Java Reference
In-Depth Information
<!ELEMENT Priority EMPTY>
<!ATTLIST Priority
name (Lowest|Low|Medium|High|Highest) >
name
—The priority of the provider. It can be one of the following values:
Lowest
,
Low
,
Medium
,
High
, or
Highest
. Dependencies must be considered
when choosing the priority. The layout operation is executed on the first provider
(in descending order of priority) that is found to provide the operation.
Examples:
The following is an example of a layout provider extension contribution:
<extension-point="org.eclipse.gmf.runtime.diagram.ui.layoutProviders">
<layoutProvider class=
"org.eclipse.gmf.runtime.diagram.ui.providers.layout.RadialProvider">
<Priority name="Lowest"/>
</layoutProvider>
</extension>
API information:
For API information, see the interfaces defined in the package
org.eclipse.gmf.runtime.diagram.ui.services.layout
. Clients that
provide an extension to the layout service need to create a provider class that
implements the
org.eclipse.gmf.runtime.diagram.ui.services.
layout.ILayoutNodeProvider
interface.
Notes:
Diagrams generated using the GMF tooling do not currently use this
extension-point, which is understandable, given that currently no way exists to
specify diagram layout in a diagram-definition model.
10.4.11 ContributionItemService
The
ContributionItemService
allows for the addition of items into an
IWorkbenchPart
contribution manager for action bars and pop-up menus, but
with the added benefit of specified priority and execution strategy available in all
runtime Services. The
IContributionItemProvider
interface specifies meth-
ods for these contributions, their update, and their disposal. The corresponding
extension-point allows for these contributions to be made declaratively. An
AbstractContributionItemProvider
is provided, along with several con-
crete implementations, including the Diagram and Printing providers shown in
Figure 10-35. These provide most of the generic contributions needed for most
diagrams, including font properties, alignment actions, save, print, and so on.
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