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Diffstat (limited to 'gfx/thebes/gfxBlur.h')
| -rw-r--r-- | gfx/thebes/gfxBlur.h | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/gfx/thebes/gfxBlur.h b/gfx/thebes/gfxBlur.h new file mode 100644 index 000000000..9cc5f3716 --- /dev/null +++ b/gfx/thebes/gfxBlur.h @@ -0,0 +1,194 @@ +/* -*- 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 */ |