зеркало из https://github.com/mozilla/pjs.git
490 строки
17 KiB
C++
490 строки
17 KiB
C++
/* -*- Mode: C++; tab-width: 4; 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 gfx thebes code.
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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) 2008
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Eric Butler <zantifon@gmail.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 "gfxBlur.h"
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#include "nsMathUtils.h"
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#include "nsTArray.h"
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#ifndef M_PI
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#define M_PI 3.14159265358979323846
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#endif
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gfxAlphaBoxBlur::gfxAlphaBoxBlur()
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{
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}
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gfxAlphaBoxBlur::~gfxAlphaBoxBlur()
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{
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}
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gfxContext*
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gfxAlphaBoxBlur::Init(const gfxRect& aRect,
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const gfxIntSize& aSpreadRadius,
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const gfxIntSize& aBlurRadius,
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const gfxRect* aDirtyRect,
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const gfxRect* aSkipRect)
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{
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mSpreadRadius = aSpreadRadius;
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mBlurRadius = aBlurRadius;
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gfxRect rect(aRect);
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rect.Outset(aBlurRadius + aSpreadRadius);
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rect.RoundOut();
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if (rect.IsEmpty())
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return nsnull;
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if (aDirtyRect) {
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// If we get passed a dirty rect from layout, we can minimize the
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// shadow size and make painting faster.
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mHasDirtyRect = PR_TRUE;
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mDirtyRect = *aDirtyRect;
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gfxRect requiredBlurArea = mDirtyRect.Intersect(rect);
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requiredBlurArea.Outset(aBlurRadius + aSpreadRadius);
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rect = requiredBlurArea.Intersect(rect);
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} else {
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mHasDirtyRect = PR_FALSE;
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}
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if (aSkipRect) {
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// If we get passed a skip rect, we can lower the amount of
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// blurring/spreading we need to do. We convert it to nsIntRect to avoid
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// expensive int<->float conversions if we were to use gfxRect instead.
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gfxRect skipRect = *aSkipRect;
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skipRect.RoundIn();
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skipRect.Inset(aBlurRadius + aSpreadRadius);
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gfxUtils::GfxRectToIntRect(skipRect, &mSkipRect);
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nsIntRect shadowIntRect;
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gfxUtils::GfxRectToIntRect(rect, &shadowIntRect);
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mSkipRect.IntersectRect(mSkipRect, shadowIntRect);
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if (mSkipRect == shadowIntRect)
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return nsnull;
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mSkipRect -= shadowIntRect.TopLeft();
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} else {
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mSkipRect = nsIntRect(0, 0, 0, 0);
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}
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// Make an alpha-only surface to draw on. We will play with the data after
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// everything is drawn to create a blur effect.
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mImageSurface = new gfxImageSurface(gfxIntSize(static_cast<PRInt32>(rect.Width()), static_cast<PRInt32>(rect.Height())),
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gfxASurface::ImageFormatA8);
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if (!mImageSurface || mImageSurface->CairoStatus())
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return nsnull;
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// Use a device offset so callers don't need to worry about translating
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// coordinates, they can draw as if this was part of the destination context
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// at the coordinates of rect.
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mImageSurface->SetDeviceOffset(-rect.TopLeft());
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mContext = new gfxContext(mImageSurface);
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return mContext;
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}
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void
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gfxAlphaBoxBlur::PremultiplyAlpha(gfxFloat alpha)
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{
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if (!mImageSurface)
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return;
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unsigned char* data = mImageSurface->Data();
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PRInt32 length = mImageSurface->GetDataSize();
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for (PRInt32 i=0; i<length; ++i)
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data[i] = static_cast<unsigned char>(data[i] * alpha);
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}
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/**
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* Box blur involves looking at one pixel, and setting its value to the average
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* of its neighbouring pixels.
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* @param aInput The input buffer.
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* @param aOutput The output buffer.
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* @param aLeftLobe The number of pixels to blend on the left.
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* @param aRightLobe The number of pixels to blend on the right.
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* @param aWidth The number of columns in the buffers.
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* @param aRows The number of rows in the buffers.
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* @param aSkipRect An area to skip blurring in.
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* XXX shouldn't we pass stride in separately here?
