/* -*- Mode: C++; tab-width: 2; 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/. */ /* utility functions for drawing borders and backgrounds */ #ifndef nsCSSRendering_h___ #define nsCSSRendering_h___ #include "gfxBlur.h" #include "gfxContext.h" #include "nsLayoutUtils.h" #include "nsStyleStruct.h" #include "nsIFrame.h" class nsStyleContext; class nsPresContext; class nsRenderingContext; namespace mozilla { namespace layers { class ImageContainer; } // A CSSSizeOrRatio represents a (possibly partially specified) size for use // in computing image sizes. Either or both of the width and height might be // given. A ratio of width to height may also be given. If we at least two // of these then we can compute a concrete size, that is a width and height. struct CSSSizeOrRatio { CSSSizeOrRatio() : mRatio(0, 0) , mHasWidth(false) , mHasHeight(false) {} bool CanComputeConcreteSize() const { return mHasWidth + mHasHeight + HasRatio() >= 2; } bool IsConcrete() const { return mHasWidth && mHasHeight; } bool HasRatio() const { return mRatio.width > 0 && mRatio.height > 0; } bool IsEmpty() const { return (mHasWidth && mWidth <= 0) || (mHasHeight && mHeight <= 0) || mRatio.width <= 0 || mRatio.height <= 0; } // CanComputeConcreteSize must return true when ComputeConcreteSize is // called. nsSize ComputeConcreteSize() const; void SetWidth(nscoord aWidth) { mWidth = aWidth; mHasWidth = true; if (mHasHeight) { mRatio = nsSize(mWidth, mHeight); } } void SetHeight(nscoord aHeight) { mHeight = aHeight; mHasHeight = true; if (mHasWidth) { mRatio = nsSize(mWidth, mHeight); } } void SetSize(const nsSize& aSize) { mWidth = aSize.width; mHeight = aSize.height; mHasWidth = true; mHasHeight = true; mRatio = aSize; } void SetRatio(const nsSize& aRatio) { MOZ_ASSERT(!mHasWidth || !mHasHeight, "Probably shouldn't be setting a ratio if we have a concrete size"); mRatio = aRatio; } nsSize mRatio; nscoord mWidth; nscoord mHeight; bool mHasWidth; bool mHasHeight; }; } /** * This is a small wrapper class to encapsulate image drawing that can draw an * nsStyleImage image, which may internally be a real image, a sub image, or a * CSS gradient. * * @note Always call the member functions in the order of PrepareImage(), * SetSize(), and Draw*(). */ class nsImageRenderer { public: typedef mozilla::layers::LayerManager LayerManager; typedef mozilla::layers::ImageContainer ImageContainer; enum { FLAG_SYNC_DECODE_IMAGES = 0x01, FLAG_PAINTING_TO_WINDOW = 0x02 }; enum FitType { CONTAIN, COVER }; nsImageRenderer(nsIFrame* aForFrame, const nsStyleImage* aImage, uint32_t aFlags); ~nsImageRenderer(); /** * Populates member variables to get ready for rendering. * @return true iff the image is ready, and there is at least a pixel to * draw. */ bool PrepareImage(); /** * The three Compute*Size functions correspond to the sizing algorthms and * definitions from the CSS Image Values and Replaced Content spec. See * http://dev.w3.org/csswg/css-images-3/#sizing . */ /** * Compute the intrinsic size of the image as defined in the CSS Image Values * spec. The intrinsic size is the unscaled size which the image would ideally * like to be in app units. */ mozilla::CSSSizeOrRatio ComputeIntrinsicSize(); /** * Compute the size of the rendered image using either the 'cover' or * 'contain' constraints (aFitType). * aIntrinsicRatio may be an invalid ratio, that is one or both of its * dimensions can be less than or equal to zero. */ static nsSize ComputeConstrainedSize(const nsSize& aConstrainingSize, const nsSize& aIntrinsicRatio, FitType aFitType); /** * Compute the size of the rendered image (the concrete size) where no cover/ * contain constraints are given. The 'default algorithm' from the CSS Image * Values spec. */ static nsSize ComputeConcreteSize(const mozilla::CSSSizeOrRatio& aSpecifiedSize, const mozilla::CSSSizeOrRatio& aIntrinsicSize, const nsSize& aDefaultSize); /** * Set this image's preferred size. This will be its intrinsic size where * specified and the default size where it is not. Used as the unscaled size * when rendering the image. */ void