ThumbnailPlugin

Thumbnails for everyone

Syntax Rules

%THUMBNAIL{ name="filename" variant="size" }%

Given an image file name, returns the name of its thumbnail file of the given size.

Normally, you don't give the size, as it will default from a preference variable. But if you want an especially large (or small) icon selectively, the syntax allows for that.

This plugin can be enabled on a per-topic, web, or site basis using the THUMBNAILPLUGIN_ENABLE preference variable.

When this plugin is enabled for a topic, any image attachment that is saved will have one or more thumbnails autogenerated for it. Image attachments types currently supported are: .jpg .gif .png

The thumbnail's size will be determined from the preference variable THUMBNAILPLUGIN_SIZE, which defaults to 150 (pixels).

The preference variables can be set in the containing topic, your home topic, the containing web's WebPreferences topic, or the site WebPreferences topics. If a preference is set in multiple places, the value closest to the topic using the plugin will be used.

Use multiple sizes for accessibility as well as for esthetics. However, they do take time to generate, so don't go too wild.

Used with the AttachLinkPlugin and ImgPlugin, it becomes easy to do things like display hyperlinks to images as thumbnails of that image. Examples below. But if that's what you want, use %THUMBVIEW instead.

Note that the THUMBNAILPLUGIN_ENABLE preference controls thumbnail generation on upload; it does not control expansion of the %THUMBNAIL and %THUMBVIEW variables.

%THUMBVIEW{ name="filename" variant="size" topic="topic" web="web" caption="string" cpos="position" align="string" border="" height="" width="" id="" class=""  link="filename" ltopic="topic" lweb="web" fullpath="" }%

This is a lot simpler than it looks, as all the defaults are reasonable.

• name - Filename of image to be displayed. Required.
• variant - Thumnail size to be displayed. Defaults to the first value of the THUMBNAILPLUGIN_SIZE preference variable.
• topic - the topic to which the image is attached. Defaults to the current topic.
• web - the web containing the topic to which the image is attached. Defaults to the current web.
• caption - string to be used to caption the thumbnail. If present, the thumbnail will be displayed within a small table. If not, no caption will be used.
• cpos - caption position: top, bottom, left or right. Where to position the caption. Default is bottom.
• align, border, height, width, id, class - usual HTML tags, applied to the thumbnail or the table that contains it.
• attrs="string" - arbitrary html tag='value' list if you really need that level of control - e.g. onclick= or some such
• link - filename of attachment to be displayed when the thumbnail image is clicked. Defaults to the name argument (that is, the full size version of the thumbnail)
• ltopic, lweb - topic & web to which the link target is attached. Default to the topic, web arguments.
• nolink - set to 1 if you don't want the thumbnail to be clickable.
• lid, lclass, ltarget, lname - HTML parameters applied (without the leading l) to the link.
• fullpath - set to 1 if you want the link references to include the hostname; 0 will just specify the resource. Default is THUMBNAILPLUGIN_FULLPATH, or 0 if undefined.
• lalign, lborder, lheight, lwidth, lid, lclass - usual HTML tags, applied to the link.
• lattrs="string" - arbitrary html tag='value' list for the link if you really need that level of control

This plugin requires the GD and Image::MetaData::JPEG libraries from CPAN.

CAVEAT

This is a working prototype. Because of limitations of the current plugin interface, thumbnail auto-creation is unclean.

• Do not rely on the filenames or locations of the thumbnail files, which are subject to change.
• Do not name attachments _thumbnail_size. - these are the currently auto-created files.
• You probably will not want the {AutoAttachPubFiles} configuration option set, as the thumbnail files are not (yet) first class attachments.
• Until the plugin interface issues are resovled, this may break in future versions of the wiki.

It is intended, but not guaranteed that updates to correct these issues will not require changes to your topics. They may require running an upgrade script.

