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User:JPAUL/Theme Development

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L'article qui suit traite du développement et de la conception de votre proper théme WordPress. si vous désirez en savoir plus au sujet de l'installation et de l'utilisation des thèmes, revoyez la documentation FR:Using Themes.

Vous pouvez désirer réaliser des thèmes pour votre propre compte ou bine pour les distribuer. Ce sujet est différent de FR:Using Themes car il concerne l'aspect technique qui consiste à écrire du code pour construire votre propre thème plutôt que de l'activation des thèmes ou l'obtention de nouveaux thèmes.


A quoi servent les thèmes WordPress

Les thèmes WordPress sont des fichiers et des feuilles de styles qui fonctionnent ensemble pour créer la présentation ou l'apparence d'un site WordPress. Les thèmes peuvent être différents les uns des autres. Ils offrent ainsi beaucoup des choix dont les utilisateurs peuvent tirer parti en changeant instantannément l'apparence de leur site Web. Pourquoi construire sont propre thème WordPress ?

  • Pour donner une apparence unique à votre site WordPress site
  • Pour tirer parti des modèles, tags de modèles, et de la boucle WordPress afin de générer des résultats de pages dynamiques différents ainsi que des apparences différentes.
  • Pour avoir des modèmes alternatifs pour les parties spécifiques du site, comme les pages de catégories et les pages affichant les résultats des recherches.
  • Pour pouvoir changer rapidement la disposition du site, ou pour exploiter les plugin de modification dethème ou de style pour permettre aux utilisateur de choisir parmi les looks de votre site.
  • Créer des thèmes WordPress ainsi les autres pourront se réjouir de pourvoir utiliser vos thèmes.

Un thème WrodPress à aussi beaucoup d'avantages.

  • Il sépare le style de présentation et les fichiers de modèles des fichiers système Ainsi WordPress peut être mis à jour sabns grosses modificatins de l'apparence du site.
  • Il permet une personnalisation de la présentation et des pages web générées unique pour ce thème.
  • Il permet des changement rapides de l'apparence du site
  • Il évite aux utilisateurs de WordPress d'apprendre CSS, HTML, et PHP tous en leur permettant d'avoir un beau site Web.

Pourquoi devriez-vous faire votre propre thème WordPress ? Voici la question.

Anatomie d'un Thème

Les thèmes WordPress sont situés dans des sous répertoires que l'on trouve dans wp-content/themes/. Ce répertoire va contenir tous les fichiers des feuilles de style des thèmes, template files, et les images. Par exemple, un thème se nommant "test" va être contenu dans le répertoire wp-content/themes/test/.

La version téléchargeable de WordPress est livrée avec 2 thèmes, l'un "Classic" et l'autre "Default". Each one is different and uses different functions and tags to generate their web page results and looks. Examine the files carefully for these Themes to get a better idea of how to build your own Theme files.

WordPress Themes consist of two main files, in addition to images. One is the style sheet called style.css, which controls the presentation (look) of the web pages, and the other files are the template files which control the way the web page generates the information from the Database to be displayed as a web page. Let's look at these individually.

See Theme cheatsheet.

Theme Style Sheet

The stylesheet, style.css must provide details about the Theme in the form of comments. No two Themes are allowed to have the same details listed in their comment headers, as this will lead to problems in the Theme selection dialog. If you make your own Theme by copying an existing one, make sure you change this information first.

The following is an example of the first few lines of the stylesheet, called the style sheet header, for the Theme "Rose":

/*   
Theme Name: Rose
Theme URI: the-theme's-homepage
Description: a-brief-description
Author: your-name
Author URI: your-URI
Template: use-this-to-define-a-parent-theme--optional
Version: a-number--optional
.
General comments/License Statement if any.
.
*/

The simplest Theme includes only a style.css file, plus images, if any. To create such a Theme, you must specify a set of templates to inherit for use with the Theme by editing the Template: line in the style.css header comments. For example, if you wanted the Theme "Rose" to inherit the templates from another Theme called "test", you would include Template: test in the comments at the beginning of Rose's style.css. Now "test" is the parent Theme for "Rose", which still consists only of a style.css file and the concomitant images, all located in the directory wp-content/themes/Rose. (Note that specifying a parent Theme will inherit all of the template files from that Theme — meaning that any template files in the child Theme's directory will be ignored.)

The comment header lines in style.css are required for WordPress to be able to identify a Theme and display it in the Admin panel > Presentation as an available Theme option along with any other installed Themes.

Note : When defining the parent Theme, in the Template: section of the comment header, you must use the name of the directory of the style. For example, to use as parent template the Default Wordpress Theme, don't write Template: WordPress Default, but Template: default, because default is the directory of this Theme.

Theme Template Files

Templates are PHP source files used to generate the pages requested by visitors. Let's look at the various templates that can be defined as part of a Theme.

