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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef GFX_BLUR_H
#define GFX_BLUR_H
#include "gfxTypes.h"
#include "nsSize.h"
#include "gfxPoint.h"
#include "mozilla/RefPtr.h"
#include "mozilla/UniquePtr.h"
class gfxContext;
struct gfxRect;
namespace mozilla {
namespace gfx {
class AlphaBoxBlur;
struct Color;
struct RectCornerRadii;
class SourceSurface;
class DrawTarget;
} // namespace gfx
} // namespace mozilla
/**
* Implementation of a triple box blur approximation of a Gaussian blur.
*
* A Gaussian blur is good for blurring because, when done independently
* in the horizontal and vertical directions, it matches the result that
* would be obtained using a different (rotated) set of axes. A triple
* box blur is a very close approximation of a Gaussian.
*
* Creates an 8-bit alpha channel context for callers to draw in,
* spreads the contents of that context, blurs the contents, and applies
* it as an alpha mask on a different existing context.
*
* A spread N makes each output pixel the maximum value of all source
* pixels within a square of side length 2N+1 centered on the output pixel.
*
* A temporary surface is created in the Init function. The caller then draws
* any desired content onto the context acquired through GetContext, and lastly
* calls Paint to apply the blurred content as an alpha mask.
*/
class gfxAlphaBoxBlur
{
typedef mozilla::gfx::Color Color;
typedef mozilla::gfx::DrawTarget DrawTarget;
typedef mozilla::gfx::RectCornerRadii RectCornerRadii;
public:
gfxAlphaBoxBlur();
~gfxAlphaBoxBlur();
/**
* Constructs a box blur and initializes the temporary surface.
* @param aRect The coordinates of the surface to create in device units.
*
* @param aBlurRadius The blur radius in pixels. This is the radius of
* the entire (triple) kernel function. Each individual box blur has
* radius approximately 1/3 this value, or diameter approximately 2/3
* this value. This parameter should nearly always be computed using
* CalculateBlurRadius, below.
*
* @param aDirtyRect A pointer to a dirty rect, measured in device units,
* if available. This will be used for optimizing the blur operation. It
* is safe to pass nullptr here.
*
* @param aSkipRect A pointer to a rect, measured in device units, that
* represents an area where blurring is unnecessary and shouldn't be done
* for speed reasons. It is safe to pass nullptr here.
*/
gfxContext* Init(const gfxRect& aRect,
const mozilla::gfx::IntSize& aSpreadRadius,
const mozilla::gfx::IntSize& aBlurRadius,
const gfxRect* aDirtyRect,
const gfxRect* aSkipRect);
/**
* Returns the context that should be drawn to supply the alpha mask to be
* blurred. If the returned surface is null, then there was an error in
* its creation.
*/
gfxContext* GetContext()
{
return mContext;
}
already_AddRefed<mozilla::gfx::SourceSurface>
DoBlur(DrawTarget* aDT, mozilla::gfx::IntPoint* aTopLeft);
/**
* Does the actual blurring/spreading and mask applying. Users of this
* object must have drawn whatever they want to be blurred onto the internal
* gfxContext returned by GetContext before calling this.
*
* @param aDestinationCtx The graphics context on which to apply the
* blurred mask.
*/
void Paint(gfxContext* aDestinationCtx);
/**
* Calculates a blur radius that, when used with box blur, approximates
* a Gaussian blur with the given standard deviation. The result of
* this function should be used as the aBlurRadius parameter to Init,
* above.
*/
static mozilla::gfx::IntSize CalculateBlurRadius(const gfxPoint& aStandardDeviation);
/**
* Blurs a coloured rectangle onto aDestinationCtx. This is equivalent
* to calling Init(), drawing a rectangle onto the returned surface
* and then calling Paint, but may let us optimize better in the
* backend.
*
* @param aDestinationCtx The destination to blur to.
* @param aRect The rectangle to blur in device pixels.
* @param aCornerRadii Corner radii for aRect, if it is a rounded
* rectangle.
* @param aBlurRadius The standard deviation of the blur.
* @param aShadowColor The color to draw the blurred shadow.
* @param aDirtyRect An area in device pixels that is dirty and needs
* to be redrawn.
* @param aSkipRect An area in device pixels to avoid blurring over,
* to prevent unnecessary work.
*/
static void BlurRectangle(gfxContext *aDestinationCtx,
const gfxRect& aRect,
RectCornerRadii* aCornerRadii,
const gfxPoint& aBlurStdDev,
const Color& aShadowColor,
const gfxRect& aDirtyRect,
const gfxRect& aSkipRect);
static void ShutdownBlurCache();
/***
* Blurs an inset box shadow according to a given path.
* This is equivalent to calling Init(), drawing the inset path,
* and calling paint. Do not call Init() if using this method.
*
* @param aDestinationCtx The destination to blur to.
* @param aDestinationRect The destination rect in device pixels
* @param aShadowClipRect The destiniation inner rect of the
* inset path in device pixels.
* @param aBlurRadius The standard deviation of the blur.
* @param aSpreadRadius The spread radius in device pixels.
* @param aShadowColor The color of the blur.
* @param aHasBorderRadius If this element also has a border radius
* @param aInnerClipRadii Corner radii for the inside rect if it is a rounded rect.
* @param aSKipRect An area in device pixels we don't have to paint in.
*/
void BlurInsetBox(gfxContext* aDestinationCtx,
const mozilla::gfx::Rect aDestinationRect,
const mozilla::gfx::Rect aShadowClipRect,
const mozilla::gfx::IntSize aBlurRadius,
const mozilla::gfx::IntSize aSpreadRadius,
const mozilla::gfx::Color& aShadowColor,
const bool aHasBorderRadius,
const RectCornerRadii& aInnerClipRadii,
const mozilla::gfx::Rect aSkipRect,
const mozilla::gfx::Point aShadowOffset);
protected:
already_AddRefed<mozilla::gfx::SourceSurface>
GetInsetBlur(const mozilla::gfx::Rect aOuterRect,
const mozilla::gfx::Rect aWhitespaceRect,
const bool aIsDestRect,
const mozilla::gfx::Color& aShadowColor,
const mozilla::gfx::IntSize& aBlurRadius,
const bool aHasBorderRadius,
const RectCornerRadii& aInnerClipRadii,
DrawTarget* aDestDrawTarget);
/**
* The context of the temporary alpha surface.
*/
RefPtr<gfxContext> mContext;
/**
* The temporary alpha surface.
*/
mozilla::UniquePtr<unsigned char[]> mData;
/**
* The object that actually does the blurring for us.
*/
mozilla::UniquePtr<mozilla::gfx::AlphaBoxBlur> mBlur;
};
#endif /* GFX_BLUR_H */
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