allow canvas to force conservative clips (for speed)

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"
@@ skipping 63 matching lines @@
     values: they reflect the top of the save stack, but translated and clipped
     by the device's XY offset and bitmap-bounds.
 */
 struct DeviceCM {
     DeviceCM*           fNext;
     SkBaseDevice*       fDevice;
     SkRasterClip        fClip;
     const SkMatrix*     fMatrix;
     SkPaint*            fPaint; // may be null (in the future)
 
-    DeviceCM(SkBaseDevice* device, int x, int y, const SkPaint* paint, SkCanvas* canvas)
-            : fNext(NULL) {
-        if (device) {
+    DeviceCM(SkBaseDevice* device, int x, int y, const SkPaint* paint, SkCanvas* canvas,
+             bool conservativeRasterClip)
+        : fNext(NULL)
+        , fClip(conservativeRasterClip)
+    {
+        if (NULL != device) {
             device->ref();
             device->onAttachToCanvas(canvas);
         }
         fDevice = device;
         fPaint = paint ? SkNEW_ARGS(SkPaint, (*paint)) : NULL;
     }
 
     ~DeviceCM() {
         if (fDevice) {
             fDevice->onDetachFromCanvas();
@@ skipping 47 matching lines @@
 
 /*  This is the record we keep for each save/restore level in the stack.
     Since a level optionally copies the matrix and/or stack, we have pointers
     for these fields. If the value is copied for this level, the copy is
     stored in the ...Storage field, and the pointer points to that. If the
     value is not copied for this level, we ignore ...Storage, and just point
     at the corresponding value in the previous level in the stack.
 */
 class SkCanvas::MCRec {
 public:
+    SkRasterClip    fRasterClip;
     SkMatrix        fMatrix;
-    SkRasterClip    fRasterClip;
     SkDrawFilter*   fFilter;    // the current filter (or null)
-
-    DeviceCM*   fLayer;
+    DeviceCM*       fLayer;
     /*  If there are any layers in the stack, this points to the top-most
         one that is at or below this level in the stack (so we know what
         bitmap/device to draw into from this level. This value is NOT
         reference counted, since the real owner is either our fLayer field,
         or a previous one in a lower level.)
     */
     DeviceCM*   fTopLayer;
 
-    MCRec(const MCRec* prev) {
-        if (prev) {
-            fMatrix = prev->fMatrix;
-            fRasterClip = prev->fRasterClip;
-
-            fFilter = prev->fFilter;
-            SkSafeRef(fFilter);
-
-            fTopLayer = prev->fTopLayer;
-        } else {   // no prev
-            fMatrix.reset();
-            fFilter     = NULL;
-            fTopLayer   = NULL;
-        }
-        fLayer = NULL;
-
+    MCRec(bool conservativeRasterClip) : fRasterClip(conservativeRasterClip) {
+        fMatrix.reset();
+        fFilter     = NULL;
+        fLayer      = NULL;
+        fTopLayer   = NULL;
+        
         // don't bother initializing fNext
         inc_rec();
     }
+    MCRec(const MCRec& prev) : fRasterClip(prev.fRasterClip) {
+        fMatrix = prev.fMatrix;
+        fFilter = SkSafeRef(prev.fFilter);
+        fLayer = NULL;
+        fTopLayer = prev.fTopLayer;
+        
+        // don't bother initializing fNext
+        inc_rec();
+    }
     ~MCRec() {
         SkSafeUnref(fFilter);
         SkDELETE(fLayer);
         dec_rec();
     }
 };
 
 class SkDrawIter : public SkDraw {
 public:
     SkDrawIter(SkCanvas* canvas, bool skipEmptyClips = true) {
@@ skipping 178 matching lines @@
 #define LOOPER_BEGIN(paint, type, bounds)                           \
     this->predrawNotify();                                          \
     AutoDrawLooper  looper(this, paint, false, bounds);             \
     while (looper.next(type)) {                                     \
         SkDrawIter          iter(this);
 
 #define LOOPER_END    }
 
 ////////////////////////////////////////////////////////////////////////////
 
-SkBaseDevice* SkCanvas::init(SkBaseDevice* device) {
+SkBaseDevice* SkCanvas::init(SkBaseDevice* device, InitFlags flags) {
+    fConservativeRasterClip = SkToBool(flags & kConservativeRasterClip_InitFlag);
     fCachedLocalClipBounds.setEmpty();
     fCachedLocalClipBoundsDirty = true;
     fAllowSoftClip = true;
     fAllowSimplifyClip = false;
     fDeviceCMDirty = true;
     fSaveLayerCount = 0;
     fCullCount = 0;
     fMetaData = NULL;
 
+    if (device && device->forceConservativeRasterClip()) {
+        fConservativeRasterClip = true;
+    }
+    
     fMCRec = (MCRec*)fMCStack.push_back();
-    new (fMCRec) MCRec(NULL);
+    new (fMCRec) MCRec(fConservativeRasterClip);
 
