зеркало из https://github.com/mozilla/gecko-dev.git
295 строки
12 KiB
C++
295 строки
12 KiB
C++
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is Thebes gfx.
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*
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* The Initial Developer of the Original Code is Mozilla Foundation.
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* Portions created by the Initial Developer are Copyright (C) 2007
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Vladimir Vukicevic <vladimir@pobox.com>
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* Bas Schouten <bschouten@mozilla.com>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#include "gfxAlphaRecovery.h"
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#include "gfxImageSurface.h"
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#define MOZILLA_SSE_INCLUDE_HEADER_FOR_SSE2
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#include "mozilla/SSE.h"
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/** from cairo-xlib-utils.c, modified */
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/**
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* Given the RGB data for two image surfaces, one a source image composited
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* with OVER onto a black background, and one a source image composited with
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* OVER onto a white background, reconstruct the original image data into
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* black_data.
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*
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* Consider a single color channel and a given pixel. Suppose the original
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* premultiplied color value was C and the alpha value was A. Let the final
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* on-black color be B and the final on-white color be W. All values range
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* over 0-255.
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* Then B=C and W=(255*(255 - A) + C*255)/255. Solving for A, we get
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* A=255 - (W - C). Therefore it suffices to leave the black_data color
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* data alone and set the alpha values using that simple formula. It shouldn't
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* matter what color channel we pick for the alpha computation, but we'll
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* pick green because if we went through a color channel downsample the green
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* bits are likely to be the most accurate.
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*/
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static inline PRUint32
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RecoverPixel(PRUint32 black, PRUint32 white)
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{
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const PRUint32 GREEN_MASK = 0x0000FF00;
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const PRUint32 ALPHA_MASK = 0xFF000000;
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/* |diff| here is larger when the source image pixel is more transparent.
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If both renderings are from the same source image composited with OVER,
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then the color values on white will always be greater than those on
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black, so |diff| would not overflow. However, overflow may happen, for
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example, when a plugin plays a video and the image is rapidly changing.
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If there is overflow, then behave as if we limit to the difference to
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>= 0, which will make the rendering opaque. (Without this overflow
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will make the rendering transparent.) */
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PRUint32 diff = (white & GREEN_MASK) - (black & GREEN_MASK);
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/* |diff| is 0xFFFFxx00 on overflow and 0x0000xx00 otherwise, so use this
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to limit the transparency. */
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PRUint32 limit = diff & ALPHA_MASK;
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/* The alpha bits of the result */
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PRUint32 alpha = (ALPHA_MASK - (diff << 16)) | limit;
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return alpha | (black & ~ALPHA_MASK);
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}
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/* static */ PRBool
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gfxAlphaRecovery::RecoverAlpha(gfxImageSurface* blackSurf,
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const gfxImageSurface* whiteSurf,
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Analysis* analysis)
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{
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gfxIntSize size = blackSurf->GetSize();
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if (size != whiteSurf->GetSize() ||
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(blackSurf->Format() != gfxASurface::ImageFormatARGB32 &&
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blackSurf->Format() != gfxASurface::ImageFormatRGB24) ||
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(whiteSurf->Format() != gfxASurface::ImageFormatARGB32 &&
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whiteSurf->Format() != gfxASurface::ImageFormatRGB24))
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return PR_FALSE;
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if (!analysis && RecoverAlphaSSE2(blackSurf, whiteSurf)) {
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return PR_TRUE;
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}
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blackSurf->Flush();
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whiteSurf->Flush();
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unsigned char* blackData = blackSurf->Data();
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unsigned char* whiteData = whiteSurf->Data();
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/* Get the alpha value of 'first' */
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PRUint32 first;
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if (size.width == 0 || size.height == 0) {
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first = 0;
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} else {
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if (!blackData || !whiteData)
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return PR_FALSE;
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first = RecoverPixel(*reinterpret_cast<PRUint32*>(blackData),
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*reinterpret_cast<PRUint32*>(whiteData));
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}
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PRUint32 deltas = 0;
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for (PRInt32 i = 0; i < size.height; ++i) {
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PRUint32* blackPixel = reinterpret_cast<PRUint32*>(blackData);
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const PRUint32* whitePixel = reinterpret_cast<PRUint32*>(whiteData);
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for (PRInt32 j = 0; j < size.width; ++j) {
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PRUint32 recovered = RecoverPixel(blackPixel[j], whitePixel[j]);
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blackPixel[j] = recovered;
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deltas |= (first ^ recovered);
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}
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blackData += blackSurf->Stride();
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whiteData += whiteSurf->Stride();
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}
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blackSurf->MarkDirty();
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if (analysis) {
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analysis->uniformAlpha = (deltas >> 24) == 0;
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analysis->uniformColor = PR_FALSE;
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if (analysis->uniformAlpha) {
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double d_first_alpha = first >> 24;
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analysis->alpha = d_first_alpha/255.0;
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/* we only set uniformColor when the alpha is already uniform.
