The Tor Browser: gfx/thebes/gfxBlur.h@6474c204b198 (annotated)

gfx/thebes/gfxBlur.h@6474c204b198 (annotated)

gfx/thebes/gfxBlur.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- 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 "nsAutoPtr.h"
 #include "gfxPoint.h"
 #include "mozilla/RefPtr.h"
 class gfxContext;
 struct gfxRect;
 struct gfxRGBA;
 class gfxCornerSizes;
 class gfxMatrix;
 namespace mozilla {
   namespace gfx {
     class AlphaBoxBlur;
     class SourceSurface;
     class DrawTarget;
   }
 }
 /**
  * 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
 {
 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 gfxIntSize& aSpreadRadius,
                      const gfxIntSize& 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;
     }
     /**
      * 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 gfxIntSize 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,
                               gfxCornerSizes* aCornerRadii,
                               const gfxPoint& aBlurStdDev,
                               const gfxRGBA& aShadowColor,
                               const gfxRect& aDirtyRect,
                               const gfxRect& aSkipRect);
 protected:
     /**
      * The context of the temporary alpha surface.
      */
     nsRefPtr<gfxContext> mContext;
     /**
      * The temporary alpha surface.
      */
     nsAutoArrayPtr<unsigned char> mData;
      /**
       * The object that actually does the blurring for us.
       */
     mozilla::gfx::AlphaBoxBlur *mBlur;
 };
 #endif /* GFX_BLUR_H */

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gfx/thebes/gfxBlur.h@6474c204b198 (annotated)

gfx/thebes/gfxBlur.h