[SVGDom] Deferred SampleApp parsing

samplecode/SampleSVGFile.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 "SampleCode.h"
 #include "SkCanvas.h"
 #include "SkDOM.h"
 #include "SkOSFile.h"
 #include "SkStream.h"
 #include "SkSVGDOM.h"
 #include "SkView.h"
 
 namespace {
 
 class SVGFileView : public SampleView {
 public:
-    SVGFileView(const char path[])
-        : fLabel(SkStringPrintf("[%s]", SkOSPath::Basename(path).c_str())) {
-        SkFILEStream svgStream(path);
+    SVGFileView(const SkString& path)
+        : fPath(path), fLabel(SkStringPrintf("[%s]", SkOSPath::Basename(path.c_str()).c_str())) {}
+    virtual ~SVGFileView() = default;
+
+protected:
+    void onOnceBeforeDraw() override {

[robertphillips, 2016/08/14 20:15:29]

Do you need this if check? Shouldn't 'fDom' always be null?

[f(malita), 2016/08/15 13:18:56]

I was thinking it may trigger when navigating back to a slide, since I've
noticed a bunch of re-parsing when switching back and forth.  I'll double-check
to make sure it does have an impact, and take out if not.

+        if (fDom) {
+            return;
+        }
+        SkFILEStream svgStream(fPath.c_str());
         if (!svgStream.isValid()) {
-            SkDebugf("file not found: \"path\"\n", path);
+            SkDebugf("file not found: \"path\"\n", fPath.c_str());
             return;
         }
 
         SkDOM xmlDom;
         if (!xmlDom.build(svgStream)) {
-            SkDebugf("XML parsing failed: \"path\"\n", path);
+            SkDebugf("XML parsing failed: \"path\"\n", fPath.c_str());
             return;
         }
 
         fDom = SkSVGDOM::MakeFromDOM(xmlDom, SkSize::Make(this->width(), this->height()));
     }
 
-    virtual ~SVGFileView() = default;
-
-protected:
     void onDrawContent(SkCanvas* canvas) override {
         if (fDom) {
             fDom->render(canvas);
         }
     }
 
     void onSizeChange() override {
         if (fDom) {
             fDom->setContainerSize(SkSize::Make(this->width(), this->height()));
         }
 
         this->INHERITED::onSizeChange();
     }
 
     bool onQuery(SkEvent* evt) override {
         if (SampleCode::TitleQ(*evt)) {
             SampleCode::TitleR(evt, fLabel.c_str());
             return true;
         }
 
         return this->INHERITED::onQuery(evt);
     }
 private:
     sk_sp<SkSVGDOM> fDom;
+    SkString        fPath;
     SkString        fLabel;
 
     typedef SampleView INHERITED;
 };
 
 } // anonymous namespace
 
-SampleView* CreateSampleSVGFileView(const char filename[]);
-SampleView* CreateSampleSVGFileView(const char filename[]) {
+SampleView* CreateSampleSVGFileView(const SkString& filename);
+SampleView* CreateSampleSVGFileView(const SkString& filename) {
     return new SVGFileView(filename);
 }