NAME
XAO::ImageCache - Images caching by URLs stored in XAO::FS database
SYNOPSIS
use XAO::ImageCache;
# Making new instance of Image Cache object
my $image_Cache = XAO::ImageCache->new(
list => $odb->fetch("/Products"),
cache_path => "/var/httpd/shop/product/images/",
cache_url => "/products/images/",
source_url_key => "source_img",
) || die "Can't make Image cache!";
# Init new empty Cache
$image_cache->init() || die "Can't init new cache!";
# Start images checking and downloading to cache
$image_cache->check();
DESCRIPTION
When we store images links on own database we have no real images on own
site. Some time it may be a problem cause images may have no right
dimension or may be deleted from source site.
XAO::ImageCache made for cache locally images his URL stored in XAO
Founsation Server. Also, images may be resized automaticaly.
This module provide easy methods to scan XAO Foundation Server data
lists, to extract images source URLs from data objects, to download
images to local cache, to resize a local copy of the image to fit into
given dimensions and to store the new local URL of the image back to the
data object.
METHODS
new($%)
The constructor returns a new "XAO::ImageCache" object. You can use
it to make new images cache or check images of already existent
cache.
my $image_cache = XAO::ImageCache->new(
cache_path => "cache", # set cache directory to './cache/'
source_path => "cache/source", # set source directory to './cache/source/'
local_path => "images/copy", # (optional) try to resolve local urls
cache_url => "images/", # set cached images (relative) path to 'images/'
list => $odb->fetch("/Products"),
source_url_key => 'source_image_url',
dest_url_key => 'dest_image_url',
filename_key => 'product_id',
min_width => 50, # Source image is ignored if smaller
min_height => 50,
size => {
width => 320,
height => 200,
save_aspect_ratio => 1,
},
thumbnails => {
path => '/var/httpd/shop/product/images/tbn',
url => '/products/images/tbn/'
geometry => "25%",
url_key => 'thumbnail_url',
},
autocreate => 1,
useragent => {
agent => 'My Lovely Browser/v13.01',
timeout => 30,
},
force_download => 1, # to enforce re-downloads
force_scale => 1, # to enforce re-scaling
clear_on_error => 0, # don't clear DB properties even on permanent errors
) || die "Image cache creation failure!";
A number of configuration parameters can be passed to
XAO::ImageCache to tune functionality.
autocreate
cache_path
cache_url
clear_on_error
dest_url_key
force_download
force_scale
list
source_url_key
size
thumbnails
useragent
Follow to CONFIGURATION PARAMETERS section to see what each
parameter does.
If any required parameter is not present an error will be thrown.
init($)
Cache structure initialization.
Executed automaticaly if "autocreate" parameter present.
Create image cache directory if non existent and thumbnail cache
directory if non existent and defined as initialization parameter.
check($)
Goes through given XAO FS data list, downloads images from source
url to cache and puts cache url into destination url key and
thumbnail url key (where applicable).
XAO::ImageCache->download() will be executed for downloading each
image.
download($$)
Downloads image into cache directory.
If "thumbnails" contains "cache_path" parameter, thumbnail is either
downloaded into thumbnail cache directory or created from downloaded
image.
Source image URL should be passed as parameter. Source thumbnail URL
is an optional parameter:
$img_cache->download($image_source_url, $thumbnail_source_url);
Downloaded image is resized if "size" parameter present. Thumbnail
is resized as specified by "thumbnails" "geometry" parameter.
When "force_download" configuration parameter is not set to True
value, image will be downloaded into cache only if image is not
already cached or if cached image has a later modification date than
source image.
scale_large($$$)
Scaling image to given size.
scale_thumbnail($$$)
Creates thumbnail image from given source image.
remove_cache($)
Removing the ENTIRE cache directory from disk.
Be carefully to use this method!!!
Cache structure will be removed from disk completely! Set
"force_download" parameter to True value to download images to cache
without any conditions.
get_filename($)
File name generation for cached images.
Source image URL should be passed. Returned file name is an MD5
digest of the source URL converted to Base64 string with all non
alpha numeric characters are converted to "_".
Example.
Location:
http://localhost/icons/medbutton.jpeg
provide file name:
4aFNA1utpmCNG2wEIF69mg.jpeg
treat_filename($)
Makes sure only file name friendly characters are present: all non
alpha numeric characters are converted to "_".
