Add GrAASmallPathRenderer.

src/gpu/GrAADistanceFieldPathRenderer.cpp

Index: src/gpu/GrAADistanceFieldPathRenderer.cpp
diff --git a/src/gpu/GrAADistanceFieldPathRenderer.cpp b/src/gpu/GrAADistanceFieldPathRenderer.cpp
new file mode 100755
index 0000000000000000000000000000000000000000..364217c5768eba348f9dcad255eff548c22609be
--- /dev/null
+++ b/src/gpu/GrAADistanceFieldPathRenderer.cpp
@@ -0,0 +1,340 @@
+
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "GrAADistanceFieldPathRenderer.h"
+
+#include "GrAtlas.h"
+#include "GrContext.h"
+#include "GrDrawState.h"
+#include "GrSurfacePriv.h"
+#include "GrSWMaskHelper.h"
+#include "GrTexturePriv.h"
+#include "effects/GrDistanceFieldTextureEffect.h"
+
+#include "SkDistanceFieldGen.h"
+#include "SkRTConf.h"
+
+#define ATLAS_TEXTURE_WIDTH 1024
+#define ATLAS_TEXTURE_HEIGHT 1024
+
+#define PLOT_WIDTH  256
+#define PLOT_HEIGHT 256
+
+#define NUM_PLOTS_X   (ATLAS_TEXTURE_WIDTH / PLOT_WIDTH)
+#define NUM_PLOTS_Y   (ATLAS_TEXTURE_HEIGHT / PLOT_HEIGHT)
+
+SK_CONF_DECLARE(bool, c_DumpPathCache, "gpu.dumpPathCache", false,
+                "Dump the contents of the path cache before every purge.");
+
+////////////////////////////////////////////////////////////////////////////////
+GrAADistanceFieldPathRenderer::~GrAADistanceFieldPathRenderer() {
+    PathDataList::Iter iter;
+    iter.init(fPathList, PathDataList::Iter::kHead_IterStart);
+    PathData* pathData;
+    while ((pathData = iter.get())) {
+        iter.next();
+        fPathList.remove(pathData);
+        SkDELETE(pathData);
+    }
+    
+    SkDELETE(fAtlas);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+bool GrAADistanceFieldPathRenderer::canDrawPath(const SkPath& path,
+                                                const SkStrokeRec& stroke,
+                                                const GrDrawTarget* target,
+                                                bool antiAlias) const {
+    // TODO: Support inverse fill
+    // TODO: Support strokes
+    if (!target->caps()->shaderDerivativeSupport() || !antiAlias || path.isInverseFillType()
+        || SkStrokeRec::kFill_Style != stroke.getStyle()) {
+        return false;
+    }
+
+    // currently don't support perspective or scaling more than 3x
+    const GrDrawState& drawState = target->getDrawState();
+    const SkMatrix& vm = drawState.getViewMatrix();
+    if (vm.hasPerspective() || vm.getMaxScale() > 3.0f) {
+        return false;
+    }
+    
+    // only support paths smaller than 64 x 64
+    const SkRect& bounds = path.getBounds();
+    return bounds.width() < 64.f && bounds.height() < 64.f;
+}
+
+
+GrPathRenderer::StencilSupport GrAADistanceFieldPathRenderer::onGetStencilSupport(
+                                                                       const SkPath&,
+                                                                       const SkStrokeRec&,
+                                                                       const GrDrawTarget*) const {
+    return GrPathRenderer::kNoSupport_StencilSupport;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+// position + texture coord
+extern const GrVertexAttrib gSDFPathVertexAttribs[] = {
+    { kVec2f_GrVertexAttribType, 0, kPosition_GrVertexAttribBinding },
+    { kVec2f_GrVertexAttribType, sizeof(SkPoint), kGeometryProcessor_GrVertexAttribBinding }
+};
+static const size_t kSDFPathVASize = 2 * sizeof(SkPoint);
+
+bool GrAADistanceFieldPathRenderer::onDrawPath(const SkPath& path,
+                                               const SkStrokeRec& stroke,
+                                               GrDrawTarget* target,
+                                               bool antiAlias) {
+    // we've already bailed on inverse filled paths, so this is safe
+    if (path.isEmpty()) {
+        return true;
+    }
+
+    SkASSERT(fContext);
+
+    // check to see if path is cached
+    // TODO: handle stroked vs. filled version of same path
+    PathData* pathData = fPathCache.find(path.getGenerationID());
+    if (NULL == pathData) {
+        pathData = this->addPathToAtlas(path, stroke, antiAlias);
+        if (NULL == pathData) {
+            return false;
+        }
+    }
+
+    // use signed distance field to render
+    return this->internalDrawPath(path, pathData, target);
+}
+
+// factor used to scale the path prior to building distance field
+const SkScalar kScaleFactor = 2.0f;
+// padding around path bounds to allow for antialiased pixels
