[SVGDom] Avoid some unneeded canvas save()s

The canvas only needs to be saved once, per local SkSVGRenderContext.

Add a helper (saveOnce) to implement this optimization.

Change-Id: I0c21fa78ad9fd5d3d11de0a29f8441620488d676
Reviewed-on: https://skia-review.googlesource.com/58340
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Robert Phillips <robertphillips@google.com>

5 files changed, 14 insertions, 7 deletions

diff --git a/experimental/svg/model/SkSVGRenderContext.cpp b/experimental/svg/model/SkSVGRenderContext.cpp
index d8c269a56f..7fa61d48a3 100644
--- a/experimental/svg/model/SkSVGRenderContext.cpp
+++ b/experimental/svg/model/SkSVGRenderContext.cpp
@@ -333,6 +333,15 @@ void SkSVGRenderContext::applyOpacity(SkScalar opacity, uint32_t flags) {
     }
 }
 
+void SkSVGRenderContext::saveOnce() {
+    // The canvas only needs to be saved once, per local SkSVGRenderContext.
+    if (fCanvas->getSaveCount() == fCanvasSaveCount) {
+        fCanvas->save();
+    }
+
+    SkASSERT(fCanvas->getSaveCount() > fCanvasSaveCount);
+}
+
 void SkSVGRenderContext::applyClip(const SkSVGClip& clip) {
     if (clip.type() != SkSVGClip::Type::kIRI) {
         return;
@@ -352,10 +361,7 @@ void SkSVGRenderContext::applyClip(const SkSVGClip& clip) {
     //
     // TODO: the two uses are exclusive, avoid canvas churn when non needed.
 
-    // Only save if needed
-    if (fCanvas->getSaveCount() == fCanvasSaveCount) {
-        fCanvas->save();
-    }
+    this->saveOnce();
 
     fCanvas->clipPath(clipPath, true);
     fClipPath.set(clipPath);
diff --git a/experimental/svg/model/SkSVGRenderContext.h b/experimental/svg/model/SkSVGRenderContext.h
index 3cd38cbd7f..b5d8720ab3 100644
--- a/experimental/svg/model/SkSVGRenderContext.h
+++ b/experimental/svg/model/SkSVGRenderContext.h
@@ -69,6 +69,7 @@ public:
     const SkSVGPresentationContext& presentationContext() const { return *fPresentationContext; }
 
     SkCanvas* canvas() const { return fCanvas; }
+    void saveOnce();
 
     enum ApplyFlags {
         kLeaf = 1 << 0, // the target node doesn't have descendants
diff --git a/experimental/svg/model/SkSVGSVG.cpp b/experimental/svg/model/SkSVGSVG.cpp
index 592992760a..ef919a8ec1 100644
--- a/experimental/svg/model/SkSVGSVG.cpp
+++ b/experimental/svg/model/SkSVGSVG.cpp
@@ -33,7 +33,7 @@ bool SkSVGSVG::onPrepareToRender(SkSVGRenderContext* ctx) const {
     }
 
     if (!contentMatrix.isIdentity()) {
-        ctx->canvas()->save();
+        ctx->saveOnce();
         ctx->canvas()->concat(contentMatrix);
     }
 
diff --git a/experimental/svg/model/SkSVGTransformableNode.cpp b/experimental/svg/model/SkSVGTransformableNode.cpp
index aa2a814f58..e8713c03c4 100644
--- a/experimental/svg/model/SkSVGTransformableNode.cpp
+++ b/experimental/svg/model/SkSVGTransformableNode.cpp
@@ -17,7 +17,7 @@ SkSVGTransformableNode::SkSVGTransformableNode(SkSVGTag tag)
 
 bool SkSVGTransformableNode::onPrepareToRender(SkSVGRenderContext* ctx) const {
     if (!fTransform.value().isIdentity()) {
-        ctx->canvas()->save();
+        ctx->saveOnce();
         ctx->canvas()->concat(fTransform);
     }
 
diff --git a/experimental/svg/model/SkSVGUse.cpp b/experimental/svg/model/SkSVGUse.cpp
index b98909f8b4..b0d6f93b77 100644
--- a/experimental/svg/model/SkSVGUse.cpp
+++ b/experimental/svg/model/SkSVGUse.cpp
@@ -58,7 +58,7 @@ bool SkSVGUse::onPrepareToRender(SkSVGRenderContext* ctx) const {
 
     if (fX.value() || fY.value()) {
         // Restored when the local SkSVGRenderContext leaves scope.
-        ctx->canvas()->save();
+        ctx->saveOnce();
         ctx->canvas()->translate(fX.value(), fY.value());
     }