CONFIGURATION PARAMETERS
The set of configuration parameters contain required and optional
parameters.
Required parameters should be defined. Execution will be stoped if
required parameter not present.
Optional parameters just configure aditional functionality and may not
present.
Required parameters
cache_path
- Path string where the cache should be placed.
May be absolute or relative from current execution directory path.
For example. Set it to "./cache" if you whant to place cache in
"cache" subdirectory of your script working directory.
cache_url
- complet URL (or relative location) to cached images.
Place here your URL reflection of cache directory in condition with
your HTTP server configuration.
For example. Set it to "http://my.host.com/images/" if your HTTP
server configured for provide access to your cache directory by
hostname "my.host.com" and location "images/". Cached images names
will be added to image URL automaticaly.
list
- reference to "XAO::DO::FS::List" object containing the data
objects with Image source URL
Meaning, your data look like a XAO Foundation Server list of objects
with references to images. This parameter should contain reference
to to XAO::DO::FS::List object. This reference may be result of
XAO::Objects->fetch() methode.
XAO::ImageCache will process each record of this list.
source_url_key
- data key containing the URL of source image.
Contain the name of key of data object containing the source image
reference.
Optional parameters
dest_url_key
- data key for storing URL of image in cache.
Optional parameter cause image name in cache will be a MD5 Base64
digest of source image path where "=" character removed, "\" and "+"
translated to "_" and "-" simultaniosely.
To get cached image name
size
- Prefered image size may set as "geometry" equal to "geometry"
parameter of Image::Magick module to pass it dirrectly to
Image::Magick Scale function.
Other way to set the image size is set a width and height keys to
preffered values.
If one of image dimension is not defined then corresponding
parameter of original image will be used.
This way, image will be resized with same aspect ratio (same
proportions) to the original image if "save_aspect_ratio" parameter
present.
Image width and height will be resized exactly to given size if
"save_aspect_ratio" parameter not present.
Parameter "geometry" has higher priority and other parameters has no
effects if "geometry" peresent.
For example.
# Size 320x200 as geometry settings
%params = (size => {geometry => "320x200!"} );
# Size 320x200 as dimensions settings
%params = (size => {width => 320, height => 200} );
# Fit size into 320x200 with saving image proportions
%params = (
size => {
width => 320,
height => 200,
save_aspect_ratio => 1,
}
);
autocreate
- create or check cache content automaticaly.
If non zero value present, cache directory will be created and
images checking will be runned. Otherwithe you should run init() and
check() methodes manualy.
Existent cache directory will not be removed. You may do it manualy
using remove_cache() methode.
force_download
- each image should be reloaded to cache and processed without
dependance of source image modification time. Any conditions
ignored.
thumbnail
- thumbnails creator configuration
Some thubnails configuration parameters may be set for automatic
thumbnails creation. This parameter should contain the reference to
hash with thumbnails configuration parameters.
Only "path" parameter is required. Other parameters are optional.
path
path where thumbnail images should be placed.
url URL for access to thumbnails directory. Same way as "cache_url".
url_key
Data object key name where thumbnail URL should be stored.
geometry
Geometry string to set thumbnail images size in Image Magick
geometry format. May be set as dimension ("320x200!") or as
persent of actual size of cached image ("25%").
Default value is "50%" the half of actual image size.
useragent
- configuration parameters hash for LWP::UserAgent
agent
Default value "XAO-ImageCache/#.##"
env_proxy
Default value 1
keep_alive
Default value 1
timeout
Default value 30
For more information please follow to LWP::UserAgent
SEE ALSO
Specifics of List API can be found in
XAO::DO::FS::List.
For additional information please see
XAO::DO::FS::Glue,
XAO::DO::FS::Global,
XAO::DO::FS::Glue::MySQL_DBI,
Refer to Image::Magick documentation for additional information about
setting of image scaling parameters.
Refer to LWP::UserAgent documentation for additional information about
user agent parameters.
BUGS
Please, inform me about found bugs.
AUTHORS
The XAO::ImageCache package maintained by Konstantin Safronov
<skv@xao.com>. Specification by Andrew Maltsew <am@xao.com>