add drawPicture variant that takes a matrix and paint

src/core/SkCanvas.cpp

Index: src/core/SkCanvas.cpp
diff --git a/src/core/SkCanvas.cpp b/src/core/SkCanvas.cpp
index 757e7110196ce87f68f624450ed07f9402c19f3d..e51c1cd6f4fabb3f0c91a50e609b8eb2b8c21831 100644
--- a/src/core/SkCanvas.cpp
+++ b/src/core/SkCanvas.cpp
@@ -2397,23 +2397,48 @@ void SkCanvas::EXPERIMENTAL_optimize(const SkPicture* picture) {
 
 void SkCanvas::drawPicture(const SkPicture* picture) {
     if (NULL != picture) {
-        this->onDrawPicture(picture);
+        this->onDrawPicture(picture, NULL, NULL);
     }
 }
 
-void SkCanvas::onDrawPicture(const SkPicture* picture) {
-    SkASSERT(NULL != picture);
+void SkCanvas::drawPicture(const SkPicture* picture, const SkMatrix* matrix, const SkPaint* paint) {
+    if (NULL != picture) {
+        if (matrix && matrix->isIdentity()) {

[mtklein, 2014/08/07 21:25:20]

Sort of weird?  Can't we just not do this?

[reed1, 2014/08/08 13:57:29]

Possibly, though null saves us having to do a save/restore. I figured any
canonicalization tweaks should happen in the non-virtual method (here). That way
all the subclasses need have no checks.

+            matrix = NULL;
+        }
+        this->onDrawPicture(picture, matrix, paint);
+    }
+}
+
+void SkCanvas::onDrawPicture(const SkPicture* pic, const SkMatrix* matrix, const SkPaint* paint) {
+    SkASSERT(NULL != pic);
+
+    SkRect bounds = SkRect::MakeWH(SkIntToScalar(pic->width()), SkIntToScalar(pic->height()));
+    if (matrix) {
+        matrix->mapRect(&bounds);
+    }
+
+    SkAutoCanvasRestore acr(this, false);
+
+    if (paint) {
+        this->SkCanvas::saveLayer(&bounds, paint);
+    } else if (matrix) {
+        this->SkCanvas::save();
+    }
+
+    if (matrix) {
+        this->SkCanvas::concat(*matrix);
+    }
 
     SkBaseDevice* device = this->getTopDevice();
     if (NULL != device) {
         // Canvas has to first give the device the opportunity to render
         // the picture itself.
-        if (device->EXPERIMENTAL_drawPicture(this, picture)) {
+        if (device->EXPERIMENTAL_drawPicture(this, pic)) {
             return; // the device has rendered the entire picture
         }
     }
-
-    picture->draw(this);
+    pic->draw(this);
 }
 
 ///////////////////////////////////////////////////////////////////////////////