reduce alloc overhead for SkCanvas

src/core/SkCanvas.cpp

 /*
  * Copyright 2008 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCanvas.h"
 #include "SkCanvasPriv.h"
 #include "SkBitmapDevice.h"
@@ skipping 215 matching lines @@
     }
 };
 
 class SkDrawIter : public SkDraw {
 public:
     SkDrawIter(SkCanvas* canvas, bool skipEmptyClips = true) {
         canvas = canvas->canvasForDrawIter();
         fCanvas = canvas;
         canvas->updateDeviceCMCache();
 
-        fClipStack = canvas->fClipStack.get();
+        fClipStack = &canvas->fClipStack;
         fCurrLayer = canvas->fMCRec->fTopLayer;
         fSkipEmptyClips = skipEmptyClips;
     }
 
     bool next() {
         // skip over recs with empty clips
         if (fSkipEmptyClips) {
             while (fCurrLayer && fCurrLayer->fClip.isEmpty()) {
                 fCurrLayer = fCurrLayer->fNext;
             }
@@ skipping 184 matching lines @@
     fCachedLocalClipBoundsDirty = true;
     fAllowSoftClip = true;
     fAllowSimplifyClip = false;
     fDeviceCMDirty = true;
     fSaveCount = 1;
     fMetaData = NULL;
 
     fMCRec = (MCRec*)fMCStack.push_back();
     new (fMCRec) MCRec(fConservativeRasterClip);
 
-    fMCRec->fLayer = SkNEW_ARGS(DeviceCM, (NULL, NULL, NULL, fConservativeRasterClip));
+    SkASSERT(sizeof(DeviceCM) <= sizeof(fBaseLayerStorage));
+    fMCRec->fLayer = (DeviceCM*)fBaseLayerStorage;
+    new (fBaseLayerStorage) DeviceCM(NULL, NULL, NULL, fConservativeRasterClip);
+
     fMCRec->fTopLayer = fMCRec->fLayer;
 
     fSurfaceBase = NULL;
 
-    fClipStack.reset(SkNEW(SkClipStack));
-
     if (device) {
         device->initForRootLayer(fProps.pixelGeometry());
         if (device->forceConservativeRasterClip()) {
             fConservativeRasterClip = true;
         }
         device->onAttachToCanvas(this);
         fMCRec->fLayer->fDevice = SkRef(device);
         fMCRec->fRasterClip.setRect(device->getGlobalBounds());
     }
     return device;
@@ skipping 273 matching lines @@
 
 //////////////////////////////////////////////////////////////////////////////
 
 void SkCanvas::updateDeviceCMCache() {
     if (fDeviceCMDirty) {
         const SkMatrix& totalMatrix = this->getTotalMatrix();
         const SkRasterClip& totalClip = fMCRec->fRasterClip;
         DeviceCM*       layer = fMCRec->fTopLayer;
 
         if (NULL == layer->fNext) {   // only one layer
-            layer->updateMC(totalMatrix, totalClip, *fClipStack, NULL);
+            layer->updateMC(totalMatrix, totalClip, fClipStack, NULL);
         } else {
             SkRasterClip clip(totalClip);
             do {
-                layer->updateMC(totalMatrix, clip, *fClipStack, &clip);
+                layer->updateMC(totalMatrix, clip, fClipStack, &clip);
             } while ((layer = layer->fNext) != NULL);
         }
         fDeviceCMDirty = false;
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 void SkCanvas::checkForDeferredSave() {
     if (fMCRec->fDeferredSaveCount > 0) {
@@ skipping 56 matching lines @@
     for (int i = 0; i < n; ++i) {
         this->restore();
     }
 }
 
 void SkCanvas::internalSave() {
     MCRec* newTop = (MCRec*)fMCStack.push_back();
     new (newTop) MCRec(*fMCRec);    // balanced in restore()
     fMCRec = newTop;
 
-    fClipStack->save();
+    fClipStack.save();
 }
 
 static bool bounds_affects_clip(SkCanvas::SaveFlags flags) {
 #ifdef SK_SUPPORT_LEGACY_CLIPTOLAYERFLAG
     return (flags & SkCanvas::kClipToLayer_SaveFlag) != 0;
 #else
     return true;
 #endif
 }
 
