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/*
* Copyright 2010 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrClip_DEFINED
#define GrClip_DEFINED
#include "GrAppliedClip.h"
#include "GrRenderTargetContext.h"
#include "SkRRect.h"
#include "SkRect.h"
class GrContext;
/**
* GrClip is an abstract base class for applying a clip. It constructs a clip mask if necessary, and
* fills out a GrAppliedClip instructing the caller on how to set up the draw state.
*/
class GrClip {
public:
virtual bool quickContains(const SkRect&) const = 0;
virtual bool quickContains(const SkRRect& rrect) const {
return this->quickContains(rrect.getBounds());
}
virtual void getConservativeBounds(int width, int height, SkIRect* devResult,
bool* isIntersectionOfRects = nullptr) const = 0;
/**
* This computes a GrAppliedClip from the clip which in turn can be used to build a GrPipeline.
* To determine the appropriate clipping implementation the GrClip subclass must know whether
* the draw will enable HW AA or uses the stencil buffer. On input 'bounds' is a conservative
* bounds of the draw that is to be clipped. After return 'bounds' has been intersected with a
* conservative bounds of the clip. A return value of false indicates that the draw can be
* skipped as it is fully clipped out.
*/
virtual bool apply(GrContext*, GrRenderTargetContext*, bool useHWAA,
bool hasUserStencilSettings, GrAppliedClip*, SkRect* bounds) const = 0;
virtual ~GrClip() {}
/**
* This method quickly and conservatively determines whether the entire clip is equivalent to
* intersection with a rrect. This will only return true if the rrect does not fully contain
* the render target bounds. Moreover, the returned rrect need not be contained by the render
* target bounds. We assume all draws will be implicitly clipped by the render target bounds.
*
* @param rtBounds The bounds of the render target that the clip will be applied to.
* @param rrect If return is true rrect will contain the rrect equivalent to the clip within
* rtBounds.
* @param aa If return is true aa will indicate whether the rrect clip is antialiased.
* @return true if the clip is equivalent to a single rrect, false otherwise.
*
*/
virtual bool isRRect(const SkRect& rtBounds, SkRRect* rrect, GrAA* aa) const = 0;
/**
* This is the maximum distance that a draw may extend beyond a clip's boundary and still count
* count as "on the other side". We leave some slack because floating point rounding error is
* likely to blame. The rationale for 1e-3 is that in the coverage case (and barring unexpected
* rounding), as long as coverage stays within 0.5 * 1/256 of its intended value it shouldn't
* have any effect on the final pixel values.
*/
constexpr static SkScalar kBoundsTolerance = 1e-3f;
/**
* Returns true if the given query bounds count as entirely inside the clip.
*
* @param innerClipBounds device-space rect contained by the clip (SkRect or SkIRect).
* @param queryBounds device-space bounds of the query region.
*/
template <typename TRect>
constexpr static bool IsInsideClip(const TRect& innerClipBounds, const SkRect& queryBounds) {
return innerClipBounds.fRight > innerClipBounds.fLeft + kBoundsTolerance &&
innerClipBounds.fBottom > innerClipBounds.fTop + kBoundsTolerance &&
innerClipBounds.fLeft < queryBounds.fLeft + kBoundsTolerance &&
innerClipBounds.fTop < queryBounds.fTop + kBoundsTolerance &&
innerClipBounds.fRight > queryBounds.fRight - kBoundsTolerance &&
innerClipBounds.fBottom > queryBounds.fBottom - kBoundsTolerance;
}
/**
* Returns true if the given query bounds count as entirely outside the clip.
*
* @param outerClipBounds device-space rect that contains the clip (SkRect or SkIRect).
* @param queryBounds device-space bounds of the query region.
