Add slides to VulkanViewer

tools/vulkan/viewer/SKPSlide.cpp

+/*
+* Copyright 2016 Google Inc.
+*
+* Use of this source code is governed by a BSD-style license that can be
+* found in the LICENSE file.
+*/
+
+#include "SKPSlide.h"
+
+#include "SkCanvas.h"
+
+SKPSlide::SKPSlide(const char* name, sk_sp<const SkPicture> pic)
+    : fPic(pic)
+    , fCullRect(fPic->cullRect().roundOut()) {
+    fName = name;
+}
+
+SKPSlide::~SKPSlide() {}
+
+void SKPSlide::draw(SkCanvas* canvas) {
+    bool isOffset = SkToBool(fCullRect.left() | fCullRect.top());
+    if (isOffset) {
+        canvas->save();
+        canvas->translate(SkIntToScalar(-fCullRect.left()), SkIntToScalar(-fCullRect.top()));
+    }
+
+    canvas->drawPicture(fPic.get());
+
+    if (isOffset) {
+        canvas->restore();
+    }
+}