gears/base/common/html_event_monitor_np.cc

   1 // Copyright 2007, Google Inc.
   2 //
   3 // Redistribution and use in source and binary forms, with or without
   4 // modification, are permitted provided that the following conditions are met:
   5 //
   6 //  1. Redistributions of source code must retain the above copyright notice,
   7 //     this list of conditions and the following disclaimer.
   8 //  2. Redistributions in binary form must reproduce the above copyright notice,
   9 //     this list of conditions and the following disclaimer in the documentation
  10 //     and/or other materials provided with the distribution.
  11 //  3. Neither the name of Google Inc. nor the names of its contributors may be
  12 //     used to endorse or promote products derived from this software without
  13 //     specific prior written permission.
  14 //
  15 // THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  16 // WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  17 // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
  18 // EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  19 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  20 // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  21 // OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  22 // WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  23 // OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  24 // ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25 //
  26 // This implementation makes use of window.addEventListener() to watch the
  27 // event.  IE does not support this, but it's not a target for the NPAPI port,
  28 // so we're OK.
  29
  30 #include "gears/base/common/html_event_monitor.h"
  31
  32 #include <assert.h>
  33
  34 #include "gears/base/common/dispatcher.h"
  35 #include "gears/base/common/string_utils.h"
  36 #include "gears/base/npapi/np_utils.h"
  37 #include "gears/base/npapi/plugin.h"
  38 #include "gears/base/npapi/scoped_npapi_handles.h"
  39
  40 DECLARE_DISPATCHER(HtmlEventMonitorHook);
  41
  42 class HtmlEventMonitorHook : public PluginBase {
  43  public:
  44   HtmlEventMonitorHook(NPP instance)
  45       : PluginBase(instance), dispatcher_(this) {
  46     PluginBase::Init(&dispatcher_);
  47   }
  48
  49   void Init(HtmlEventMonitor::HtmlEventCallback function, void *user_param) {
  50     function_ = function;
  51     user_param_ = user_param;
  52   }
  53
  54   void HandleEvent(JsCallContext *context) {
  55     function_(user_param_);  // invoke user callback
  56   }
  57
  58  private:
  59   HtmlEventMonitor::HtmlEventCallback function_;
  60   void *user_param_;
  61
  62   Dispatcher<HtmlEventMonitorHook> dispatcher_;
  63
  64   DISALLOW_EVIL_CONSTRUCTORS(HtmlEventMonitorHook);
  65 };
  66
  67 // static
  68 template <>
  69 void Dispatcher<HtmlEventMonitorHook>::Init() {
  70   // Safari treats "handleEvent" as a method, while Firefox treats it as a
  71   // property.  Go figure.
  72   RegisterMethod("handleEvent", &HtmlEventMonitorHook::HandleEvent);
  73   RegisterProperty("handleEvent", &HtmlEventMonitorHook::HandleEvent, NULL);
  74 }
  75
  76 HtmlEventMonitorHook* CreateHtmlEventMonitorHook(JsContextPtr context) {
  77   return static_cast<HtmlEventMonitorHook *>(
  78       NPN_CreateObject(context, GetNPClass<HtmlEventMonitorHook>()));
  79 }
  80
  81 //
  82 // HtmlEventMonitor
  83 //
  84
  85 bool HtmlEventMonitor::Start(NPP context, NPObject *event_source) {
  86   assert(!event_hook_);
  87   assert(NPVARIANT_IS_VOID(event_source_));
  88
  89   // create the event hook
  90   HtmlEventMonitorHook *event_hook = CreateHtmlEventMonitorHook(context);
  91   ScopedNPObject event_hook_scoped(event_hook);
  92   event_hook->Init(function_, user_param_);
  93
  94   // call window.addEventListener(event_name, event_hook, false)
  95   NPObject* window = event_source;
  96
  97   NPIdentifier add_event_listener_id =
  98       NPN_GetStringIdentifier("addEventListener");
  99
 100   std::string event_name_utf8;
 101   if (!String16ToUTF8(&event_name_[2], &event_name_utf8))  // skip leading "on"
 102     return false;
 103
 104   NPVariant args[3];
 105   STDSTRING_TO_NPVARIANT(event_name_utf8, args[0]);
 106   OBJECT_TO_NPVARIANT(event_hook, args[1]);
 107   BOOLEAN_TO_NPVARIANT(false, args[2]);
 108
 109   // call the method
 110   ScopedNPVariant result;
 111   if (!NPN_Invoke(context, window, add_event_listener_id, args,
 112                   ARRAYSIZE(args), &result))
 113     return false;
 114
 115   // only modify data members if everything succeeded
 116   event_hook_scoped.release();
 117   event_context_ = context;
 118   event_hook_ = event_hook;
 119   event_source_.Reset(event_source);
 120   return true;
 121 }
 122
 123 void HtmlEventMonitor::Stop() {
 124   assert(NPVARIANT_IS_OBJECT(event_source_));
 125   assert(event_hook_);
 126
 127   // call window.removeEventListener(event_name, event_hook, false)
 128   NPObject* window = NPVARIANT_TO_OBJECT(event_source_);
 129
 130   NPIdentifier remove_event_listener_id =
 131       NPN_GetStringIdentifier("removeEventListener");
 132
 133   std::string event_name_utf8;
 134   if (!String16ToUTF8(&event_name_[2], &event_name_utf8))  // skip leading "on"
 135     return;
 136
 137   NPVariant args[3];
 138   STDSTRING_TO_NPVARIANT(event_name_utf8, args[0]);
 139   OBJECT_TO_NPVARIANT(event_hook_, args[1]);
 140   BOOLEAN_TO_NPVARIANT(false, args[2]);
 141
 142   // call the method
 143   ScopedNPVariant result;
 144   if (!NPN_Invoke(event_context_, window, remove_event_listener_id,
 145                   args, 3, &result))
 146     return;
 147
 148   // destroy the event hook
 149   NPN_ReleaseObject(event_hook_);
 150   event_context_ = NULL;
 151   event_hook_ = NULL;
 152   event_source_.Reset();
 153 }