public interface SCImgURL
extends URL

Properties that refer to images by URL, such as Img.src and Button.icon, are specially interpreted in Smart GWT to allow for simpler and more uniform image URLs, and to allow applications to be restructured more easily.

the application image directory

When specifying URLs to image files via Smart GWT component properties such as StretchImg.src, any relative path is assumed to be relative to the "application image directory" (appImgDir). The application image directory can be set via Page.setAppImgDir(), and defaults to "images/", representing the typical practice of placing images in a subdirectory relative to the URL at which the application is accessed.

For applications that may be launched from multiple URLs, the appImgDir can be set to the correct relative path to the image directory by calling Page.setAppImgDir() before any Smart GWT components are created. This enables applications or components of an application to be launched from multiple locations, or to be relocated, without changing any image URLs supplied to Smart GWT components.

the "[SKIN]" URL prefix

The special prefix "[SKIN]" can be used to refer to images within the skin folder whenever image URLs are supplied to Smart GWT components.

The value of "[SKIN]" is the combination of:

• the "skin directory", established in load_skin.js via Page.setSkinDir(), plus..
• the setting for skinImgDir on the component where you set an image URL property

skinImgDir defaults to "images/", so creating an Img component with Img.src set to "[SKIN]myButton/button.gif" will expand to Page.getSkinDir() + "/images/myButton/button.gif".

Some components that use a large number of images use skinImgDir to group them together and make it possible to relocate all the media for the component with a single setting. For example, the TreeGrid class sets skinImgDir to "images/TreeGrid/". This allows TreeGrid.folderIcon to be set to just "[SKIN]folder.gif" but refer to Page.getSkinDir() + "/images/TreeGrid/folder.gif".

A custom subclass of TreeGrid can set skinImgDir to a different path, such as "/images/MyTreeGrid", to source all media from a different location.

TIPS:

• subcomponents may not share the parent component's setting for skinImgDir. For example, the Window.minimizeButton has the default setting for "skinImgDir" ("images/"), so the src property used with this component is set to "[SKIN]/Window/minimize.png" (in the "Smart GWT" sample skin).
• for a particular image, the skinImgDir setting on the component may not be convenient. The prefix "[SKINIMG]" can be used to refer to Page.getSkinDir() + "/images" regardless of the setting for skinImgDir

Stateful image URLs

Many image URLs in Smart GWT are "stateful", meaning that the actual URL used to fetch an image will vary according to the component's state (eg, "Disabled"), generally, by adding a suffix to the image URL. See the Skinning Overview for more information on statefulness and the Img.src documentation for information on how stateful image URLs are formed.

SVG Images

If the URL represents an SVG image, you may specify tag as a query param to control whether it's rendered in an object or image tag, provided Canvas.useImageForSVG isn't set. If that query param is present and has any value other than object, then the SVG image will be rendered in an image tag. Otherwise, it will be rendered in an object tag. For example, an SCImgURL of "circle.svg?tag=image" will render in an image tag.