gecko-dev/gfx/thebes/gfxBlur.cpp

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/* -*- Mode: C++; tab-width: 4; 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 gfx thebes code.
*
* The Initial Developer of the Original Code is Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2008
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Eric Butler <zantifon@gmail.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 "gfxBlur.h"
#include "nsMathUtils.h"
#include "nsTArray.h"
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
gfxAlphaBoxBlur::gfxAlphaBoxBlur()
{
}
gfxAlphaBoxBlur::~gfxAlphaBoxBlur()
{
}
gfxContext*
gfxAlphaBoxBlur::Init(const gfxRect& aRect,
const gfxIntSize& aSpreadRadius,
const gfxIntSize& aBlurRadius,
const gfxRect* aDirtyRect,
const gfxRect* aSkipRect)
{
mSpreadRadius = aSpreadRadius;
mBlurRadius = aBlurRadius;
gfxRect rect(aRect);
rect.Outset(aBlurRadius + aSpreadRadius);
rect.RoundOut();
if (rect.IsEmpty())
return nsnull;
if (aDirtyRect) {
// If we get passed a dirty rect from layout, we can minimize the
// shadow size and make painting faster.
mHasDirtyRect = PR_TRUE;
mDirtyRect = *aDirtyRect;
gfxRect requiredBlurArea = mDirtyRect.Intersect(rect);
requiredBlurArea.Outset(aBlurRadius + aSpreadRadius);
rect = requiredBlurArea.Intersect(rect);
} else {
mHasDirtyRect = PR_FALSE;
}
if (aSkipRect) {
// If we get passed a skip rect, we can lower the amount of
// blurring/spreading we need to do. We convert it to nsIntRect to avoid
// expensive int<->float conversions if we were to use gfxRect instead.
gfxRect skipRect = *aSkipRect;
skipRect.RoundIn();
skipRect.Inset(aBlurRadius + aSpreadRadius);
gfxUtils::GfxRectToIntRect(skipRect, &mSkipRect);
nsIntRect shadowIntRect;
gfxUtils::GfxRectToIntRect(rect, &shadowIntRect);
mSkipRect.IntersectRect(mSkipRect, shadowIntRect);
if (mSkipRect == shadowIntRect)
return nsnull;
mSkipRect -= shadowIntRect.TopLeft();
} else {
mSkipRect = nsIntRect(0, 0, 0, 0);
}
// Make an alpha-only surface to draw on. We will play with the data after
// everything is drawn to create a blur effect.
mImageSurface = new gfxImageSurface(gfxIntSize(static_cast<PRInt32>(rect.Width()), static_cast<PRInt32>(rect.Height())),
gfxASurface::ImageFormatA8);
if (!mImageSurface || mImageSurface->CairoStatus())
return nsnull;
// Use a device offset so callers don't need to worry about translating
// coordinates, they can draw as if this was part of the destination context
// at the coordinates of rect.
mImageSurface->SetDeviceOffset(-rect.TopLeft());
mContext = new gfxContext(mImageSurface);
return mContext;
}
void
gfxAlphaBoxBlur::PremultiplyAlpha(gfxFloat alpha)
{
if (!mImageSurface)
return;
unsigned char* data = mImageSurface->Data();
PRInt32 length = mImageSurface->GetDataSize();
for (PRInt32 i=0; i<length; ++i)
data[i] = static_cast<unsigned char>(data[i] * alpha);
}
/**
* Box blur involves looking at one pixel, and setting its value to the average
* of its neighbouring pixels.
* @param aInput The input buffer.
* @param aOutput The output buffer.
* @param aLeftLobe The number of pixels to blend on the left.
* @param aRightLobe The number of pixels to blend on the right.
* @param aWidth The number of columns in the buffers.
* @param aRows The number of rows in the buffers.
* @param aSkipRect An area to skip blurring in.
* XXX shouldn't we pass stride in separately here?
*/
static void
BoxBlurHorizontal(unsigned char* aInput,
unsigned char* aOutput,
PRInt32 aLeftLobe,
PRInt32 aRightLobe,
PRInt32 aWidth,
PRInt32 aRows,
const nsIntRect& aSkipRect)
{
PRInt32 boxSize = aLeftLobe + aRightLobe + 1;
PRBool skipRectCoversWholeRow = 0 >= aSkipRect.x &&
aWidth <= aSkipRect.XMost();
for (PRInt32 y = 0; y < aRows; y++) {
// Check whether the skip rect intersects this row. If the skip
// rect covers the whole surface in this row, we can avoid
// this row entirely (and any others along the skip rect).
