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。