Add GPU support for roundrects

src/gpu/GrOvalRenderer.cpp

Index: src/gpu/GrOvalRenderer.cpp
===================================================================
--- src/gpu/GrOvalRenderer.cpp	(revision 8845)
+++ src/gpu/GrOvalRenderer.cpp	(working copy)
@@ -14,6 +14,9 @@
 
 #include "GrDrawState.h"
 #include "GrDrawTarget.h"
+#include "GrGpu.h"
+
+#include "SkRRect.h"
 #include "SkStrokeRec.h"
 
 SK_DEFINE_INST_COUNT(GrOvalRenderer)
@@ -35,6 +38,13 @@
     GrPoint  fInnerOffset;
 };
 
+struct RRectVertex {
+    GrPoint  fPos;
+    GrPoint  fOffset;
+    GrPoint  fOuterRadii;
+    GrPoint  fInnerRadii;
+};
+
 inline bool circle_stays_circle(const SkMatrix& m) {
     return m.isSimilarity();
 }
@@ -275,6 +285,146 @@
 
 ///////////////////////////////////////////////////////////////////////////////
 
+/**
+ * The output of this effect is a modulation of the input color and coverage for an axis-aligned
+ * ellipse, specified as an offset vector from center and outer and inner radii in both
+ * x and y directions.
+ *
+ * This uses a slightly different algorithm than the EllipseEdgeEffect, above. Rather than
+ * scaling an ellipse to be a circle, it attempts to find the distance from the offset point to the 
+ * ellipse by determining where the line through the origin and offset point would cross the 
+ * ellipse, and computing the distance to that. This is slower but works better for roundrects 
+ * because the straight edges will be more accurate.
+ */
+
+class AltEllipseEdgeEffect : public GrEffect {
+public:
+    static GrEffectRef* Create(bool stroke) {
+        // we go through this so we only have one copy of each effect (stroked/filled)
+        GR_CREATE_STATIC_EFFECT(gAltEllipseStrokeEdge, AltEllipseEdgeEffect, (true));
+        GR_CREATE_STATIC_EFFECT(gAltEllipseFillEdge, AltEllipseEdgeEffect, (false));
+        
+        if (stroke) {
+            gAltEllipseStrokeEdge->ref();
+            return gAltEllipseStrokeEdge;
+        } else {
+            gAltEllipseFillEdge->ref();
+            return gAltEllipseFillEdge;
+        }
+    }
+
+    virtual void getConstantColorComponents(GrColor* color,
+                                            uint32_t* validFlags) const SK_OVERRIDE {
+        *validFlags = 0;
+    }
+
+    virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE {
+        return GrTBackendEffectFactory<AltEllipseEdgeEffect>::getInstance();
+    }
+
+    virtual ~AltEllipseEdgeEffect() {}
+
+    static const char* Name() { return "RRectEdge"; }
+
+    inline bool isStroked() const { return fStroke; }
+
+    class GLEffect : public GrGLEffect {
+    public:
+        GLEffect(const GrBackendEffectFactory& factory, const GrDrawEffect&)
+            : INHERITED (factory) {}
+
+        virtual void emitCode(GrGLShaderBuilder* builder,
+                              const GrDrawEffect& drawEffect,
+                              EffectKey key,
+                              const char* outputColor,
+                              const char* inputColor,
+                              const TextureSamplerArray& samplers) SK_OVERRIDE {
+            const AltEllipseEdgeEffect& rrectEffect = drawEffect.castEffect<AltEllipseEdgeEffect>();
+
+            const char *vsOffsetName, *fsOffsetName;
+            const char *vsRadiiName, *fsRadiiName;
+
+            builder->addVarying(kVec2f_GrSLType, "EllipseOffsets", &vsOffsetName, &fsOffsetName);
+            const SkString* attr0Name =