-    fMCRec->fLayer = SkNEW_ARGS(DeviceCM, (NULL, 0, 0, NULL, NULL));
+    fMCRec->fLayer = SkNEW_ARGS(DeviceCM, (NULL, 0, 0, NULL, NULL, fConservativeRasterClip));
     fMCRec->fTopLayer = fMCRec->fLayer;
 
     fSurfaceBase = NULL;
 
     if (device) {
         device->onAttachToCanvas(this);
         fMCRec->fLayer->fDevice = SkRef(device);
         fMCRec->fRasterClip.setRect(SkIRect::MakeWH(device->width(), device->height()));
     }
     return device;
 }
 
 SkCanvas::SkCanvas()
     : fMCStack(sizeof(MCRec), fMCRecStorage, sizeof(fMCRecStorage))
 {
     inc_canvas();
 
-    this->init(NULL);
+    this->init(NULL, kDefault_InitFlags);
 }
 
+static SkBitmap make_nopixels(int width, int height) {
+    SkBitmap bitmap;
+    bitmap.setInfo(SkImageInfo::MakeUnknown(width, height));
+    return bitmap;
+}
+
+class SkNoPixelsBitmapDevice : public SkBitmapDevice {
+public:
+    SkNoPixelsBitmapDevice(int width, int height) : INHERITED(make_nopixels(width, height)) {}
+
+private:
+    
+    typedef SkBitmapDevice INHERITED;
+};
+
 SkCanvas::SkCanvas(int width, int height)
     : fMCStack(sizeof(MCRec), fMCRecStorage, sizeof(fMCRecStorage))
 {
     inc_canvas();
+    
+    this->init(SkNEW_ARGS(SkNoPixelsBitmapDevice, (width, height)), kDefault_InitFlags)->unref();
+}
 
-    SkBitmap bitmap;
-    bitmap.setInfo(SkImageInfo::MakeUnknown(width, height));
-    this->init(SkNEW_ARGS(SkBitmapDevice, (bitmap)))->unref();
+SkCanvas::SkCanvas(int width, int height, InitFlags flags)
+    : fMCStack(sizeof(MCRec), fMCRecStorage, sizeof(fMCRecStorage))
+{
+    inc_canvas();
+    
+    this->init(SkNEW_ARGS(SkNoPixelsBitmapDevice, (width, height)), flags)->unref();
+}
+
+SkCanvas::SkCanvas(SkBaseDevice* device, InitFlags flags)
+    : fMCStack(sizeof(MCRec), fMCRecStorage, sizeof(fMCRecStorage))
+{
+    inc_canvas();
+    
+    this->init(device, flags);
 }
 
 SkCanvas::SkCanvas(SkBaseDevice* device)
     : fMCStack(sizeof(MCRec), fMCRecStorage, sizeof(fMCRecStorage))
 {
     inc_canvas();
-
-    this->init(device);
+    
+    this->init(device, kDefault_InitFlags);
 }
 
 SkCanvas::SkCanvas(const SkBitmap& bitmap)
     : fMCStack(sizeof(MCRec), fMCRecStorage, sizeof(fMCRecStorage))
 {
     inc_canvas();
 
-    this->init(SkNEW_ARGS(SkBitmapDevice, (bitmap)))->unref();
+    this->init(SkNEW_ARGS(SkBitmapDevice, (bitmap)), kDefault_InitFlags)->unref();
 }
 
 SkCanvas::~SkCanvas() {
     // free up the contents of our deque
     this->restoreToCount(1);    // restore everything but the last
     SkASSERT(0 == fSaveLayerCount);
 
     this->internalRestore();    // restore the last, since we're going away
 
     SkDELETE(fMetaData);
@@ skipping 275 matching lines @@
         fDeviceCMDirty = false;
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 int SkCanvas::internalSave() {
     int saveCount = this->getSaveCount(); // record this before the actual save
 
     MCRec* newTop = (MCRec*)fMCStack.push_back();
-    new (newTop) MCRec(fMCRec);    // balanced in restore()
+    new (newTop) MCRec(*fMCRec);    // balanced in restore()
     fMCRec = newTop;
 
     fClipStack.save();
 
     return saveCount;
 }
 
 int SkCanvas::save() {
     this->willSave();
     return this->internalSave();
@@ skipping 111 matching lines @@
         }
     } else {
         device = this->createLayerDevice(info);
     }
     if (NULL == device) {
         SkDebugf("Unable to create device for layer.");
         return count;
     }
 
     device->setOrigin(ir.fLeft, ir.fTop);
-    DeviceCM* layer = SkNEW_ARGS(DeviceCM, (device, ir.fLeft, ir.fTop, paint, this));
+    DeviceCM* layer = SkNEW_ARGS(DeviceCM,
+                                 (device, ir.fLeft, ir.fTop, paint, this, fConservativeRasterClip));
     device->unref();
 
