gecko-dev/gfx/public/nsCoord.h
2006-11-13 14:42:33 +00:00

158 lines
4.9 KiB
C

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
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* ***** END LICENSE BLOCK ***** */
#ifndef NSCOORD_H
#define NSCOORD_H
#include <math.h>
#include "nsDebug.h"
/*
* Basic type used for the geometry classes.
*
* Normally all coordinates are maintained in the twips coordinate
* space. A twip is 1/20th of a point, and there are 72 points per
* inch. However, nscoords do appear in pixel space and other
* coordinate spaces.
*
* Twips are used because they are a device-independent unit of measure. See
* header file nsUnitConversion.h for many useful macros to convert between
* different units of measure.
*/
// This controls whether we're using integers or floats for coordinates. We
// want to eventually use floats. If you change this, you need to manually
// change the definition of nscoord in gfx/idl/gfxtypes.idl.
//#define NS_COORD_IS_FLOAT
inline float NS_IEEEPositiveInfinity() {
union { PRUint32 mPRUint32; float mFloat; } pun;
pun.mPRUint32 = 0x7F800000;
return pun.mFloat;
}
inline PRBool NS_IEEEIsNan(float aF) {
union { PRUint32 mBits; float mFloat; } pun;
pun.mFloat = aF;
return (pun.mBits & 0x7F800000) == 0x7F800000 &&
(pun.mBits & 0x007FFFFF) != 0;
}
#ifdef NS_COORD_IS_FLOAT
typedef float nscoord;
#define nscoord_MAX NS_IEEEPositiveInfinity()
#else
typedef PRInt32 nscoord;
#define nscoord_MAX nscoord(1 << 30)
#endif
#define nscoord_MIN (-nscoord_MAX)
inline void VERIFY_COORD(nscoord aCoord) {
#ifdef NS_COORD_IS_FLOAT
NS_ASSERTION(floorf(aCoord) == aCoord,
"Coords cannot have fractions");
#endif
}
inline nscoord NSCoordMultiply(nscoord aCoord, float aVal) {
VERIFY_COORD(aCoord);
#ifdef NS_COORD_IS_FLOAT
return floorf(aCoord*aVal);
#else
return (PRInt32)(aCoord*aVal);
#endif
}
inline nscoord NSCoordMultiply(nscoord aCoord, PRInt32 aVal) {
VERIFY_COORD(aCoord);
return aCoord*aVal;
}
inline nscoord NSCoordDivide(nscoord aCoord, float aVal) {
VERIFY_COORD(aCoord);
#ifdef NS_COORD_IS_FLOAT
return floorf(aCoord/aVal);
#else
return (PRInt32)(aCoord/aVal);
#endif
}
inline nscoord NSCoordDivide(nscoord aCoord, PRInt32 aVal) {
VERIFY_COORD(aCoord);
#ifdef NS_COORD_IS_FLOAT
return floorf(aCoord/aVal);
#else
return aCoord/aVal;
#endif
}
/**
* Convert an nscoord to a PRInt32. This *does not* do rounding because
* coords are never fractional. They can be out of range, so this does
* clamp out of bounds coord values to PR_INT32_MIN and PR_INT32_MAX.
*/
inline PRInt32 NSCoordToInt(nscoord aCoord) {
VERIFY_COORD(aCoord);
#ifdef NS_COORD_IS_FLOAT
NS_ASSERTION(!NS_IEEEIsNan(aCoord), "NaN encountered in int conversion");
if (aCoord < -2147483648.0f) {
// -2147483648 is the smallest 32-bit signed integer that can be
// exactly represented as a float
return PR_INT32_MIN;
} else if (aCoord > 2147483520.0f) {
// 2147483520 is the largest 32-bit signed integer that can be
// exactly represented as an IEEE float
return PR_INT32_MAX;
} else {
return (PRInt32)aCoord;
}
#else
return aCoord;
#endif
}
inline float NSCoordToFloat(nscoord aCoord) {
VERIFY_COORD(aCoord);
#ifdef NS_COORD_IS_FLOAT
NS_ASSERTION(!NS_IEEEIsNan(aCoord), "NaN encountered in float conversion");
#endif
return (float)aCoord;
}
#endif /* NSCOORD_H */