.comment: A Whole New Desktop with Anti-Aliasing

By: Dennis E. Powell
Wednesday, March 14, 2001 09:43:31 AM EST
URL: http://www.linuxplanet.com/linuxplanet/tutorials/3093/1/

A Really Polished Look for Linux

I've spent a couple of days procrastinating, putting off writing this column. Not because it will contain unhappy news or will be particularly difficult to put together, but because I'll have to use StarOffice or WordPerfect or Applix Words, and during that time I'll have to look at screen fonts that aren't anti-aliased.

As you have probably heard, Keith Packard's Xft extension, which had been available hacked into versions of QT since 2.2.3, took up permanent and official residence there with last week's release of QT-2.3.0. This means that if you build QT with the -xft compile option (or obtain a binary that has it compiled in), and you do a few more things I'll discuss in a moment, you'll have anti-aliased screen fonts.

They are a joy.

For those who are not familiar with the term, anti-aliasing is a sleight-of-hand in which the jagged edges of curved letters and numerals are rounded off, making them look more like real letters and less like letters made from Lego blocks. This is done by placing gray pixels in the places where the rounding ought to take place and would if our screens were made up of something other than pixels. The two magnified images here show the effects of anti-aliasing and the alternative (what? aliasing?) on similar but not identical typefaces. They'll give you a sense of what I'm talking about, anyway.

The whole process is reminiscent of the "Resolution Enhancement" employed by H-P in their LaserJet III series, in which the size of the dots was varied, making an actual 300-dpi printer seem like a 600-dpi one.

TrollTech's inclusion of support for the anti-aliasing extension in XFree86-4.02 and later, which is therefore made available to KDE-2.x users, represents a considerable step for Linux in my view. Windows and the Mac have long had this feature. It's the first time a full Linux desktop has offered it. (I feel compelled to note that there are some people who find that anti-aliasing makes letters look fuzzy. They don't like the effect. It can be turned off in Windows, and on the Mac, and, yes, in KDE. My bet is that most people who try it will never look back. Take a look at the other screenshots here, and you'll see what I mean.)

So. How can you bring this marvel to your very own desktop?

My Embarrassingly Needless Ordeal

Let me say right off the bat that if your hardware is supported, as mine is, enabling screen font anti-aliasing is incredibly simple. I need to provide this anti-caveat because it was anything but simple for the four days I spent trying to get it to work here, which story I tell because otherwise the four days will have been entirely wasted, because it gives me the opportunity to thank some people who time after time go the extra mile to help users resolve problems, and because it is illustrative of the fact that software problems arise sometimes from completely unexpected places.

When a hacked QT-2.2.3 that Keith Packard had put together was made available a couple of months ago, I took it for a spin. It was pretty enough, but my typeface selection dialogs had all become empty. My desktop comprised a sans serif proportional typeface, and a nondescript fixed one, and those were the choices. Others reported no problems. After hammering away at it for awhile, I decided that perhaps I was expecting too much. Meanwhile, the typefaces were not especially objectionable even if they would not have been my first choice, and anti-aliasing gave KDE such a delightfully polished appearance that I decided I'd live with them -- after all, this was just a hack, and one does have to expect certain inconveniences when dealing with software so developmental that the official KDE stance was that it would countenance no bug reports connected with anti-aliasing.

So when QT-2.3.0 came out, and it was now official, I figured it would probably work just fine, and whatever gremlin had denied me my full range of typefaces had probably now been banished. I was wrong.

I built the new QT. I fired up KDE. Same problem as before. Okay, I rebuilt KDE against the new QT. Shouldn't have been necessary, and as it turns out isn't (though there's one little advantage to doing so, which I'll get to). No joy. Recompiled the very newest XFree86 as reflected in that day's CVS tree. Nope. (By the way, doing so just about doubled the speed of the video here. It could be something specific to my video card, but if it's more general, XFree86-4.03 is going to be an enormous improvement.)

Desperate, I gave in: I read the docs. The XFree documentation is a little odd. First, the good stuff lives off in the boonies: /usr/X11R6/lib/X11/doc. Second, there is one README[something].txt for every computer sold since the Altair. Third, the nearby HTML version contains none of the good stuff, which is in those text files. The fonts textfile seemed appropriate, so I consulted it. It said that I should set up the XFree font manager, xfs, which I did. (For purposes of brevity rather than to hide my stupidity, I'll leave out here how I set it up at one point such that my machine booted, launched xfs, and stopped there, and my panicked late-night phone call to Kurt Wall, who a.) wrote much of the Caldera eDesktop documentation and who b.) is in the phone book and is a friend and who c.) talked me through the fix.) Xfs was not the answer, even when the machine booted all the way to a prompt.

I annoyed the good people on the KDE development and XFree86 mailing lists, and got lots of encouraging help. Malte Straostik from the KDE developers list stayed up very late Thursday night (I know it was late, because it was late here and he's in Germany) offering suggestions, code, and moral support in a series of rapid-fire emails. Lars Knoll of TrollTech offered help and even a HOW-TO that he put together (possibly partially in hope of shutting me up). Keith Packard explained the workings of the Xft configuration file, which at some point I had concluded (incorrectly) was the culprit. The community again proved that it is tremendously helpful if it thinks you're really trying, even if it also thinks you've maybe gone crazy because stuff that works everyplace else is not, you say, working for you.