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*/
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static void
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BoxBlurHorizontal(unsigned char* aInput,
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unsigned char* aOutput,
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PRInt32 aLeftLobe,
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PRInt32 aRightLobe,
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PRInt32 aWidth,
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PRInt32 aRows,
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const nsIntRect& aSkipRect)
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{
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PRInt32 boxSize = aLeftLobe + aRightLobe + 1;
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PRBool skipRectCoversWholeRow = 0 >= aSkipRect.x &&
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aWidth <= aSkipRect.XMost();
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for (PRInt32 y = 0; y < aRows; y++) {
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// Check whether the skip rect intersects this row. If the skip
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// rect covers the whole surface in this row, we can avoid
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// this row entirely (and any others along the skip rect).
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PRBool inSkipRectY = y >= aSkipRect.y &&
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y < aSkipRect.YMost();
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if (inSkipRectY && skipRectCoversWholeRow) {
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y = aSkipRect.YMost() - 1;
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continue;
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}
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PRInt32 alphaSum = 0;
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for (PRInt32 i = 0; i < boxSize; i++) {
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PRInt32 pos = i - aLeftLobe;
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pos = NS_MAX(pos, 0);
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pos = NS_MIN(pos, aWidth - 1);
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alphaSum += aInput[aWidth * y + pos];
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}
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for (PRInt32 x = 0; x < aWidth; x++) {
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// Check whether we are within the skip rect. If so, go
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// to the next point outside the skip rect.
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if (inSkipRectY && x >= aSkipRect.x &&
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x < aSkipRect.XMost()) {
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x = aSkipRect.XMost();
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if (x >= aWidth)
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break;
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// Recalculate the neighbouring alpha values for
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// our new point on the surface.
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alphaSum = 0;
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for (PRInt32 i = 0; i < boxSize; i++) {
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PRInt32 pos = x + i - aLeftLobe;
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pos = NS_MAX(pos, 0);
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pos = NS_MIN(pos, aWidth - 1);
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alphaSum += aInput[aWidth * y + pos];
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}
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}
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PRInt32 tmp = x - aLeftLobe;
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PRInt32 last = NS_MAX(tmp, 0);
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PRInt32 next = NS_MIN(tmp + boxSize, aWidth - 1);
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aOutput[aWidth * y + x] = alphaSum/boxSize;
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alphaSum += aInput[aWidth * y + next] -
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aInput[aWidth * y + last];
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}
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}
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}
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/**
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* Identical to BoxBlurHorizontal, except it blurs top and bottom instead of
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* left and right.
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* XXX shouldn't we pass stride in separately here?
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*/
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static void
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BoxBlurVertical(unsigned char* aInput,
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unsigned char* aOutput,
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PRInt32 aTopLobe,
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PRInt32 aBottomLobe,
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PRInt32 aWidth,
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PRInt32 aRows,
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const nsIntRect& aSkipRect)
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{
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PRInt32 boxSize = aTopLobe + aBottomLobe + 1;
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PRBool skipRectCoversWholeColumn = 0 >= aSkipRect.y &&
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aRows <= aSkipRect.YMost();
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for (PRInt32 x = 0; x < aWidth; x++) {
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PRBool inSkipRectX = x >= aSkipRect.x &&
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x < aSkipRect.XMost();
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if (inSkipRectX && skipRectCoversWholeColumn) {
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x = aSkipRect.XMost() - 1;
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continue;
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}
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PRInt32 alphaSum = 0;
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for (PRInt32 i = 0; i < boxSize; i++) {
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PRInt32 pos = i - aTopLobe;
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pos = NS_MAX(pos, 0);
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pos = NS_MIN(pos, aRows - 1);
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alphaSum += aInput[aWidth * pos + x];
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}
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for (PRInt32 y = 0; y < aRows; y++) {
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if (inSkipRectX && y >= aSkipRect.y &&
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y < aSkipRect.YMost()) {
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y = aSkipRect.YMost();
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if (y >= aRows)
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break;
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alphaSum = 0;
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for (PRInt32 i = 0; i < boxSize; i++) {
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PRInt32 pos = y + i - aTopLobe;
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pos = NS_MAX(pos, 0);
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pos = NS_MIN(pos, aRows - 1);
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alphaSum += aInput[aWidth * pos + x];
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}
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}
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PRInt32 tmp = y - aTopLobe;
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PRInt32 last = NS_MAX(tmp, 0);
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PRInt32 next = NS_MIN(tmp + boxSize, aRows - 1);
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aOutput[aWidth * y + x] = alphaSum/boxSize;
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alphaSum += aInput[aWidth * next + x] -
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aInput[aWidth * last + x];
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}
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}
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}
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static void ComputeLobes(PRInt32 aRadius, PRInt32 aLobes[3][2])
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{
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PRInt32 major, minor, final;
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/* See http://www.w3.org/TR/SVG/filters.html#feGaussianBlur for
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* some notes about approximating the Gaussian blur with box-blurs.
