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About the OverviewControl
The OverviewControl is similar to a MapControl. However, the purpose of the overview map is to provide a point of reference for the area displayed on its associated MapControl. The OverviewControl always shows the map at full extent. A small box on the overview map represents the currently displayed area on its associated MapControl. You can interactively move this box around to pan the area displayed in the MapControl.
The OverviewControl works with the WebOverview object. The WebOverview object is created by the parent context control. The OverviewEvent object is used by the control to extract the point on the overview map to center the overview rectangle. The OverviewRenderer class renders the control to the appropriate markup, and the OverviewTag class exposes the control as a JavaServer Pages (JSP) custom tag named overview. See the following diagram:
Accessing the overview through WebContext
The WebOverview object provides an application programming interface (API) to access information about the overview and control its behavior.
The WebOverview object can be retrieved through WebContext using the following code example:
[Java]
WebContext ctx = WebUtil.getWebContext(FacesContext.getCurrentInstance(), CONTEXTID);
WebOverview ov = (WebOverview)ctx.getWebOverview();
// The WebOverview retrieved from the WebContext can be used
// to retrieve the Overview Functionalities in the WebContext object.
List < OverViewFunctionality > ovf = ov.getOverViewFunctionalities();
The following code example shows how to generate the overview map image and retrieve a reference to it. This reference can be a uniform resource locator (URL) or a Multipurpose Internet Mail Extensions (MIME) data string.
[Java]
WebOverview ov = (WebOverview)ctx.getWebOverview();
String ovMap = ov.getImageURL();
The following code example shows how to determine the width and height of the area of interest (AOI) box on the overview map. The getImageRectangle() method returns the extent in screen coordinates of the area of interest box representing the current extent of the main map.
[Java]
WebOverview ov = (WebOverview)ctx.getWebOverview();
WebExtent ext = ov.getImageRectangle();
double height = ext.getHeight();
double width = ext.getWidth();