Contributing Workbench Wizards thru Commands

Written by Prakash G. R.
Posted in Tips

You must have been used this JDT toolbar quite often.

The New Class tool item is contributed as an Action in plugin.xml (id "org.eclipse.jdt.ui.actions.NewTypeDropDown"), and then the Menu on the Action is contributed via code. In this tip, let us see how to do the same via command framework and without any code.

The first step is to add a ToolBar and then the New Wizard command to it:

<extension point="org.eclipse.ui.menus">
	<menuContribution
    	allPopups="false"
        locationURI="toolbar:org.eclipse.ui.main.toolbar">
		<toolbar
        	id="com.eclipsetips.commands.workbenchWizards.jdtToolbar"
            label="Java Creation Elements">
            <command
                  commandId="org.eclipse.ui.newWizard"
                  style="push">
            </command>
         </toolbar>
	</menuContribution>
</extension>

Now we get:

Two issues with this. First, what we get is simply the New Wizard Dialog, (The one which you get when you press Ctrl+N). We want the New Java Class wizard. To make that happen, we need to pass on a parameter - which New Wizard to show to the user. Second, its just a toolbar item. There is no drop down menu associated with it. To have that we need to change the style of the command from 'push' to 'pulldown'.

            <command
                  commandId="org.eclipse.ui.newWizard"
                  style="pulldown">
               <parameter
                     name="newWizardId"
                     value="org.eclipse.jdt.ui.wizards.NewClassCreationWizard">
               </parameter>
            </command>

Now we can get the New Class Wizard when we click the tool item, still nothing is there in the dropdown menu of it. The command framework assigns menu:<id-of-the-toolitem> as the uri for menu contributions. So if we create a menu contribution to that URI:

 <menuContribution
       allPopups="false"
       locationURI="menu:com.eclipsetips.commands.workbenchWizards.jdtNewClass">
    <command
          commandId="org.eclipse.ui.newWizard"
          style="push">
       <parameter
             name="newWizardId"
             value="org.eclipse.jdt.ui.wizards.NewClassCreationWizard">
       </parameter>
    </command>
    <command
          commandId="org.eclipse.ui.newWizard"
          style="push">
       <parameter
             name="newWizardId"
             value="org.eclipse.jdt.ui.wizards.NewAnnotationCreationWizard">
       </parameter>
    </command>
    <command
          commandId="org.eclipse.ui.newWizard"
          style="push">
       <parameter
             name="newWizardId"
             value="org.eclipse.jdt.ui.wizards.NewInterfaceCreationWizard">
       </parameter>
    </command>
 </menuContribution>
</extension>

then we get this:

The beauty of this is any other plugin can now contribute to this drop down. Consider some other plugin which wants to add another command to this drop down. It can also use the same URI:

      <menuContribution
            allPopups="false"
            locationURI="menu:com.eclipsetips.commands.workbenchWizards.jdtNewClass">
         <command
               commandId="org.eclipse.ui.newWizard"
               style="push">
            <parameter
                  name="newWizardId"
                  value="org.eclipse.jdt.ui.wizards.NewPackageCreationWizard">
            </parameter>
         </command>
      </menuContribution>

There is however one annoying thing about this is that the toolbar is shown in always. You can limit the visibility using visibleWhen and expressions. Say if we want to see this only in Java Perspective:

<command
      commandId="org.eclipse.ui.newWizard"
      id="com.eclipsetips.commands.workbenchWizards.jdtNewClass"
      style="pulldown">
   <parameter
         name="newWizardId"
         value="org.eclipse.jdt.ui.wizards.NewClassCreationWizard">
   </parameter>
   <visibleWhen
         checkEnabled="false">
      <with
            variable="activeWorkbenchWindow.activePerspective">
         <equals
               value="org.eclipse.jdt.ui.JavaPerspective">
         </equals>
      </with>
   </visibleWhen>
</command>

If you have multiple toolitems in the toolbar and want the visibleWhen on the entire toolbar, you have to wait till this bug gets fixed.