zoomtools.cxx

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 * This file is part of the LibreOffice project.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
 
#include <basegfx/utils/zoomtools.hxx>
 
namespace basegfx::zoomtools
{
 
const double ZOOM_FACTOR = 1.12246205;
 
static sal_uInt16 roundMultiple(sal_uInt16 nCurrent, int nMultiple)
{
    // round zoom to a multiple of nMultiple
    return (( nCurrent + nMultiple / 2 ) - ( nCurrent + nMultiple / 2 ) % nMultiple);
}
 
static sal_uInt16 roundZoom(double nCurrent)
{
    // convert nCurrent properly to int
    sal_uInt16 nNew = nCurrent + 0.5;
 
    // round to more common numbers above 50
    if (nNew > 1000) {
        nNew = roundMultiple(nNew, 100);
    } else if ( nNew > 500 ) {
        nNew = roundMultiple(nNew, 50);
    } else if ( nNew > 100 ) {
        nNew = roundMultiple(nNew, 10);
    } else if ( nNew > 50 ) {
        nNew = roundMultiple(nNew, 5);
    }
 
    return nNew;
}
 
static sal_uInt16 enforceStep(sal_uInt16 nCurrent, sal_uInt16 nPrevious, unsigned int nStep)
{
    if ((( nCurrent > nStep ) && ( nPrevious < nStep ))
    || (( nCurrent < nStep ) && ( nPrevious > nStep )))
        return nStep;
    else
        return nCurrent;
}
 
sal_uInt16 zoomIn(sal_uInt16 nCurrent)
{
    sal_uInt16 nNew = roundZoom( nCurrent * ZOOM_FACTOR );
    // make sure some values are not skipped
    nNew = enforceStep(nNew, nCurrent, 200);
    nNew = enforceStep(nNew, nCurrent, 100);
    nNew = enforceStep(nNew, nCurrent, 75);
    nNew = enforceStep(nNew, nCurrent, 50);
    nNew = enforceStep(nNew, nCurrent, 25);
    return nNew;
}
 
sal_uInt16 zoomOut(sal_uInt16 nCurrent)
{
    sal_uInt16 nNew = roundZoom( nCurrent / ZOOM_FACTOR );
    // make sure some values are not skipped
    nNew = enforceStep(nNew, nCurrent, 200);
    nNew = enforceStep(nNew, nCurrent, 100);
    nNew = enforceStep(nNew, nCurrent, 75);
    nNew = enforceStep(nNew, nCurrent, 50);
    nNew = enforceStep(nNew, nCurrent, 25);
    return nNew;
}
} // namespace
 
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