2008-09-25 12:53:09 -07:00
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/* -*- 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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2009-12-21 13:50:30 -08:00
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* The Initial Developer of the Original Code is Mozilla Foundation.
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2008-09-25 12:53:09 -07:00
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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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#ifndef GFX_BLUR_H
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#define GFX_BLUR_H
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#include "gfxContext.h"
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#include "gfxImageSurface.h"
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#include "gfxTypes.h"
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#include "gfxThebesUtils.h"
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2008-09-25 12:53:09 -07:00
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/**
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* Implementation of a box blur approximation of a Gaussian blur.
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*
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* Creates an 8-bit alpha channel context for callers to draw in, blurs the
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* contents of that context and applies it as an alpha mask on a
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* different existing context.
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*
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* A temporary surface is created in the Init function. The caller then draws
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* any desired content onto the context acquired through GetContext, and lastly
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* calls Paint to apply the blurred content as an alpha mask.
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*/
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class THEBES_API gfxAlphaBoxBlur
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{
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public:
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gfxAlphaBoxBlur();
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~gfxAlphaBoxBlur();
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/**
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* Constructs a box blur and initializes the temporary surface.
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* @param aRect The coordinates of the surface to create in device units.
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*
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* @param aBlurRadius The blur radius in pixels
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*
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* @param aDirtyRect A pointer to a dirty rect, measured in device units, if available.
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* This will be used for optimizing the blur operation. It is safe to pass NULL here.
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*
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* @param aSkipRect A pointer to a rect, measured in device units, that represents an area
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* where blurring is unnecessary and shouldn't be done for speed reasons. It is safe to
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* pass NULL here.
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*/
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gfxContext* Init(const gfxRect& aRect,
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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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* Returns the context that should be drawn to supply the alpha mask to be
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* blurred. If the returned surface is null, then there was an error in
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* its creation.
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*/
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gfxContext* GetContext()
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{
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return mContext;
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}
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/**
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* Premultiplies the image by the given alpha.
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*/
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void PremultiplyAlpha(gfxFloat alpha);
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/**
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* Does the actual blurring and mask applying. Users of this object
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* must have drawn whatever they want to be blurred onto the internal
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* gfxContext returned by GetContext before calling this.
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*
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* @param aDestinationCtx The graphics context on which to apply the
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* blurred mask.
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*/
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void Paint(gfxContext* aDestinationCtx, const gfxPoint& offset = gfxPoint(0.0, 0.0));
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/**
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* Calculates a blur radius that, when used with box blur, approximates
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* a Gaussian blur with the given standard deviation.
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*/
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static gfxIntSize CalculateBlurRadius(const gfxPoint& aStandardDeviation);
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protected:
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/**
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* The blur radius, in pixels.
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*/
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gfxIntSize mBlurRadius;
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/**
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* The context of the temporary alpha surface.
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*/
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nsRefPtr<gfxContext> mContext;
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/**
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* The temporary alpha surface.
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*/
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nsRefPtr<gfxImageSurface> mImageSurface;
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/**
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* A copy of the dirty rect passed to Init(). This will only be valid if
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* mHasDirtyRect is TRUE.
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*/
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gfxRect mDirtyRect;
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/**
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* A rect indicating the area where blurring is unnecessary, and the blur
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* algorithm should skip over it.
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*/
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nsIntRect mSkipRect;
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PRPackedBool mHasDirtyRect;
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};
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#endif /* GFX_BLUR_H */
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