Preloading Webimages

To optimize the performance and avoid having to download webimages individually each time they're needed, multiple webimages can be downloaded in parallel. For this, the webimages-library is used. First, a list of urls is retrieved from the XML-datafile using the data-provider-library. By default the content-attribute on all item-nodes with type="asset" are retrieved.

<item key="main_image" content="https://url/to/an/image" type="asset"/>
<item key="second_image" content="https://url/to/another/image" type="asset"/>

The list of urls can then be used as input for the parallel-download.

webimage_lib = comet.pyImport('[xml]/library/framework/webimages.py')
dataprovider_lib = comet.pyImport('[xml]/library/framework/data_provider.py')

asset_urls = dataprovider_lib.get_preload_urls(type="asset")

preloader = webimage_lib.WebImageBundle(asset_urls)
preloader.download_queue(url)

Paths to the downloaded images are cached. When loading images later on, in placeholder-scripts, the matching path to a url is used when evaluating the found url with the function webimages_lib.get_webimage_url().

image_url:str = dataprovider.get_attribute_value("main_image") 
# => "https://url/to/an/image"

path:str = webimage_lib.get_webimage_url(image_url)
# => checking cached urls {"https://url/to/an/image":"/path/to/downloaded/image.jpg"}
# => "/path/to/downloaded/image.jpg"

info

See here for more information: webimages-library