@@ skipping 24 matching lines @@
             return false;
         }
     } else {    // no user bounds, so just use the clip
         ir = clipBounds;
     }
     SkASSERT(!ir.isEmpty());
 
     if (bounds_affects_clip(flags)) {
         // Simplify the current clips since they will be applied properly during restore()
         fCachedLocalClipBoundsDirty = true;
-        fClipStack->clipDevRect(ir, SkRegion::kReplace_Op);
+        fClipStack.clipDevRect(ir, SkRegion::kReplace_Op);
         fMCRec->fRasterClip.setRect(ir);
     }
 
     if (intersection) {
         *intersection = ir;
     }
     return true;
 }
 
 int SkCanvas::saveLayer(const SkRect* bounds, const SkPaint* paint) {
@@ skipping 88 matching lines @@
         return this->saveLayer(bounds, &tmpPaint, flags);
     }
 }
 
 void SkCanvas::internalRestore() {
     SkASSERT(fMCStack.count() != 0);
 
     fDeviceCMDirty = true;
     fCachedLocalClipBoundsDirty = true;
 
-    fClipStack->restore();
+    fClipStack.restore();
 
     // reserve our layer (if any)
     DeviceCM* layer = fMCRec->fLayer;   // may be null
     // now detach it from fMCRec so we can pop(). Gets freed after its drawn
     fMCRec->fLayer = NULL;
 
     // now do the normal restore()
     fMCRec->~MCRec();       // balanced in save()
     fMCStack.pop_back();
     fMCRec = (MCRec*)fMCStack.back();
 
     /*  Time to draw the layer's offscreen. We can't call the public drawSprite,
         since if we're being recorded, we don't want to record this (the
         recorder will have already recorded the restore).
     */
     if (layer) {
         if (layer->fNext) {
             const SkIPoint& origin = layer->fDevice->getOrigin();
             this->internalDrawDevice(layer->fDevice, origin.x(), origin.y(),
                                      layer->fPaint);
             // reset this, since internalDrawDevice will have set it to true
             fDeviceCMDirty = true;
+            SkDELETE(layer);
+        } else {
+            // we're at the root
+            SkASSERT(layer == (void*)fBaseLayerStorage);
+            layer->~DeviceCM();
         }
-        SkDELETE(layer);
     }
 }
 
 SkSurface* SkCanvas::newSurface(const SkImageInfo& info, const SkSurfaceProps* props) {
     if (NULL == props) {
         props = &fProps;
     }
     return this->onNewSurface(info, *props);
 }
 
@@ skipping 260 matching lines @@
     }
 
     if (fMCRec->fMatrix.rectStaysRect()) {
         // for these simpler matrices, we can stay a rect even after applying
         // the matrix. This means we don't have to a) make a path, and b) tell
         // the region code to scan-convert the path, only to discover that it
         // is really just a rect.
         SkRect      r;
 
         fMCRec->fMatrix.mapRect(&r, rect);
-        fClipStack->clipDevRect(r, op, kSoft_ClipEdgeStyle == edgeStyle);
+        fClipStack.clipDevRect(r, op, kSoft_ClipEdgeStyle == edgeStyle);
         fMCRec->fRasterClip.op(r, this->getBaseLayerSize(), op, kSoft_ClipEdgeStyle == edgeStyle);
     } else {
         // since we're rotated or some such thing, we convert the rect to a path
         // and clip against that, since it can handle any matrix. However, to
         // avoid recursion in the case where we are subclassed (e.g. Pictures)
         // we explicitly call "our" version of clipPath.
         SkPath  path;
 
         path.addRect(rect);
         this->SkCanvas::onClipPath(path, op, edgeStyle);
@@ skipping 19 matching lines @@
     SkRRect transformedRRect;
     if (rrect.transform(fMCRec->fMatrix, &transformedRRect)) {
         AutoValidateClip avc(this);
 
         fDeviceCMDirty = true;
         fCachedLocalClipBoundsDirty = true;
         if (!fAllowSoftClip) {
             edgeStyle = kHard_ClipEdgeStyle;
         }
 