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* The comments below are in the terminology of that page.
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*/
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PRInt32 z = aRadius/3;
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switch (aRadius % 3) {
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case 0:
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// aRadius = z*3; choose d = 2*z + 1
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major = minor = final = z;
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break;
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case 1:
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// aRadius = z*3 + 1
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// This is a tricky case since there is no value of d which will
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// yield a radius of exactly aRadius. If d is odd, i.e. d=2*k + 1
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// for some integer k, then the radius will be 3*k. If d is even,
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// i.e. d=2*k, then the radius will be 3*k - 1.
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// So we have to choose values that don't match the standard
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// algorithm.
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major = z + 1;
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minor = final = z;
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break;
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case 2:
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// aRadius = z*3 + 2; choose d = 2*z + 2
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major = final = z + 1;
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minor = z;
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break;
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default:
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NS_ERROR("Mathematical impossibility.");
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major = minor = final = 0;
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}
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NS_ASSERTION(major + minor + final == aRadius,
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"Lobes don't sum to the right length");
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aLobes[0][0] = major;
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aLobes[0][1] = minor;
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aLobes[1][0] = minor;
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aLobes[1][1] = major;
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aLobes[2][0] = final;
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aLobes[2][1] = final;
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}
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static void
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SpreadHorizontal(unsigned char* aInput,
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unsigned char* aOutput,
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PRInt32 aRadius,
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PRInt32 aWidth,
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PRInt32 aRows,
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PRInt32 aStride,
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const nsIntRect& aSkipRect)
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{
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if (aRadius == 0) {
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memcpy(aOutput, aInput, aStride*aRows);
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return;
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}
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PRBool skipRectCoversWholeRow = 0 >= aSkipRect.x &&
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aWidth <= aSkipRect.XMost();
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for (PRInt32 y = 0; y < aRows; y++) {
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// Check whether the skip rect intersects this row. If the skip
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// rect covers the whole surface in this row, we can avoid
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// this row entirely (and any others along the skip rect).
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PRBool inSkipRectY = y >= aSkipRect.y &&
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y < aSkipRect.YMost();
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if (inSkipRectY && skipRectCoversWholeRow) {
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y = aSkipRect.YMost() - 1;
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continue;
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}
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for (PRInt32 x = 0; x < aWidth; x++) {
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// Check whether we are within the skip rect. If so, go
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// to the next point outside the skip rect.
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if (inSkipRectY && x >= aSkipRect.x &&
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x < aSkipRect.XMost()) {
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x = aSkipRect.XMost();
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if (x >= aWidth)
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break;
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}
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PRInt32 sMin = PR_MAX(x - aRadius, 0);
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PRInt32 sMax = PR_MIN(x + aRadius, aWidth - 1);
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PRInt32 v = 0;
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for (PRInt32 s = sMin; s <= sMax; ++s) {
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v = PR_MAX(v, aInput[aStride * y + s]);
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}
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aOutput[aStride * y + x] = v;
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}
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}
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}
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static void
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SpreadVertical(unsigned char* aInput,
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unsigned char* aOutput,
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PRInt32 aRadius,
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PRInt32 aWidth,
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PRInt32 aRows,
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PRInt32 aStride,
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const nsIntRect& aSkipRect)
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{
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if (aRadius == 0) {
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memcpy(aOutput, aInput, aStride*aRows);
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return;
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}
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PRBool skipRectCoversWholeColumn = 0 >= aSkipRect.y &&
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aRows <= aSkipRect.YMost();
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for (PRInt32 x = 0; x < aWidth; x++) {
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PRBool inSkipRectX = x >= aSkipRect.x &&
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x < aSkipRect.XMost();
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if (inSkipRectX && skipRectCoversWholeColumn) {
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x = aSkipRect.XMost() - 1;
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continue;
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}
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for (PRInt32 y = 0; y < aRows; y++) {
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// Check whether we are within the skip rect. If so, go
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// to the next point outside the skip rect.