WordPress allows you to define separate templates for the various aspects of your weblog, however, it is not essential to have all these different template files for your blog to function fully. Templates are chosen and generated based upon the Template Hierarchy, depending upon what templates are available in a particular Theme. As a Theme developer, you can choose the amount of customization you want to implement using templates. For example, as an extreme case, you can use only one template file, called index.php as the template for all pages generated and displayed by the weblog. A more common use is to have different template files generate different results, to allow maximum customization.

Basic Templates

At the very minimum, a WordPress Theme consists of two files:

  • style.css
  • index.php

The index.php template file is unique and flexible. It can be used to include all references to the header, sidebar, footer, content, categories, archives, search, error, and other web pages generated by the user on your site. Or it can be subdivided into modular template files, each one taking on part of the workload. If you do not provide any other template files, WordPress will use the built-in default files. For example, if you do not have either a comments.php or comments-popup.php template file, then WordPress will automatically use the wp-comments.php and wp-comments-popup.php template files using Template Hierarchy. These default templates may not match your Theme very well, so you probably will want to provide your own.

If you want to subdivide the index.php master template file, as showcased in the Default WordPress Theme, you can. Such subdivision or modularization is optional. These modular template files may include these basic files:

  • header.php
  • sidebar.php
  • footer.php
  • comments.php
  • comments-popup.php

These are the basic files needed to make a Theme. Place them with style.css, and index.php into their own subdirectory beneath wp-content/themes/, and you have a Theme.

Using these modular template files, you can put template tags within the index.php master file to include or get these units where you want them to appear in the final generated web page.

Here is an example of the include usage:

<?php get_sidebar(); ?>

<?php get_footer(); ?>

For more on how these various Templates work and how to generate different information within them, read the Templates documentation.

Query-based Templates

WordPress can load different Templates for different query types. It does this as part of the built-in Template Hierarchy, or through the use of Conditional Tags within The Loop of a template file, like the index.php file.

Using the Template Hierarchy, if your Theme provides a template called category.php and a category is being queried, category.php will be loaded instead of index.php. If category.php is not present, index.php is used as usual.

If you wish to design a template for one specific category, so that only that category ID number will generate a different category page, and the rest will fall back to the category.php or index.php template file, name the file category-#.php where "#" is the category's ID number (found in Manage > Categories if you are logged in as the site administrator). If you set category-6.php to be the category page for Category 6, then it would display, overriding category.php. For a more detailed look at how this process works, see Category Templates.

To generate a different template file based upon a Conditional Tag usage or query, if the conditions are met, then that template file will be used by WordPress, otherwise it will fall back on the next file in the Template Hierarchy.

For example, to generate a distinctive style sheet in a post only found within a specific category, the code might look like this:

<?php
if (is_category(9)) {
        // looking for category 9 posts
include(TEMPLATEPATH . '/single2.php');
} else {
        // put this on every other category post
include(TEMPLATEPATH . '/single1.php');
        }
?>

Or, using a query, it might look like this:

<?php
$post = $wp_query->post;
if ( in_category('9') ) {
include(TEMPLATEPATH . '/single2.php');
} else {
include(TEMPLATEPATH . '/single1.php');
}
?>

So if the condition or query is met, that the post is in Category 9, then it would display in the template file called single2.php. If the query is not met, then it would use the single1.php template file.

These query conditions are not limited to posts. You can also design different Templates for different Pages. See that reference for details.

Theme Template Files List

Here is the list of Theme template files recognized by WordPress. Of course, your Theme can contain any other style sheets, images, or files. Just keep in mind that the following have special meaning to WordPress.

style.css
The main stylesheet. This must be included with your Theme.
index.php
The main template. If your Theme provides its own templates, index.php must be present.
comments.php
The comments template. If not present, comments.php from the "default" Theme is used.
comments-popup.php
The popup comments template. If not present, comments-popup.php from the "default" Theme is used.
home.php
The home page template.
single.php
The single post template. Used when a single post is queried. For this and all other query templates, index.php is used if the query template is not present.
page.php
The page template. Used when an individual Page is queried.
category.php
The category template. Used when a category is queried.
author.php
The author template. Used when an author is queried.
date.php
The date/time template. Used when a date or time is queried. Year, month, day, hour, minute, second.
archive.php
The archive template. Used when a category, author, or date is queried. Note that this template will be overridden by category.php, author.php, and date.php for their respective query types.
search.php
The search template. Used when a search is performed.
404.php
The 404 Not Found template. Used when WordPress cannot find a post or page that matches the query.

These files have a special meaning with regard to WordPress because they are used as a replacement for index.php, when available, and when the corresponding Conditional Tag (a.k.a is_*(); function) returns true. For example, if only a single post is being displayed, the is_single() function returns 'true', and, if there is a single.php file in the active Theme, that template is used to generate the page.

