WOActiveImage

Element Description

A WOActiveImage displays an image within the HTML page. If the WOActiveImage is disabled, it simply displays its image as a passive element in the page. If enabled, the image is active; that is, clicking the image generates a request.

WOActiveImages are intended to be used outside of an HTML form. WOActiveImage functions as a mapped, active image. When the user clicks such a WOActiveImage, the coordinates of the click are sent back to the server. Depending on where the user clicks, different actions can be invoked. An image map file associates actions with each of the defined areas of the image. If an image map file is not specified, the method specified by the action attribute is performed when the image is clicked, or if the href attribute is specified, the image acts as a hyperlink and takes you to that destination.

Within an HTML form, a WOActiveImage functions as a graphical submit button. However, it is better to use a WOImageButton instead of WOActiveImage to create a graphic submit button or a mapped image within a form.

Synopsis

WOActiveImage {filename= imageFileName; [framework = frameworkBaseName|"app";] | src=aURL; | value=aMethod; action=aMethod | href=aURL; | data=dataObject; mimeType=typeString; [key=cacheKey;] [imageMapFile=aString]; [name=aString;] [x=aNumber; y=aNumber;] [target=frameName;] [disabled=aBoolean;] ... };

Bindings

filename: Path to the image relative to the WebServerResources directory.

framework: Framework that contains the image file. This attribute is only necessary if the image file is in a different location from the component. That is, if the component and the image file are both in the application or if the component and the image file are both in the same framework, this attribute isn't necessary. If the image file is in a framework and the component is in the application, specify the framework's name here (minus the .framework extension). If the image file should be in the application but the component is in a framework, specify the "app" keyword in place of the framework name.

src: URL containing the image data. Use this attribute for complete URLs; for relative URLs use filename instead.

value: Image data in the form of a WOElement object. This data can come from a database, a file, or memory.

action: Method to invoke when this element is clicked. If imageMapFile is specified, action is only invoked if the click is outside any mapped area. In other words, action defines the default action of the active image.

href: URL to direct the browser to as a default when the image is clicked and no hot zones are hit.

data: Specifies an image resource in the form of an NSData; this data can come from a database, a file, or memory. If you specify resource data, you must specify a MIME type.

mimeType: A string designating a MIME resource type, such as "image/gif", to be put in the content-type header field; this type tells the client what to do with data. If you provide data but no MIME type, WebObjects will raise.

key: A string that the application uses as a key for caching the data specified in data. If you do not provide a key, the data object must be fetched each time it is needed. For further information, see the reference documentation for the WOResourceManager class, (in particular, see the flushDataCache method).

imageMapFile: Name of the image map file.

name: If name is specified then the hit point is specified as name.x=value; name.y=value; in the form. This is useful when you need to use this element to submit a form to an external URL that expects the hit point to be expressed in a certain format.

x, y: If specified, returns the coordinates of the user's click within the image.

target: Frame in a frameset that will receive the page returned as a result of the user's click.

disabled: If disabled evaluates to true (or YES), a regular image element (<IMG>) is generated rather than an active image.

The Image Map File

If the imageMapFile is specified, WebObjects searches for the image map file in the application and, if the image is in a framework, the search continues in the framework where the image resides. You should put image map files into the Resources suitcase in your Project Builder project. If your project has localized images, the image map file may also need to be localized. If you choose to have localized mapped images, you must have a corresponding map file for each localized image (unless you only have one map file which is not in any locale-specific .lproj directory).

Each line in the image map file has this format:

shape action coordinate-list

shape: Either rect, circle, or poly. For a rect shape, the coordinates x1,y1 specify the upper-left corner of the hot zone, and x2,y2 specify lower-right corner. For a circle shape, the x1,y1 is the origin, and x2,y2 is a point on the circle. For the poly shape, each coordinate is a vertex: up to 100 vertices are supported.

action: Name of the method to invoke when the image is clicked.

coordinate-list: The list of coordinates (x1,y1 x2,y2 ...) as described under shape, above.

Here are some sample entries in an image map file:

rect home 0,0 135,56
rect buy 135,0 270,56

The image map file must be in the same location as the image. For example, if the image is in a framework, the image map file must be in that same framework.