How the Drupal theme system works

A theme is a collection of files that define the presentation layer. You can also create one or more "sub-themes" or variations on a theme. Only the .info file is required, but most themes and sub-themes will use other files as well. The following diagram illustrates the files that are found in a typical theme and sub-theme.
Drupal 6

theming requirements
Drupal 7

theming requirements

.info (required)

All that is required for Drupal to see your theme is a ".info" file. Should the theme require them, meta data, style sheets, JavaScripts, block regions and more can be defined here. Everything else is optional.

The internal name of the theme is also derived from this file. For example, if it is named "drop.info", then Drupal will see the name of the theme as "drop". Drupal 5 and below used the name of the enclosing folder of the theme.

Info files for themes are new in Drupal 6. In version 5, .info files were used solely for modules.
template files (.tpl.php)

These templates are used for the (x)HTML markup and PHP variables. In some situations they may output other types of data --xml rss for example. Each .tpl.php file handles the output of a specific themable chunk of data, and in some situations it can handle multiple .tpl.php files through suggestions. They are optional, and if none exists in your theme it will fall back to the default output. Refrain from having complex logic in these files. In most cases, it should be straight (x)HTML tags and PHP variables. A handful of these templates exist in directories where core and contributed modules exist. Copying them to your theme folder will force Drupal to read your version.

Note: The theme registry caches information about the available theming data. You must reset it when adding or removing template files or theme functions from your theme.
template.php

For all the conditional logic and data processing of the output, there is the template.php file. It is not required, but to keep the .tpl.php files tidy it can be used to hold preprocessors for generating variables before they are merged with the markup inside .tpl.php files. Custom functions, overriding theme functions or any other customization of the raw output should also be done here. This file must start with a PHP opening tag "http://drupal.org/node/337173

Module: - ImageCache

ImageCache allows you to setup presets for image processing. If an ImageCache derivative doesn't exist the web server's rewrite rules will pass the request to Drupal which in turn hands it off to ImageCache to dynamically generate the file.

http://drupal.org/project/imagecache

Module - ImageField

ImageField provides an image upload field for CCK. ImageField is a CCK-based alternative to the legacy Image project. It boasts features such as multiple images per node, resolution restrictions, default images, and extensive Views support.

ImageField does not provide a built-in thumbnail solution, but complements the incredibly powerful thumbnail generation module ImageCache.
ImageField related projects

ImageCache - Dynamic thumbnail generation.
ImageField Extended - Add additional data to images other than the default Description, Title and Alt.
ImageField Focus - Define custom focus and crop areas to be combined with ImageCache.
ImageField Crop - Crop images permanently after upload.
Image FUpload - Bulk image uploader.

Dependencies

ImageField 6.x depends on the CCK and FileField modules.
ImageField 5.x depends on the CCK and ImageAPI modules.

Compatibility notes

Image.module - Imagefield is not compatible with image.module content types. If you add an imagefield CCK field to the image type provided by image module, image module will delete all the imagefield images on every node update.

Migration

See the FileField Handbook for a list of migration scripts from other modules such as Image.module, Image Attach, or Node Images.

Read More...

www.drupal.org

Module - FileField

FileField provides a universal file upload field for CCK. It is a robust alternative to core's Upload module and an absolute must for users uploading a large number of files. Great for managing video and audio files for podcasts on your own site.

Features

Configurable upload paths allow you to save files into per-field or per-user directories
Per-field and per-node file size limits
Extensive API for extending field widgets and managing files
Full revision/translation file management
Views support
Ajax Uploads (and progress bar support with the PECL uploadprogress extension)
Pretty Icons
All the goodness of CCK (multiple output formats, shared fields, multiple values, and much more)

Read More...

www.drupal.org

Module - Administration menu

Provides a theme-independent administration interface (aka. "navigation", "back-end"). It's a helper for novice users coming from other CMS, a time-saver for site administrators, and useful for developers and site builders.

Administrative links are displayed in a CSS/JS-based menu at the top on all pages of your site. It not only contains regular menu items — tasks and actions are also included, enabling fast access to any administrative resource your Drupal site provides.
Showcase and Quality Assurance

Test-drive in various themes on the demonstration site or watch a short demo reel.

Behaviour and Integration

Works in all themes and all browsers.
Exposes all administration links including all tabs/tasks and actions to provide direct access to any page.
Extensible with add-on features by other modules. Devel integration is built-in.
Themeable administration menu icon.
(3.x only) Implements client-side caching to minimize server-side performance impact.
(7.x-3.x only) Exposes links to individual configuration items (e.g., content types, menus, views, etc.) including their contextual links.

Related modules

This module is intended for administrative users, not for regular/anonymous users. Try SimpleMenu, Nice Menus, or DHTML Menu.

Installation

Read the documentation.
Grant the "access administration menu" and "access administration pages" user permissions to selected roles.
Drupal 6 only:
The "Administer" menu link must be enabled, but may reside in a different menu than "Navigation".
Ensure your theme outputs $closure. If the menu does not appear, consult the README.txt first.


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www.drupal.org

Module - Pathauto

he Pathauto module automatically generates path aliases for various kinds of content (nodes, categories, users) without requiring the user to manually specify the path alias. This allows you to get aliases like /category/my-node-title.html instead of /node/123. The aliases are based upon a "pattern" system which the administrator can control.

Pathauto depends on the Token module. See screenshots of the bulk delete and the admin settings screen. View a screencast of Using Pathauto and Views to get Index Aliases.

Stable 6.x version: Most Drupal 6 users will want to use the official 6.x-1.x releases (which were ported from 5.x-2.x). If you are upgrading from Drupal 5, be sure to read the upgrade guide
Development 6.x version: For the daring Drupal 6 users who want to test out improvements from the Drupal 7 version, the 6.x-2.x version is where all the cool stuff is being back-ported. Make sure you're using the latest 6.x-1.x-dev version of Token as well.
Development 7.x version: Drupal 7 users can start testing the 7.x-1.x releases which are currently in development. Any new features or UI changes will be only accepted for this version, and then back-ported to 6.x-2.x if possible.


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WWW.Drupal.org

Module- Content Construction Kit (CCK)

The Content Construction Kit allows you to add custom fields to nodes using a web browser.
Drupal 7 and Fields in Core

Most of CCK has moved to core in the Drupal 7 version.

Please note that this is not the place to get support for D7 Fields! We are getting a number of support requests, bug reports, and even feature requests for D7 fields. Fields are in core in D7, you must file issues there, not here.

The D7 version of the contrib CCK package currently contains:

D6 -> D7 data migration code, see Migrating D6 Content Construction Kit (CCK) to D7 Fields for an explanation of how to upgrade your data.
some miscellaneous helpers to do things that core will not do, like maintain the PHP code snippets some fields may have been using to define allowed values (partially working)

The following features are now handled by separate, dedicated projects:

nodereference and userreference : References project - co-maintainer needed
content_permissions: Field permissions module. See this issue for progress on the D7 version.
fieldgroup : Field group module - with much more awesomeness than in D6 !

Yet to be defined, nothing ported yet:

content_copy : The D7 branch of the Features module supports expoting and importing content types and fields in 'feature' modules. There is currently no UI to manually export and import field definitions.

Integration with other modules:

Views - all Views field integration is handled by Views in D7.
Panels - all Panels field integration is handled by Panels in D7.
Token - see the D7 version of the Token module.
Devel - the Devel module will handle field generation code in D7.

Everything else is in Drupal 7 core.

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