Add XferProcessor factory in GrPaint and GrDrawState.

include/gpu/GrXferProcessor.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrXferProcessor_DEFINED
+#define GrXferProcessor_DEFINED
+
+#include "GrColor.h"
+#include "GrFragmentProcessor.h"
+#include "GrTypes.h"
+#include "SkXfermode.h"
+
+class GrDrawState;
+
+/**
+ * A GrGeomteryProcessor is used to perform computation in the vertex shader and
+ * add support for custom vertex attributes. A GrGemeotryProcessor is typically
+ * tied to the code that does a specific type of high-level primitive rendering
+ * (e.g. anti-aliased circle rendering). The GrGeometryProcessor used for a draw is
+ * specified using GrDrawState. There can only be one geometry processor active for
+ * a draw. The custom vertex attributes required by the geometry processor must be
+ * added to the vertex attribute array specified on the GrDrawState.
+ * GrGeometryProcessor subclasses should be immutable after construction.
+ */

[joshualitt, 2014/11/26 20:10:34]

Comment refers to GP

[egdaniel, 2014/12/01 18:18:24]

Done.

+class GrXferProcessor : public GrFragmentProcessor {
+public:
+    /** Returns true if this and other prceossor conservatively draw identically. It can only return
+        true when the two prceossor are of the same subclass (i.e. they return the same object from

[bsalomon, 2014/11/26 21:02:44]

Does this comment apply? Will these have a backend effect factory?

[egdaniel, 2014/12/01 18:18:24]

In this current version the XP is derived from a fragment processor so it does
have a backend effect factory from them. In the final XP cl, xp's will have
their own BEF and this statement will be valid.

+        from getFactory()).
+
+        A return value of true from isEqual() should not be used to test whether the prceossor would
+        generate the same shader code. To test for identical code generation use the prceossor' keys
+        computed by the GrBackendProcessorFactory. */
+    bool isEqual(const GrXferProcessor& that) const {

[bsalomon, 2014/11/26 21:02:45]

non-virtual override?

[egdaniel, 2014/12/01 18:18:24]

Code deleted since coeff's have been moved off base class

+        /*

[bsalomon, 2014/11/26 21:02:45]

?

[egdaniel, 2014/12/01 18:18:24]

Done.

+        if (fSrcBlend != that.fSrcBlend || fDstBlend != that.fDstBlend) {
+            return false;
+        }
+        */

[joshualitt, 2014/11/26 20:10:34]

Is this code supposed to be commented out?

[egdaniel, 2014/12/01 18:18:24]

nope

+        return this->onIsEqual(that);
+    }
+
+protected:
+    GrXferProcessor() : fSrcBlend(kOne_GrBlendCoeff), fDstBlend(kZero_GrBlendCoeff) {}
+
+    GrXferProcessor(GrBlendCoeff srcBlend, GrBlendCoeff dstBlend)
+        : fSrcBlend(srcBlend), fDstBlend(dstBlend) {}
+
+private:
+    virtual bool onIsEqual(const GrFragmentProcessor&) const = 0;
+
+    GrBlendCoeff fSrcBlend;
+    GrBlendCoeff fDstBlend;
+    
+    typedef GrFragmentProcessor INHERITED;
+};
+
+class GrXPFactory : public GrProgramElement {
+public:
+    virtual const GrXferProcessor* createXferProcessor() const = 0;

[bsalomon, 2014/11/26 21:02:44]

no inputs?

[egdaniel, 2014/12/01 18:18:24]

In this cl it has none, but in the next DrawState is added in as input since we
will start doing blend optimizations there

+
+    virtual bool supportsLCDText(const GrDrawState&) const { return false; }

[bsalomon, 2014/11/26 21:02:44]

Can we call it LCDCoverage or RGBCoverage rather than LCDText?

[egdaniel, 2014/12/01 18:18:24]

Done.

+

[joshualitt, 2014/11/26 20:10:34]

Is there a way to name this more generally?  ie, what is special about the kind
of blend mode LCD text requires?  I might not know what I'm talking about here
though.

+    virtual bool canApplyCoverage(const GrDrawState&) const { return false; }

[bsalomon, 2014/11/26 21:02:44]

This and the above need some clear documentation about what they mean and what
answering true implies for the xp

[egdaniel, 2014/12/01 18:18:24]

Removed for now since it is unused in this CL. Will add back with documentation
on follow up cl that calls it.

+
+protected:
+    GrXPFactory()
+        : INHERITED(), fSrc(kOne_GrBlendCoeff), fDst(kZero_GrBlendCoeff) {}
+
+    GrXPFactory(GrBlendCoeff src, GrBlendCoeff dst)
+        : fSrc(src), fDst(dst) {}
+
+    GrBlendCoeff fSrc;
+    GrBlendCoeff fDst;
+
+private:
+    typedef GrProgramElement INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+ * This creates an effect outside of the effect memory pool. The effect's destructor will be called
+ * at global destruction time. NAME will be the name of the created GrProcessor.
+ */
+#define GR_CREATE_STATIC_XP_FACTORY(NAME, XPF_CLASS, ARGS)                                     \

[bsalomon, 2014/11/26 21:02:44]

You must be coming from a really old revision. There is now
GR_CREATE_STATIC_PROCESSOR(NAME, PROC_CLASS, ARGS) which should with any
processor subclass. I think you can just delete this.

[egdaniel, 2014/12/01 18:18:24]

This isn't a GrProcessor subclass, it is for GrXPFactory. Comment updated.

[bsalomon, 2014/12/01 19:24:39]

Acknowledged.

+static SkAlignedSStorage<sizeof(XPF_CLASS)> g_##NAME##_Storage;                                \
+static GrXPFactory* NAME SkNEW_PLACEMENT_ARGS(g_##NAME##_Storage.get(), XPF_CLASS, ARGS);      \
+static SkAutoTDestroy<GrXPFactory> NAME##_ad(NAME);
+
+#endif
+