Show/hide menu and toolbar entries depending on the selected perspective

I’ve searched for a way to show menu and toolbar entries only in certain perspectives. In case of OpenChrom, the “Chromatogram Edit” entries should be only visible when the user has the ability to modify chromatographic data.

The “Chromatogram Edit” menu entries don’t make sense if the user tries to synchronize repositories or analyze log files.

No big thing, we could disable distinct perspectives concerning the editing of chromatgrams, but if another perspective is added by an additional plug-in, the menu/toolbar entries will be visible again. Thus, we should enable the chromatogram editing menu/toolbar entries only when perspectives with focus to edit chromatographic data are activated. To achieve this, we need a unique identifier for the chromatogram editing perspectives. The perspective id is used here for instance. All perspectives that start with the identifier “net.openchrom.chromatogram.” will be used to activate the “Chromatogram Edit” menu and toolbar entries.

package net.openchrom.chromatogram.msd.ui.perspective.propertytester;

import org.eclipse.core.expressions.PropertyTester;
import org.eclipse.ui.IPerspectiveDescriptor;
import org.eclipse.ui.PlatformUI;

public class PerspecticePropertyTester extends PropertyTester {

  @Override
  public boolean test(Object receiver, String property, Object[] args, Object expectedValue) {

    /*
    * Returns true if the actual perspective supports chromatogram editing.
    */
    IPerspectiveDescriptor perspective = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage().getPerspective();
    String perspectiveId = perspective.getId();
    if(perspectiveId.startsWith("net.openchrom.chromatogram.")) {
      return true;
    }
    return false;
  }
}

But how do we link the property tester with the menu/toolbar entries? First of all, the “PerspecticePropertyTester” class needs to be associated with the “org.eclipse.core.expressions.propertyTesters” extension point.

<extension
  point="org.eclipse.core.expressions.propertyTesters">
  <propertyTester
    class="net.openchrom.chromatogram.msd.ui.perspective.propertytester.PerspecticePropertyTester"
    id="net.openchrom.chromatogram.msd.ui.perspective.perspectivePropertyTester"
    namespace="net.openchrom.chromatogram.msd.ui.perspective.perspectivePropertyTester"
    properties="isKnownPerspective"
    type="java.lang.Object">
  </propertyTester>
</extension>

In the next step, the property tester will referenced by the declaration of a test definition using the extension point “org.eclipse.core.expressions.definitions”. That’s very comfortable as we don’t need to reference the property tester directly in the menu and toolbar contributions. Further on, the plug-in will be activated on request.

<extension
  point="org.eclipse.core.expressions.definitions">
  <definition
    id="net.openchrom.chromatogram.msd.ui.perspective.isChromatogramPerspectiveDefinition">
    <with
      variable="activeWorkbenchWindow.activePerspective">
      <test
        forcePluginActivation="true"
        property="net.openchrom.chromatogram.msd.ui.perspective.perspectivePropertyTester.isKnownPerspective">
      </test>
    </with>
  </definition>
</extension>

Now, we’ve prepared everything to use the test definition to enable/disable the menu/toolbar entries. It’s easy to disable a whole menu contribution.

<menuContribution
  locationURI="menu:org.eclipse.ui.main.menu?after=edit">
  <menu
    id="net.openchrom.chromatogram.msd.ui.perspective.chromatogram.menu"
    label="Chromatogram Edit">
    ...
    <visibleWhen
      checkEnabled="false">
      <reference
        definitionId="net.openchrom.chromatogram.msd.ui.perspective.isChromatogramPerspectiveDefinition">
      </reference>
    </visibleWhen>
  </menu>
</menuContribution>

In contrary to the menu contribution, each toolbar entry must be enabled/disabled separately.

<menuContribution
  locationURI="toolbar:org.eclipse.ui.main.toolbar?after=additions">
  ...
  <toolbar
    id="net.openchrom.chromatogram.msd.ui.perspective.chromatogram.toolbar.miscellaneous">
    <command
      commandId="net.openchrom.chromatogram.msd.ui.perspective.commands.createSnapshotCommand"
      icon="icons/create_snapshot.png"
      style="push">
      <visibleWhen
        checkEnabled="false">
        <reference
          definitionId="net.openchrom.chromatogram.msd.ui.perspective.isChromatogramPerspectiveDefinition">
        </reference>
      </visibleWhen>
    </command>
  </toolbar>
</menuContribution>

That’s it. The source files can be viewed here:

PropertyTester.java
plugin.xml