SetPreferredSize(const mozilla::CSSSizeOrRatio& aIntrinsicSize, const nsSize& aDefaultSize); /** * Draws the image to the target rendering context. * aSrc is a rect on the source image which will be mapped to aDest. * @see nsLayoutUtils::DrawImage() for other parameters. */ void Draw(nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, const nsRect& aDirtyRect, const nsRect& aFill, const nsRect& aDest, const mozilla::CSSIntRect& aSrc); /** * Draws the image to the target rendering context using background-specific * arguments. * @see nsLayoutUtils::DrawImage() for parameters. */ void DrawBackground(nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, const nsRect& aDest, const nsRect& aFill, const nsPoint& aAnchor, const nsRect& aDirty); /** * Draw the image to a single component of a border-image style rendering. * aFill The destination rect to be drawn into * aSrc is the part of the image to be rendered into a tile (aUnitSize in * aFill), if aSrc and the dest tile are different sizes, the image will be * scaled to map aSrc onto the dest tile. * aHFill and aVFill are the repeat patterns for the component - * NS_STYLE_BORDER_IMAGE_REPEAT_* * aUnitSize The scaled size of a single source rect (in destination coords) * aIndex identifies the component: 0 1 2 * 3 4 5 * 6 7 8 */ void DrawBorderImageComponent(nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, const nsRect& aDirtyRect, const nsRect& aFill, const mozilla::CSSIntRect& aSrc, uint8_t aHFill, uint8_t aVFill, const nsSize& aUnitSize, uint8_t aIndex); bool IsRasterImage(); bool IsAnimatedImage(); already_AddRefed GetContainer(LayerManager* aManager); bool IsReady() { return mIsReady; } private: /** * Helper method for creating a gfxDrawable from mPaintServerFrame or * mImageElementSurface. * Requires mType is eStyleImageType_Element. * Returns null if we cannot create the drawable. */ already_AddRefed DrawableForElement(const nsRect& aImageRect, nsRenderingContext& aRenderingContext); nsIFrame* mForFrame; const nsStyleImage* mImage; nsStyleImageType mType; nsCOMPtr mImageContainer; nsRefPtr mGradientData; nsIFrame* mPaintServerFrame; nsLayoutUtils::SurfaceFromElementResult mImageElementSurface; bool mIsReady; nsSize mSize; // unscaled size of the image, in app units uint32_t mFlags; }; /** * A struct representing all the information needed to paint a background * image to some target, taking into account all CSS background-* properties. * See PrepareBackgroundLayer. */ struct nsBackgroundLayerState { /** * @param aFlags some combination of nsCSSRendering::PAINTBG_* flags */ nsBackgroundLayerState(nsIFrame* aForFrame, const nsStyleImage* aImage, uint32_t aFlags) : mImageRenderer(aForFrame, aImage, aFlags), mCompositingOp(gfxContext::OPERATOR_OVER) {} /** * The nsImageRenderer that will be used to draw the background. */ nsImageRenderer mImageRenderer; /** * A rectangle that one copy of the image tile is mapped onto. Same * coordinate system as aBorderArea/aBGClipRect passed into * PrepareBackgroundLayer. */ nsRect mDestArea; /** * The actual rectangle that should be filled with (complete or partial) * image tiles. Same coordinate system as aBorderArea/aBGClipRect passed into * PrepareBackgroundLayer. */ nsRect mFillArea; /** * The anchor point that should be snapped to a pixel corner. Same * coordinate system as aBorderArea/aBGClipRect passed into * PrepareBackgroundLayer. */ nsPoint mAnchor; /** * The compositing operation that the image should use */ gfxContext::GraphicsOperator mCompositingOp; }; struct nsCSSRendering { typedef nsIFrame::Sides Sides; /** * Initialize any static variables used by nsCSSRendering. */ static void Init(); /** * Clean up any static variables used by nsCSSRendering. */ static void Shutdown(); static void PaintBoxShadowInner(nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, nsIFrame* aForFrame, const nsRect& aFrameArea, const nsRect& aDirtyRect); static void PaintBoxShadowOuter(nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, nsIFrame* aForFrame, const nsRect& aFrameArea, const nsRect& aDirtyRect, float