Convert GrClip to an abstract base class

include/gpu/GrClip.h

 /*
  * 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 "GrFragmentProcessor.h"
+#include "GrTypesPriv.h"
 #include "SkClipStack.h"
 
-struct SkIRect;
+class GrClipMaskManager;
+class GrPipelineBuilder;
 
 /**
- * GrClip encapsulates the information required to construct the clip
- * masks. 'A GrClip is either wide open, just an IRect, just a Rect, or a full clipstack.
- * If the clip is a clipstack than the origin is used to translate the stack with
- * respect to device coordinates. This allows us to use a clip stack that is
- * specified for a root device with a layer device that is restricted to a subset
- * of the original canvas. For other clip types the origin will always be (0,0).
- *
- * NOTE: GrClip *must* point to a const clipstack
+ * Produced by GrClip. It provides a set of modifications to the drawing state that are used to
+ * create the final GrPipeline for a GrBatch.
  */
-class GrClip : SkNoncopyable {
+class GrAppliedClip {
 public:
-    GrClip() : fClipType(kWideOpen_ClipType) {
-        fOrigin.setZero();
+    GrAppliedClip() : fHasStencilClip(false) {}
+    const GrFragmentProcessor* clipCoverageFragmentProcessor() const { return fClipCoverageFP; }
+    const GrScissorState& scissorState() const { return fScissorState; }
+    bool hasStencilClip() const { return fHasStencilClip; }
+
+private:
+    SkAutoTUnref<const GrFragmentProcessor> fClipCoverageFP;
+    GrScissorState                          fScissorState;
+    bool                                    fHasStencilClip;
+
+    friend class GrFixedClip;
+    friend class GrClipMaskManager;
+
+    typedef SkNoncopyable INHERITED;
+};
+
+/**
+ * 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 void getConservativeBounds(int width, int height, SkIRect* devResult,
+                                       bool* isIntersectionOfRects = nullptr) const = 0;
+    virtual bool apply(GrClipMaskManager*, const GrPipelineBuilder&, const SkRect* devBounds,
+                       GrAppliedClip*) const = 0;
+
+    virtual ~GrClip() {}
+};
+
+/**
+ * Specialized implementation for no clip.
+ */
+class GrNoClip final : public GrClip {
+private:
+    bool quickContains(const SkRect&) const final { return true; }
+    void getConservativeBounds(int width, int height, SkIRect* devResult,
+                               bool* isIntersectionOfRects) const final;
+    bool apply(GrClipMaskManager*, const GrPipelineBuilder&,
+               const SkRect*, GrAppliedClip*) const final { return true; }
+};
+
+/**
+ * GrFixedClip is a clip that can be represented by fixed-function hardware. It never modifies the
+ * stencil buffer itself, but can be configured to use whatever clip is already there.
+ */
+class GrFixedClip final : public GrClip {
+public:
+    GrFixedClip() : fHasStencilClip(false) {}
+    GrFixedClip(const SkIRect& scissorRect) : fScissorState(scissorRect), fHasStencilClip(false) {}
+
+    void reset() {
+        fScissorState.setDisabled();
+        fHasStencilClip = false;
     }
 
-    GrClip(const SkIRect& rect) : fClipType(kIRect_ClipType) {
-        fOrigin.setZero();
-        fClip.fIRect = rect;
+    void reset(const SkIRect& scissorRect) {
+        fScissorState.set(scissorRect);
+        fHasStencilClip = false;
     }
 
-    GrClip(const SkRect& rect) : fClipType(kIRect_ClipType) {
-        fOrigin.setZero();
-        fClip.fIRect.fLeft   = SkScalarRoundToInt(rect.fLeft);
-        fClip.fIRect.fTop    = SkScalarRoundToInt(rect.fTop);
-        fClip.fIRect.fRight  = SkScalarRoundToInt(rect.fRight);
-        fClip.fIRect.fBottom = SkScalarRoundToInt(rect.fBottom);
+    void enableStencilClip(bool enable) { fHasStencilClip = enable; }
+
+    const GrScissorState& scissorState() const { return fScissorState; }
+    bool hasStencilClip() const { return fHasStencilClip; }
+
+    bool quickContains(const SkRect&) const final;
+    void getConservativeBounds(int width, int height, SkIRect* devResult,
+                               bool* isIntersectionOfRects) const final;
+
+private:
+    bool apply(GrClipMaskManager*, const GrPipelineBuilder&,
+               const SkRect* devBounds, GrAppliedClip* out) const final;
+
+    GrScissorState   fScissorState;
+    bool             fHasStencilClip;
+};
+
+/**
+ * GrClipStackClip can apply a generic SkClipStack to the draw state. It may generate clip masks or
+ * write to the stencil buffer during apply().
+ */
+class GrClipStackClip final : public GrClip {
+public:
+    GrClipStackClip(const SkClipStack* stack = nullptr, const SkIPoint* origin = nullptr) {
+        this->reset(stack, origin);
     }
 
