Move oval rendering code to GrOvalRenderer

src/gpu/GrOvalRenderer.cpp

Index: src/gpu/GrOvalRenderer.cpp
===================================================================
--- src/gpu/GrOvalRenderer.cpp	(revision 0)
+++ src/gpu/GrOvalRenderer.cpp	(working copy)
@@ -0,0 +1,278 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "GrOvalRenderer.h"
+
+#include "effects/GrCircleEdgeEffect.h"
+#include "effects/GrEllipseEdgeEffect.h"
+
+#include "GrDrawState.h"
+#include "GrDrawTarget.h"
+#include "SkStrokeRec.h"
+
+SK_DEFINE_INST_COUNT(GrOvalRenderer)
+
+namespace {
+
+struct CircleVertex {
+    GrPoint fPos;
+    GrPoint fCenter;
+    SkScalar fOuterRadius;
+    SkScalar fInnerRadius;
+};
+
+struct EllipseVertex {
+    GrPoint fPos;
+    GrPoint fCenter;
+    SkScalar fOuterXRadius;
+    SkScalar fOuterXYRatio;
+    SkScalar fInnerXRadius;
+    SkScalar fInnerXYRatio;
+};
+
+inline bool circle_stays_circle(const SkMatrix& m) {
+    return m.isSimilarity();
+}
+
+}
+
+bool GrOvalRenderer::drawOval(GrDrawTarget* target, const GrContext* context, const GrPaint& paint, 
+                    const GrRect& oval, const SkStrokeRec& stroke)
+{
+    if (!paint.isAntiAlias()) {
+        return false;
+    }
+
+    const SkMatrix& vm = context->getMatrix();
+
+    // we can draw circles 
+    if (SkScalarNearlyEqual(oval.width(), oval.height()) 
+        && circle_stays_circle(vm)) {
+        drawCircle(target, paint, oval, stroke);
+
+    // and axis-aligned ellipses only
+    } else if (vm.rectStaysRect()) {
+        drawEllipse(target, paint, oval, stroke);
+
+    } else {
+        return false;
+    }
+
+    return true;
+}
+
+void GrOvalRenderer::drawCircle(GrDrawTarget* target, 
+                                const GrPaint& paint,
+                                const GrRect& circle,
+                                const SkStrokeRec& stroke)
+{
+    GrDrawState* drawState = target->drawState();
+
+    const SkMatrix& vm = drawState->getViewMatrix();
+    GrPoint center = GrPoint::Make(circle.centerX(), circle.centerY());
+    vm.mapPoints(&center, 1);
+    SkScalar radius = vm.mapRadius(SkScalarHalf(circle.width()));
+    SkScalar strokeWidth = vm.mapRadius(stroke.getWidth());
+
+    GrDrawState::AutoDeviceCoordDraw adcd(drawState);
+    if (!adcd.succeeded()) {
+        return;
+    }
+
+    // position + edge
+    static const GrVertexAttrib kVertexAttribs[] = {
+        {kVec2f_GrVertexAttribType, 0},
+        {kVec4f_GrVertexAttribType, sizeof(GrPoint)}
+    };
+    drawState->setVertexAttribs(kVertexAttribs, SK_ARRAY_COUNT(kVertexAttribs));
+    drawState->setAttribIndex(GrDrawState::kPosition_AttribIndex, 0);
+    GrAssert(sizeof(CircleVertex) == drawState->getVertexSize());
+
+    GrDrawTarget::AutoReleaseGeometry geo(target, 4, 0);
+    if (!geo.succeeded()) {
+        GrPrintf("Failed to get space for vertices!\n");
+        return;
+    }
+
+    CircleVertex* verts = reinterpret_cast<CircleVertex*>(geo.vertices());
+
+    SkStrokeRec::Style style = stroke.getStyle();
+    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,
+    };
+    drawState->setAttribBindings(GrDrawState::kDefault_AttribBindings);
+    
+    GrEffectRef* effect = GrCircleEdgeEffect::Create(isStroked);
+    static const int kCircleEdgeAttrIndex = 1;
+    drawState->setEffect(kEdgeEffectStage, effect, kCircleEdgeAttrIndex)->unref();
+
+    SkScalar innerRadius = 0.0f;
+    SkScalar outerRadius = radius;
+    SkScalar halfWidth = 0;
+    if (style != SkStrokeRec::kFill_Style) {
+        if (SkScalarNearlyZero(strokeWidth)) {
+            halfWidth = SK_ScalarHalf;
+        } else {
+            halfWidth = SkScalarHalf(strokeWidth);
+        }
+
+        outerRadius += halfWidth;
+        if (isStroked) {
+            innerRadius = SkMaxScalar(0, radius - halfWidth);
+        }
+    }
+
+    for (int i = 0; i < 4; ++i) {
+        verts[i].fCenter = center;
+        verts[i].fOuterRadius = outerRadius + 0.5f;
+        verts[i].fInnerRadius = innerRadius - 0.5f;
+    }
+
+    SkScalar L = -outerRadius;
+    SkScalar R = +outerRadius;
+    SkScalar T = -outerRadius;
+    SkScalar B = +outerRadius;
+
+    // We've extended the outer radius out half a pixel to antialias.
+    // Expand the drawn rect here so all the pixels will be captured.