aOpacity = 1.0); static void ComputePixelRadii(const nscoord *aAppUnitsRadii, nscoord aAppUnitsPerPixel, gfxCornerSizes *oBorderRadii); /** * Render the border for an element using css rendering rules * for borders. aSkipSides says which sides to skip * when rendering, the default is to skip none. */ static void PaintBorder(nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, nsIFrame* aForFrame, const nsRect& aDirtyRect, const nsRect& aBorderArea, nsStyleContext* aStyleContext, Sides aSkipSides = Sides()); /** * Like PaintBorder, but taking an nsStyleBorder argument instead of * getting it from aStyleContext. aSkipSides says which sides to skip * when rendering, the default is to skip none. */ static void PaintBorderWithStyleBorder(nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, nsIFrame* aForFrame, const nsRect& aDirtyRect, const nsRect& aBorderArea, const nsStyleBorder& aBorderStyle, nsStyleContext* aStyleContext, Sides aSkipSides = Sides()); /** * Render the outline for an element using css rendering rules * for borders. */ static void PaintOutline(nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, nsIFrame* aForFrame, const nsRect& aDirtyRect, const nsRect& aBorderArea, nsStyleContext* aStyleContext); /** * Render keyboard focus on an element. * |aFocusRect| is the outer rectangle of the focused element. * Uses a fixed style equivalent to "1px dotted |aColor|". * Not used for controls, because the native theme may differ. */ static void PaintFocus(nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, const nsRect& aFocusRect, nscolor aColor); /** * Render a gradient for an element. * aDest is the rect for a single tile of the gradient on the destination. * aFill is the rect on the destination to be covered by repeated tiling of * the gradient. * aSrc is the part of the gradient to be rendered into a tile (aDest), if * aSrc and aDest are different sizes, the image will be scaled to map aSrc * onto aDest. * aIntrinsicSize is the size of the source gradient. */ static void PaintGradient(nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, nsStyleGradient* aGradient, const nsRect& aDirtyRect, const nsRect& aDest, const nsRect& aFill, const mozilla::CSSIntRect& aSrc, const nsSize& aIntrinsiceSize); /** * Find the frame whose background style should be used to draw the * canvas background. aForFrame must be the frame for the root element * whose background style should be used. This function will return * aForFrame unless the background should be propagated, in * which case we return the frame associated with the 's background. */ static nsIFrame* FindBackgroundStyleFrame(nsIFrame* aForFrame); /** * @return true if |aFrame| is a canvas frame, in the CSS sense. */ static bool IsCanvasFrame(nsIFrame* aFrame); /** * Fill in an aBackgroundSC to be used to paint the background * for an element. This applies the rules for propagating * backgrounds between BODY, the root element, and the canvas. * @return true if there is some meaningful background. */ static bool FindBackground(nsIFrame* aForFrame, nsStyleContext** aBackgroundSC); /** * As FindBackground, but the passed-in frame is known to be a root frame * (returned from nsCSSFrameConstructor::GetRootElementStyleFrame()) * and there is always some meaningful background returned. */ static nsStyleContext* FindRootFrameBackground(nsIFrame* aForFrame); /** * Returns background style information for the canvas. * * @param aForFrame * the frame used to represent the canvas, in the CSS sense (i.e. * nsCSSRendering::IsCanvasFrame(aForFrame) must be true) * @param aRootElementFrame * the frame representing the root element of the document * @param aBackground * contains background style information for the canvas on return */ static nsStyleContext* FindCanvasBackground(nsIFrame* aForFrame, nsIFrame* aRootElementFrame) { NS_ABORT_IF_FALSE(IsCanvasFrame(aForFrame), "not a canvas frame"); if (aRootElementFrame) return FindRootFrameBackground(aRootElementFrame); // This should always give transparent, so we'll fill it in with the // default color if needed. This