Although this warning may sound a bit scary, the plugin seems useful in its current state -- feedback is welcome (as is assistance with the plugin API issues, which are documented on twiki.org.)

Examples

%ATTACHMENT{"foo.jpg" label="%IMG{"%THUMBNAIL{"foo.jpg"}%" align="left" }%"}%

This is equivalent to the previously-required HTML markup

<a href="%ATTACHURL%/foo.jpg"><img src="%ATTACHURL%/foo_thumbnail_150.jpg" align="left" /></a>

or the slightly better:

%ATTACHMENT{ "foo.jpg" label="%IMG{ "foo_thumb_150.jpg" align="left" width="40" class="none" }%}%

Of course, neither of the previous methods support multiple sizes as easily, nor are they as well abstracted from the attachment implementation.

The easiest, and recommended use is:

%THUMBVIEW{"foo.jpg"}%

This will display a default sized thumbnail of foo, making it clickable to the full-sized version.

%THUMBVIEW{"foo.jpg" caption="foo revealed"}%

is about as complex as is ordinarily needed.

Plugin Settings

Plugin settings are stored as preferences variables. To reference a plugin setting write %<plugin>_<setting>%, i.e. %NEWPLUGIN_SHORTDESCRIPTION%

• One line description, is shown in the TextFormattingRules topic:
  • Set SHORTDESCRIPTION = Painless links to attachments

• THUMBNAILPLUGIN_ENABLE = on, off : enables thumbnail auto-creation on save. Inherits by the usual preference rules.
• THUMBNAILPLUGIN_SIZE= decimal_number : defines the default size of auto-created thumbnails. You can specify a (space or comma-separated) list, in which case multiple thumbnails (1 of each size) will be generated. The first (or only) size listed is the default variant used by %THUMBNAIL%.
• THUMBNAILPLUGIN_FULLPATH = on, off: default fullpath parameter: on will include hostname (protocol and port) in links; off will not. You may want to set this on a global basis for things like GenPDF.

Plugin Installation Instructions

Note: You do not need to install anything on the browser to use this plugin. The following instructions are for the administrator who installs the plugin on the TWiki server.

• Download the ZIP file from the Plugin Home (see below)
• Unzip ThumbnailPlugin.zip in your twiki installation directory. Content:

  File:	Description:
  data/TWiki/ThumbnailPlugin.txt	Plugin topic
  data/TWiki/ThumbnailPlugin.txt,v	Plugin topic repository
  lib/TWiki/Plugins/ThumbnailPlugin.pm	Plugin Perl module

• Configure the Plugin:
  • TWiki 4.0 and up: Run the configure script to enable the Plugin
  • Change the Plugin settings as needed

Plugin Info

Plugin Author:	TWiki:Main.TimotheLitt
Copyright:	© 2008, TWiki:Main.TimotheLitt
License:	GPL (GNU General Public License, Perl artistic)
Plugin Version:	21 Dec 2008 (V1.000)
Change History:
20 Dec 2008:	Initial version
TWiki Dependency:	$TWiki::Plugins::VERSION 1.1
CPAN Dependencies:	GD:: Image::MetaData::JPEG
Other Dependencies:	none
Perl Version:	5.005
Benchmarks:	GoodStyle nn%, FormattedSearch nn%, ThumbnailPlugin nn%
Plugin Home:	http://TWiki.org/cgi-bin/view/Plugins/ThumbnailPlugin
Feedback:	http://TWiki.org/cgi-bin/view/Plugins/ThumbnailPluginDev
Appraisal:	http://TWiki.org/cgi-bin/view/Plugins/ThumbnailPluginAppraisal

Related Topics: TWikiPlugins, DeveloperDocumentationCategory, AdminDocumentationCategory, TWikiPreferences http://TWiki.org/cgi-bin/view/Plugins/AttachmentPlugin http://TWiki.org/cgi-bin/view/Plugins/ImgPlugin

-- TWiki:Main.TimotheLitt - 21 Dec 2008