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gecko-dev/gfx/public/nsCoord.h

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/* -*- 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
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef NSCOORD_H
#define NSCOORD_H
#include "nscore.h"
#include "nsMathUtils.h"
#include <math.h>
#include <float.h>
#include "nsDebug.h"
/*
* Basic type used for the geometry classes.
*
* Normally all coordinates are maintained in an app unit coordinate
* space. An app unit is 1/60th of a CSS device pixel, which is, in turn
* an integer number of device pixels, such at the CSS DPI is as close to
* 96dpi as possible.
*/
// 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
}
/**
* Returns a + b, capping the sum to nscoord_MAX.
*
* This function assumes that neither argument is nscoord_MIN.
*
* Note: If/when we start using floats for nscoords, this function won't be as
* necessary. Normal float addition correctly handles adding with infinity,
* assuming we aren't adding nscoord_MIN. (-infinity)
*/
inline nscoord
NSCoordSaturatingAdd(nscoord a, nscoord b)
{
VERIFY_COORD(a);
VERIFY_COORD(b);
NS_ASSERTION(a != nscoord_MIN && b != nscoord_MIN,
"NSCoordSaturatingAdd got nscoord_MIN as argument");
#ifdef NS_COORD_IS_FLOAT
// Float math correctly handles a+b, given that neither is -infinity.
return a + b;
#else
if (a == nscoord_MAX || b == nscoord_MAX) {
// infinity + anything = anything + infinity = infinity
return nscoord_MAX;
} else {
// a + b = a + b
NS_ASSERTION(a < nscoord_MAX && b < nscoord_MAX,
"Doing nscoord addition with values > nscoord_MAX");
NS_ASSERTION((PRInt64)a + (PRInt64)b > (PRInt64)nscoord_MIN,
"nscoord addition will reach or pass nscoord_MIN");
// This one's only a warning because the PR_MIN below means that
// we'll handle this case correctly.
NS_WARN_IF_FALSE((PRInt64)a + (PRInt64)b < (PRInt64)nscoord_MAX,
"nscoord addition capped to nscoord_MAX");
// Cap the result, just in case we're dealing with numbers near nscoord_MAX
return PR_MIN(nscoord_MAX, a + b);
}
#endif
}
/**
* Returns a - b, gracefully handling cases involving nscoord_MAX.
* This function assumes that neither argument is nscoord_MIN.
*
* The behavior is as follows:
*
* a) infinity - infinity -> infMinusInfResult
* b) N - infinity -> 0 (unexpected -- triggers NOTREACHED)
* c) infinity - N -> infinity
* d) N1 - N2 -> N1 - N2
*
* Note: For float nscoords, cases (c) and (d) are handled by normal float
* math. We still need to explicitly specify the behavior for cases (a)
* and (b), though. (Under normal float math, those cases would return NaN
* and -infinity, respectively.)
*/
inline nscoord
NSCoordSaturatingSubtract(nscoord a, nscoord b,
nscoord infMinusInfResult)
{
VERIFY_COORD(a);
VERIFY_COORD(b);
NS_ASSERTION(a != nscoord_MIN && b != nscoord_MIN,
"NSCoordSaturatingSubtract got nscoord_MIN as argument");
if (b == nscoord_MAX) {
if (a == nscoord_MAX) {
// case (a)
return infMinusInfResult;
} else {
// case (b)
NS_NOTREACHED("Attempted to subtract [n - nscoord_MAX]");
return 0;
}
} else {
#ifdef NS_COORD_IS_FLOAT
// case (c) and (d) for floats. (float math handles both)
return a - b;
#else
if (a == nscoord_MAX) {
// case (c) for integers
return nscoord_MAX;
} else {
// case (d) for integers
NS_ASSERTION(a < nscoord_MAX && b < nscoord_MAX,
"Doing nscoord subtraction with values > nscoord_MAX");
NS_ASSERTION((PRInt64)a - (PRInt64)b > (PRInt64)nscoord_MIN,
"nscoord subtraction will reach or pass nscoord_MIN");
// This one's only a warning because the PR_MIN below means that
// we'll handle this case correctly.
NS_WARN_IF_FALSE((PRInt64)a - (PRInt64)b < (PRInt64)nscoord_MAX,
"nscoord subtraction capped to nscoord_MAX");
// Cap the result, in case we're dealing with numbers near nscoord_MAX
return PR_MIN(nscoord_MAX, a - b);
}
}
#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;
}
/*
* Coord Rounding Functions
*/
inline nscoord NSToCoordFloor(float aValue)
{
return nscoord(NS_floorf(aValue));
}
inline nscoord NSToCoordCeil(float aValue)
{
return nscoord(NS_ceilf(aValue));
}
inline nscoord NSToCoordRound(float aValue)
{
return nscoord(NS_floorf(aValue + 0.5f));
}
/*
* Int Rounding Functions
*/
inline PRInt32 NSToIntFloor(float aValue)
{
return PRInt32(NS_floorf(aValue));
}
inline PRInt32 NSToIntCeil(float aValue)
{
return PRInt32(NS_ceilf(aValue));
}
inline PRInt32 NSToIntRound(float aValue)
{
return NS_lroundf(aValue);
}
/*
* App Unit/Pixel conversions
*/
inline nscoord NSFloatPixelsToAppUnits(float aPixels, PRInt32 aAppUnitsPerPixel)
{
float product = aPixels * aAppUnitsPerPixel;
nscoord result;
#ifdef NS_COORD_IS_FLOAT
// No need to bounds-check if converting float to float
result = NSToCoordRound(product);
#else
// Bounds-check before converting out of float, to avoid overflow
if (product >= nscoord_MAX) {
NS_WARNING("Overflowed nscoord_MAX in conversion to nscoord");
result = nscoord_MAX;
} else if (product <= nscoord_MIN) {
NS_WARNING("Overflowed nscoord_MIN in conversion to nscoord");
result = nscoord_MIN;
} else {
result = NSToCoordRound(product);
}
#endif
VERIFY_COORD(result);
return result;
}
inline nscoord NSIntPixelsToAppUnits(PRInt32 aPixels, PRInt32 aAppUnitsPerPixel)
{
// The cast to nscoord makes sure we don't overflow if we ever change
// nscoord to float
nscoord r = aPixels * (nscoord)aAppUnitsPerPixel;
VERIFY_COORD(r);
return r;
}
inline float NSAppUnitsToFloatPixels(nscoord aAppUnits, PRInt32 aAppUnitsPerPixel)
{
return (float(aAppUnits) / aAppUnitsPerPixel);
}
inline PRInt32 NSAppUnitsToIntPixels(nscoord aAppUnits, PRInt32 aAppUnitsPerPixel)
{
return NSToIntRound(float(aAppUnits) / aAppUnitsPerPixel);
}
/// handy constants
#define TWIPS_PER_POINT_INT 20
#define TWIPS_PER_POINT_FLOAT 20.0f
/*
* Twips/unit conversions
*/
inline nscoord NSUnitsToTwips(float aValue, float aPointsPerUnit)
{
return NSToCoordRound(aValue * aPointsPerUnit * TWIPS_PER_POINT_FLOAT);
}
inline float NSTwipsToUnits(nscoord aTwips, float aUnitsPerPoint)
{
return (aTwips * (aUnitsPerPoint / TWIPS_PER_POINT_FLOAT));
}
/// Unit conversion macros
//@{
#define NS_POINTS_TO_TWIPS(x) NSUnitsToTwips((x), 1.0f)
#define NS_INCHES_TO_TWIPS(x) NSUnitsToTwips((x), 72.0f) // 72 points per inch
#define NS_FEET_TO_TWIPS(x) NSUnitsToTwips((x), (72.0f * 12.0f)) // 12 inches per foot
#define NS_MILES_TO_TWIPS(x) NSUnitsToTwips((x), (72.0f * 12.0f * 5280.0f)) // 5280 feet per mile
#define NS_MILLIMETERS_TO_TWIPS(x) NSUnitsToTwips((x), (72.0f * 0.03937f))
#define NS_CENTIMETERS_TO_TWIPS(x) NSUnitsToTwips((x), (72.0f * 0.3937f))
#define NS_METERS_TO_TWIPS(x) NSUnitsToTwips((x), (72.0f * 39.37f))
#define NS_KILOMETERS_TO_TWIPS(x) NSUnitsToTwips((x), (72.0f * 39370.0f))
#define NS_PICAS_TO_TWIPS(x) NSUnitsToTwips((x), 12.0f) // 12 points per pica
#define NS_DIDOTS_TO_TWIPS(x) NSUnitsToTwips((x), (16.0f / 15.0f)) // 15 didots per 16 points
#define NS_CICEROS_TO_TWIPS(x) NSUnitsToTwips((x), (12.0f * (16.0f / 15.0f))) // 12 didots per cicero
#define NS_TWIPS_TO_POINTS(x) NSTwipsToUnits((x), 1.0f)
#define NS_TWIPS_TO_INCHES(x) NSTwipsToUnits((x), 1.0f / 72.0f)
#define NS_TWIPS_TO_FEET(x) NSTwipsToUnits((x), 1.0f / (72.0f * 12.0f))
#define NS_TWIPS_TO_MILES(x) NSTwipsToUnits((x), 1.0f / (72.0f * 12.0f * 5280.0f))
#define NS_TWIPS_TO_MILLIMETERS(x) NSTwipsToUnits((x), 1.0f / (72.0f * 0.03937f))
#define NS_TWIPS_TO_CENTIMETERS(x) NSTwipsToUnits((x), 1.0f / (72.0f * 0.3937f))
#define NS_TWIPS_TO_METERS(x) NSTwipsToUnits((x), 1.0f / (72.0f * 39.37f))
#define NS_TWIPS_TO_KILOMETERS(x) NSTwipsToUnits((x), 1.0f / (72.0f * 39370.0f))
#define NS_TWIPS_TO_PICAS(x) NSTwipsToUnits((x), 1.0f / 12.0f)
#define NS_TWIPS_TO_DIDOTS(x) NSTwipsToUnits((x), 1.0f / (16.0f / 15.0f))
#define NS_TWIPS_TO_CICEROS(x) NSTwipsToUnits((x), 1.0f / (12.0f * (16.0f / 15.0f)))
//@}
#endif /* NSCOORD_H */
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