seems to happen a bit while a page is // being loaded. return aForFrame->StyleContext(); } /** * Find a frame which draws a non-transparent background, * for various table-related and HR-related backwards-compatibility hacks. * This function will also stop if it finds themed frame which might draw * background. * * Be very hesitant if you're considering calling this function -- it's * usually not what you want. */ static nsIFrame* FindNonTransparentBackgroundFrame(nsIFrame* aFrame, bool aStartAtParent = false); /** * Determine the background color to draw taking into account print settings. */ static nscolor DetermineBackgroundColor(nsPresContext* aPresContext, nsStyleContext* aStyleContext, nsIFrame* aFrame, bool& aDrawBackgroundImage, bool& aDrawBackgroundColor); static nsRect ComputeBackgroundPositioningArea(nsPresContext* aPresContext, nsIFrame* aForFrame, const nsRect& aBorderArea, const nsStyleBackground::Layer& aLayer, nsIFrame** aAttachedToFrame); static nsBackgroundLayerState PrepareBackgroundLayer(nsPresContext* aPresContext, nsIFrame* aForFrame, uint32_t aFlags, const nsRect& aBorderArea, const nsRect& aBGClipRect, const nsStyleBackground::Layer& aLayer); /** * Render the background for an element using css rendering rules * for backgrounds. */ enum { /** * When this flag is passed, the element's nsDisplayBorder will be * painted immediately on top of this background. */ PAINTBG_WILL_PAINT_BORDER = 0x01, /** * When this flag is passed, images are synchronously decoded. */ PAINTBG_SYNC_DECODE_IMAGES = 0x02, /** * When this flag is passed, painting will go to the screen so we can * take advantage of the fact that it will be clipped to the viewport. */ PAINTBG_TO_WINDOW = 0x04 }; static void PaintBackground(nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, nsIFrame* aForFrame, const nsRect& aDirtyRect, const nsRect& aBorderArea, uint32_t aFlags, nsRect* aBGClipRect = nullptr, int32_t aLayer = -1); static void PaintBackgroundColor(gfxRGBA aColor, nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, nsIFrame* aForFrame, const nsRect& aDirtyRect, const nsRect& aBorderArea, uint32_t aFlags); /** * Same as |PaintBackground|, except using the provided style structs. * This short-circuits the code that ensures that the root element's * background is drawn on the canvas. * The aLayer parameter allows you to paint a single layer of the background. * The default value for aLayer, -1, means that all layers will be painted. * The background color will only be painted if the back-most layer is also * being painted. */ static void PaintBackgroundWithSC(nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, nsIFrame* aForFrame, const nsRect& aDirtyRect, const nsRect& aBorderArea, nsStyleContext *aStyleContext, const nsStyleBorder& aBorder, uint32_t aFlags, nsRect* aBGClipRect = nullptr, int32_t aLayer = -1); static void PaintBackgroundColorWithSC(gfxRGBA aColor, nsPresContext* aPresContext, nsRenderingContext& aRenderingContext, nsIFrame* aForFrame, const nsRect& aDirtyRect, const nsRect& aBorderArea, nsStyleContext *aStyleContext, const nsStyleBorder& aBorder, uint32_t aFlags); /** * Returns the rectangle covered by the given background layer image, taking * into account background positioning, sizing, and repetition, but not * clipping. */ static nsRect GetBackgroundLayerRect(nsPresContext* aPresContext, nsIFrame* aForFrame, const nsRect& aBorderArea, const nsRect& aClipRect, const nsStyleBackground::Layer& aLayer, uint32_t aFlags); /** * Checks if image in layer aLayer of aBackground is currently decoded. */ static bool IsBackgroundImageDecodedForStyleContextAndLayer( const nsStyleBackground *aBackground, uint32_t aLayer); /** * Checks if all images that are part of the background for aFrame are * currently decoded. */ static bool AreAllBackgroundImagesDecodedForFrame(nsIFrame* aFrame); /** * Called when we start creating a display list. The frame tree will not * change until a matching EndFrameTreeLocked is called. */ static void BeginFrameTreesLocked(); /** * Called when we've finished using