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185e021dbe
mBlur creates and owns an A8 data buffer that we pass to mImageSurface, targeted by mContext. Sometimes, when we remove the last reference to mContext cairo wants to take a snapshot copy of the data buffer. If this happens after we've deleted mBlur in ~gfxAlphaBoxBlur, we may crash due to the data buffer having been deleted already. A partial solution is to clear mContext and mImageSurface to force those snapshots to be taken before deleting mBlur. This is only a partial solution since in principle the client of gfxAlphaBoxBlur may have kept mContext alive with its own reference. In practice we don't do that though. A complete solution would require making the data buffer be owned by mImageSurface, either directly or indirectly.
106 lines
3.5 KiB
C++
106 lines
3.5 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "gfxBlur.h"
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#include "mozilla/gfx/Blur.h"
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using namespace mozilla::gfx;
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gfxAlphaBoxBlur::gfxAlphaBoxBlur()
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: mBlur(nullptr)
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{
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}
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gfxAlphaBoxBlur::~gfxAlphaBoxBlur()
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{
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// Drop references to mContext and mImageSurface before we delete mBlur,
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// because the image surface points to data in mBlur.
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mContext = nullptr;
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mImageSurface = nullptr;
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delete mBlur;
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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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mozilla::gfx::Rect rect(aRect.x, aRect.y, aRect.width, aRect.height);
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IntSize spreadRadius(aSpreadRadius.width, aSpreadRadius.height);
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IntSize blurRadius(aBlurRadius.width, aBlurRadius.height);
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nsAutoPtr<mozilla::gfx::Rect> dirtyRect;
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if (aDirtyRect) {
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dirtyRect = new mozilla::gfx::Rect(aDirtyRect->x, aDirtyRect->y, aDirtyRect->width, aDirtyRect->height);
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}
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nsAutoPtr<mozilla::gfx::Rect> skipRect;
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if (aSkipRect) {
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skipRect = new mozilla::gfx::Rect(aSkipRect->x, aSkipRect->y, aSkipRect->width, aSkipRect->height);
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}
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mBlur = new AlphaBoxBlur(rect, spreadRadius, blurRadius, dirtyRect, skipRect);
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unsigned char* data = mBlur->GetData();
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if (!data)
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return nullptr;
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IntSize size = mBlur->GetSize();
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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(data, gfxIntSize(size.width, size.height),
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mBlur->GetStride(),
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gfxASurface::ImageFormatA8);
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if (mImageSurface->CairoStatus())
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return nullptr;
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IntRect irect = mBlur->GetRect();
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gfxPoint topleft(irect.TopLeft().x, irect.TopLeft().y);
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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(-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::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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mBlur->Blur();
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mozilla::gfx::Rect* dirtyrect = mBlur->GetDirtyRect();
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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 (dirtyrect) {
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aDestinationCtx->Save();
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aDestinationCtx->NewPath();
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gfxRect dirty(dirtyrect->x, dirtyrect->y, dirtyrect->width, dirtyrect->height);
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gfxRect imageRect(offset - mImageSurface->GetDeviceOffset(), mImageSurface->GetSize());
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dirty.IntersectRect(dirty, imageRect);
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aDestinationCtx->Rectangle(dirty);
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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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gfxIntSize gfxAlphaBoxBlur::CalculateBlurRadius(const gfxPoint& aStd)
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{
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mozilla::gfx::Point std(aStd.x, aStd.y);
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IntSize size = AlphaBoxBlur::CalculateBlurRadius(std);
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return gfxIntSize(size.width, size.height);
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}
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