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it's only useful in that case ... and if the alpha was nonuniform
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then computing whether the color is uniform would require unpremultiplying
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every pixel */
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analysis->uniformColor = deltas == 0;
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if (analysis->uniformColor) {
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if (d_first_alpha == 0.0) {
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/* can't unpremultiply, this is OK */
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analysis->r = analysis->g = analysis->b = 0.0;
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} else {
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analysis->r = (first & 0xFF)/d_first_alpha;
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analysis->g = ((first >> 8) & 0xFF)/d_first_alpha;
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analysis->b = ((first >> 16) & 0xFF)/d_first_alpha;
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}
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}
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}
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}
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return PR_TRUE;
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}
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// Align these for all platforms supporting MOZILLA_COMPILE_WITH_SSE2
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#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64))
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__declspec(align(16)) PRUint32 greenMaski[] =
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{ 0x0000ff00, 0x0000ff00, 0x0000ff00, 0x0000ff00 };
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__declspec(align(16)) PRUint32 alphaMaski[] =
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{ 0xff000000, 0xff000000, 0xff000000, 0xff000000 };
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#elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
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PRUint32 greenMaski[] __attribute__ ((aligned (16))) =
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{ 0x0000ff00, 0x0000ff00, 0x0000ff00, 0x0000ff00 };
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PRUint32 alphaMaski[] __attribute__ ((aligned (16))) =
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{ 0xff000000, 0xff000000, 0xff000000, 0xff000000 };
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#elif defined(__SUNPRO_CC) && (defined(__i386) || defined(__x86_64__))
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#pragma align 16 (greenMaski, alphaMaski)
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PRUint32 greenMaski[] = { 0x0000ff00, 0x0000ff00, 0x0000ff00, 0x0000ff00 };
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PRUint32 alphaMaski[] = { 0xff000000, 0xff000000, 0xff000000, 0xff000000 };
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#endif
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PRBool
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gfxAlphaRecovery::RecoverAlphaSSE2(gfxImageSurface* blackSurf,
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const gfxImageSurface* whiteSurf)
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{
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#if defined(MOZILLA_COMPILE_WITH_SSE2)
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if (!mozilla::supports_sse2()) {
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return PR_FALSE;
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}
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gfxIntSize size = blackSurf->GetSize();
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if (size != whiteSurf->GetSize() ||
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(blackSurf->Format() != gfxASurface::ImageFormatARGB32 &&
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blackSurf->Format() != gfxASurface::ImageFormatRGB24) ||
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(whiteSurf->Format() != gfxASurface::ImageFormatARGB32 &&
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whiteSurf->Format() != gfxASurface::ImageFormatRGB24))
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return PR_FALSE;
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blackSurf->Flush();
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whiteSurf->Flush();
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unsigned char* blackData = blackSurf->Data();
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unsigned char* whiteData = whiteSurf->Data();
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if ((NS_PTR_TO_UINT32(blackData) & 0xf) != (NS_PTR_TO_UINT32(whiteData) & 0xf) ||
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(blackSurf->Stride() - whiteSurf->Stride()) & 0xf) {
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// Cannot keep these in alignment.
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return PR_FALSE;
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}
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__m128i greenMask = _mm_load_si128((__m128i*)greenMaski);
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__m128i alphaMask = _mm_load_si128((__m128i*)alphaMaski);
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for (PRInt32 i = 0; i < size.height; ++i) {
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PRInt32 j = 0;
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// Loop single pixels until at 4 byte alignment.
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while (NS_PTR_TO_UINT32(blackData) & 0xf && j < size.width) {
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*((PRUint32*)blackData) =
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RecoverPixel(*reinterpret_cast<PRUint32*>(blackData),
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*reinterpret_cast<PRUint32*>(whiteData));
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blackData += 4;
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whiteData += 4;
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j++;
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}
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// This extra loop allows the compiler to do some more clever registry
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// management and makes it about 5% faster than with only the 4 pixel
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// at a time loop.
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for (; j < size.width - 8; j += 8) {
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__m128i black1 = _mm_load_si128((__m128i*)blackData);
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__m128i white1 = _mm_load_si128((__m128i*)whiteData);
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__m128i black2 = _mm_load_si128((__m128i*)(blackData + 16));
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__m128i white2 = _mm_load_si128((__m128i*)(whiteData + 16));
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// Execute the same instructions as described in RecoverPixel, only
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// using an SSE2 packed saturated subtract.
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white1 = _mm_subs_epu8(white1, black1);
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white2 = _mm_subs_epu8(white2, black2);
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white1 = _mm_subs_epu8(greenMask, white1);
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white2 = _mm_subs_epu8(greenMask, white2);
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// Producing the final black pixel in an XMM register and storing
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// that is actually faster than doing a masked store since that
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// does an unaligned storage. We have the black pixel in a register
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// anyway.
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black1 = _mm_andnot_si128(alphaMask, black1);
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black2 = _mm_andnot_si128(alphaMask, black2);
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white1 = _mm_slli_si128(white1, 2);
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white2 = _mm_slli_si128(white2, 2);
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white1 = _mm_and_si128(alphaMask, white1);
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white2 = _mm_and_si128(alphaMask, white2);
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black1 = _mm_or_si128(white1, black1);
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black2 = _mm_or_si128(white2, black2);
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_mm_store_si128((__m128i*)blackData, black1);
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_mm_store_si128((__m128i*)(blackData + 16), black2);
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blackData += 32;
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whiteData += 32;
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}
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for (; j < size.width - 4; j += 4) {
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__m128i black = _mm_load_si128((__m128i*)blackData);
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__m128i white = _mm_load_si128((__m128i*)whiteData);
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white = _mm_subs_epu8(white, black);
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white = _mm_subs_epu8(greenMask, white);
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black = _mm_andnot_si128(alphaMask, black);
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white = _mm_slli_si128(white, 2);
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white = _mm_and_si128(alphaMask, white);
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black = _mm_or_si128(white, black);
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_mm_store_si128((__m128i*)blackData, black);
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blackData += 16;
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whiteData += 16;
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}
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// Loop single pixels until we're done.
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while (j < size.width) {
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*((PRUint32*)blackData) =
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RecoverPixel(*reinterpret_cast<PRUint32*>(blackData),
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*reinterpret_cast<PRUint32*>(whiteData));
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blackData += 4;
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whiteData += 4;
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j++;
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}
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blackData += blackSurf->Stride() - j * 4;
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whiteData += whiteSurf->Stride() - j * 4;
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}
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blackSurf->MarkDirty();
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return PR_TRUE;
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#else
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return PR_FALSE;
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#endif
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}
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