*/
template <typename TRect>
constexpr static bool IsOutsideClip(const TRect& outerClipBounds, const SkRect& queryBounds) {
return
// Is the clip so small that it is effectively empty?
outerClipBounds.fRight - outerClipBounds.fLeft <= kBoundsTolerance ||
outerClipBounds.fBottom - outerClipBounds.fTop <= kBoundsTolerance ||
// Are the query bounds effectively outside the clip?
outerClipBounds.fLeft >= queryBounds.fRight - kBoundsTolerance ||
outerClipBounds.fTop >= queryBounds.fBottom - kBoundsTolerance ||
outerClipBounds.fRight <= queryBounds.fLeft + kBoundsTolerance ||
outerClipBounds.fBottom <= queryBounds.fTop + kBoundsTolerance;
}
/**
* Returns the minimal integer rect that counts as containing a given set of bounds.
*/
static SkIRect GetPixelIBounds(const SkRect& bounds) {
return SkIRect::MakeLTRB(SkScalarFloorToInt(bounds.fLeft + kBoundsTolerance),
SkScalarFloorToInt(bounds.fTop + kBoundsTolerance),
SkScalarCeilToInt(bounds.fRight - kBoundsTolerance),
SkScalarCeilToInt(bounds.fBottom - kBoundsTolerance));
}
/**
* Returns the minimal pixel-aligned rect that counts as containing a given set of bounds.
*/
static SkRect GetPixelBounds(const SkRect& bounds) {
return SkRect::MakeLTRB(SkScalarFloorToScalar(bounds.fLeft + kBoundsTolerance),
SkScalarFloorToScalar(bounds.fTop + kBoundsTolerance),
SkScalarCeilToScalar(bounds.fRight - kBoundsTolerance),
SkScalarCeilToScalar(bounds.fBottom - kBoundsTolerance));
}
/**
* Returns true if the given rect counts as aligned with pixel boundaries.
*/
static bool IsPixelAligned(const SkRect& rect) {
return SkScalarAbs(SkScalarRoundToScalar(rect.fLeft) - rect.fLeft) <= kBoundsTolerance &&
SkScalarAbs(SkScalarRoundToScalar(rect.fTop) - rect.fTop) <= kBoundsTolerance &&
SkScalarAbs(SkScalarRoundToScalar(rect.fRight) - rect.fRight) <= kBoundsTolerance &&
SkScalarAbs(SkScalarRoundToScalar(rect.fBottom) - rect.fBottom) <= kBoundsTolerance;
}
};
/**
* GrHardClip never uses coverage FPs. It can only enforce the clip using the already-existing
* stencil buffer contents and/or fixed-function state like scissor. Always aliased if MSAA is off.
*/
class GrHardClip : public GrClip {
public:
/**
* Sets the appropriate hardware state modifications on GrAppliedHardClip that will implement
* the clip. On input 'bounds' is a conservative bounds of the draw that is to be clipped. After
* return 'bounds' has been intersected with a conservative bounds of the clip. A return value
* of false indicates that the draw can be skipped as it is fully clipped out.
*/
virtual bool apply(int rtWidth, int rtHeight, GrAppliedHardClip* out, SkRect* bounds) const = 0;
private:
bool apply(GrContext*, GrRenderTargetContext* rtc, bool useHWAA, bool hasUserStencilSettings,
GrAppliedClip* out, SkRect* bounds) const final {
return this->apply(rtc->width(), rtc->height(), &out->hardClip(), bounds);
}
};
/**
* Specialized implementation for no clip.
*/
class GrNoClip final : public GrHardClip {
private:
bool quickContains(const SkRect&) const final { return true; }
bool quickContains(const SkRRect&) const final { return true; }
void getConservativeBounds(int width, int height, SkIRect* devResult,
bool* isIntersectionOfRects) const final {
devResult->setXYWH(0, 0, width, height);
if (isIntersectionOfRects) {
*isIntersectionOfRects = true;
}
}
bool apply(int rtWidth, int rtHeight, GrAppliedHardClip*, SkRect*) const final { return true; }
bool isRRect(const SkRect&, SkRRect*, GrAA*) const override { return false; }
};
#endif
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