+const SkScalar kAntiAliasPad = 1.0f;
+
+GrAADistanceFieldPathRenderer::PathData* GrAADistanceFieldPathRenderer::addPathToAtlas(
+                                                                        const SkPath& path,
+                                                                        const SkStrokeRec& stroke,
+                                                                        bool antiAlias) {
+
+    // generate distance field and add to atlas
+    if (NULL == fAtlas) {
+        SkISize textureSize = SkISize::Make(ATLAS_TEXTURE_WIDTH, ATLAS_TEXTURE_HEIGHT);
+        fAtlas = SkNEW_ARGS(GrAtlas, (fContext->getGpu(), kAlpha_8_GrPixelConfig,
+                                      kNone_GrTextureFlags, textureSize,
+                                      NUM_PLOTS_X, NUM_PLOTS_Y, false));
+        if (NULL == fAtlas) {
+            return NULL;
+        }
+    }
+    
+    const SkRect& bounds = path.getBounds();
+    
+    // generate bounding rect for bitmap draw
+    SkRect scaledBounds = bounds;
+    // scale up to improve maxification range
+    scaledBounds.fLeft *= kScaleFactor;
+    scaledBounds.fTop *= kScaleFactor;
+    scaledBounds.fRight *= kScaleFactor;
+    scaledBounds.fBottom *= kScaleFactor;
+    // move the origin to an integer boundary (gives better results)
+    SkScalar dx = SkScalarFraction(scaledBounds.fLeft);
+    SkScalar dy = SkScalarFraction(scaledBounds.fTop);
+    scaledBounds.offset(-dx, -dy);
+    // get integer boundary
+    SkIRect devPathBounds;
+    scaledBounds.roundOut(&devPathBounds);
+    // pad to allow room for antialiasing
+    devPathBounds.outset(SkScalarCeilToInt(kAntiAliasPad), SkScalarCeilToInt(kAntiAliasPad));
+    // move origin to upper left corner
+    devPathBounds.offsetTo(0,0);
+    
+    // draw path to bitmap
+    SkMatrix drawMatrix;
+    drawMatrix.setTranslate(-bounds.left(), -bounds.top());
+    drawMatrix.postScale(kScaleFactor, kScaleFactor);
+    drawMatrix.postTranslate(kAntiAliasPad, kAntiAliasPad);
+    GrSWMaskHelper helper(fContext);
+    
+    if (!helper.init(devPathBounds, &drawMatrix)) {
+        return NULL;
+    }
+    helper.draw(path, stroke, SkRegion::kReplace_Op, antiAlias, 0xFF);
+    
+    // generate signed distance field
+    devPathBounds.outset(SK_DistanceFieldPad, SK_DistanceFieldPad);
+    int width = devPathBounds.width();
+    int height = devPathBounds.height();
+    SkAutoSMalloc<1024> dfStorage(width*height*sizeof(unsigned char));
+    helper.toSDF((unsigned char*) dfStorage.get());
+    
+    // add to atlas
+    SkIPoint16  atlasLocation;
+    GrPlot* plot = fAtlas->addToAtlas(&fPlotUsage, width, height, dfStorage.get(),
+                                      &atlasLocation);
+    
+    // if atlas full
+    if (NULL == plot) {
+        if (this->freeUnusedPlot()) {
+            plot = fAtlas->addToAtlas(&fPlotUsage, width, height, dfStorage.get(),
+                                      &atlasLocation);
+            if (plot) {
+                goto HAS_ATLAS;
+            }
+        }
+    
+        if (c_DumpPathCache) {
+#ifdef SK_DEVELOPER
+            GrTexture* texture = fAtlas->getTexture();
+            texture->surfacePriv().savePixels("pathcache.png");
+#endif
+        }
+        
+        // before we purge the cache, we must flush any accumulated draws
+        fContext->flush();
+        
+        if (this->freeUnusedPlot()) {
+            plot = fAtlas->addToAtlas(&fPlotUsage, width, height, dfStorage.get(),
+                                      &atlasLocation);
+            if (plot) {
+                goto HAS_ATLAS;
+            }
+        }
+            
+        return NULL;
+    }
+    
+HAS_ATLAS:
+    // add to cache
+    PathData* pathData = SkNEW(PathData);
+    pathData->fGenID = path.getGenerationID();
+    pathData->fPlot = plot;
+    // change the scaled rect to match the size of the inset distance field
+    scaledBounds.fRight = scaledBounds.fLeft +
+        SkIntToScalar(devPathBounds.width() - 2*SK_DistanceFieldInset);
+    scaledBounds.fBottom = scaledBounds.fTop +
+        SkIntToScalar(devPathBounds.height() - 2*SK_DistanceFieldInset);
+    // shift the origin to the correct place relative to the distance field
+    // need to also restore the fractional translation
+    scaledBounds.offset(-SkIntToScalar(SK_DistanceFieldInset) - kAntiAliasPad + dx,
+                        -SkIntToScalar(SK_DistanceFieldInset) - kAntiAliasPad + dy);