PRBool inSkipRectY = y >= aSkipRect.y &&
y < aSkipRect.YMost();
if (inSkipRectY && skipRectCoversWholeRow) {
y = aSkipRect.YMost() - 1;
continue;
}
PRInt32 alphaSum = 0;
for (PRInt32 i = 0; i < boxSize; i++) {
PRInt32 pos = i - aLeftLobe;
pos = NS_MAX(pos, 0);
pos = NS_MIN(pos, aWidth - 1);
alphaSum += aInput[aWidth * y + pos];
}
for (PRInt32 x = 0; x < aWidth; x++) {
// Check whether we are within the skip rect. If so, go
// to the next point outside the skip rect.
if (inSkipRectY && x >= aSkipRect.x &&
x < aSkipRect.XMost()) {
x = aSkipRect.XMost();
if (x >= aWidth)
break;
// Recalculate the neighbouring alpha values for
// our new point on the surface.
alphaSum = 0;
for (PRInt32 i = 0; i < boxSize; i++) {
PRInt32 pos = x + i - aLeftLobe;
pos = NS_MAX(pos, 0);
pos = NS_MIN(pos, aWidth - 1);
alphaSum += aInput[aWidth * y + pos];
}
}
PRInt32 tmp = x - aLeftLobe;
PRInt32 last = NS_MAX(tmp, 0);
PRInt32 next = NS_MIN(tmp + boxSize, aWidth - 1);
aOutput[aWidth * y + x] = alphaSum/boxSize;
alphaSum += aInput[aWidth * y + next] -
aInput[aWidth * y + last];
}
}
}
/**
* Identical to BoxBlurHorizontal, except it blurs top and bottom instead of
* left and right.
* XXX shouldn't we pass stride in separately here?
*/
static void
BoxBlurVertical(unsigned char* aInput,
unsigned char* aOutput,
PRInt32 aTopLobe,
PRInt32 aBottomLobe,
PRInt32 aWidth,
PRInt32 aRows,
const nsIntRect& aSkipRect)
{
PRInt32 boxSize = aTopLobe + aBottomLobe + 1;
PRBool skipRectCoversWholeColumn = 0 >= aSkipRect.y &&
aRows <= aSkipRect.YMost();
for (PRInt32 x = 0; x < aWidth; x++) {
PRBool inSkipRectX = x >= aSkipRect.x &&
x < aSkipRect.XMost();
if (inSkipRectX && skipRectCoversWholeColumn) {
x = aSkipRect.XMost() - 1;
continue;
}
PRInt32 alphaSum = 0;
for (PRInt32 i = 0; i < boxSize; i++) {
PRInt32 pos = i - aTopLobe;
pos = NS_MAX(pos, 0);
pos = NS_MIN(pos, aRows - 1);
alphaSum += aInput[aWidth * pos + x];
}
for (PRInt32 y = 0; y < aRows; y++) {
if (inSkipRectX && y >= aSkipRect.y &&
y < aSkipRect.YMost()) {
y = aSkipRect.YMost();
if (y >= aRows)
break;
alphaSum = 0;
for (PRInt32 i = 0; i < boxSize; i++) {
PRInt32 pos = y + i - aTopLobe;
pos = NS_MAX(pos, 0);
pos = NS_MIN(pos, aRows - 1);
alphaSum += aInput[aWidth * pos + x];
}
}
PRInt32 tmp = y - aTopLobe;
PRInt32 last = NS_MAX(tmp, 0);
PRInt32 next = NS_MIN(tmp + boxSize, aRows - 1);
aOutput[aWidth * y + x] = alphaSum/boxSize;
alphaSum += aInput[aWidth * next + x] -
aInput[aWidth * last + x];
}
}
}
static void ComputeLobes(PRInt32 aRadius, PRInt32 aLobes[3][2])
{
PRInt32 major, minor, final;
/* See http://www.w3.org/TR/SVG/filters.html#feGaussianBlur for
* some notes about approximating the Gaussian blur with box-blurs.
* The comments below are in the terminology of that page.
*/
PRInt32 z = aRadius/3;
switch (aRadius % 3) {
case 0:
// aRadius = z*3; choose d = 2*z + 1
major = minor = final = z;
break;
case 1:
// aRadius = z*3 + 1
// This is a tricky case since there is no value of d which will
// yield a radius of exactly aRadius. If d is odd, i.e. d=2*k + 1
// for some integer k, then the radius will be 3*k. If d is even,
// i.e. d=2*k, then the radius will be 3*k - 1.
