Implement path cover with nv_path_rendering

src/gpu/GrStencilAndCoverPathRenderer.cpp

Index: src/gpu/GrStencilAndCoverPathRenderer.cpp
diff --git a/src/gpu/GrStencilAndCoverPathRenderer.cpp b/src/gpu/GrStencilAndCoverPathRenderer.cpp
index f7330a81f649246530ff3fa56162d83ecf3f854f..c59082c1ee6a651c1c29d686432419418647dad7 100644
--- a/src/gpu/GrStencilAndCoverPathRenderer.cpp
+++ b/src/gpu/GrStencilAndCoverPathRenderer.cpp
@@ -40,6 +40,7 @@ bool GrStencilAndCoverPathRenderer::canDrawPath(const SkPath& path,
                                                 bool antiAlias) const {
     return stroke.isFillStyle() &&
            !antiAlias && // doesn't do per-path AA, relies on the target having MSAA
+           !target->getDrawState().willEffectReadDstColor() && // not supported yet

[Chris Dalton, 2013/09/13 19:49:58]

I don't think we need this constraint anymore. With the vertexless shaders
everything should "just work".

[bsalomon, 2013/09/13 20:25:28]

Really? I think onDrawPath will have to handle this.

Of course we should also add support for advanced blending.. though there may
still be effects that require dst access so it's not a replacement for adding
support for willEffectReadDstColor().

[Kimmo Kinnunen, 2013/09/18 07:52:38]

I don't think there's code for this yet.. Left as is for now.

            target->getDrawState().getStencil().isDisabled();
 }
 
@@ -70,27 +71,24 @@ bool GrStencilAndCoverPathRenderer::onDrawPath(const SkPath& path,
 
     SkAutoTUnref<GrPath> p(fGpu->createPath(path));
 
-    SkPath::FillType nonInvertedFill = SkPath::ConvertToNonInverseFillType(path.getFillType());
-    target->stencilPath(p, stroke, nonInvertedFill);
-
-    // TODO: Use built in cover operation rather than a rect draw. This will require making our
-    // fragment shaders be able to eat varyings generated by a matrix.
-
-    // fill the path, zero out the stencil
-    SkRect bounds = p->getBounds();
-    SkScalar bloat = drawState->getViewMatrix().getMaxStretch() * SK_ScalarHalf;
-    GrDrawState::AutoViewMatrixRestore avmr;
-
-    if (nonInvertedFill == path.getFillType()) {
+    if (!path.isInverseFillType()) {
         GR_STATIC_CONST_SAME_STENCIL(kStencilPass,
-            kZero_StencilOp,
-            kZero_StencilOp,
-            kNotEqual_StencilFunc,
-            0xffff,
-            0x0000,
-            0xffff);
+                                     kZero_StencilOp,
+                                     kZero_StencilOp,
+                                     kNotEqual_StencilFunc,
+                                     0xffff,
+                                     0x0000,
+                                 0xffff);
+
         *drawState->stencil() = kStencilPass;
+
+        target->drawPath(p, stroke, path.getFillType());
     } else {
+        SkPath::FillType nonInvertedFill = SkPath::ConvertToNonInverseFillType(path.getFillType());
+        target->stencilPath(p, stroke, nonInvertedFill);
+
+        GrDrawState::AutoViewMatrixRestore avmr;
+
         GR_STATIC_CONST_SAME_STENCIL(kInvertedStencilPass,
             kZero_StencilOp,
             kZero_StencilOp,
@@ -101,23 +99,25 @@ bool GrStencilAndCoverPathRenderer::onDrawPath(const SkPath& path,
             0xffff,
             0x0000,
             0xffff);
+
+
         SkMatrix vmi;
-        bounds.setLTRB(0, 0,
-                       SkIntToScalar(drawState->getRenderTarget()->width()),
-                       SkIntToScalar(drawState->getRenderTarget()->height()));
+        SkRect bounds = SkRect::MakeLTRB(0, 0,
+                                         SkIntToScalar(drawState->getRenderTarget()->width()),
+                                         SkIntToScalar(drawState->getRenderTarget()->height()));
         // mapRect through persp matrix may not be correct
         if (!drawState->getViewMatrix().hasPerspective() && drawState->getViewInverse(&vmi)) {
             vmi.mapRect(&bounds);
             // theoretically could set bloat = 0, instead leave it because of matrix inversion
             // precision.
+            SkScalar bloat = drawState->getViewMatrix().getMaxStretch() * SK_ScalarHalf;
+            bounds.outset(bloat, bloat);
         } else {
             avmr.setIdentity(drawState);
-            bloat = 0;
         }
         *drawState->stencil() = kInvertedStencilPass;
+        target->drawSimpleRect(bounds, NULL);
     }
-    bounds.outset(bloat, bloat);
-    target->drawSimpleRect(bounds, NULL);
     target->drawState()->stencil()->setDisabled();
     return true;
 }