-        fClipStack->clipDevRRect(transformedRRect, op, kSoft_ClipEdgeStyle == edgeStyle);
+        fClipStack.clipDevRRect(transformedRRect, op, kSoft_ClipEdgeStyle == edgeStyle);
 
         SkPath devPath;
         devPath.addRRect(transformedRRect);
 
         rasterclip_path(&fMCRec->fRasterClip, this, devPath, op, kSoft_ClipEdgeStyle == edgeStyle);
         return;
     }
 
     SkPath path;
     path.addRRect(rrect);
@@ skipping 44 matching lines @@
     // made us empty. Note this can also happen if we contained NaN
     // values. computing the bounds detects this, and will set our
     // bounds to empty if that is the case. (see SkRect::set(pts, count))
     if (devPath.getBounds().isEmpty()) {
         // resetting the path will remove any NaN or other wanky values
         // that might upset our scan converter.
         devPath.reset();
     }
 
     // if we called path.swap() we could avoid a deep copy of this path
-    fClipStack->clipDevPath(devPath, op, kSoft_ClipEdgeStyle == edgeStyle);
+    fClipStack.clipDevPath(devPath, op, kSoft_ClipEdgeStyle == edgeStyle);
 
     if (fAllowSimplifyClip) {
         bool clipIsAA = getClipStack()->asPath(&devPath);
         if (clipIsAA) {
             edgeStyle = kSoft_ClipEdgeStyle;
         }
 
         op = SkRegion::kReplace_Op;
     }
 
     rasterclip_path(&fMCRec->fRasterClip, this, devPath, op, edgeStyle);
 }
 
 void SkCanvas::clipRegion(const SkRegion& rgn, SkRegion::Op op) {
     this->checkForDeferredSave();
     this->onClipRegion(rgn, op);
 }
 
 void SkCanvas::onClipRegion(const SkRegion& rgn, SkRegion::Op op) {
     AutoValidateClip avc(this);
 
     fDeviceCMDirty = true;
     fCachedLocalClipBoundsDirty = true;
 
     // todo: signal fClipStack that we have a region, and therefore (I guess)
     // we have to ignore it, and use the region directly?
-    fClipStack->clipDevRect(rgn.getBounds(), op);
+    fClipStack.clipDevRect(rgn.getBounds(), op);
 
     fMCRec->fRasterClip.op(rgn, op);
 }
 
 #ifdef SK_DEBUG
 void SkCanvas::validateClip() const {
     // construct clipRgn from the clipstack
     const SkBaseDevice* device = this->getDevice();
     if (!device) {
         SkASSERT(this->isClipEmpty());
         return;
     }
 
     SkIRect ir;
     ir.set(0, 0, device->width(), device->height());
     SkRasterClip tmpClip(ir, fConservativeRasterClip);
 
-    SkClipStack::B2TIter                iter(*fClipStack);
+    SkClipStack::B2TIter                iter(fClipStack);
     const SkClipStack::Element* element;
     while ((element = iter.next()) != NULL) {
         switch (element->getType()) {
             case SkClipStack::Element::kRect_Type:
                 element->getRect().round(&ir);
                 tmpClip.op(ir, element->getOp());
                 break;
             case SkClipStack::Element::kEmpty_Type:
                 tmpClip.setEmpty();
                 break;
             default: {
                 SkPath path;
                 element->asPath(&path);
                 rasterclip_path(&tmpClip, this, path, element->getOp(), element->isAA());
                 break;
             }
         }
     }
 }
 #endif
 
 void SkCanvas::replayClips(ClipVisitor* visitor) const {
-    SkClipStack::B2TIter                iter(*fClipStack);
+    SkClipStack::B2TIter                iter(fClipStack);
     const SkClipStack::Element*         element;
 
     while ((element = iter.next()) != NULL) {
         element->replay(visitor);
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 bool SkCanvas::isClipEmpty() const {
@@ skipping 1047 matching lines @@
     }
 
     if (matrix) {
         canvas->concat(*matrix);
     }
 }
 
 SkAutoCanvasMatrixPaint::~SkAutoCanvasMatrixPaint() {
     fCanvas->restoreToCount(fSaveCount);
 }