a display list. When all * BeginFrameTreeLocked calls have been balanced by an EndFrameTreeLocked, * the frame tree may start changing again. */ static void EndFrameTreesLocked(); // Draw a border segment in the table collapsing border model without // beveling corners static void DrawTableBorderSegment(nsRenderingContext& aContext, uint8_t aBorderStyle, nscolor aBorderColor, const nsStyleBackground* aBGColor, const nsRect& aBorderRect, int32_t aAppUnitsPerCSSPixel, uint8_t aStartBevelSide = 0, nscoord aStartBevelOffset = 0, uint8_t aEndBevelSide = 0, nscoord aEndBevelOffset = 0); /** * Function for painting the decoration lines for the text. * NOTE: aPt, aLineSize, aAscent and aOffset are non-rounded device pixels, * not app units. * input: * @param aFrame the frame which needs the decoration line * @param aGfxContext * @param aDirtyRect no need to paint outside this rect * @param aColor the color of the decoration line * @param aPt the top/left edge of the text * @param aXInFrame the distance between aPt.x and left edge of * aFrame. If the decoration line is for shadow, * set the distance between the left edge of * the aFrame and the position of the text as * positioned without offset of the shadow. * @param aLineSize the width and the height of the decoration * line * @param aAscent the ascent of the text * @param aOffset the offset of the decoration line from * the baseline of the text (if the value is * positive, the line is lifted up) * @param aDecoration which line will be painted. The value can be * NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE or * NS_STYLE_TEXT_DECORATION_LINE_OVERLINE or * NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH. * @param aStyle the style of the decoration line such as * NS_STYLE_TEXT_DECORATION_STYLE_*. * @param aDescentLimit If aDescentLimit is zero or larger and the * underline overflows from the descent space, * the underline should be lifted up as far as * possible. Note that this does not mean the * underline never overflows from this * limitation. Because if the underline is * positioned to the baseline or upper, it causes * unreadability. Note that if this is zero * or larger, the underline rect may be shrunken * if it's possible. Therefore, this value is * used for strikeout line and overline too. */ static void PaintDecorationLine(nsIFrame* aFrame, gfxContext* aGfxContext, const gfxRect& aDirtyRect, const nscolor aColor, const gfxPoint& aPt, const gfxFloat aXInFrame, const gfxSize& aLineSize, const gfxFloat aAscent, const gfxFloat aOffset, const uint8_t aDecoration, const uint8_t aStyle, const gfxFloat aDescentLimit = -1.0); /** * Adds a path corresponding to the outline of the decoration line to * the specified context. Arguments have the same meaning as for * PaintDecorationLine. Currently this only works for solid * decorations; for other decoration styles, an empty path is added * to the context. */ static void DecorationLineToPath(nsIFrame* aFrame, gfxContext* aGfxContext, const gfxRect& aDirtyRect, const nscolor aColor, const gfxPoint& aPt, const gfxFloat aXInFrame, const gfxSize& aLineSize, const gfxFloat aAscent, const gfxFloat aOffset, const uint8_t aDecoration, const uint8_t aStyle, const gfxFloat aDescentLimit = -1.0); /** * Function for getting the decoration line rect for the text. * NOTE: aLineSize, aAscent and aOffset are non-rounded device pixels, * not app units. * input: * @param aPresContext * @param aLineSize the width and the height of the decoration * line * @param aAscent the ascent of the text * @param aOffset the offset of the decoration line from * the baseline of the text (if the value is * positive, the line is lifted up) * @param aDecoration which line will be painted. The value can be * NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE or * NS_STYLE_TEXT_DECORATION_LINE_OVERLINE or * NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH. * @param aStyle the style of the decoration line such as * NS_STYLE_TEXT_DECORATION_STYLE_*. * @param aDescentLimit If aDescentLimit is zero or larger and the * underline