     layer->fNext = fMCRec->fTopLayer;
     fMCRec->fLayer = layer;
     fMCRec->fTopLayer = layer;    // this field is NOT an owner of layer
 
     fSaveLayerCount += 1;
     return count;
 }
 
@@ skipping 399 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);
-        fMCRec->fRasterClip.op(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 114 matching lines @@
             if (element->isAA()) {
                 edgeStyle = kSoft_ClipEdgeStyle;
             }
         }
         op = SkRegion::kReplace_Op;
     }
 
     rasterclip_path(&fMCRec->fRasterClip, this, devPath, op, edgeStyle);
 }
 
-void SkCanvas::updateClipConservativelyUsingBounds(const SkRect& bounds, SkRegion::Op op,
-                                                   bool inverseFilled) {
-    // This is for updating the clip conservatively using only bounds
-    // information.
-    // Contract:
-    //    The current clip must contain the true clip. The true
-    //    clip is the clip that would have normally been computed
-    //    by calls to clipPath and clipRRect
-    // Objective:
-    //    Keep the current clip as small as possible without
-    //    breaking the contract, using only clip bounding rectangles
-    //    (for performance).
-
-    // N.B.: This *never* calls back through a virtual on canvas, so subclasses
-    // don't have to worry about getting caught in a loop. Thus anywhere
-    // we call a virtual method, we explicitly prefix it with
-    // SkCanvas:: to be sure to call the base-class.
-
-    if (inverseFilled) {
-        switch (op) {
-            case SkRegion::kIntersect_Op:
-            case SkRegion::kDifference_Op:
-                // These ops can only shrink the current clip. So leaving
-                // the clip unchanged conservatively respects the contract.
-                break;
-            case SkRegion::kUnion_Op:
-            case SkRegion::kReplace_Op:
-            case SkRegion::kReverseDifference_Op:
-            case SkRegion::kXOR_Op: {
-                    // These ops can grow the current clip up to the extents of
-                    // the input clip, which is inverse filled, so we just set
-                    // the current clip to the device bounds.
-                    SkRect deviceBounds;
-                    SkIRect deviceIBounds;
-                    this->getDevice()->getGlobalBounds(&deviceIBounds);
-                    deviceBounds = SkRect::Make(deviceIBounds);
-
-                    // set the clip in device space
-                    SkMatrix savedMatrix = this->getTotalMatrix();
-                    this->SkCanvas::setMatrix(SkMatrix::I());
-                    this->SkCanvas::onClipRect(deviceBounds, SkRegion::kReplace_Op,
-                                               kHard_ClipEdgeStyle);
-                    this->setMatrix(savedMatrix);
-                    break;
-            }
-            default:
-                SkASSERT(0); // unhandled op?
-        }
-    } else {
-        // Not inverse filled
-        switch (op) {
-            case SkRegion::kIntersect_Op:
-            case SkRegion::kUnion_Op:
-            case SkRegion::kReplace_Op:
-                this->SkCanvas::onClipRect(bounds, op, kHard_ClipEdgeStyle);
-                break;
-            case SkRegion::kDifference_Op:
-                // Difference can only shrink the current clip.
-                // Leaving clip unchanged conservatively fullfills the contract.
-                break;
-            case SkRegion::kReverseDifference_Op:
-                // To reverse, we swap in the bounds with a replace op.
-                // As with difference, leave it unchanged.
-                this->SkCanvas::onClipRect(bounds, SkRegion::kReplace_Op, kHard_ClipEdgeStyle);
-                break;
-            case SkRegion::kXOR_Op:
-                // Be conservative, based on (A XOR B) always included in (A union B),
-                // which is always included in (bounds(A) union bounds(B))
-                this->SkCanvas::onClipRect(bounds, SkRegion::kUnion_Op, kHard_ClipEdgeStyle);
-                break;
-            default:
-                SkASSERT(0); // unhandled op?
-        }
-    }
-}
-
 void SkCanvas::clipRegion(const SkRegion& rgn, SkRegion::Op op) {
     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);
 
     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);
+    SkRasterClip tmpClip(ir, fConservativeRasterClip);
 
     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:
@@ skipping 23 matching lines @@
 
 bool SkCanvas::isClipEmpty() const {
     return fMCRec->fRasterClip.isEmpty();
 }
 
 bool SkCanvas::isClipRect() const {
     return fMCRec->fRasterClip.isRect();
 }
 
 bool SkCanvas::quickReject(const SkRect& rect) const {
-
     if (!rect.isFinite())
         return true;
 
     if (fMCRec->fRasterClip.isEmpty()) {
         return true;
     }
 
     if (fMCRec->fMatrix.hasPerspective()) {
         SkRect dst;
         fMCRec->fMatrix.mapRect(&dst, rect);
@@ skipping 949 matching lines @@
     }
 
     if (matrix) {
         canvas->concat(*matrix);
     }
 }
 
 SkAutoCanvasMatrixPaint::~SkAutoCanvasMatrixPaint() {
     fCanvas->restoreToCount(fSaveCount);
 }