Builder class for SkLayerRasterizer.

Provide builder class to make SkLayerRasterizer immutable. We have to keep the
addLayer() methods for now because they are used in Chrome. They will be removed
once this changed has been rolled into Chrome.
An added benefit of this is that this class can only be allocated on the heap.

BUG=skia:2187
R=reed@google.com, scroggo@google.com, mtklein@google.com

Author: dominikg@chromium.org

Review URL: https://codereview.chromium.org/176873004

git-svn-id: http://skia.googlecode.com/svn/trunk@13590 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 52 insertions, 10 deletions

diff --git a/src/effects/SkLayerRasterizer.cpp b/src/effects/SkLayerRasterizer.cpp
index a10d758ede..e35c5e828f 100644
--- a/src/effects/SkLayerRasterizer.cpp
+++ b/src/effects/SkLayerRasterizer.cpp
@@ -25,25 +25,36 @@ struct SkLayerRasterizer_Rec {
     SkVector    fOffset;
 };
 
-SkLayerRasterizer::SkLayerRasterizer() : fLayers(sizeof(SkLayerRasterizer_Rec))
+SkLayerRasterizer::SkLayerRasterizer()
+    : fLayers(SkNEW_ARGS(SkDeque, (sizeof(SkLayerRasterizer_Rec))))
+{
+}
+
+SkLayerRasterizer::SkLayerRasterizer(SkDeque* layers) : fLayers(layers)
 {
 }
 
 SkLayerRasterizer::~SkLayerRasterizer() {
-    SkDeque::F2BIter        iter(fLayers);
+    SkASSERT(fLayers);
+    SkDeque::F2BIter        iter(*fLayers);
     SkLayerRasterizer_Rec*  rec;
 
     while ((rec = (SkLayerRasterizer_Rec*)iter.next()) != NULL)
         rec->fPaint.~SkPaint();
+
+    SkDELETE(fLayers);
 }
 
+#ifdef SK_SUPPORT_LEGACY_LAYERRASTERIZER_API
 void SkLayerRasterizer::addLayer(const SkPaint& paint, SkScalar dx,
                                  SkScalar dy) {
-    SkLayerRasterizer_Rec* rec = (SkLayerRasterizer_Rec*)fLayers.push_back();
+    SkASSERT(fLayers);
+    SkLayerRasterizer_Rec* rec = (SkLayerRasterizer_Rec*)fLayers->push_back();
 
     SkNEW_PLACEMENT_ARGS(&rec->fPaint, SkPaint, (paint));
     rec->fOffset.set(dx, dy);
 }
+#endif
 
 static bool compute_bounds(const SkDeque& layers, const SkPath& path,
                            const SkMatrix& matrix,
@@ -89,12 +100,13 @@ static bool compute_bounds(const SkDeque& layers, const SkPath& path,
 bool SkLayerRasterizer::onRasterize(const SkPath& path, const SkMatrix& matrix,
                                     const SkIRect* clipBounds,
                                     SkMask* mask, SkMask::CreateMode mode) const {
-    if (fLayers.empty()) {
+    SkASSERT(fLayers);
+    if (fLayers->empty()) {
         return false;
     }
 
     if (SkMask::kJustRenderImage_CreateMode != mode) {
-        if (!compute_bounds(fLayers, path, matrix, clipBounds, &mask->fBounds))
+        if (!compute_bounds(*fLayers, path, matrix, clipBounds, &mask->fBounds))
             return false;
     }
 
@@ -131,7 +143,7 @@ bool SkLayerRasterizer::onRasterize(const SkPath& path, const SkMatrix& matrix,
         // we set the matrixproc in the loop, as the matrix changes each time (potentially)
         draw.fBounder   = NULL;
 
-        SkDeque::F2BIter        iter(fLayers);
+        SkDeque::F2BIter        iter(*fLayers);
         SkLayerRasterizer_Rec*  rec;
 
         while ((rec = (SkLayerRasterizer_Rec*)iter.next()) != NULL) {
@@ -144,24 +156,29 @@ bool SkLayerRasterizer::onRasterize(const SkPath& path, const SkMatrix& matrix,
 }
 
 SkLayerRasterizer::SkLayerRasterizer(SkReadBuffer& buffer)
-    : SkRasterizer(buffer), fLayers(sizeof(SkLayerRasterizer_Rec)) {
+    : SkRasterizer(buffer), fLayers(ReadLayers(buffer)) {}
+
+SkDeque* SkLayerRasterizer::ReadLayers(SkReadBuffer& buffer) {
     int count = buffer.readInt();
 
+    SkDeque* layers = SkNEW_ARGS(SkDeque, (sizeof(SkLayerRasterizer_Rec)));
     for (int i = 0; i < count; i++) {
-        SkLayerRasterizer_Rec* rec = (SkLayerRasterizer_Rec*)fLayers.push_back();
+        SkLayerRasterizer_Rec* rec = (SkLayerRasterizer_Rec*)layers->push_back();
 
         SkNEW_PLACEMENT(&rec->fPaint, SkPaint);
         buffer.readPaint(&rec->fPaint);
         buffer.readPoint(&rec->fOffset);
     }
+    return layers;
 }
 
 void SkLayerRasterizer::flatten(SkWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
 
-    buffer.writeInt(fLayers.count());
+    SkASSERT(fLayers);
+    buffer.writeInt(fLayers->count());
 
-    SkDeque::F2BIter                iter(fLayers);
+    SkDeque::F2BIter                iter(*fLayers);
     const SkLayerRasterizer_Rec*    rec;
 
     while ((rec = (const SkLayerRasterizer_Rec*)iter.next()) != NULL) {
@@ -169,3 +186,28 @@ void SkLayerRasterizer::flatten(SkWriteBuffer& buffer) const {
         buffer.writePoint(rec->fOffset);
     }
 }
+
+SkLayerRasterizer::Builder::Builder()
+        : fLayers(SkNEW_ARGS(SkDeque, (sizeof(SkLayerRasterizer_Rec))))
+{
+}
+
+SkLayerRasterizer::Builder::~Builder()
+{
+    SkDELETE(fLayers);
+}
+
+void SkLayerRasterizer::Builder::addLayer(const SkPaint& paint, SkScalar dx,
+                                          SkScalar dy) {
+    SkASSERT(fLayers);
+    SkLayerRasterizer_Rec* rec = (SkLayerRasterizer_Rec*)fLayers->push_back();
+
+    SkNEW_PLACEMENT_ARGS(&rec->fPaint, SkPaint, (paint));
+    rec->fOffset.set(dx, dy);
+}
+
+SkLayerRasterizer* SkLayerRasterizer::Builder::detachRasterizer() {
+    SkLayerRasterizer* rasterizer = SkNEW_ARGS(SkLayerRasterizer, (fLayers));
+    fLayers = NULL;
+    return rasterizer;
+}