overflows from the descent space, * the underline should be lifted up as far as * possible. Note that this does not mean the * underline never overflows from this * limitation. Because if the underline is * positioned to the baseline or upper, it causes * unreadability. Note that if this is zero * or larger, the underline rect may be shrunken * if it's possible. Therefore, this value is * used for strikeout line and overline too. * output: * @return the decoration line rect for the input, * the each values are app units. */ static nsRect GetTextDecorationRect(nsPresContext* aPresContext, const gfxSize& aLineSize, const gfxFloat aAscent, const gfxFloat aOffset, const uint8_t aDecoration, const uint8_t aStyle, const gfxFloat aDescentLimit = -1.0); static gfxContext::GraphicsOperator GetGFXBlendMode(uint8_t mBlendMode) { switch (mBlendMode) { case NS_STYLE_BLEND_NORMAL: return gfxContext::OPERATOR_OVER; case NS_STYLE_BLEND_MULTIPLY: return gfxContext::OPERATOR_MULTIPLY; case NS_STYLE_BLEND_SCREEN: return gfxContext::OPERATOR_SCREEN; case NS_STYLE_BLEND_OVERLAY: return gfxContext::OPERATOR_OVERLAY; case NS_STYLE_BLEND_DARKEN: return gfxContext::OPERATOR_DARKEN; case NS_STYLE_BLEND_LIGHTEN: return gfxContext::OPERATOR_LIGHTEN; case NS_STYLE_BLEND_COLOR_DODGE: return gfxContext::OPERATOR_COLOR_DODGE; case NS_STYLE_BLEND_COLOR_BURN: return gfxContext::OPERATOR_COLOR_BURN; case NS_STYLE_BLEND_HARD_LIGHT: return gfxContext::OPERATOR_HARD_LIGHT; case NS_STYLE_BLEND_SOFT_LIGHT: return gfxContext::OPERATOR_SOFT_LIGHT; case NS_STYLE_BLEND_DIFFERENCE: return gfxContext::OPERATOR_DIFFERENCE; case NS_STYLE_BLEND_EXCLUSION: return gfxContext::OPERATOR_EXCLUSION; case NS_STYLE_BLEND_HUE: return gfxContext::OPERATOR_HUE; case NS_STYLE_BLEND_SATURATION: return gfxContext::OPERATOR_SATURATION; case NS_STYLE_BLEND_COLOR: return gfxContext::OPERATOR_COLOR; case NS_STYLE_BLEND_LUMINOSITY: return gfxContext::OPERATOR_LUMINOSITY; default: MOZ_ASSERT(false); return gfxContext::OPERATOR_OVER; } return gfxContext::OPERATOR_OVER; } protected: static gfxRect GetTextDecorationRectInternal(const gfxPoint& aPt, const gfxSize& aLineSize, const gfxFloat aAscent, const gfxFloat aOffset, const uint8_t aDecoration, const uint8_t aStyle, const gfxFloat aDscentLimit); /** * Returns inflated rect for painting a decoration line. * Complex style decoration lines should be painted from leftmost of nearest * ancestor block box because that makes better look of connection of lines * for different nodes. ExpandPaintingRectForDecorationLine() returns * a rect for actual painting rect for the clipped rect. * * input: * @param aFrame the frame which needs the decoration line. * @param aStyle the style of the complex decoration line * NS_STYLE_TEXT_DECORATION_STYLE_DOTTED or * NS_STYLE_TEXT_DECORATION_STYLE_DASHED or * NS_STYLE_TEXT_DECORATION_STYLE_WAVY. * @param aClippedRect the clipped rect for the decoration line. * in other words, visible area of the line. * @param aXInFrame the distance between left edge of aFrame and * aClippedRect.pos.x. * @param aCycleLength the width of one cycle of the line style. */ static gfxRect ExpandPaintingRectForDecorationLine( nsIFrame* aFrame, const uint8_t aStyle, const gfxRect &aClippedRect, const gfxFloat aXInFrame, const gfxFloat aCycleLength); }; /* * nsContextBoxBlur * Creates an 8-bit alpha channel context for callers to draw in, blurs the * contents of that context and applies it as a 1-color mask on a * different existing context. Uses gfxAlphaBoxBlur as its back end. * * You must call Init() first to create a suitable temporary surface to draw * on. You must then draw any desired content onto the given context, then * call DoPaint() to apply the blurred content as a single-color mask. You * can only call Init() once, so objects cannot be reused. * * This is very useful for creating drop shadows or silhouettes. */ class nsContextBoxBlur { public: enum { FORCE_MASK = 0x01 }; /** * Prepares a gfxContext to draw on. Do not call this twice; if you want * to get the gfxContext again use GetContext(). * * @param aRect