+                builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[0]);
+            builder->vsCodeAppendf("\t%s = %s;\n", vsOffsetName, attr0Name->c_str());
+
+            builder->addVarying(kVec4f_GrSLType, "EllipseRadii", &vsRadiiName, &fsRadiiName);
+            const SkString* attr1Name =
+                builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[1]);
+            builder->vsCodeAppendf("\t%s = %s;\n", vsRadiiName, attr1Name->c_str());
+
+            builder->fsCodeAppend("\tfloat edgeAlpha;\n");
+            // get length of offset
+            builder->fsCodeAppendf("\tfloat len = length(%s.xy);\n", fsOffsetName);
+            builder->fsCodeAppend("\tvec2 offset;\n");
+ 
+            // for outer curve
+            builder->fsCodeAppendf("\toffset.xy = %s.xy*%s.yx;\n", 
+                                   fsOffsetName, fsRadiiName);
+            builder->fsCodeAppendf("\tfloat tOuter = "
+                                   "%s.x*%s.y*inversesqrt(dot(offset.xy, offset.xy));\n",
+                                   fsRadiiName, fsRadiiName);
+            builder->fsCodeAppend("\tedgeAlpha = clamp(len*tOuter - len, 0.0, 1.0);\n");
+
+            // for inner curve
+            if (rrectEffect.isStroked()) {
+                builder->fsCodeAppendf("\toffset.xy = %s.xy*%s.wz;\n", 
+                                       fsOffsetName, fsRadiiName);
+                builder->fsCodeAppendf("\tfloat tInner = "
+                                       "%s.z*%s.w*inversesqrt(dot(offset.xy, offset.xy));\n",
+                                       fsRadiiName, fsRadiiName);
+                builder->fsCodeAppend("\tedgeAlpha *= clamp(len - len*tInner, 0.0, 1.0);\n");
+            }
+
+            SkString modulate;
+            GrGLSLModulatef<4>(&modulate, inputColor, "edgeAlpha");
+            builder->fsCodeAppendf("\t%s = %s;\n", outputColor, modulate.c_str());
+        }
+
+        static inline EffectKey GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
+            const AltEllipseEdgeEffect& rrectEffect = drawEffect.castEffect<AltEllipseEdgeEffect>();
+
+            return rrectEffect.isStroked() ? 0x1 : 0x0;
+        }
+
+        virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE {
+        }
+
+    private:
+        typedef GrGLEffect INHERITED;
+    };
+
+private:
+    AltEllipseEdgeEffect(bool stroke) : GrEffect() {
+        this->addVertexAttrib(kVec2f_GrSLType);
+        this->addVertexAttrib(kVec4f_GrSLType);
+        fStroke = stroke;
+    }
+
+    virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE {
+        const AltEllipseEdgeEffect& aeee = CastEffect<AltEllipseEdgeEffect>(other);
+        return aeee.fStroke == fStroke;
+    }
+
+    bool fStroke;
+
+    GR_DECLARE_EFFECT_TEST;
+
+    typedef GrEffect INHERITED;
+};
+
+GR_DEFINE_EFFECT_TEST(AltEllipseEdgeEffect);
+
+GrEffectRef* AltEllipseEdgeEffect::TestCreate(SkMWCRandom* random,
+                                           GrContext* context,
+                                           const GrDrawTargetCaps&,
+                                           GrTexture* textures[]) {
+    return AltEllipseEdgeEffect::Create(random->nextBool());
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 bool GrOvalRenderer::drawOval(GrDrawTarget* target, const GrContext* context, const GrPaint& paint,
                     const GrRect& oval, const SkStrokeRec& stroke)
 {
@@ -302,6 +452,8 @@
 