+    L += center.fX - SK_ScalarHalf;
+    R += center.fX + SK_ScalarHalf;
+    T += center.fY - SK_ScalarHalf;
+    B += center.fY + SK_ScalarHalf;
+
+    verts[0].fPos = SkPoint::Make(L, T);
+    verts[1].fPos = SkPoint::Make(R, T);
+    verts[2].fPos = SkPoint::Make(L, B);
+    verts[3].fPos = SkPoint::Make(R, B);
+
+    target->drawNonIndexed(kTriangleStrip_GrPrimitiveType, 0, 4);
+}
+
+void GrOvalRenderer::drawEllipse(GrDrawTarget* target, 
+                                 const GrPaint& paint,
+                                 const GrRect& ellipse,
+                                 const SkStrokeRec& stroke)
+{
+    GrDrawState* drawState = target->drawState();
+#ifdef SK_DEBUG
+    {
+        // we should have checked for this previously
+        bool isAxisAlignedEllipse = drawState->getViewMatrix().rectStaysRect();
+        SkASSERT(paint.isAntiAlias() && isAxisAlignedEllipse);
+    }
+#endif
+
+    const SkMatrix& vm = drawState->getViewMatrix();
+    GrPoint center = GrPoint::Make(ellipse.centerX(), ellipse.centerY());
+    vm.mapPoints(&center, 1);
+    SkRect xformedRect;
+    vm.mapRect(&xformedRect, ellipse);
+
+    GrDrawState::AutoDeviceCoordDraw adcd(drawState);
+    if (!adcd.succeeded()) {
+        return;
+    }
+
+    // position + edge
+    static const GrVertexAttrib kVertexAttribs[] = {
+        {kVec2f_GrVertexAttribType, 0},
+        {kVec2f_GrVertexAttribType, sizeof(GrPoint)},
+        {kVec4f_GrVertexAttribType, 2*sizeof(GrPoint)}
+    };
+    drawState->setVertexAttribs(kVertexAttribs, SK_ARRAY_COUNT(kVertexAttribs));
+    drawState->setAttribIndex(GrDrawState::kPosition_AttribIndex, 0);
+    GrAssert(sizeof(EllipseVertex) == drawState->getVertexSize());
+
+    GrDrawTarget::AutoReleaseGeometry geo(target, 4, 0);
+    if (!geo.succeeded()) {
+        GrPrintf("Failed to get space for vertices!\n");
+        return;
+    }
+
+    EllipseVertex* verts = reinterpret_cast<EllipseVertex*>(geo.vertices());
+
+    SkStrokeRec::Style style = stroke.getStyle();
+    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,
+    };
+    drawState->setAttribBindings(GrDrawState::kDefault_AttribBindings);
+
+    GrEffectRef* effect = GrEllipseEdgeEffect::Create(isStroked);
+    static const int kEllipseCenterAttrIndex = 1;
+    static const int kEllipseEdgeAttrIndex = 2;
+    drawState->setEffect(kEdgeEffectStage, effect,
+                         kEllipseCenterAttrIndex, kEllipseEdgeAttrIndex)->unref();
+
+    SkScalar xRadius = SkScalarHalf(xformedRect.width());
+    SkScalar yRadius = SkScalarHalf(xformedRect.height());
+    SkScalar innerXRadius = 0.0f;
+    SkScalar innerRatio = 1.0f;
+
+    if (SkStrokeRec::kFill_Style != style) {
+        SkScalar strokeWidth = stroke.getWidth();
+
+        // do (potentially) anisotropic mapping
+        SkVector scaledStroke;
+        scaledStroke.set(strokeWidth, strokeWidth);
+        vm.mapVectors(&scaledStroke, 1);
+
+        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) {
+            SkScalar innerYRadius = SkMaxScalar(0, yRadius - scaledStroke.fY);
+            if (innerYRadius > SK_ScalarNearlyZero) {
+                innerXRadius = SkMaxScalar(0, xRadius - scaledStroke.fX);
+                innerRatio = innerXRadius/innerYRadius;
+            }
+        }
+        xRadius += scaledStroke.fX;
+        yRadius += scaledStroke.fY;
+    }
+
+    SkScalar outerRatio = SkScalarDiv(xRadius, yRadius);
+
+    for (int i = 0; i < 4; ++i) {
+        verts[i].fCenter = center;
+        verts[i].fOuterXRadius = xRadius + 0.5f;
+        verts[i].fOuterXYRatio = outerRatio;
+        verts[i].fInnerXRadius = innerXRadius - 0.5f;
+        verts[i].fInnerXYRatio = innerRatio;
+    }
+
+    SkScalar L = -xRadius;
+    SkScalar R = +xRadius;
+    SkScalar T = -yRadius;
+    SkScalar B = +yRadius;
+
+    // We've extended the outer x radius out half a pixel to antialias.
+    // Expand the drawn rect here so all the pixels will be captured.
+    L += center.fX - SK_ScalarHalf;
+    R += center.fX + SK_ScalarHalf;
+    T += center.fY - SK_ScalarHalf;
+    B += center.fY + SK_ScalarHalf;
+
+    verts[0].fPos = SkPoint::Make(L, T);
+    verts[1].fPos = SkPoint::Make(R, T);
+    verts[2].fPos = SkPoint::Make(L, B);
+    verts[3].fPos = SkPoint::Make(R, B);
+
+    target->drawNonIndexed(kTriangleStrip_GrPrimitiveType, 0, 4);
+}
+