Eclipse 插件开发在打开和关闭透视图时显示和隐藏菜单贡献

Question

I am developing my Eclipse Plugin using E4 2020-09 version. I created a Perspective and a menuContribution using Model Fragments. I have searched several tutorials but I have not seen any that showing how to make a menuContribution appear/disappear when opening/closing a Perspective in E4 during development. What I found was these examples: https://github.com/vogellacompany/codeexamples-eclipse but this function is implemented for E3 and I want to implement it in E4. Can you give me some hints/advices about this technique and how it is called or where to start with it?

Thanks and best regards.

Answer 1

You can do this in the 'Visible-When Expression' for the menu items.

Set the expression to be 'ImperativeExpression'. And create a class to handle the expression. This class just has a single method annotated with @Evaluate which is called each time the menu item might be displayed:

@Evaluate
public boolean evaluate(EModelService modelService, .... other parameters)
{
  // TODO determine if menu item should be visible
}

This class can then use the getActivePerspective method of EModelService to check if the menu item should be visible.

Answer 2

449,

Thank you for you answer, I finally made it according to your instruction. I will leave my reference code here in case there are people asking about this:

1. Create MenuContributionsHandler class

package com.catto.ide.dev.handlers;

import javax.inject.Inject;

import org.eclipse.e4.core.di.annotations.Evaluate;
import org.eclipse.e4.ui.model.application.ui.advanced.MPerspective;
import org.eclipse.e4.ui.model.application.ui.basic.MWindow;
import org.eclipse.e4.ui.workbench.modeling.EModelService;

public class MenuContributionsHandler 
{
    @Inject MWindow window;
    
    @Evaluate
    public boolean evaluate(EModelService modelService)
    {
        // TODO determine if menu item should be visible (return true)
        MPerspective currentPerspective = modelService.getActivePerspective(window);
        
        if (null != currentPerspective)
        {
            return currentPerspective.getLabel().equals("SnowCatto");
        }
        
        return false;
    }
}

2. Add this class to the Imperative Expression to MenuContribution Class URI.

Best regards.