--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/zoom_func.h	Tue Jan 22 21:00:30 2008 +0000
@@ -0,0 +1,66 @@
+/* $Id$ */
+
+/** @file zoom_func.hpp */
+
+#ifndef ZOOM_FUNC_H
+#define ZOOM_FUNC_H
+
+#include "zoom_type.h"
+
+extern ZoomLevel _saved_scrollpos_zoom;
+
+/**
+ * Scale by zoom level, usually shift left (when zoom > ZOOM_LVL_NORMAL)
+ * When shifting right, value is rounded up
+ * @param value value to shift
+ * @param zoom  zoom level to shift to
+ * @return shifted value
+ */
+static inline int ScaleByZoom(int value, ZoomLevel zoom)
+{
+	if (zoom == ZOOM_LVL_NORMAL) return value;
+	int izoom = zoom - ZOOM_LVL_NORMAL;
+	return (zoom > ZOOM_LVL_NORMAL) ? value << izoom : (value + (1 << -izoom) - 1) >> -izoom;
+}
+
+/**
+ * Scale by zoom level, usually shift right (when zoom > ZOOM_LVL_NORMAL)
+ * When shifting right, value is rounded up
+ * @param value value to shift
+ * @param zoom  zoom level to shift to
+ * @return shifted value
+ */
+static inline int UnScaleByZoom(int value, ZoomLevel zoom)
+{
+	if (zoom == ZOOM_LVL_NORMAL) return value;
+	int izoom = zoom - ZOOM_LVL_NORMAL;
+	return (zoom > ZOOM_LVL_NORMAL) ? (value + (1 << izoom) - 1) >> izoom : value << -izoom;
+}
+
+/**
+ * Scale by zoom level, usually shift left (when zoom > ZOOM_LVL_NORMAL)
+ * @param value value to shift
+ * @param zoom  zoom level to shift to
+ * @return shifted value
+ */
+static inline int ScaleByZoomLower(int value, ZoomLevel zoom)
+{
+	if (zoom == ZOOM_LVL_NORMAL) return value;
+	int izoom = zoom - ZOOM_LVL_NORMAL;
+	return (zoom > ZOOM_LVL_NORMAL) ? value << izoom : value >> -izoom;
+}
+
+/**
+ * Scale by zoom level, usually shift right (when zoom > ZOOM_LVL_NORMAL)
+ * @param value value to shift
+ * @param zoom  zoom level to shift to
+ * @return shifted value
+ */
+static inline int UnScaleByZoomLower(int value, ZoomLevel zoom)
+{
+	if (zoom == ZOOM_LVL_NORMAL) return value;
+	int izoom = zoom - ZOOM_LVL_NORMAL;
+	return (zoom > ZOOM_LVL_NORMAL) ? value >> izoom : value << -izoom;
+}
+
+#endif /* ZOOM_FUNC_H */