-    ~GrClip() { this->reset(); }
-
-    const GrClip& operator=(const GrClip& other) {
-        this->reset();
-        fClipType = other.fClipType;
-        switch (other.fClipType) {
-            case kWideOpen_ClipType:
-                fOrigin.setZero();
-                break;
-            case kClipStack_ClipType:
-                fClip.fStack = SkRef(other.clipStack());
-                fOrigin = other.origin();
-                break;
-            case kIRect_ClipType:
-                fClip.fIRect = other.irect();
-                fOrigin.setZero();
-                break;
-        }
-        return *this;
+    void reset(const SkClipStack* stack = nullptr, const SkIPoint* origin = nullptr) {
+        fOrigin = origin ? *origin : SkIPoint::Make(0, 0);
+        fStack.reset(SkSafeRef(stack));
     }
 
-    bool operator==(const GrClip& other) const {
-        if (this->clipType() != other.clipType()) {
-            return false;
-        }
+    const SkIPoint& origin() const { return fOrigin; }
+    const SkClipStack* clipStack() const { return fStack; }
 
-        switch (fClipType) {
-            case kWideOpen_ClipType:
-                return true;
-            case kClipStack_ClipType:
-                if (this->origin() != other.origin()) {
-                    return false;
-                }
-
-                if (this->clipStack() && other.clipStack()) {
-                    return *this->clipStack() == *other.clipStack();
-                } else {
-                    return this->clipStack() == other.clipStack();
-                }
-                break;
-            case kIRect_ClipType:
-                return this->irect() == other.irect();
-                break;
-        }
-        SkFAIL("This should not occur\n");
-        return false;
-    }
-
-    bool operator!=(const GrClip& other) const {
-        return !(*this == other);
-    }
-
-    const SkClipStack* clipStack() const {
-        SkASSERT(kClipStack_ClipType == fClipType);
-        return fClip.fStack;
-    }
-
-    void setClipStack(const SkClipStack* clipStack, const SkIPoint* origin = NULL) {
-        this->reset();
-        if (clipStack->isWideOpen()) {
-            fClipType = kWideOpen_ClipType;
-            fOrigin.setZero();
-        } else {
-            fClipType = kClipStack_ClipType;
-            fClip.fStack = SkRef(clipStack);
-            if (origin) {
-                fOrigin = *origin;
-            } else {
-                fOrigin.setZero();
-            }
-        }
-    }
-
-    void setIRect(const SkIRect& irect) {
-        this->reset();
-        fClipType = kIRect_ClipType;
-        fOrigin.setZero();
-        fClip.fIRect = irect;
-    }
-
-    const SkIRect& irect() const {
-        SkASSERT(kIRect_ClipType == fClipType);
-        return fClip.fIRect;
-    }
-
-    void reset() {
-        if (kClipStack_ClipType == fClipType) {
-            fClip.fStack->unref();
-            fClip.fStack = NULL;
-        }
-        fClipType = kWideOpen_ClipType;
-        fOrigin.setZero();
-    }
-
-    // We support this for all cliptypes to simplify the logic a bit in clip mask manager.
-    // non clipstack clip types MUST have a (0,0) origin
-    const SkIPoint& origin() const {
-        SkASSERT(fClipType == kClipStack_ClipType || (fOrigin.fX == 0 && fOrigin.fY == 0));
-        return fOrigin;
-    }
-
-    bool isWideOpen(const SkRect& rect) const {
-        return (kWideOpen_ClipType == fClipType) ||
-               (kClipStack_ClipType == fClipType && this->clipStack()->isWideOpen()) ||
-               (kIRect_ClipType == fClipType && this->irect().contains(rect));
-    }
-
-    bool isWideOpen(const SkIRect& rect) const {
-        return (kWideOpen_ClipType == fClipType) ||
-               (kClipStack_ClipType == fClipType && this->clipStack()->isWideOpen()) ||
-               (kIRect_ClipType == fClipType && this->irect().contains(rect));
-    }
-
-    bool isWideOpen() const {
-        return (kWideOpen_ClipType == fClipType) ||
-               (kClipStack_ClipType == fClipType && this->clipStack()->isWideOpen());
-    }
-
-    bool quickContains(const SkRect& rect) const {
-        return (kWideOpen_ClipType == fClipType) ||
-               (kClipStack_ClipType == fClipType && this->clipStack()->quickContains(rect)) ||
-               (kIRect_ClipType == fClipType && this->irect().contains(rect));
-    }
-
-    void getConservativeBounds(int width, int height,
-                               SkIRect* devResult,
-                               bool* isIntersectionOfRects = NULL) const;
-
-    static const GrClip& WideOpen();
-
-    enum ClipType {
-        kClipStack_ClipType,
-        kWideOpen_ClipType,
-        kIRect_ClipType,
-    };
-
-    ClipType clipType() const { return fClipType; }
+    bool quickContains(const SkRect&) const final;
+    void getConservativeBounds(int width, int height, SkIRect* devResult,
+                               bool* isIntersectionOfRects) const final;
+    bool apply(GrClipMaskManager*, const GrPipelineBuilder&,
+               const SkRect* devBounds, GrAppliedClip*) const final;
 
 private:
-    union Clip {
-        const SkClipStack* fStack;
-        SkIRect fIRect;
-    } fClip;
-
-    SkIPoint fOrigin;
-    ClipType fClipType;
+    SkIPoint                          fOrigin;
+    SkAutoTUnref<const SkClipStack>   fStack;
 };
 
 #endif