public interface SCImgURL extends URL
Img.src and Button.icon,
Smart GWT provides various capabilities to allow for simpler and more uniform settings,
and to allow applications to be restructured more easily.
StockIcons
Smart GWT defines a list of known-icons which can be used
by name in src-strings. For example, setting a button's icon
property
to "Edit" will show the current image mapped to the builtin StockIcon
with that name. You can also modify the image currently assigned to the "Edit" icon by
calling Media.updateIconMapping("Edit", "new src").
When using a StockIcon-name as a src, you may also include additional settings to extend the StockIcon if applicable. For example, a src of "Edit:size:24,24;" will take the "Edit" stockIcon's current src and, if that src represents a sprite-string, apply the additional size attributes and render the Edit icon at a larger size.
These features are especially useful in combination with
SVG Symbols using runtime-styling, where colors can be easily
modified on a per usage-basis, for example with "Edit:color:red;".
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:
load_skin.js via Page.setSkinDir(),
plus..
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:
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).
Page.getSkinDir() +
"/images" regardless of the setting for skinImgDir
In some cases, instead of an explicit image URL, developers may wish to apply a named css class with a background-image to an image based component. This may be achieved by specifying your image URL in the format "style:<styleName>".
For example if your application loads the following css class:
.starImg {
width: 48px; height: 48px;
background: url(/images/star.gif) 0 0;
}
It may be displayed in an Img component by setting Img.src to
"style:startImg".
Sprited images
In addition to the "style:..." prefix for specifying a css class instead of a
simple image URL, the prefix "sprite:..." may be used to specify properties
required to extract an image from an image
sprite.
For details on how this format may be used, see the SCSpriteConfig documentation.
Stateful image URLs
Many Smart GWT components support changing their appearance to reflect their current
"state" ["Focused", "Disabled", etc]. As such they may display different
image media to reflect their current state.
See the Stateful Images overview
for details on how image states are managed in Smart GWT.
SVG Images
For more information about using stylable SVGs for spriting in a way that doesn't involve
lots of file-loads or the flickering typically associated with modifying SVGs in-browser,
see the SVG Symbols Overview.
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.
the special "blank" constant
If you don't have to show any image for any reason or you need to reset the area where an image is, you can call myImage.setSrc('blank') or set:
Img myImage = new Img();
myImage.setWidth(48);
myImage.setHeight(48);
myImage.setSrc("blank");
This will render an empty space, where the blank.gif image, that each skin has, will be used
for this purpose.