// So we have to choose values that don't match the standard
// algorithm.
major = z + 1;
minor = final = z;
break;
case 2:
// aRadius = z*3 + 2; choose d = 2*z + 2
major = final = z + 1;
minor = z;
break;
default:
NS_ERROR("Mathematical impossibility.");
major = minor = final = 0;
}
NS_ASSERTION(major + minor + final == aRadius,
"Lobes don't sum to the right length");
aLobes[0][0] = major;
aLobes[0][1] = minor;
aLobes[1][0] = minor;
aLobes[1][1] = major;
aLobes[2][0] = final;
aLobes[2][1] = final;
}
static void
SpreadHorizontal(unsigned char* aInput,
unsigned char* aOutput,
PRInt32 aRadius,
PRInt32 aWidth,
PRInt32 aRows,
PRInt32 aStride,
const nsIntRect& aSkipRect)
{
if (aRadius == 0) {
memcpy(aOutput, aInput, aStride*aRows);
return;
}
PRBool skipRectCoversWholeRow = 0 >= aSkipRect.x &&
aWidth <= aSkipRect.XMost();
for (PRInt32 y = 0; y < aRows; y++) {
// Check whether the skip rect intersects this row. If the skip
// rect covers the whole surface in this row, we can avoid
// this row entirely (and any others along the skip rect).
PRBool inSkipRectY = y >= aSkipRect.y &&
y < aSkipRect.YMost();
if (inSkipRectY && skipRectCoversWholeRow) {
y = aSkipRect.YMost() - 1;
continue;
}
for (PRInt32 x = 0; x < aWidth; x++) {
// Check whether we are within the skip rect. If so, go
// to the next point outside the skip rect.
if (inSkipRectY && x >= aSkipRect.x &&
x < aSkipRect.XMost()) {
x = aSkipRect.XMost();
if (x >= aWidth)
break;
}
PRInt32 sMin = PR_MAX(x - aRadius, 0);
PRInt32 sMax = PR_MIN(x + aRadius, aWidth - 1);
PRInt32 v = 0;
for (PRInt32 s = sMin; s <= sMax; ++s) {
v = PR_MAX(v, aInput[aStride * y + s]);
}
aOutput[aStride * y + x] = v;
}
}
}
static void
SpreadVertical(unsigned char* aInput,
unsigned char* aOutput,
PRInt32 aRadius,
PRInt32 aWidth,
PRInt32 aRows,
PRInt32 aStride,
const nsIntRect& aSkipRect)
{
if (aRadius == 0) {
memcpy(aOutput, aInput, aStride*aRows);
return;
}
PRBool skipRectCoversWholeColumn = 0 >= aSkipRect.y &&
aRows <= aSkipRect.YMost();
for (PRInt32 x = 0; x < aWidth; x++) {
PRBool inSkipRectX = x >= aSkipRect.x &&
x < aSkipRect.XMost();
if (inSkipRectX && skipRectCoversWholeColumn) {
x = aSkipRect.XMost() - 1;
continue;
}
for (PRInt32 y = 0; y < aRows; y++) {
// Check whether we are within the skip rect. If so, go
// to the next point outside the skip rect.
if (inSkipRectX && y >= aSkipRect.y &&
y < aSkipRect.YMost()) {
y = aSkipRect.YMost();
if (y >= aRows)
break;
}
PRInt32 sMin = PR_MAX(y - aRadius, 0);
PRInt32 sMax = PR_MIN(y + aRadius, aRows - 1);
PRInt32 v = 0;
for (PRInt32 s = sMin; s <= sMax; ++s) {
v = PR_MAX(v, aInput[aStride * s + x]);
}
aOutput[aStride * y + x] = v;
}
}
}
void
gfxAlphaBoxBlur::Paint(gfxContext* aDestinationCtx, const gfxPoint& offset)
{
if (!mContext)
return;
unsigned char* boxData = mImageSurface->Data();
// no need to do all this if not blurring or spreading
if (mBlurRadius != gfxIntSize(0,0) || mSpreadRadius != gfxIntSize(0,0)) {
nsTArray<unsigned char> tempAlphaDataBuf;
PRSize szB = mImageSurface->GetDataSize();
if (!tempAlphaDataBuf.SetLength(szB))
return; // OOM
unsigned char* tmpData = tempAlphaDataBuf.Elements();
// .SetLength above doesn't initialise the new elements since
// they are unsigned chars and so have no default constructor.
