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/* $Id$ */

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/** @file zoom_func.h Functions related to zooming. */

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#ifndef ZOOM_FUNC_H

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#define ZOOM_FUNC_H

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#include "zoom_type.h"

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extern ZoomLevel _saved_scrollpos_zoom;

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/**

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 * Scale by zoom level, usually shift left (when zoom > ZOOM_LVL_NORMAL)

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 * When shifting right, value is rounded up

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 * @param value value to shift

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 * @param zoom  zoom level to shift to

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 * @return shifted value

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 */

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static inline int ScaleByZoom(int value, ZoomLevel zoom)

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{

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	if (zoom == ZOOM_LVL_NORMAL) return value;

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	int izoom = zoom - ZOOM_LVL_NORMAL;

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	return (zoom > ZOOM_LVL_NORMAL) ? value << izoom : (value + (1 << -izoom) - 1) >> -izoom;

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}

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/**

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 * Scale by zoom level, usually shift right (when zoom > ZOOM_LVL_NORMAL)

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 * When shifting right, value is rounded up

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 * @param value value to shift

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 * @param zoom  zoom level to shift to

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 * @return shifted value

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 */

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static inline int UnScaleByZoom(int value, ZoomLevel zoom)

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{

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	if (zoom == ZOOM_LVL_NORMAL) return value;

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	int izoom = zoom - ZOOM_LVL_NORMAL;

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	return (zoom > ZOOM_LVL_NORMAL) ? (value + (1 << izoom) - 1) >> izoom : value << -izoom;

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}

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/**

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 * Scale by zoom level, usually shift left (when zoom > ZOOM_LVL_NORMAL)

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 * @param value value to shift

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 * @param zoom  zoom level to shift to

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 * @return shifted value

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 */

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static inline int ScaleByZoomLower(int value, ZoomLevel zoom)

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{

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	if (zoom == ZOOM_LVL_NORMAL) return value;

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	int izoom = zoom - ZOOM_LVL_NORMAL;

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	return (zoom > ZOOM_LVL_NORMAL) ? value << izoom : value >> -izoom;

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}

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/**

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 * Scale by zoom level, usually shift right (when zoom > ZOOM_LVL_NORMAL)

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 * @param value value to shift

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 * @param zoom  zoom level to shift to

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 * @return shifted value

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 */

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static inline int UnScaleByZoomLower(int value, ZoomLevel zoom)

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{

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	if (zoom == ZOOM_LVL_NORMAL) return value;

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	int izoom = zoom - ZOOM_LVL_NORMAL;

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	return (zoom > ZOOM_LVL_NORMAL) ? value >> izoom : value << -izoom;

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}

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#endif /* ZOOM_FUNC_H */