 namespace {
 
+///////////////////////////////////////////////////////////////////////////////
+
 // position + edge
 extern const GrVertexAttrib gCircleVertexAttribs[] = {
     {kVec2f_GrVertexAttribType, 0,               kPosition_GrVertexAttribBinding},
@@ -405,6 +557,8 @@
     target->drawNonIndexed(kTriangleStrip_GrPrimitiveType, 0, 4, &bounds);
 }
 
+///////////////////////////////////////////////////////////////////////////////
+
 namespace {
 
 // position + edge
@@ -485,8 +639,6 @@
     SkScalar innerRatio = 1.0f;
 
     if (SkStrokeRec::kFill_Style != style) {
-
-
         if (SkScalarNearlyZero(scaledStroke.length())) {
             scaledStroke.set(SK_ScalarHalf, SK_ScalarHalf);
         } else {
@@ -552,3 +704,289 @@
 
     return true;
 }
+
+///////////////////////////////////////////////////////////////////////////////
+
+static const uint16_t gRRectIndices[] = {
+    // corners
+    0, 1, 5, 0, 5, 4,
+    2, 3, 7, 2, 7, 6,
+    8, 9, 13, 8, 13, 12,
+    10, 11, 15, 10, 15, 14,
+    
+    // edges
+    1, 2, 6, 1, 6, 5,
+    4, 5, 9, 4, 9, 8,
+    6, 7, 11, 6, 11, 10,
+    9, 10, 14, 9, 14, 13,
+    
+    // center
+    // we place this at the end so that we can ignore these indices when rendering stroke-only
+    5, 6, 10, 5, 10, 9
+};
+
+
+GrIndexBuffer* GrOvalRenderer::rRectIndexBuffer(GrGpu* gpu) {
+    if (NULL == fRRectIndexBuffer) {
+        fRRectIndexBuffer =
+        gpu->createIndexBuffer(sizeof(gRRectIndices), false);
+        if (NULL != fRRectIndexBuffer) {
+#if GR_DEBUG
+            bool updated =
+#endif
+            fRRectIndexBuffer->updateData(gRRectIndices,
+                                          sizeof(gRRectIndices));
+            GR_DEBUGASSERT(updated);
+        }
+    }
+    return fRRectIndexBuffer;
+}
+
+bool GrOvalRenderer::drawSimpleRRect(GrDrawTarget* target, GrContext* context,
+                                     const GrPaint& paint, const SkRRect& rrect,
+                                     const SkStrokeRec& stroke)
+{
+    const SkMatrix& vm = context->getMatrix();
+#ifdef SK_DEBUG
+    {
+        // we should have checked for this previously
+        SkASSERT(paint.isAntiAlias() && vm.rectStaysRect() && rrect.isSimple());
+    }
+#endif
+
+    // do any matrix crunching before we reset the draw state for device coords
+    const SkRect& rrectBounds = rrect.getBounds();
+    SkRect bounds;
+    vm.mapRect(&bounds, rrectBounds);
+
+    SkVector radii = rrect.getSimpleRadii();
+    SkScalar xRadius = SkScalarAbs(vm[SkMatrix::kMScaleX]*radii.fX + 
+                                   vm[SkMatrix::kMSkewY]*radii.fY);
+    SkScalar yRadius = SkScalarAbs(vm[SkMatrix::kMSkewX]*radii.fX + 
+                                   vm[SkMatrix::kMScaleY]*radii.fY);
+    // tall or wide quarter-ellipse corners aren't handled
+    if (SkScalarDiv(xRadius, yRadius) > 2 || SkScalarDiv(yRadius, xRadius) > 2) {
+        return false;
+    }
+    // if hairline stroke is greater than radius, we don't handle that right now
+    SkStrokeRec::Style style = stroke.getStyle();
+    if (SkStrokeRec::kHairline_Style == style &&
+        (SK_ScalarHalf >= xRadius || SK_ScalarHalf >= yRadius)) {
+        return false;
+    }
+
+    // do (potentially) anisotropic mapping of stroke
+    SkVector scaledStroke;
+    SkScalar strokeWidth = stroke.getWidth();
+    scaledStroke.fX = SkScalarAbs(strokeWidth*(vm[SkMatrix::kMScaleX] + vm[SkMatrix::kMSkewY]));
+    scaledStroke.fY = SkScalarAbs(strokeWidth*(vm[SkMatrix::kMSkewX] + vm[SkMatrix::kMScaleY]));
+
+    // if half of strokewidth is greater than radius, we don't handle that right now
+    if (SK_ScalarHalf*scaledStroke.fX >= xRadius || SK_ScalarHalf*scaledStroke.fY >= yRadius) {
+        return false;
+    }
+
+    // reset to device coordinates
+    GrDrawState* drawState = target->drawState();
+    GrDrawState::AutoDeviceCoordDraw adcd(drawState);
+    if (!adcd.succeeded()) {
+        return false;
+    }
+
+    bool isStroked = (SkStrokeRec::kStroke_Style == style || SkStrokeRec::kHairline_Style == style);
+
+    enum {
+        // the edge effects share this stage with glyph rendering
+        // (kGlyphMaskStage in GrTextContext) && SW path rendering
