iron-image is an element for displaying an image that provides useful sizing and
preloading options not found on the standard <img> tag.
The sizing option allows the image to be either cropped (cover) or
letterboxed (contain) to fill a fixed user-size placed on the element.
The preload option prevents the browser from rendering the image until the
image is fully loaded. In the interim, either the element's CSS background-color
can be be used as the placeholder, or the placeholder property can be
set to a URL (preferably a data-URI, for instant rendering) for an
placeholder image.
The fade option (only valid when preload is set) will cause the placeholder
image/color to be faded out once the image is rendered.
Examples:
Basically identical to <img src="..."> tag:
<iron-image src="http://lorempixel.com/400/400"></iron-image>Will letterbox the image to fit:
<iron-image style="width:400px; height:400px;" sizing="contain"
src="http://lorempixel.com/600/400"></iron-image>Will crop the image to fit:
<iron-image style="width:400px; height:400px;" sizing="cover"
src="http://lorempixel.com/600/400"></iron-image>Will show light-gray background until the image loads:
<iron-image style="width:400px; height:400px; background-color: lightgray;"
sizing="cover" preload src="http://lorempixel.com/600/400"></iron-image>Will show a base-64 encoded placeholder image until the image loads:
<iron-image style="width:400px; height:400px;" placeholder="data:image/gif;base64,..."
sizing="cover" preload src="http://lorempixel.com/600/400"></iron-image>Will fade the light-gray background out once the image is loaded:
<iron-image style="width:400px; height:400px; background-color: lightgray;"
sizing="cover" preload fade src="http://lorempixel.com/600/400"></iron-image>