Referencing Files From a Template

The WordPress Default Theme (based on Michael Heilemann's Kubrick layout for WordPress 1.2) provides a good example of how queries are mapped onto templates.

The code <?php bloginfo('template_directory'); ?> inserts the URL of the template directory into the template output. You can append any additional URI information to this output to reference files in your Theme.

The code <?php bloginfo('stylesheet_directory'); ?> inserts the URL of the directory that contains the current Theme stylesheet into the template output. You can append any additional URI information to this output to reference files for your Theme, specifically those that are used by the stylesheet.

The constant TEMPLATEPATH is a reference to the absolute path to the template directory for the current Theme (without the / at the end).

Note that URIs that are used in the stylesheet are relative to the stylesheet, not the page that references the stylesheet. This obviates the need to include PHP code in the CSS file to specify directories. For example, if you include an images/ directory in your Theme, you need only specify this relative directory in the CSS, like so:

h1 { background-image: URL(images/my_background.jpg); }

It is a good practice to use URIs in the manner described above to reference files from within a template, since, then your template will not depend on absolute paths.

Defining Custom Templates

It is possible to use the WordPress plugin system to define additional templates that are shown based on your own custom criteria. This advanced feature can be accomplished using the template_redirect action hook. More information about creating plugins can be found in the Plugin API reference.

Plugin API Hooks

When developing themes, it's good to keep in mind the specialized group of Plugin API functions listed below. These plugin hooks are called as Template Tags, either as a parameter to WordPress' do_action() function:

<?php do_action( 'hook_name' [, optional second parameter] ); ?>

or as functions in their own right (one exception noted below):

<?php hook_name(); ?>

When you include the template-specific hooks in your theme, plugins will be able to run code or display data directly in it, without requiring their own template tag functions be added. So it's important to include these plugin hooks in your templates especially if you plan on redistributing your theme, otherwise you risk breaking important features of a plugin which makes use of one or more of them. See Current Hooks For Actions for a full list of do_action hooks (note that most are not intended as template hooks for plugins).

Template Plugin Hooks:

wp_head
Goes in the HTML <head> element of a theme; header.php template. This hook has no second parameter. Example plugin use: add javascript code.
Usage: <?php do_action('wp_head'); ?>  -or-  <?php wp_head(); ?>
wp_footer
Goes in the "footer" of a theme; footer.php template. This hook has no second parameter. Example plugin use: insert PHP code that needs to run after everything else.
Usage: <?php do_action('wp_footer'); ?>  -or-  <?php wp_footer(); ?>
wp_meta
Typically goes in the <li>Meta</li> section of a theme's menu or sidebar; sidebar.php template. This hook has no second parameter. Example plugin use: include a rotating advert.
Usage: <?php do_action('wp_meta'); ?>  -or-  <?php wp_meta(); ?>
comment_form
Goes in comments.php and comments-popup.php, directly before the comment form's closing tag (</form>). Its second parameter must be $post->ID. Example plugin use: display a comment preview.
Usage: <?php do_action('comment_form', $post->ID); ?>

For a real world usage example, you'll find these plugin hooks included in the default theme's templates.

Theme Development General Guidelines

Please be clear about the following in your documentation (a README file included with your Theme helps many users over any potential stumbling blocks):

  1. Indicate precisely what your Theme and template files will achieve.
  2. Indicate deficiencies in your Themes, if any.
  3. Clearly reference any special modifications or notes to comments within the template and style sheet files and comment modifications, template sections, and CSS styles, especially those which cross template files.
  4. If you have any special requirements, which may include custom RewriteRules, or the use of some additional, special templates, images or files, please explicitly state the steps of action a user should take to get your Theme working.
  5. Try and test your Theme across browsers to catch at least a few of the problems the users of the Theme may find later.
  6. Provide contact information (web page or email), if possible, for support information and questions.

Since the concept of using Themes is currently new to WordPress, the additional effort you put in to make the Themes user-friendly will be greatly appreciated. Take time to read through Designing Themes for Public Release, an article with good tips on preparing your Theme for the public. For criteria on how to release your Theme to the public, see Promoting Your Theme.

References and Resources

To help you develop your WordPress Theme, here are some resources and references.

WordPress Resources

CSS and Layout

Theme and Template Resources

Testing and Validating

General Resources

References

Tools

Plain Text Editors 
A list of plain text editors for all platforms.
Developing_a_Colour_Scheme 
Article on developing a colour scheme for your site.
WordPress Index Builder 
This tool will ask you a series of questions about your site to generate a working WordPress template page and CSS file. Criteria include number of columns and color matching.
Flumpcakes CSS Optimizer 
Optimize your CSS file. Contains a possibly "not safe for work" header image.

Other Resources

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