+        // (kPathMaskStage in GrSWMaskHelper)
+        kEdgeEffectStage = GrPaint::kTotalStages,
+    };
+
+    GrIndexBuffer* indexBuffer = this->rRectIndexBuffer(context->getGpu());
+    if (NULL == indexBuffer) {
+        GrPrintf("Failed to create index buffer!\n");
+        return false;
+    }    
+    
+    // if the corners are circles, use the circle renderer
+    if ((!isStroked || scaledStroke.fX == scaledStroke.fY) && xRadius == yRadius) {
+        drawState->setVertexAttribs<gCircleVertexAttribs>(SK_ARRAY_COUNT(gCircleVertexAttribs));
+        GrAssert(sizeof(CircleVertex) == drawState->getVertexSize());
+        
+        GrDrawTarget::AutoReleaseGeometry geo(target, 16, 0);
+        if (!geo.succeeded()) {
+            GrPrintf("Failed to get space for vertices!\n");
+            return false;
+        }
+        CircleVertex* verts = reinterpret_cast<CircleVertex*>(geo.vertices());
+        
+        GrEffectRef* effect = CircleEdgeEffect::Create(isStroked);
+        static const int kCircleEdgeAttrIndex = 1;
+        drawState->setEffect(kEdgeEffectStage, effect, kCircleEdgeAttrIndex)->unref();
+        
+        SkScalar innerRadius = 0.0f;
+        SkScalar outerRadius = xRadius;
+        SkScalar halfWidth = 0;
+        if (style != SkStrokeRec::kFill_Style) {
+            if (SkScalarNearlyZero(scaledStroke.fX)) {
+                halfWidth = SK_ScalarHalf;
+            } else {
+                halfWidth = SkScalarHalf(scaledStroke.fX);
+            }
+            
+            if (isStroked) {
+                innerRadius = SkMaxScalar(0, xRadius - halfWidth);
+            }
+            outerRadius += halfWidth;
+            bounds.outset(halfWidth, halfWidth);
+        }
+        
+        // The radii are outset for two reasons. First, it allows the shader to simply perform
+        // clamp(distance-to-center - radius, 0, 1). Second, the outer radius is used to compute the
+        // verts of the bounding box that is rendered and the outset ensures the box will cover all
+        // pixels partially covered by the circle.
+        outerRadius += SK_ScalarHalf;
+        innerRadius -= SK_ScalarHalf;
+        
+        // Expand the rect so all the pixels will be captured.
+        bounds.outset(SK_ScalarHalf, SK_ScalarHalf);
+        
+        SkScalar yCoords[4] = {
+            bounds.fTop,
+            bounds.fTop + outerRadius,
+            bounds.fBottom - outerRadius,
+            bounds.fBottom
+        };
+        SkScalar yOuterRadii[4] = {
+            -outerRadius,
+            0,
+            0,
+            outerRadius
+        };
+        for (int i = 0; i < 4; ++i) {
+            verts->fPos = SkPoint::Make(bounds.fLeft, yCoords[i]);
+            verts->fOffset = SkPoint::Make(-outerRadius, yOuterRadii[i]);
+            verts->fOuterRadius = outerRadius;
+            verts->fInnerRadius = innerRadius;
+            verts++;
+            
+            verts->fPos = SkPoint::Make(bounds.fLeft + outerRadius, yCoords[i]);
+            verts->fOffset = SkPoint::Make(0, yOuterRadii[i]);
+            verts->fOuterRadius = outerRadius;
+            verts->fInnerRadius = innerRadius;
+            verts++;
+            
+            verts->fPos = SkPoint::Make(bounds.fRight - outerRadius, yCoords[i]);
+            verts->fOffset = SkPoint::Make(0, yOuterRadii[i]);
+            verts->fOuterRadius = outerRadius;
+            verts->fInnerRadius = innerRadius;
+            verts++;
+            
+            verts->fPos = SkPoint::Make(bounds.fRight, yCoords[i]);
+            verts->fOffset = SkPoint::Make(outerRadius, yOuterRadii[i]);
+            verts->fOuterRadius = outerRadius;
+            verts->fInnerRadius = innerRadius;
+            verts++;
+        }
+        
+        // drop out the middle quad if we're stroked
+        int indexCnt = isStroked ? GR_ARRAY_COUNT(gRRectIndices)-6 : GR_ARRAY_COUNT(gRRectIndices);
+        target->setIndexSourceToBuffer(indexBuffer);
+        target->drawIndexed(kTriangles_GrPrimitiveType, 0, 0, 16, indexCnt, &bounds);
+        
+    // otherwise we use the special ellipse renderer
+    } else {
+    
