native_client_sdk/src/examples/api/url_loader/url_loader.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // This example demonstrates how to load content of the page into NaCl module.
   6
   7 #include <cstdio>
   8 #include <string>
   9 #include "ppapi/cpp/instance.h"
  10 #include "ppapi/cpp/module.h"
  11 #include "ppapi/cpp/url_loader.h"
  12 #include "ppapi/cpp/var.h"
  13
  14 #include "url_loader_handler.h"
  15
  16 // These are the method names as JavaScript sees them.
  17 namespace {
  18 const char* const kLoadUrlMethodId = "getUrl";
  19 static const char kMessageArgumentSeparator = ':';
  20 }  // namespace
  21
  22 class URLLoaderInstance : public pp::Instance {
  23  public:
  24   explicit URLLoaderInstance(PP_Instance instance) : pp::Instance(instance) {}
  25   virtual ~URLLoaderInstance() {}
  26
  27   // Called by the browser to handle the postMessage() call in Javascript.
  28   // The message in this case is expected to contain the string 'getUrl'
  29   // followed by a ':' separator, then the URL to fetch.  If a valid message
  30   // of the form 'getUrl:URL' is received, then start up an asynchronous
  31   // download of URL.  In the event that errors occur, this method posts an
  32   // error string back to the browser.
  33   virtual void HandleMessage(const pp::Var& var_message);
  34 };
  35
  36 void URLLoaderInstance::HandleMessage(const pp::Var& var_message) {
  37   if (!var_message.is_string()) {
  38     return;
  39   }
  40   std::string message = var_message.AsString();
  41   if (message.find(kLoadUrlMethodId) == 0) {
  42     // The argument to getUrl is everything after the first ':'.
  43     size_t sep_pos = message.find_first_of(kMessageArgumentSeparator);
  44     if (sep_pos != std::string::npos) {
  45       std::string url = message.substr(sep_pos + 1);
  46       printf("URLLoaderInstance::HandleMessage('%s', '%s')\n",
  47              message.c_str(),
  48              url.c_str());
  49       fflush(stdout);
  50       URLLoaderHandler* handler = URLLoaderHandler::Create(this, url);
  51       if (handler != NULL) {
  52         // Starts asynchronous download. When download is finished or when an
  53         // error occurs, |handler| posts the results back to the browser
  54         // vis PostMessage and self-destroys.
  55         handler->Start();
  56       }
  57     }
  58   }
  59 }
  60
  61 class URLLoaderModule : public pp::Module {
  62  public:
  63   URLLoaderModule() : pp::Module() {}
  64   virtual ~URLLoaderModule() {}
  65
  66   // Create and return a URLLoaderInstance object.
  67   virtual pp::Instance* CreateInstance(PP_Instance instance) {
  68     return new URLLoaderInstance(instance);
  69   }
  70 };
  71
  72 namespace pp {
  73 Module* CreateModule() { return new URLLoaderModule(); }
  74 }  // namespace pp