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/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrReducedClip_DEFINED
#define GrReducedClip_DEFINED
#include "GrWindowRectangles.h"
#include "SkClipStack.h"
#include "SkTLList.h"
class GrContext;
class GrRenderTargetContext;
/**
* This class takes a clip stack and produces a reduced set of elements that are equivalent to
* applying that full stack within a specified query rectangle.
*/
class SK_API GrReducedClip {
public:
using Element = SkClipStack::Element;
using ElementList = SkTLList<SkClipStack::Element, 16>;
GrReducedClip(const SkClipStack&, const SkRect& queryBounds, int maxWindowRectangles = 0);
/**
* If hasScissor() is true, the clip mask is not valid outside this rect and the caller must
* enforce this scissor during draw.
*/
const SkIRect& scissor() const { SkASSERT(fHasScissor); return fScissor; }
int left() const { return this->scissor().left(); }
int top() const { return this->scissor().top(); }
int width() const { return this->scissor().width(); }
int height() const { return this->scissor().height(); }
/**
* Indicates whether scissor() is defined. It will always be defined if the maskElements() are
* nonempty.
*/
bool hasScissor() const { return fHasScissor; }
/**
* If nonempty, the clip mask is not valid inside these windows and the caller must clip them
* out using the window rectangles GPU extension.
*/
const GrWindowRectangles& windowRectangles() const { return fWindowRects; }
/**
* An ordered list of clip elements that could not be skipped or implemented by other means. If
* nonempty, the caller must create an alpha and/or stencil mask for these elements and apply it
* during draw.
*/
const ElementList& maskElements() const { return fMaskElements; }
/**
* If maskElements() are nonempty, uniquely identifies the region of the clip mask that falls
* inside of scissor().
* NOTE: since clip elements might fall outside the query bounds, different regions of the same
* clip stack might have more or less restrictive IDs.
* FIXME: this prevents us from reusing a sub-rect of a perfectly good mask when that rect has
* been assigned a less restrictive ID.
*/
uint32_t maskGenID() const { SkASSERT(!fMaskElements.isEmpty()); return fMaskGenID; }
/**
* Indicates whether antialiasing is required to process any of the mask elements.
*/
bool maskRequiresAA() const { SkASSERT(!fMaskElements.isEmpty()); return fMaskRequiresAA; }
enum class InitialState : bool {
kAllIn,
kAllOut
};
InitialState initialState() const { return fInitialState; }
bool drawAlphaClipMask(GrRenderTargetContext*) const;
bool drawStencilClipMask(GrContext*, GrRenderTargetContext*) const;
private:
void walkStack(const SkClipStack&, const SkRect& queryBounds, int maxWindowRectangles);
enum class ClipResult {
kNotClipped,
kClipped,
kMadeEmpty
};
// Clips the the given element's interior out of the final clip.
// NOTE: do not call for elements followed by ops that can grow the clip.
ClipResult clipInsideElement(const Element* element);
// Clips the the given element's exterior out of the final clip.
// NOTE: do not call for elements followed by ops that can grow the clip.
ClipResult clipOutsideElement(const Element* element, int maxWindowRectangles);
void addWindowRectangle(const SkRect& elementInteriorRect, bool elementIsAA);
void makeEmpty();
SkIRect fScissor;
bool fHasScissor;
SkRect fAAClipRect;
uint32_t fAAClipRectGenID; // GenID the mask will have if includes the AA clip rect.
GrWindowRectangles fWindowRects;
ElementList fMaskElements;
uint32_t fMaskGenID;
bool fMaskRequiresAA;
InitialState fInitialState;
};
#endif
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