+        drawState->setVertexAttribs<gEllipseVertexAttribs>(SK_ARRAY_COUNT(gEllipseVertexAttribs));
+        GrAssert(sizeof(RRectVertex) == drawState->getVertexSize());
+
+        GrDrawTarget::AutoReleaseGeometry geo(target, 16, 0);
+        if (!geo.succeeded()) {
+            GrPrintf("Failed to get space for vertices!\n");
+            return false;
+        }
+        RRectVertex* verts = reinterpret_cast<RRectVertex*>(geo.vertices());
+
+        GrEffectRef* effect = AltEllipseEdgeEffect::Create(isStroked);
+        static const int kEllipseOffsetAttrIndex = 1;
+        static const int kEllipseRadiiAttrIndex = 2;
+        drawState->setEffect(kEdgeEffectStage, effect,
+                             kEllipseOffsetAttrIndex, kEllipseRadiiAttrIndex)->unref();
+
+        SkScalar innerXRadius = 0.0f;
+        SkScalar innerYRadius = 0.0f;
+
+        if (SkStrokeRec::kFill_Style != style) {
+            if (SkScalarNearlyZero(scaledStroke.length())) {
+                scaledStroke.set(SK_ScalarHalf, SK_ScalarHalf);
+            } else {
+                scaledStroke.scale(0.5f);
+            }
+
+            // this is legit only if scale & translation (which should be the case at the moment)
+            if (SkStrokeRec::kStroke_Style == style || SkStrokeRec::kHairline_Style == style) {
+                innerXRadius = SkMaxScalar(0, xRadius - scaledStroke.fX);
+                innerYRadius = SkMaxScalar(0, yRadius - scaledStroke.fY);
+            }
+            xRadius += scaledStroke.fX;
+            yRadius += scaledStroke.fY;
+            bounds.outset(scaledStroke.fX, scaledStroke.fY);
+        }
+
+        // Extend the radii out half a pixel to antialias.
+        SkScalar xOuterRadius = xRadius + SK_ScalarHalf;
+        SkScalar yOuterRadius = yRadius + SK_ScalarHalf;
+        SkScalar xInnerRadius = SkMaxScalar(innerXRadius - SK_ScalarHalf, 0);
+        SkScalar yInnerRadius = SkMaxScalar(innerYRadius - SK_ScalarHalf, 0);
+
+        // Expand the rect so all the pixels will be captured.
+        bounds.outset(SK_ScalarHalf, SK_ScalarHalf);
+
+        SkScalar yCoords[4] = {
+            bounds.fTop,
+            bounds.fTop + yOuterRadius,
+            bounds.fBottom - yOuterRadius,
+            bounds.fBottom
+        };
+        SkScalar yOuterOffsets[4] = {
+            -yOuterRadius,
+            SK_ScalarNearlyZero, // we're using inversesqrt() in the shader, so can't be exactly 0
+            SK_ScalarNearlyZero,
+            yOuterRadius
+        };
+
+        for (int i = 0; i < 4; ++i) {
+            verts->fPos = SkPoint::Make(bounds.fLeft, yCoords[i]);
+            verts->fOffset = SkPoint::Make(-xOuterRadius, yOuterOffsets[i]);
+            verts->fOuterRadii = SkPoint::Make(xOuterRadius, yOuterRadius);
+            verts->fInnerRadii = SkPoint::Make(xInnerRadius, yInnerRadius);
+            verts++;
+
+            verts->fPos = SkPoint::Make(bounds.fLeft + xOuterRadius, yCoords[i]);
+            verts->fOffset = SkPoint::Make(SK_ScalarNearlyZero, yOuterOffsets[i]);
+            verts->fOuterRadii = SkPoint::Make(xOuterRadius, yOuterRadius);
+            verts->fInnerRadii = SkPoint::Make(xInnerRadius, yInnerRadius);
+            verts++;
+
+            verts->fPos = SkPoint::Make(bounds.fRight - xOuterRadius, yCoords[i]);
+            verts->fOffset = SkPoint::Make(SK_ScalarNearlyZero, yOuterOffsets[i]);
+            verts->fOuterRadii = SkPoint::Make(xOuterRadius, yOuterRadius);
+            verts->fInnerRadii = SkPoint::Make(xInnerRadius, yInnerRadius);
+            verts++;
+
+            verts->fPos = SkPoint::Make(bounds.fRight, yCoords[i]);
+            verts->fOffset = SkPoint::Make(xOuterRadius, yOuterOffsets[i]);
+            verts->fOuterRadii = SkPoint::Make(xOuterRadius, yOuterRadius);
+            verts->fInnerRadii = SkPoint::Make(xInnerRadius, yInnerRadius);
+            verts++;
+        }
+     
+        // drop out the middle quad if we're stroked
+        int indexCnt = isStroked ? GR_ARRAY_COUNT(gRRectIndices)-6 : GR_ARRAY_COUNT(gRRectIndices);
+        target->setIndexSourceToBuffer(indexBuffer);
+        target->drawIndexed(kTriangles_GrPrimitiveType, 0, 0, 16, indexCnt, &bounds);
+    }
+        
+    return true;
+}
+