table of contents
| Template::Plugin::Image(3) | User Contributed Perl Documentation | Template::Plugin::Image(3) |
NAME¶
Template::Plugin::Image - Plugin access to image sizes
SYNOPSIS¶
[% USE Image(filename) %]
[% Image.width %]
[% Image.height %]
[% Image.size.join(', ') %]
[% Image.attr %]
[% Image.tag %]
DESCRIPTION¶
This plugin provides an interface to the Image::Info or Image::Size modules for determining the size of image files.
You can specify the plugin name as either '"Image"' or '"image"'. The plugin object created will then have the same name. The file name of the image should be specified as a positional or named argument.
[% # all these are valid, take your pick %]
[% USE Image('foo.gif') %]
[% USE image('bar.gif') %]
[% USE Image 'ping.gif' %]
[% USE image(name='baz.gif') %]
[% USE Image name='pong.gif' %]
A "root" parameter can be used to specify the location of the image file:
[% USE Image(root='/path/to/root', name='images/home.png') %]
# image path: /path/to/root/images/home.png
# img src: images/home.png
In cases where the image path and image url do not match up, specify the file name directly:
[% USE Image(file='/path/to/home.png', name='/images/home.png') %]
The "alt" parameter can be used to specify an alternate name for the image, for use in constructing an XHTML element (see the tag() method below).
[% USE Image('home.png', alt="Home") %]
You can also provide an alternate name for an "Image" plugin object.
[% USE img1 = image 'foo.gif' %]
[% USE img2 = image 'bar.gif' %]
The "name" method returns the image file name.
[% img1.name %] # foo.gif
The "width" and "height" methods return the width and height of the image, respectively. The "size" method returns a reference to a 2 element list containing the width and height.
[% USE image 'foo.gif' %]
width: [% image.width %]
height: [% image.height %]
size: [% image.size.join(', ') %]
The "modtime" method returns the modification time of the file in question, suitable for use with the Date plugin, for example:
[% USE image 'foo.gif' %]
[% USE date %]
[% date.format(image.modtime, "%B, %e %Y") %]
The "attr" method returns the height and width as HTML/XML attributes.
[% USE image 'foo.gif' %]
[% image.attr %]
Typical output:
width="60" height="20"
The "tag" method returns a complete XHTML tag referencing the image.
[% USE image 'foo.gif' %]
[% image.tag %]
Typical output:
<img src="foo.gif" width="60" height="20" alt="" />
You can provide any additional attributes that should be added to the XHTML tag.
[% USE image 'foo.gif' %]
[% image.tag(class="logo" alt="Logo") %]
Typical output:
<img src="foo.gif" width="60" height="20" alt="Logo" class="logo" />
Note that the "alt" attribute is mandatory in a strict XHTML "img" element (even if it's empty) so it is always added even if you don't explicitly provide a value for it. You can do so as an argument to the "tag" method, as shown in the previous example, or as an argument
[% USE image('foo.gif', alt='Logo') %]
CATCHING ERRORS¶
If the image file cannot be found then the above methods will throw an "Image" error. You can enclose calls to these methods in a "TRY...CATCH" block to catch any potential errors.
[% TRY;
image.width;
CATCH;
error; # print error
END
%]
USING Image::Info¶
At run time, the plugin tries to load Image::Info in preference to Image::Size. If Image::Info is found, then some additional methods are available, in addition to "size", "width", "height", "attr", and "tag". These additional methods are named after the elements that Image::Info retrieves from the image itself. The types of methods available depend on the type of image (see Image::Info for more details). These additional methods will always include the following:
file_media_type¶
This is the MIME type that is appropriate for the given file format. The corresponding value is a string like: ""image/png"" or ""image/jpeg"".
file_ext¶
The is the suggested file name extension for a file of the given file format. The value is a 3 letter, lowercase string like ""png"", ""jpg"".
color_type¶
The value is a short string describing what kind of values the pixels encode. The value can be one of the following:
Gray
GrayA
RGB
RGBA
CMYK
YCbCr
CIELab
These names can also be prefixed by ""Indexed-"" if the image is composed of indexes into a palette. Of these, only ""Indexed-RGB"" is likely to occur.
(It is similar to the TIFF field PhotometricInterpretation, but this name was found to be too long, so we used the PNG inspired term instead.)
resolution¶
The value of this field normally gives the physical size of the image on screen or paper. When the unit specifier is missing then this field denotes the squareness of pixels in the image.
The syntax of this field is:
<res> <unit> <xres> "/" <yres> <unit> <xres> "/" <yres>
The "<res>", "<xres>" and "<yres>" fields are numbers. The "<unit>" is a string like "dpi", "dpm" or "dpcm" (denoting "dots per inch/cm/meter).
SamplesPerPixel¶
This says how many channels there are in the image. For some image formats this number might be higher than the number implied from the "color_type".
BitsPerSample¶
This says how many bits are used to encode each of samples. The value is a reference to an array containing numbers. The number of elements in the array should be the same as "SamplesPerPixel".
Comment¶
Textual comments found in the file. The value is a reference to an array if there are multiple comments found.
Interlace¶
If the image is interlaced, then this returns the interlace type.
Compression¶
This returns the name of the compression algorithm is used.
Gamma¶
A number indicating the gamma curve of the image (e.g. 2.2)
AUTHOR¶
Andy Wardley <abw@wardley.org> <http://wardley.org/>
COPYRIGHT¶
Copyright (C) 1996-2022 Andy Wardley. All Rights Reserved.
This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
SEE ALSO¶
Template::Plugin, Image::Info
| 2024-06-23 | perl v5.40.0 |