tor-browser

gfxBlur.h (7715B)

---

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* 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 "gfxRect.h"
#include "nsSize.h"
#include "gfxPoint.h"
#include "mozilla/RefPtr.h"
#include "mozilla/gfx/Blur.h"

class gfxContext;

namespace mozilla {
namespace gfx {
struct sRGBColor;
struct RectCornerRadii;
class SourceSurface;
class DrawTarget;
}  // namespace gfx
}  // namespace mozilla

/**
* Implementation 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.
*
* 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 gfxGaussianBlur final {
 typedef mozilla::gfx::sRGBColor sRGBColor;
 typedef mozilla::gfx::DrawTarget DrawTarget;
 typedef mozilla::gfx::RectCornerRadii RectCornerRadii;

public:
 gfxGaussianBlur() = default;

 ~gfxGaussianBlur();

 /**
  * Constructs a gaussian blur and initializes the temporary surface.
  *
  * @param aDestinationCtx The destination to blur to.
  *
  * @param aRect The coordinates of the surface to create in device units.
  *
  * @param aBlurSigma The blur sigma.
  *
  * @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.
  *
  * @param aClamp Whether clamping at border pixels is required.
  */
 mozilla::UniquePtr<gfxContext> Init(
     gfxContext* aDestinationCtx, const gfxRect& aRect,
     const mozilla::gfx::IntSize& aSpreadRadius,
     const mozilla::gfx::Point& aBlurSigma, const gfxRect* aDirtyRect,
     const gfxRect* aSkipRect, bool aClamp = false);

 mozilla::UniquePtr<gfxContext> Init(
     gfxContext* aDestinationCtx, const gfxRect& aRect,
     const mozilla::gfx::IntSize& aSpreadRadius,
     const mozilla::gfx::IntSize& aBlurRadius, const gfxRect* aDirtyRect,
     const gfxRect* aSkipRect, bool aClamp = false);

 already_AddRefed<DrawTarget> InitDrawTarget(
     const mozilla::gfx::DrawTarget* aReferenceDT,
     const mozilla::gfx::Rect& aRect,
     const mozilla::gfx::IntSize& aSpreadRadius,
     const mozilla::gfx::Point& aBlurSigma,
     const mozilla::gfx::Rect* aDirtyRect = nullptr,
     const mozilla::gfx::Rect* aSkipRect = nullptr, bool aClamp = false);

 /**
  * Performs the blur and optionally colors the result if aShadowColor is not
  * null.
  */
 already_AddRefed<mozilla::gfx::SourceSurface> DoBlur(
     const mozilla::gfx::sRGBColor* aShadowColor = nullptr,
     mozilla::gfx::IntPoint* aOutTopLeft = nullptr);

 /**
  * 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);
 static mozilla::gfx::Point CalculateBlurSigma(
     const mozilla::gfx::IntSize& aBlurRadius);

 /**
  * 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,
                           const RectCornerRadii* aCornerRadii,
                           const gfxPoint& aBlurStdDev,
                           const sRGBColor& 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 aShadowColor        The color of the blur.
  * @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::sRGBColor& aShadowColor,
                   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, bool aIsDestRect,
     const mozilla::gfx::sRGBColor& aShadowColor,
     const mozilla::gfx::IntSize& aBlurRadius,
     const RectCornerRadii* aInnerClipRadii, DrawTarget* aDestDrawTarget,
     bool aMirrorCorners);

 /**
  * The DrawTarget of the temporary alpha surface.
  */
 RefPtr<DrawTarget> mDrawTarget;

 /**
  * The temporary alpha surface.
  */
 uint8_t* mData = nullptr;

 /**
  * The object that actually does the blurring for us.
  */
 mozilla::gfx::GaussianBlur mBlur;
};

#endif /* GFX_BLUR_H */