How to Develop an Application Using the Eclipse BIRT Design Engine API
Creating a customized report design application
Apr. 30, 2007 07:45 AM
Examining a Report Item Programmatically
Some report items, such as a label or a text element, are simple items. Other items, such as a grid or a table element, are structured items. You can access properties for the whole of a structured item in the same way as for a simple item.
You can also iterate over the contents of the structured item. For example, use this technique to determine the contents of a cell in a table. To access the contents of a structured item, you call a method to retrieve the slot handle for rows or columns. For example, to access the RowHandle objects that make up a table element's footer, call TableHandle.getFooter( ). Table and list elements also have a slot for groups. Like the body slot handle, the slot handles for the contents of structured report items can contain zero, one, or multiple elements.
Accessing the Properties of a Report Item
Some properties of a report item are simple properties, with types that are Java types or type wrapper classes. An example of this type of property is the name property, which is a String object. Some of these properties, like name, have arbitrary values.
Other simple properties have restricted values from a set of BIRT String constants. The interface, DesignChoiceConstants in the org.eclipse.birt.report.model.api.elements package, defines these constants. For example, the image source property of an image element can have only one of the values, IMAGE_REF_TYPE_EMBED, IMAGE_REF_TYPE_EXPR, IMAGE_REF_TYPE_FILE, IMAGE_REF_TYPE_NONE, or IMAGE_REF_TYPE_URL.
Other properties are complex properties and the getter method returns a handle object. For example, the DesignElementHandle.getStyle( ) method returns a StyleHandle.object and ReportItemHandle.getWidth( ) returns a DimensionHandle object.
The handle classes provide access to complex properties of a report item, as described later in this article. These classes provide getter methods for related properties. For example, StyleHandle classes provide access to font and background colors.
How To Access a Report Item by Name
How To Use the Report Structure To Access a Report Item
Modifying a Report Item in a Report Design Programmatically
To set the attributes of a complex property, such as a style, you must call methods on a handle object, as described later in this article. These classes provide setter methods for related properties. For example, StyleHandle classes provide access to style properties, such as font and background color.
Changes that you make to items in the report design don't affect the design file until you save the design to disk or to a stream. After saving the design, get an IReportRunnable handle for the modified design to generate a report.
How To Change a Simple Property of a Report Item
Accessing and Setting Complex Properties
Some String properties on a handle object, such as the font style and text alignment on a style handle, have restricted values defined by constants in the interface, DesignChoiceConstants in the org.eclipse.birt.report.model.api.elements package. For example, a font-style property can have only one of the values, FONT_STYLE_ITALIC, FONT_STYLE_NORMAL, and FONT_STYLE_OBLIQUE.
Using a Property Handle
When you set a value on a complex property, the change to the handle object affects the report item straightaway. You don't call an additional setter method on the report item itself.
Using Styles on a Report Item
A report item can use two styles: a private style and a shared style. The handle classes for these styles are PrivateStyleHandle and SharedStyleHandle, respectively. Both classes derive from StyleHandle.
A private style contains the settings that the report developer chose in the property editor when designing the report. Shared styles appear in the Outline view in BIRT Report Designer. You use shared styles to apply the same appearance to multiple items in a report design. Changes to a shared style affect all report items that use the style. Style settings in a private style override the settings in a shared style.
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