gecko-dev/layout/base/nsCSSRendering.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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*
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/* utility functions for drawing borders and backgrounds */
#ifndef nsCSSRendering_h___
#define nsCSSRendering_h___
#include "nsStyleConsts.h"
#include "gfxBlur.h"
#include "gfxContext.h"
#include "gfxImageSurface.h"
struct nsPoint;
class nsStyleContext;
class nsPresContext;
class nsRenderingContext;
struct nsCSSRendering {
/**
* 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);
static void ComputePixelRadii(const nscoord *aAppUnitsRadii,
nscoord aAppUnitsPerPixel,
gfxCornerSizes *oBorderRadii);
/**
* Render the border for an element using css rendering rules
* for borders. aSkipSides is a bitmask of the sides to skip
* when rendering. If 0 then no sides are skipped.
*/
static void PaintBorder(nsPresContext* aPresContext,
nsRenderingContext& aRenderingContext,
nsIFrame* aForFrame,
const nsRect& aDirtyRect,
const nsRect& aBorderArea,
nsStyleContext* aStyleContext,
PRIntn aSkipSides = 0);
/**
* Like PaintBorder, but taking an nsStyleBorder argument instead of
* getting it from aStyleContext.
*/
static void PaintBorderWithStyleBorder(nsPresContext* aPresContext,
nsRenderingContext& aRenderingContext,
nsIFrame* aForFrame,
const nsRect& aDirtyRect,
const nsRect& aBorderArea,
const nsStyleBorder& aBorderStyle,
nsStyleContext* aStyleContext,
PRIntn aSkipSides = 0);
/**
* Render the outline for an element using css rendering rules
* for borders. aSkipSides is a bitmask of the sides to skip
* when rendering. If 0 then no sides are skipped.
*/
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.
*/
static void PaintGradient(nsPresContext* aPresContext,
nsRenderingContext& aRenderingContext,
nsStyleGradient* aGradient,
const nsRect& aDirtyRect,
const nsRect& aOneCellArea,
const nsRect& aFillArea);
/**
* 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 <body> background should be propagated, in
* which case we return the frame associated with the <body>'s background.
*/
static nsIFrame* FindBackgroundStyleFrame(nsIFrame* aForFrame);
/**
* @return PR_TRUE if |aFrame| is a canvas frame, in the CSS sense.
*/
static PRBool 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 PR_TRUE if there is some meaningful background.
*/
static PRBool FindBackground(nsPresContext* aPresContext,
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->GetStyleContext();
}
/**
* 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,
PRBool aStartAtParent = PR_FALSE);
/**
* Determine the background color to draw taking into account print settings.
*/
static nscolor
DetermineBackgroundColor(nsPresContext* aPresContext,
nsStyleContext* aStyleContext,
nsIFrame* aFrame);
/**
* 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,
PRUint32 aFlags,
nsRect* aBGClipRect = nsnull);
/**
* 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.
*/
static void PaintBackgroundWithSC(nsPresContext* aPresContext,
nsRenderingContext& aRenderingContext,
nsIFrame* aForFrame,
const nsRect& aDirtyRect,
const nsRect& aBorderArea,
nsStyleContext *aStyleContext,
const nsStyleBorder& aBorder,
PRUint32 aFlags,
nsRect* aBGClipRect = nsnull);
/**
* 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 nsStyleBackground& aBackground,
const nsStyleBackground::Layer& aLayer);
/**
* Called by the presShell when painting is finished, so we can clear our
* inline background data cache.
*/
static void DidPaint();
// Draw a border segment in the table collapsing border model without
// beveling corners
static void DrawTableBorderSegment(nsRenderingContext& aContext,
PRUint8 aBorderStyle,
nscolor aBorderColor,
const nsStyleBackground* aBGColor,
const nsRect& aBorderRect,
PRInt32 aAppUnitsPerCSSPixel,
PRUint8 aStartBevelSide = 0,
nscoord aStartBevelOffset = 0,
PRUint8 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 aGfxContext
* @param aColor the color of the decoration line
* @param aPt the top/left edge of the text
* @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(gfxContext* aGfxContext,
const nscolor aColor,
const gfxPoint& aPt,
const gfxSize& aLineSize,
const gfxFloat aAscent,
const gfxFloat aOffset,
const PRUint8 aDecoration,
const PRUint8 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 PRUint8 aDecoration,
const PRUint8 aStyle,
const gfxFloat aDescentLimit = -1.0);
protected:
static gfxRect GetTextDecorationRectInternal(const gfxPoint& aPt,
const gfxSize& aLineSize,
const gfxFloat aAscent,
const gfxFloat aOffset,
const PRUint8 aDecoration,
const PRUint8 aStyle,
const gfxFloat aDscentLimit);
};
/*
* 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,
PRInt32 aAppUnitsPerDevPixel, gfxContext* aDestinationCtx,
const nsRect& aDirtyRect, const gfxRect* aSkipRect,
PRUint32 aFlags = 0);
/**
* Does the actual blurring/spreading. 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 DoEffects();
/**
* 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,
PRInt32 aAppUnitsPerDevPixel);
protected:
gfxAlphaBoxBlur blur;
nsRefPtr<gfxContext> mContext;
gfxContext* mDestinationCtx;
};
#endif /* nsCSSRendering_h___ */