NULL;
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for (GSList *l = _named_view->gridviews; l != NULL; l = l->next) {
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// FIXME : this is a hack since there is only one view for now
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// but when we'll handle multiple views, snapping should
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// must be rethought and maybe only the current view
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// should give back it's SHOWN lines to snap to
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// For now, the last SPCGrid in _named_view->gridviews will be used.
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griditem = SP_CGRID(l->data);
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g_assert(griditem != NULL);
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for (unsigned int i = 0; i < 2; ++i) {
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/* This is to make sure we snap to only visible grid lines */
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double scaled_spacing = griditem->sw[i]; // this is spacing of visible lines if screen pixels
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// convert screen pixels to px
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// FIXME: after we switch to snapping dist in screen pixels, this will be unnecessary
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if (SP_ACTIVE_DESKTOP) {
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scaled_spacing /= SP_ACTIVE_DESKTOP->current_zoom();
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NR::Coord const rounded = round_to_nearest_multiple_plus(p[i],
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_named_view->gridorigin[i]);
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s.push_back(std::make_pair(NR::Dim2(i), rounded));
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c-file-style:"stroustrup"
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c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
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// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :