gecko/gfx/thebes/gfxUtils.cpp

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/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* ***** 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 Corporation code.
*
* The Initial Developer of the Original Code is Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2010
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Vladimir Vukicevic <vladimir@pobox.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either 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 ***** */
#include "gfxImageSurface.h"
#include "gfxUtils.h"
static PRUint8 sUnpremultiplyTable[256*256];
static PRUint8 sPremultiplyTable[256*256];
static PRBool sTablesInitialized = PR_FALSE;
static const PRUint8 PremultiplyValue(PRUint8 a, PRUint8 v) {
return sPremultiplyTable[a*256+v];
}
static const PRUint8 UnpremultiplyValue(PRUint8 a, PRUint8 v) {
return sUnpremultiplyTable[a*256+v];
}
static void
CalculateTables()
{
// It's important that the array be indexed first by alpha and then by rgb
// value. When we unpremultiply a pixel, we're guaranteed to do three
// lookups with the same alpha; indexing by alpha first makes it likely that
// those three lookups will be close to one another in memory, thus
// increasing the chance of a cache hit.
// Unpremultiply table
// a == 0 case
for (PRUint32 c = 0; c <= 255; c++) {
sUnpremultiplyTable[c] = c;
}
for (int a = 1; a <= 255; a++) {
for (int c = 0; c <= 255; c++) {
sUnpremultiplyTable[a*256+c] = (PRUint8)((c * 255) / a);
}
}
// Premultiply table
for (int a = 0; a <= 255; a++) {
for (int c = 0; c <= 255; c++) {
sPremultiplyTable[a*256+c] = (a * c + 254) / 255;
}
}
sTablesInitialized = PR_TRUE;
}
void
gfxUtils::PremultiplyImageSurface(gfxImageSurface *aSourceSurface,
gfxImageSurface *aDestSurface)
{
if (!aDestSurface)
aDestSurface = aSourceSurface;
NS_ASSERTION(aSourceSurface->Format() == aDestSurface->Format() &&
aSourceSurface->Width() == aDestSurface->Width() &&
aSourceSurface->Height() == aDestSurface->Height() &&
aSourceSurface->Stride() == aDestSurface->Stride(),
"Source and destination surfaces don't have identical characteristics");
NS_ASSERTION(aSourceSurface->Stride() == aSourceSurface->Width() * 4,
"Source surface stride isn't tightly packed");
// Only premultiply ARGB32
if (aSourceSurface->Format() != gfxASurface::ImageFormatARGB32) {
if (aDestSurface != aSourceSurface) {
memcpy(aDestSurface->Data(), aSourceSurface->Data(),
aSourceSurface->Stride() * aSourceSurface->Height());
}
return;
}
if (!sTablesInitialized)
CalculateTables();
PRUint8 *src = aSourceSurface->Data();
PRUint8 *dst = aDestSurface->Data();
PRUint32 dim = aSourceSurface->Width() * aSourceSurface->Height();
for (PRUint32 i = 0; i < dim; ++i) {
#ifdef IS_LITTLE_ENDIAN
PRUint8 b = *src++;
PRUint8 g = *src++;
PRUint8 r = *src++;
PRUint8 a = *src++;
*dst++ = PremultiplyValue(a, b);
*dst++ = PremultiplyValue(a, g);
*dst++ = PremultiplyValue(a, r);
*dst++ = a;
#else
PRUint8 a = *src++;
PRUint8 r = *src++;
PRUint8 g = *src++;
PRUint8 b = *src++;
*dst++ = a;
*dst++ = PremultiplyValue(a, r);
*dst++ = PremultiplyValue(a, g);
*dst++ = PremultiplyValue(a, b);
#endif
}
}
void
gfxUtils::UnpremultiplyImageSurface(gfxImageSurface *aSourceSurface,
gfxImageSurface *aDestSurface)
{
if (!aDestSurface)
aDestSurface = aSourceSurface;
NS_ASSERTION(aSourceSurface->Format() == aDestSurface->Format() &&
aSourceSurface->Width() == aDestSurface->Width() &&
aSourceSurface->Height() == aDestSurface->Height() &&
aSourceSurface->Stride() == aDestSurface->Stride(),
"Source and destination surfaces don't have identical characteristics");
NS_ASSERTION(aSourceSurface->Stride() == aSourceSurface->Width() * 4,
"Source surface stride isn't tightly packed");
// Only premultiply ARGB32
if (aSourceSurface->Format() != gfxASurface::ImageFormatARGB32) {
if (aDestSurface != aSourceSurface) {
memcpy(aDestSurface->Data(), aSourceSurface->Data(),
aSourceSurface->Stride() * aSourceSurface->Height());
}
return;
}
if (!sTablesInitialized)
CalculateTables();
PRUint8 *src = aSourceSurface->Data();
PRUint8 *dst = aDestSurface->Data();
PRUint32 dim = aSourceSurface->Width() * aSourceSurface->Height();
for (PRUint32 i = 0; i < dim; ++i) {
#ifdef IS_LITTLE_ENDIAN
PRUint8 b = *src++;
PRUint8 g = *src++;
PRUint8 r = *src++;
PRUint8 a = *src++;
*dst++ = UnpremultiplyValue(a, b);
*dst++ = UnpremultiplyValue(a, g);
*dst++ = UnpremultiplyValue(a, r);
*dst++ = a;
#else
PRUint8 a = *src++;
PRUint8 r = *src++;
PRUint8 g = *src++;
PRUint8 b = *src++;
*dst++ = a;
*dst++ = UnpremultiplyValue(a, r);
*dst++ = UnpremultiplyValue(a, g);
*dst++ = UnpremultiplyValue(a, b);
#endif
}
}