Late Friday, day three of my anguish, Matt Newell posted to the KDE developers list that there was a bug somewhere that caused KDE fonts not to be listed for him. He posted a patch to kdelibs that would fix it. I applied the patch and prepared to do a recompile, not at all certain that this had anything to do with the problem I was seeing. It was a very small change -- an edit rather than a patch per se -- and I, not a coder, did not see its significance. And having had at this with the frenzy that is experienced only by a computer user determined to make something work that doesn't want to, I was exhausted, and went to sleep.

Saturday morning, there was a note from David Faure. If I knew him, he'd be the brightest guy I know. My impression is that he knows the KDE code the way Linus knows the kernel, and that somewhere in his head he's established a virtual computer that ticks through code. But more than that, he can explain it! He now took note of Matt's discovery and said that the line in question apparently pointed to a ~/.kde/share/config/kdefonts file, an artifact from the kfontmanager that is no longer a part of KDE2. It limited the typefaces available to KDE, none of which was useful to the Xft extension.

Because I have built KDE2 from the CVS tree every week or two for a year and a half, and because going around and reconfiguring everything is not much fun, I only made a habit of keeping my ~/.kde directory from build to build. When kfontmanager dropped off the screen, its configuration file remained. I found kdefonts and changed its name to oldbadkdefonts and restarted KDE. Here's my response to David's email:

"BINGO!!!! BINGO!!!! give the man a cigar! renaming this file, which appeared last june 15, solved *all* the a-a problems here!"

David responded that the discovery had actually been Matt's and also that he, David, does not like cigars.

So, I'd had about 85 hours of struggling with this problem, 84 hours, 59 minutes, and 45 seconds of which were wasted -- if I'd nuked that file, anti-aliasing would have worked from the beginning. I did not suspect that file. Hell, I didn't know I had that file. And I'd all but forgotten that I'd once had a kfontmanager.

Actually, it wasn't a waste. I learned a lot, both about the workings of typefaces in XFree86 and about the brilliance and friendliness of the community.

You have endured my tale of woe and, I hope, taken the acknowledgments seriously. Now let's move on to how you can make this thing work, including the 95 percent obvious stuff that anybody can figure out in five minutes and the 5 percent that got dribbled out over the rest of the time I was scrambling around.

Getting, Installing, and Configuring

Okay, first, in case I forget it later: If you are running KDE-2.x and you have a ~/.kde/share/config/kdefonts, rename it at once! (Do not delete Linux configuration files until a few days after you've renamed them, when you're sure you don't need them. Give them very silly names, so that you'll be able to pick them out in case you need them after all. Names like "longpurplewhiskerskdefonts." It's a good idea to keep the original name in there so that you'll know what to name it back to if you need to do that.)

Second, make sure that you're not wasting your time, which is to say make sure that your video card is supported. If you're not running XFree86-4.02, you ought to be anyway if your video card is supported. If you are running it, open a terminal emulator and do xdpyinfo, which will provide all kinds of obscure information about your video system. Scroll through it until you find a section headed "number of extensions:" followed by a number. The extensions you have available are listed, in alphabetical order. If RENDER is among them, you've passed the first test.

(Here it can be a little complicated if you've not built your XFree from source. If you compile it yourself, you'll need to make sure your source tree's /xc/config/cf/host.def file contains a line pointing to the location of your Freetype2 installation, to wit:

#define Freetype2Dir /usr/local

This is the default location for Freetype2. It is included in the XFree distribution, but must be compiled separately. It's found in /xc/extras/freetype2. Go there, do make setup followed by make and, as root, make install. Then go ahead and build your XFree. The reason it's complicated if you haven't built it yourself is that you're at the mercy of whoever it was who built the binary packages you're using, who may or may not have done so with anti-aliasing in mind.)

Presuming XFree-4.02 or better, presuming the existence of Freetype2 on your machine, and presuming the existence of libXft on your machine (all of which can be confirmed by use of the locate command), and further presuming therefore that you found RENDER, the next step is to get rid of any font server you have running. This is a two-step process. First is looking at /etc/X11/XF86Config and finding any FontPath line that points to something like unix/:7100 or unix/:anythingelse. comment it out with a pound sign and a space afterwards -- remember, the idea is to do nothing irreversible. If you have lines that point to /usr/X11R6/lib/X11/fonts/truetype and /usr/X11R6/X11/fonts/Type1 visit the pound-space (# ) on them, too. While you're there, make sure that the Section'Module' section includes:

Load "type1"


Load "freetype"

Now. If your distribution was assembled by vicious morons, the FontPath lines will list nothing but your font server, rather than the proper method of including all the font directories, commented out. This would not be an enormous concern but for one essential; if you do not have it, then where you commented out the FontPath unix/:yadayada line, insert another line:

FontPath "/usr/X11R6/lib/X11/fonts/misc"

In a multitude of experiments with anti-aliasing, I have not found a configuration that allows the elimination of this. Fact is, there are numerous FontPath lines you might want to leave. Here's the appropriate section from mine: