8.2 Font-Lock Mode
Font-lock mode is discussed primarily in Chapter 9; it's designed for coloring code to make it easier to read. But the fact is that it works well in other modes too, like the Buffer List (Chapter 4), Dired (Chapter 5), and in all the markup modes described in this chapter.
To turn on font lock mode, choose Syntax Highlighting from the Options menu. If you decide you want to turn it on for every session, select Save Options from the Options menu and Emacs writes your .emacs file.
For more details on font-lock mode, see Chapter 9.
8.3 Writing HTML
Without doubt, the most commonly used markup language today is hypertext markup language (HTML), used for creating web pages. HTML consists of text with tags that define characteristics about the text. HTML is not hard to write, and you could use Emacs or any other editor to write the tags and the text. An HTML tag generally looks like this:
<tagname>text being tagged</tagname>
For your convenience, several modes are available for writing HTML in Emacs, including HTML mode, HTML helper mode, html menus, and a variety of SGML[42] tools including sgml mode and psgml mode. Of these tools, we've chosen to describe HTML mode, a variant of sgml mode, which is included in GNU Emacs, and HTML helper mode, which is a popular add-on. If you are writing XHTML, a stricter version of HTML that can be validated, you should consider XHTML mode, described briefly in this section, or psgml mode, covered later in the XML section of this chapter.
Serious web developers may want to investigate some of the cutting edge development going on to make Emacs even more powerful. Check out HTMLModeDeluxe (http://www.emacswiki.org/cgi-bin/wiki/HtmlModeDeluxe) and the Emacs WebDev Environment by Darren Brierton (http://www.dzr-web.com/people/darren/projects/emacs-webdev). Both of these tools support mmm mode (where mmm stands for "multiple major modes"). Using this feature, the cursor changes major mode depending on the section of the page you are editing. When you edit a script, the mode changes automatically to support that type of authoring. Both are excellent tools for building complex web pages.
In the following sections, we are not going to teach you to write HTML. (For more information on writing HTML, see HTML and XHTML: The Definitive Guide by Chuck Musciano and Bill Kennedy, O'Reilly) Rather, we're going to teach you the rudiments of using HTML mode and HTML helper mode to help you create HTML documents.
8.3.1 Using HTML Mode
To start HTML mode, type M-x html-mode (or simply open an HTML file). Most authors use a standard template when they write HTML. You may already have one. If you don't, HTML mode is happy to supply one for you. Simply start by typing C-c C-t (for sgml-tag) or by selecting Insert Tag from the SGML menu. If you enter the <html> tag that signifies the start of an HTML document, Emacs inserts a basic template in your buffer.
Type: C-c C-t html Enter
Emacs prompts for a title.
Type: A Tale of Two Cities Enter
Emacs inserts an HTML template.
Note that Emacs automatically creates a first-level header that is equal to the title you entered. It also inserts a hyperlink so that readers can email you. Depending on your spam tolerance, you may want to delete that line. Also, Emacs is just guessing at your name and email address. You can set these explicitly by adding two lines to your .emacs file. Change Mr. Dickens' information to settings appropriate for you.
(setq user-mail-address cdickens@great-beyond.com)
(setq user-full-name "Charles Dickens")
You could approach HTML mode in a couple of ways. You could learn the key bindings for various tags, or you could simply use the sgml-tag command for everything. It depends how many bindings you want to learn. A mixed approach may be best, where you learn keystrokes for the most common tags and use sgml-tag for less common tags.
Key bindings are intuitive in HTML mode. Like most specialized editing modes, many functions are bound to C-c C- something. We've seen C-c C-t to insert a tag. You won't be too surprised to find that to move forward to the next tag you type C-c C-f and to move back to the previous tag you type C-c C-b. To insert an <href> tag, type C-c C-h. You see what we mean.
HTML mode is designed for writing HTML, not XHTML. XHTML is stricter, requiring all tags to have a closing tag. The common <p> tag is a salient example. HTML authors would never use the closing tag </p> that XHTML requires. HTML mode inserts a lone <p> tag even when given a command, such as sgml-tag, that normally inserts a tag pair. If you want to write XHTML, use XHTML mode instead. Emacs starts this mode itself if your file contains a reference to an XHTML document type definition. Other than completion of tags, XHTML mode is very similar to HTML mode described here.[43]
Being able to hide the tags is a helpful feature. To hide HTML tags, type C-c Tab; use the same command to display the tags again. Let's say that we've inserted some of our dickens file into the dickens.html file we were just working with.
Initial state:
dickens.html with tags showing.
Type: C-c Tab
Emacs hides the tags.
You can keep typing text, concentrating on what you're writing rather than being distracted by the markup. Emacs protects you from deleting tags when you're writing by making hidden text read-only. If you move the cursor onto a hidden tag, Emacs displays it in the minibuffer.
Of course, the whole purpose of writing HTML is to display it in a web browser. Typing C-c C-v (for browse-url-of-buffer) opens the default web browser to view the web page you're writing.
If you'd like to look at the file in a web browser each time you save, you can turn on a function called html-autoview-mode, invoked by pressing C-c C-s. When you save the file, Emacs automatically opens it in the default browser.
8.3.1.1 Character encoding in HTML mode
What if you want to include special characters or characters from other character sets in your web page? The short answer is that you can enter a character's encoding explicitly. For example, to enter a capital Ü with an umlaut, you can type Ü. Many characters can also be represented as named entities, which are certainly easier to remember than numbers. For example, the named entity for a capital Ü with an umlaut is Ü.
42
SGML stands for standardized general markup language. Both XML and HTML are descendants of SGML.
43
At this writing, there is no way to enter XHTML mode explicitly. If your file looks like an XHTML file, Emacs puts you in that mode automatically.