// So we have to initialise them by hand.
memset(tmpData, 0, szB);
PRInt32 stride = mImageSurface->Stride();
PRInt32 rows = mImageSurface->Height();
PRInt32 width = mImageSurface->Width();
if (mSpreadRadius.width > 0 || mSpreadRadius.height > 0) {
SpreadHorizontal(boxData, tmpData, mSpreadRadius.width, width, rows, stride, mSkipRect);
SpreadVertical(tmpData, boxData, mSpreadRadius.height, width, rows, stride, mSkipRect);
}
if (mBlurRadius.width > 0) {
PRInt32 lobes[3][2];
ComputeLobes(mBlurRadius.width, lobes);
BoxBlurHorizontal(boxData, tmpData, lobes[0][0], lobes[0][1], stride, rows, mSkipRect);
BoxBlurHorizontal(tmpData, boxData, lobes[1][0], lobes[1][1], stride, rows, mSkipRect);
BoxBlurHorizontal(boxData, tmpData, lobes[2][0], lobes[2][1], stride, rows, mSkipRect);
} else {
memcpy(tmpData, boxData, stride*rows);
}
if (mBlurRadius.height > 0) {
PRInt32 lobes[3][2];
ComputeLobes(mBlurRadius.height, lobes);
BoxBlurVertical(tmpData, boxData, lobes[0][0], lobes[0][1], stride, rows, mSkipRect);
BoxBlurVertical(boxData, tmpData, lobes[1][0], lobes[1][1], stride, rows, mSkipRect);
BoxBlurVertical(tmpData, boxData, lobes[2][0], lobes[2][1], stride, rows, mSkipRect);
} else {
memcpy(boxData, tmpData, stride*rows);
}
}
// Avoid a semi-expensive clip operation if we can, otherwise
// clip to the dirty rect
if (mHasDirtyRect) {
aDestinationCtx->Save();
aDestinationCtx->NewPath();
aDestinationCtx->Rectangle(mDirtyRect);
aDestinationCtx->Clip();
aDestinationCtx->Mask(mImageSurface, offset);
aDestinationCtx->Restore();
} else {
aDestinationCtx->Mask(mImageSurface, offset);
}
}
Change the blur radius for -moz-box-shadow and text-shadow to match what is specified in css3-background, and the blur radius for canvas to follow what is specified in HTML5. (Bug 590039) r=roc a2.0=blocking2.0:beta6 This fixes the multiplication by 1.5 in gfxAlphaBoxBlur::CalculateBlurRadius (originally added in changeset ce9f05b57b95 for bug 467518) to work correctly. It was previously a multiplication by 1 due to integer division. CalculateBlurRadius previously multiplied by 1.880; it now multiplies by 2.820. This changes canvas shadow handling to multiply shadowBlur by 2 before taking its square root, as described in the spec. This means that canvas shadow blurs 8px or smaller are 1.5 times larger than they were previously (due to the CalculateBlurRadius change), and canvas shadow blurs larger than 8px are 2.121 times larger than they were previously (due to the CalculateBlurRadius change *and* the additional factor of sqrt(2)). This changes text-shadow and -moz-box-shadow handling to use CalculateBlurRadius on half of the value given instead of passing the value through directly. This means that text-shadow and box-shadow blurs are multiplied by 1.410 relative to their old sizes. It also means that we round rather than floor, so that the effect that used to be drawn by a blur in the range 1px to 1.99px is now drawn by a blur anywhere in the range 0.36px to 1.05px, the effect that used to be drawn by a blur in the range 2px to 2.99px is now drawn by a blur anywhere in the range 1.06px to 1.77px, what used to be a drawn by a blur in the range 3px to 3.99px is now drawn by a blur anywhere in the range 1.78px to 2.47px, etc.
2010-09-11 20:27:12 +04:00
/**
* Compute the box blur size (which we're calling the blur radius) from
* the standard deviation.
*
* Much of this, the 3 * sqrt(2 * pi) / 4, is the known value for
* approximating a Gaussian using box blurs. This yields quite a good
* approximation for a Gaussian. Then we multiply this by 1.5 since our
* code wants the radius of the entire triple-box-blur kernel instead of
* the diameter of an individual box blur. For more details, see:
* http://www.w3.org/TR/SVG11/filters.html#feGaussianBlurElement
* https://bugzilla.mozilla.org/show_bug.cgi?id=590039#c19
*/
static const gfxFloat GAUSSIAN_SCALE_FACTOR = (3 * sqrt(2 * M_PI) / 4) * 1.5;
gfxIntSize gfxAlphaBoxBlur::CalculateBlurRadius(const gfxPoint& aStd)
{
return gfxIntSize(
static_cast<PRInt32>(floor(aStd.x * GAUSSIAN_SCALE_FACTOR + 0.5)),
static_cast<PRInt32>(floor(aStd.y * GAUSSIAN_SCALE_FACTOR + 0.5)));
}