Theming, Part 1: Custom Banner

It's been a long time since I posted anything, so I figured I'd put up a little informal documentation on the theme system. After all, who wants to be stuck with just the default themes? The answer is: me, because I'm the one who designed them. But I'm sure other people would like to personalize the look of their site a bit.

Today, let's talk about setting a custom page banner. That seems to be one of the first things most people change on their blog. Plus it's fairly easy to do in LnBlog and doesn't require a great deal of HTML or CSS knowledge. So let's get started!

For this exercise, you'll need two things. The first is a banner image. It can be anything you want, so long as a web browser can display it and it's a suitable size. Since I'll be assuming you use the default LnBlog theme, which is not fixed-width, I'd recommend a JPEG image that's at least 1024 pixels wide and around 160 pixels high. For illustrative purposes, I'll use this picture of the hills. If you have a moderately high resolution digital camera, you can probably take a decent picture yourself and use the GIMP or some other image editor to cut out an appropriately sized image.

The second thing you'll need is a copy of your banner style sheet to work on. This one is easy: just go into your LnBlog/themes folder, find the directory for your theme, and copy the styles/banner.css file to someplace on your local hard drive so that you can edit it.

Now that we've got a stylesheet and an image, setting the banner background is easy. Just open up your copy of the banner.css file, find the #banner section, and change it so it looks like this: #banner { width: 100%; border: 1px solid black; background-image: url(../images/horizon.jpg); background-repeat: no-repeat; max-width: 1281px; max-height: 160px; } This gives us a banner box with a thin border and our horizon image as the background. Note that the max-width and max-height are set to the width and height of the image. This keeps the box from expanding to larger than the size of the picture and looking funny.

As long as we're in the style sheet, we might as well consider the text. Let's say, for the sake of argument, that you wanted to change the alignment of the default banner text. Let's say you want to put the blog name on the left side of the banner and the description on the right. Well, in that case, you would look for the #banner h1 style for the name and the #banner h3 style for the description. If you look just below the section we just modified, you'll see something like this: #banner h1, #banner h2, #banner h3 { text-align: center; vertical-align: middle; color: white; } This sets the default style for the first three levels of heading. We can override the alignment by simply creating additional styles below that section, because in CSS, styles later in the file take precedence over earlier ones. So, let's add the following: #banner h1 { text-align: left; margin-left: 10%; } #banner h3 { text-align: right; font-style: italic; margin-right: 10%; } This gives us a left-aligned heading, and a right-aligned, italicized description. (If you don't see a blog description, you can turn it on in the plugin configuration page, under the "pageheader" plugin option.) Note the margins are set so that the text doesn't bump up against the edge of the banner.

So at this point, we have our image and our stylesheet. Now what? Well, we install them on the server, of course! But where to put them?

This is where the flexibility of LnBlog's theme system come in. You see, we actually have several options. First, we can always put them in our theme directory, overwriting the old style sheet. The second possibility is creating a new theme. The third is applying this only to a single blog. Changing the files for the default themes isn't really recommended, so we'll stick to the second and third options.

Creating a new theme, especially one this simple, is quite easy. Just go into your LnBlog/themes directory and create a new folder with whatever name you want the theme to have. Then, inside that folder, create four more folders with the following names: images, styles, scripts, and templates. Now copy your banner image into the images directory you just made and put the banner.css file in the styles directory. Now, if you edit your blog setting and change the theme to the one you just created, you should see your new banner.

The process for applying your custom banner to a single weblog is very similar. You would simply open up the directory for that weblog and create an images directory and a styles directory. Copy your image and style sheet to the corresponding directories and the changes will automatically take effect for that blog.

By now, you've probalby noticed the pattern here. When constructing a page to send to the client web browser, LnBlog uses a search path mechanism to find files. There are four kinds of files: images, styles, scripts, and templates. LnBlog looks for each type of file in a directory of the same name, located in the current blog's folder, the current theme's folder, or the default theme's folder. The search takes place in that order, so if you don't have a particular file in your blog or in your theme, the default will always be there. The idea is to make it easy to create small variations on existing themes. The down side, of course, is that it's somewhat more difficult to create custom themes from scratch. But, then again, given that you have to get all the template variable right in order for things to work, it's usually easier to just start from an existing theme anyway.

Next time, we'll talk about templates and how the enevt-driven plugin system interacts with them.

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