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if (inSkipRectX && y >= aSkipRect.y &&
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y < aSkipRect.YMost()) {
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y = aSkipRect.YMost();
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if (y >= aRows)
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break;
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}
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PRInt32 sMin = PR_MAX(y - aRadius, 0);
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PRInt32 sMax = PR_MIN(y + aRadius, aRows - 1);
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PRInt32 v = 0;
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for (PRInt32 s = sMin; s <= sMax; ++s) {
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v = PR_MAX(v, aInput[aStride * s + x]);
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}
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aOutput[aStride * y + x] = v;
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}
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}
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}
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void
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gfxAlphaBoxBlur::Paint(gfxContext* aDestinationCtx, const gfxPoint& offset)
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{
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if (!mContext)
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return;
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unsigned char* boxData = mImageSurface->Data();
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// no need to do all this if not blurring or spreading
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if (mBlurRadius != gfxIntSize(0,0) || mSpreadRadius != gfxIntSize(0,0)) {
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nsTArray<unsigned char> tempAlphaDataBuf;
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PRSize szB = mImageSurface->GetDataSize();
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if (!tempAlphaDataBuf.SetLength(szB))
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return; // OOM
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unsigned char* tmpData = tempAlphaDataBuf.Elements();
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// .SetLength above doesn't initialise the new elements since
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// they are unsigned chars and so have no default constructor.
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// So we have to initialise them by hand.
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memset(tmpData, 0, szB);
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PRInt32 stride = mImageSurface->Stride();
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PRInt32 rows = mImageSurface->Height();
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PRInt32 width = mImageSurface->Width();
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if (mSpreadRadius.width > 0 || mSpreadRadius.height > 0) {
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SpreadHorizontal(boxData, tmpData, mSpreadRadius.width, width, rows, stride, mSkipRect);
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SpreadVertical(tmpData, boxData, mSpreadRadius.height, width, rows, stride, mSkipRect);
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}
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if (mBlurRadius.width > 0) {
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PRInt32 lobes[3][2];
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ComputeLobes(mBlurRadius.width, lobes);
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BoxBlurHorizontal(boxData, tmpData, lobes[0][0], lobes[0][1], stride, rows, mSkipRect);
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BoxBlurHorizontal(tmpData, boxData, lobes[1][0], lobes[1][1], stride, rows, mSkipRect);
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BoxBlurHorizontal(boxData, tmpData, lobes[2][0], lobes[2][1], stride, rows, mSkipRect);
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} else {
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memcpy(tmpData, boxData, stride*rows);
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}
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if (mBlurRadius.height > 0) {
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PRInt32 lobes[3][2];
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ComputeLobes(mBlurRadius.height, lobes);
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BoxBlurVertical(tmpData, boxData, lobes[0][0], lobes[0][1], stride, rows, mSkipRect);
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BoxBlurVertical(boxData, tmpData, lobes[1][0], lobes[1][1], stride, rows, mSkipRect);
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BoxBlurVertical(tmpData, boxData, lobes[2][0], lobes[2][1], stride, rows, mSkipRect);
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} else {
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memcpy(boxData, tmpData, stride*rows);
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}
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}
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// Avoid a semi-expensive clip operation if we can, otherwise
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// clip to the dirty rect
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if (mHasDirtyRect) {
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aDestinationCtx->Save();
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aDestinationCtx->NewPath();
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aDestinationCtx->Rectangle(mDirtyRect);
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aDestinationCtx->Clip();
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aDestinationCtx->Mask(mImageSurface, offset);
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aDestinationCtx->Restore();
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} else {
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aDestinationCtx->Mask(mImageSurface, offset);
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}
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}
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/**
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* Compute the box blur size (which we're calling the blur radius) from
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* the standard deviation.
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*
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* Much of this, the 3 * sqrt(2 * pi) / 4, is the known value for
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* approximating a Gaussian using box blurs. This yields quite a good
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* approximation for a Gaussian. Then we multiply this by 1.5 since our
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* code wants the radius of the entire triple-box-blur kernel instead of
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* the diameter of an individual box blur. For more details, see:
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* http://www.w3.org/TR/SVG11/filters.html#feGaussianBlurElement
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* https://bugzilla.mozilla.org/show_bug.cgi?id=590039#c19
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*/
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static const gfxFloat GAUSSIAN_SCALE_FACTOR = (3 * sqrt(2 * M_PI) / 4) * 1.5;
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gfxIntSize gfxAlphaBoxBlur::CalculateBlurRadius(const gfxPoint& aStd)
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{
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return gfxIntSize(
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static_cast<PRInt32>(floor(aStd.x * GAUSSIAN_SCALE_FACTOR + 0.5)),
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static_cast<PRInt32>(floor(aStd.y * GAUSSIAN_SCALE_FACTOR + 0.5)));
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}
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