The coordinates of the surface to create. * All coordinates must be in app units. * This must not include the blur radius, pass * it as the second parameter and everything * is taken care of. * * @param aBlurRadius The blur radius in app units. * * @param aAppUnitsPerDevPixel The number of app units in a device pixel, * for conversion. Most of the time you'll * pass this from the current PresContext if * available. * * @param aDestinationCtx The graphics context to apply the blurred * mask to when you call DoPaint(). Make sure * it is not destroyed before you call * DoPaint(). To set the color of the * resulting blurred graphic mask, you must * set the color on this context before * calling Init(). * * @param aDirtyRect The absolute dirty rect in app units. Used to * optimize the temporary surface size and speed up blur. * * @param aSkipRect An area in device pixels (NOT app units!) to avoid * blurring over, to prevent unnecessary work. * * @param aFlags FORCE_MASK to ensure that the content drawn to the * returned gfxContext is used as a mask, and not * drawn directly to aDestinationCtx. * * @return A blank 8-bit alpha-channel-only graphics context to * draw on, or null on error. Must not be freed. The * context has a device offset applied to it given by * aRect. This means you can use coordinates as if it * were at the desired position at aRect and you don't * need to worry about translating any coordinates to * draw on this temporary surface. * * If aBlurRadius is 0, the returned context is aDestinationCtx and * DoPaint() does nothing, because no blurring is required. Therefore, you * should prepare the destination context as if you were going to draw * directly on it instead of any temporary surface created in this class. */ gfxContext* Init(const nsRect& aRect, nscoord aSpreadRadius, nscoord aBlurRadius, int32_t aAppUnitsPerDevPixel, gfxContext* aDestinationCtx, const nsRect& aDirtyRect, const gfxRect* aSkipRect, uint32_t aFlags = 0); /** * Does the actual blurring and mask applying. Users of this object *must* * have called Init() first, then have drawn whatever they want to be * blurred onto the internal gfxContext before calling this. */ void DoPaint(); /** * Gets the internal gfxContext at any time. Must not be freed. Avoid * calling this before calling Init() since the context would not be * constructed at that point. */ gfxContext* GetContext(); /** * Get the margin associated with the given blur radius, i.e., the * additional area that might be painted as a result of it. (The * margin for a spread radius is itself, on all sides.) */ static nsMargin GetBlurRadiusMargin(nscoord aBlurRadius, int32_t aAppUnitsPerDevPixel); /** * Blurs a coloured rectangle onto aDestinationCtx. This is equivalent * to calling Init(), drawing a rectangle onto the returned surface * and then calling DoPaint, but may let us optimize better in the * backend. * * @param aDestinationCtx The destination to blur to. * @param aRect The rectangle to blur in app units. * @param aAppUnitsPerDevPixel The number of app units in a device pixel, * for conversion. Most of the time you'll * pass this from the current PresContext if * available. * @param aCornerRadii Corner radii for aRect, if it is a rounded * rectangle. * @param aBlurRadius The blur radius in app units. * @param aShadowColor The color to draw the blurred shadow. * @param aDirtyRect The absolute dirty rect in app units. Used to * optimize the temporary surface size and speed up blur. * @param aSkipRect An area in device pixels (NOT app units!) to avoid * blurring over, to prevent unnecessary work. */ static void BlurRectangle(gfxContext* aDestinationCtx, const nsRect& aRect, int32_t aAppUnitsPerDevPixel, gfxCornerSizes* aCornerRadii, nscoord aBlurRadius, const gfxRGBA& aShadowColor, const nsRect& aDirtyRect, const gfxRect& aSkipRect); protected: gfxAlphaBoxBlur blur; nsRefPtr mContext; gfxContext* mDestinationCtx; /* This is true if the blur already has it's content transformed * by mDestinationCtx's transform */ bool mPreTransformed; }; #endif /* nsCSSRendering_h___ */