谷歌浏览器的源码分析(12)

当我们根据自动提示，或者完全自己输入连接后，再按下回车键，这时浏览器就会去打开网页，或者去查找内容。那么浏览器是怎么样实现这些功能的呢？又是怎么判断去打开网页，还是去打开GOOGLE的搜索引擎的呢？下面就来分析这部份的代码，如下：

#001  bool AutocompleteEdit::OnKeyDownOnlyWritable(TCHAR key,

#002                                               UINT repeat_count,

#003                                               UINT flags) {

#004    // NOTE: Annoyingly, ctrl-alt-<key> generates WM_KEYDOWN rather than

#005    // WM_SYSKEYDOWN, so we need to check (flags & KF_ALTDOWN) in various places

#006    // in this function even with a WM_SYSKEYDOWN handler.

#007 

#008    int count = repeat_count;

#009    switch (key) {

#010      case VK_RETURN:

#011        AcceptInput((flags & KF_ALTDOWN) ? NEW_FOREGROUND_TAB : CURRENT_TAB,

#012                    false);

#013        return true;

#014 

#015      case VK_UP:

#016        count = -count;

#017        // FALL THROUGH

#018      case VK_DOWN:

 

当用户按下回车键，就会调用上面的函数OnKeyDownOnlyWritable，并且在VK_RETURN按键处理回车的事件，接着就是调用函数AcceptInput来处理。

这个函数的代码如下：

#001  void AutocompleteEdit::AcceptInput(WindowOpenDisposition disposition,

#002                                     bool for_drop) {

#003    // Get the URL and transition type for the selected entry.

#004    PageTransition::Type transition;

#005    bool is_history_what_you_typed_match;

#006    std::wstring alternate_nav_url;

 

保存当前获取的URL连接串。

#007    const std::wstring url(GetURLForCurrentText(&transition,

#008                                                &is_history_what_you_typed_match,

#009                                                &alternate_nav_url));

#010    if (url.empty())

#011      return;

#012 

 

 

判断是否重新加载当前的网页。

#013    if (url == permanent_text_) {

#014      // When the user hit enter on the existing permanent URL, treat it like a

#015      // reload for scoring purposes.  We could detect this by just checking

#016      // user_input_in_progress_, but it seems better to treat "edits" that end

#017      // up leaving the URL unchanged (e.g. deleting the last character and then

#018      // retyping it) as reloads too.

#019      transition = PageTransition::RELOAD;

#020    } else if (for_drop || ((paste_state_ != NONE) &&

#021                            is_history_what_you_typed_match)) {

 

下面是打开一个新的连接。

#022      // When the user pasted in a URL and hit enter, score it like a link click

#023      // rather than a normal typed URL, so it doesn't get inline autocompleted

#024      // as aggressively later.

#025      transition = PageTransition::LINK;

#026    }

#027 

 

这里是调用OpenURL函数打开这个连接的内容。

#028    OpenURL(url, disposition, transition, alternate_nav_url,

#029            AutocompletePopupModel::kNoMatch,

#030            is_keyword_hint_ ? std::wstring() : keyword_);

#031  }

 

这段代码的流程很清楚，就是先通过判断按键输入，是否按下回车键，如果是回车键就调用函数AcceptInput处理，然后在这个函数就判断这个连接是否已经打开了，如果已经打开，只需要重新加载就行了，如果不是当前的，就是打开一个新的连接。下一次再来分析OpenURL函数是怎么样通过连接来重新加载，还是打开一个新网页。