Optimize visualbench offscreen blits

tools/VisualBench/VisualSKPBench.cpp

Index: tools/VisualBench/VisualSKPBench.cpp
diff --git a/tools/VisualBench/VisualSKPBench.cpp b/tools/VisualBench/VisualSKPBench.cpp
index 628265e53e103d9a485fd4d5c6dc76fc01c960a8..5d15d7ef2071c6ea7d35ccd027ff423d598e12b2 100644
--- a/tools/VisualBench/VisualSKPBench.cpp
+++ b/tools/VisualBench/VisualSKPBench.cpp
@@ -14,6 +14,7 @@
 
 VisualSKPBench::VisualSKPBench(const char* name, const SkPicture* pic)
     : fPic(SkRef(pic))
+    , fCullRect(fPic->cullRect().roundOut())
     , fName(name) {
     fUniqueName.printf("%s", name);
 }
@@ -30,7 +31,17 @@ bool VisualSKPBench::isSuitableFor(Backend backend) {
     return backend != kNonRendering_Backend;
 }
 
+SkIPoint VisualSKPBench::onGetSize() {
+    return SkIPoint::Make(fCullRect.width(), fCullRect.height());
+}
+
 void VisualSKPBench::onDraw(int loops, SkCanvas* canvas) {
+    bool isOffset = SkToBool(fCullRect.left() | fCullRect.top());
+    if (isOffset) {
+        canvas->save();
+        canvas->translate(SkIntToScalar(-fCullRect.left()), SkIntToScalar(-fCullRect.top()));
+    }
+
     for (int i = 0; i < loops; i++) {
         canvas->drawPicture(fPic);
 #if SK_SUPPORT_GPU
@@ -40,4 +51,8 @@ void VisualSKPBench::onDraw(int loops, SkCanvas* canvas) {
         }
 #endif
     }
+
+    if (isOffset) {
+        canvas->restore();
+    }
 }