谷歌浏览器的源码分析 4

关于对话框，主要实现了让用户查看当前软件的版本、软件信息和检查升级的功能。因此这个类主要继续ChromeViews::View类、ChromeViews::DialogDelegate和GoogleUpdateStatusListener。其中ChromeViews::View实现窗口的布局和显示问题，ChromeViews::DialogDelegate实现了事件响应，或者窗口某时是否可以显示按钮的问题，GoogleUpdateStatusListener是用来实现接收更新程序状态信息。

这个类的声明如下：

class AboutChromeView : public ChromeViews::View,

                        public ChromeViews::DialogDelegate,

                        public GoogleUpdateStatusListener {

 public:

  explicit AboutChromeView(Profile* profile);

  virtual ~AboutChromeView();

  // Initialize the controls on the dialog.

  void Init();

  // Overridden from ChromeViews::View:

  virtual void GetPreferredSize(CSize *out);

  virtual void Layout();

  virtual void ViewHierarchyChanged(bool is_add,

                                    ChromeViews::View* parent,

                                    ChromeViews::View* child);

  // Overridden from ChromeViews::DialogDelegate:

  virtual int GetDialogButtons() const;

  virtual std::wstring GetDialogButtonLabel(DialogButton button) const;

  virtual bool IsDialogButtonEnabled(DialogButton button) const;

  virtual bool IsDialogButtonVisible(DialogButton button) const;

  virtual bool CanResize() const;

  virtual bool CanMaximize() const;

  virtual bool IsAlwaysOnTop() const;

  virtual bool HasAlwaysOnTopMenu() const;

  virtual bool IsModal() const;

  virtual std::wstring GetWindowTitle() const;

  virtual bool Accept();

  virtual ChromeViews::View* GetContentsView();

  // Overridden from GoogleUpdateStatusListener:

  virtual void OnReportResults(GoogleUpdateUpgradeResult result,

                               GoogleUpdateErrorCode error_code,

                               const std::wstring& version);

 private:

  // The visible state of the Check For Updates button.

  enum CheckButtonStatus {

    CHECKBUTTON_HIDDEN = 0,

    CHECKBUTTON_DISABLED,

    CHECKBUTTON_ENABLED,

  };

  // Update the UI to show the status of the upgrade.

  void UpdateStatus(GoogleUpdateUpgradeResult result,

                    GoogleUpdateErrorCode error_code);

  Profile* profile_;

  // UI elements on the dialog.

  ChromeViews::ImageView* about_dlg_background_;

  ChromeViews::Label* about_title_label_;

  ChromeViews::TextField* version_label_;

  ChromeViews::TextField* main_text_label_;

  // UI elements we add to the parent view.

  scoped_ptr<ChromeViews::Throbber> throbber_;

  ChromeViews::ImageView success_indicator_;

  ChromeViews::ImageView update_available_indicator_;

  ChromeViews::ImageView timeout_indicator_;

  ChromeViews::Label update_label_;

  // Keeps track of the visible state of the Check For Updates button.

  CheckButtonStatus check_button_status_;

  // The class that communicates with Google Update to find out if an update is

  // available and asks it to start an upgrade.

  GoogleUpdate* google_updater_;

  // Our current version.

  std::wstring current_version_;

  // The version Google Update reports is available to us.

  std::wstring new_version_available_;

  DISALLOW_EVIL_CONSTRUCTORS(AboutChromeView);

};

通过关于对话框的分析，可以理解到chrome浏览器窗口基本组成，以及窗口继承关系，还有事件的响应方式。前面三次分析，主要是入门的分析，也是了解这么一个大工程的一种手段。比如测试整个工程是否可以编译，是否可以修改代码等等。后面的分析会以浏览器输入HTTP连接开始，直到打开网页显示为一个主线，做一个基本的分析。