谷歌浏览器的源码分析(22)

 

上一次说到消息转发，并分析了 RenderThread 类里处理消息的函数，其实大部份的消息都是在 RenderView 类里的 OnMessageReceived 函数处理，比如浏览的消息也是在这里处理。它的代码如下：

#001   void RenderView::OnMessageReceived(const IPC::Message& message) {

#002     // Let the resource dispatcher intercept resource messages first.

 

如果是资源消息，就直接分发去处理，以便提高效率。

#003     if (resource_dispatcher_->OnMessageReceived(message))

#004       return;

 

下面开始处理 RenderView 类里所有的消息。

#005     IPC_BEGIN_MESSAGE_MAP(RenderView, message)

#006       IPC_MESSAGE_HANDLER(ViewMsg_CreatingNew_ACK, OnCreatingNewAck)

#007       IPC_MESSAGE_HANDLER(ViewMsg_CaptureThumbnail, SendThumbnail)

#008       IPC_MESSAGE_HANDLER(ViewMsg_GetPrintedPagesCount, OnGetPrintedPagesCount)

#009       IPC_MESSAGE_HANDLER(ViewMsg_PrintPages, OnPrintPages)

#010       IPC_MESSAGE_HANDLER(ViewMsg_Navigate, OnNavigate)

#011       IPC_MESSAGE_HANDLER(ViewMsg_Stop, OnStop)

#012       IPC_MESSAGE_HANDLER(ViewMsg_LoadAlternateHTMLText, OnLoadAlternateHTMLText)

#013       IPC_MESSAGE_HANDLER(ViewMsg_StopFinding, OnStopFinding)

#014       IPC_MESSAGE_HANDLER(ViewMsg_Undo, OnUndo)

#015       IPC_MESSAGE_HANDLER(ViewMsg_Redo, OnRedo)

#016       IPC_MESSAGE_HANDLER(ViewMsg_Cut, OnCut)

#017       IPC_MESSAGE_HANDLER(ViewMsg_Copy, OnCopy)

#018       IPC_MESSAGE_HANDLER(ViewMsg_Paste, OnPaste)

#019       IPC_MESSAGE_HANDLER(ViewMsg_Replace, OnReplace)

#020       IPC_MESSAGE_HANDLER(ViewMsg_Delete, OnDelete)

#021       IPC_MESSAGE_HANDLER(ViewMsg_SelectAll, OnSelectAll)

#022       IPC_MESSAGE_HANDLER(ViewMsg_CopyImageAt, OnCopyImageAt)

#023       IPC_MESSAGE_HANDLER(ViewMsg_Find, OnFind)

#024       IPC_MESSAGE_HANDLER(ViewMsg_AlterTextSize, OnAlterTextSize)

#025       IPC_MESSAGE_HANDLER(ViewMsg_SetPageEncoding, OnSetPageEncoding)

#026       IPC_MESSAGE_HANDLER(ViewMsg_InspectElement, OnInspectElement)

#027       IPC_MESSAGE_HANDLER(ViewMsg_ShowJavaScriptConsole, OnShowJavaScriptConsole)

#028       IPC_MESSAGE_HANDLER(ViewMsg_DownloadImage, OnDownloadImage)

#029       IPC_MESSAGE_HANDLER(ViewMsg_ScriptEvalRequest, OnScriptEvalRequest)

#030       IPC_MESSAGE_HANDLER(ViewMsg_AddMessageToConsole, OnAddMessageToConsole)

#031       IPC_MESSAGE_HANDLER(ViewMsg_DebugAttach, OnDebugAttach)

#032       IPC_MESSAGE_HANDLER(ViewMsg_DebugDetach, OnDebugDetach)

#033       IPC_MESSAGE_HANDLER(ViewMsg_ReservePageIDRange, OnReservePageIDRange)

#034       IPC_MESSAGE_HANDLER(ViewMsg_UploadFile, OnUploadFileRequest)

#035       IPC_MESSAGE_HANDLER(ViewMsg_FormFill, OnFormFill)

#036       IPC_MESSAGE_HANDLER(ViewMsg_FillPasswordForm, OnFillPasswordForm)

#037       IPC_MESSAGE_HANDLER(ViewMsg_DragTargetDragEnter, OnDragTargetDragEnter)

#038       IPC_MESSAGE_HANDLER(ViewMsg_DragTargetDragOver, OnDragTargetDragOver)

#039       IPC_MESSAGE_HANDLER(ViewMsg_DragTargetDragLeave, OnDragTargetDragLeave)

#040       IPC_MESSAGE_HANDLER(ViewMsg_DragTargetDrop, OnDragTargetDrop)

#041       IPC_MESSAGE_HANDLER(ViewMsg_AllowDomAutomationBindings,

#042                           OnAllowDomAutomationBindings)

#043       IPC_MESSAGE_HANDLER(ViewMsg_AllowBindings, OnAllowBindings)

#044       IPC_MESSAGE_HANDLER(ViewMsg_SetDOMUIProperty, OnSetDOMUIProperty)

#045       IPC_MESSAGE_HANDLER(ViewMsg_DragSourceEndedOrMoved, OnDragSourceEndedOrMoved)

#046       IPC_MESSAGE_HANDLER(ViewMsg_DragSourceSystemDragEnded,

#047                           OnDragSourceSystemDragEnded)