+    pathData->fBounds = scaledBounds;
+    // origin we render from is inset from distance field edge
+    atlasLocation.fX += SK_DistanceFieldInset;
+    atlasLocation.fY += SK_DistanceFieldInset;
+    pathData->fAtlasLocation = atlasLocation;
+    
+    fPathCache.add(pathData);
+    fPathList.addToTail(pathData);
+    
+    return pathData;
+}
+
+bool GrAADistanceFieldPathRenderer::freeUnusedPlot() {
+    // find an unused plot
+    GrPlot* plot = fAtlas->getUnusedPlot();
+    if (NULL == plot) {
+        return false;
+    }
+    plot->resetRects();
+
+    // remove any paths that use this plot
+    PathDataList::Iter iter;
+    iter.init(fPathList, PathDataList::Iter::kHead_IterStart);
+    PathData* pathData;
+    while ((pathData = iter.get())) {
+        iter.next();
+        if (plot == pathData->fPlot) {
+            fPathCache.remove(pathData->fGenID);
+            fPathList.remove(pathData);
+            SkDELETE(pathData);
+        }
+    }
+        
+    // tell the atlas to free the plot
+    GrAtlas::RemovePlot(&fPlotUsage, plot);
+    
+    return true;
+}
+
+bool GrAADistanceFieldPathRenderer::internalDrawPath(const SkPath& path,
+                                                     const PathData* pathData,
+                                                     GrDrawTarget* target) {
+    
+    GrTexture* texture = fAtlas->getTexture();
+    GrDrawState* drawState = target->drawState();
+    
+    SkASSERT(pathData->fPlot);
+    GrDrawTarget::DrawToken drawToken = target->getCurrentDrawToken();
+    pathData->fPlot->setDrawToken(drawToken);
+    
+    // make me some vertices
+    drawState->setVertexAttribs<gSDFPathVertexAttribs>(SK_ARRAY_COUNT(gSDFPathVertexAttribs),
+                                                       kSDFPathVASize);
+    void* vertices = NULL;
+    void* indices = NULL;
+    bool success = target->reserveVertexAndIndexSpace(4, 6, &vertices, &indices);
+    GrAlwaysAssert(success);
+    
+    SkScalar dx = pathData->fBounds.fLeft;
+    SkScalar dy = pathData->fBounds.fTop;
+    SkScalar width = pathData->fBounds.width();
+    SkScalar height = pathData->fBounds.height();
+    
+    SkScalar invScale = 1.0f/kScaleFactor;
+    dx *= invScale;
+    dy *= invScale;
+    width *= invScale;
+    height *= invScale;
+    
+    SkFixed tx = SkIntToFixed(pathData->fAtlasLocation.fX);
+    SkFixed ty = SkIntToFixed(pathData->fAtlasLocation.fY);
+    SkFixed tw = SkScalarToFixed(pathData->fBounds.width());
+    SkFixed th = SkScalarToFixed(pathData->fBounds.height());
+    
+    // vertex positions
+    SkRect r = SkRect::MakeXYWH(dx, dy, width, height);    
+    size_t vertSize = 2 * sizeof(SkPoint);
+    SkPoint* positions = reinterpret_cast<SkPoint*>(vertices);
+    positions->setRectFan(r.left(), r.top(), r.right(), r.bottom(), vertSize);
+    
+    // vertex texture coords
+    intptr_t intPtr = reinterpret_cast<intptr_t>(positions);
+    SkPoint* textureCoords = reinterpret_cast<SkPoint*>(intPtr + vertSize - sizeof(SkPoint));
+    textureCoords->setRectFan(SkFixedToFloat(texture->texturePriv().normalizeFixedX(tx)),
+                              SkFixedToFloat(texture->texturePriv().normalizeFixedY(ty)),
+                              SkFixedToFloat(texture->texturePriv().normalizeFixedX(tx + tw)),
+                              SkFixedToFloat(texture->texturePriv().normalizeFixedY(ty + th)),
+                              vertSize);
+    
+    uint16_t* indexPtr = reinterpret_cast<uint16_t*>(indices);
+    *indexPtr++ = 0;
+    *indexPtr++ = 1;
+    *indexPtr++ = 2;
+    *indexPtr++ = 0;
+    *indexPtr++ = 2;
+    *indexPtr++ = 3;
+    
+    // set up any flags
+    uint32_t flags = 0;
+    const SkMatrix& vm = drawState->getViewMatrix();
+    flags |= vm.isSimilarity() ? kSimilarity_DistanceFieldEffectFlag : 0;
+    
+    GrTextureParams params(SkShader::kRepeat_TileMode, GrTextureParams::kBilerp_FilterMode);
+    drawState->setGeometryProcessor(GrDistanceFieldNoGammaTextureEffect::Create(texture,
+                                                                                params,
+                                                                                flags))->unref();
+    
+
+    vm.mapRect(&r);
+    target->drawIndexedInstances(kTriangles_GrPrimitiveType, 1, 4, 6, &r);
+    target->resetVertexSource();
+    target->resetIndexSource();
+    
+    return true;
+}
+