#048       IPC_MESSAGE_HANDLER(ViewMsg_SetInitialFocus, OnSetInitialFocus)

#049       IPC_MESSAGE_HANDLER(ViewMsg_FindReplyACK, OnFindReplyAck)

#050       IPC_MESSAGE_HANDLER(ViewMsg_UpdateTargetURL_ACK, OnUpdateTargetURLAck)

#051       IPC_MESSAGE_HANDLER(ViewMsg_UpdateWebPreferences, OnUpdateWebPreferences)

#052       IPC_MESSAGE_HANDLER(ViewMsg_SetAltErrorPageURL, OnSetAltErrorPageURL)

#053       IPC_MESSAGE_HANDLER(ViewMsg_InstallMissingPlugin, OnInstallMissingPlugin)

#054       IPC_MESSAGE_HANDLER(ViewMsg_RunFileChooserResponse, OnFileChooserResponse)

#055       IPC_MESSAGE_HANDLER(ViewMsg_EnableViewSourceMode, OnEnableViewSourceMode)

#056       IPC_MESSAGE_HANDLER(ViewMsg_UpdateBackForwardListCount,

#057                           OnUpdateBackForwardListCount)

#058       IPC_MESSAGE_HANDLER(ViewMsg_GetAllSavableResourceLinksForCurrentPage,

#059                           OnGetAllSavableResourceLinksForCurrentPage)

#060       IPC_MESSAGE_HANDLER(ViewMsg_GetSerializedHtmlDataForCurrentPageWithLocalLinks,

#061                           OnGetSerializedHtmlDataForCurrentPageWithLocalLinks)

#062       IPC_MESSAGE_HANDLER(ViewMsg_GetApplicationInfo, OnGetApplicationInfo)

#063       IPC_MESSAGE_HANDLER(ViewMsg_ShouldClose, OnMsgShouldClose)

#064       IPC_MESSAGE_HANDLER(ViewMsg_ClosePage, OnClosePage)

#065       IPC_MESSAGE_HANDLER(ViewMsg_ThemeChanged, OnThemeChanged)

#066   #ifdef CHROME_PERSONALIZATION

#067       IPC_MESSAGE_HANDLER(ViewMsg_PersonalizationEvent, OnPersonalizationEvent)

#068   #endif

#069       IPC_MESSAGE_HANDLER(ViewMsg_HandleMessageFromExternalHost,

#070                            OnMessageFromExternalHost)

 

这里对于没有处理的消息进行提示。

#071       // Have the super handle all other messages.

#072       IPC_MESSAGE_UNHANDLED(RenderWidget::OnMessageReceived(message))

#073     IPC_END_MESSAGE_MAP()

#074   }

 

从上面这个函数可以看到，它的消息处理是非常多的，下面来分析一个浏览网络连接的消息，它就是 ViewMsg_Navigate ，可以看到这个消息后面响应函数是 OnNavigate ，也就是说，当你输入网络地址之后按回车，就会通过上说过的 IPC 机制把消息发送到这里，接着来看这个函数 OnNavigate 的代码，如下：

#001   void RenderView::OnNavigate(const ViewMsg_Navigate_Params& params) {

 

判断窗口是否关闭，如果关闭就不用去打开连接地址了。

#002     if (!webview())

#003       return;

#004  

 

处理一些 about 的连接处理，比如 about:crash 。

#005     AboutHandler::MaybeHandle(params.url);

#006  

 

保存是否重新加载网页。

#007     bool is_reload = params.reload;

#008  

 

获取 WEB 的显示框架。

#009     WebFrame* main_frame = webview()->GetMainFrame();

 

判断当是重新加载时，而当前又不是历史网页的情况。

#010     if (is_reload && !main_frame->HasCurrentState()) {

#011       // We cannot reload if we do not have any history state.   This happens, for

#012        // example, when recovering from a crash.   Our workaround here is a bit of

#013       // a hack since it means that reload after a crashed tab does not cause an

#014       // end-to-end cache validation.

#015       is_reload = false;

#016     }

#017  

 

下面设置缓冲策略。

#018     WebRequestCachePolicy cache_policy;

#019     if (is_reload) {

#020       cache_policy = WebRequestReloadIgnoringCacheData;

#021     } else if (params.page_id != -1 || main_frame->GetInViewSourceMode()) {

#022       cache_policy = WebRequestReturnCacheDataElseLoad;

#023     } else {

#024       cache_policy = WebRequestUseProtocolCachePolicy;

#025     }

#026  

 

下面创建一个下载请求，并把相关参数设置到请求里面。

#027     scoped_ptr<WebRequest> request(WebRequest::Create(params.url));

#028     request->SetCachePolicy(cache_policy);

#029     request->SetExtraData(new RenderViewExtraRequestData(

#030         params.page_id, params.transition, params.url));

#031  

 

设置 WEBKIT 的请求状态。

#032     // If we are reloading, then WebKit will use the state of the current page.

#033     // Otherwise, we give it the state to navigate to.

#034     if (!is_reload)

#035       request->SetHistoryState(params.state);

#036  

 

让主 WEB 显示框架去下载请求显示。

#037     main_frame->LoadRequest(request.get());

#038   }

 

分析这个函数，就可以知道处理浏览消息的过程，下一次来分析 WebFrame 里的接口函数 LoadRequest 处理过程，到底它是怎么样处理 javascript 脚本网页下载的呢？

谷歌浏览器的源码分析(22)