Demonstrate window state handling in Vaadin portlets

[ujoni]

Create a Vaadin portlet based on the draft created from #25 which demonstrates how the user can create a portlet which

• Displays a single image in normal window mode
• Displays a fictional user form in maximized view

The demonstration should seek to align itself with the new API draft but also seek ways to improve upon the API, to make the task as easy and clear for the potential user as possible.

[caalador]

How I as a user would want to use a window state portlet.

package com.vaadin.flow.portal;

import com.vaadin.flow.component.button.Button;
import com.vaadin.flow.component.html.Image;
import com.vaadin.flow.component.textfield.TextField;

public class PortletTwo extends Div
        implements WindowStateHandler<MySecondPortlet>{

    public static final String APPLICATION_IMAGE = "data:image/png;base64,TEH_DATA_HERE";

    @Override
    void renderNormal() {
        Image image = new Image(APPLICATION_IMAGE, "Application image");
        image.addClickListener(event -> maximize());
        add(image);
    }

    @Override
    void renderMaximized() {
        TextField input = new TextField("");
        add(input, new Button("return", event -> normalize()));
    }

    @Override
    void renderMinimized() {
        // NO-OP as we have nothing to show in minimized mode.
    }
}

or public class PortletTwo extends WindowStateComponent<Div, MySecondPortlet> {

or

public class PortletTwo extends Div
        implements WindowStateHandler<MySecondPortlet>{

    public static final String APPLICATION_IMAGE = "data:image/png;base64,TEH_DATA_HERE";

    @Override
    void windowStateChange(WindowState newState) {
        if(newState.equals(WindowState.NORMAL) {
            Image image = new Image(APPLICATION_IMAGE, "Application image");
            image.addClickListener(event -> maximize());
            add(image);
        } else if(newState.equals(WindowState.MAXIMIZED)) {
            TextField input = new TextField("");
            add(input, new Button("return", event -> normalize()));
        }
    }
}

For demo see https://github.com/vaadin/portlet-support/compare/api/27_window_state

[Legioth]

What is MySecondPortlet that is referenced in the composite-like example? Why aren't the other examples referencing that class?

[caalador]

In that example it is the VaadinPortletInstance that is referenced with the generic P extends WindowStatePortlet which is a vaadin portlet and it just makes the portlet handling easier for the abstract composite class as then we have a contract that we can request certain things from the portlet.

For the others the interfaces basically make assumptions of the VaadinPortlet instance.

[Legioth]

How would the same association be expressed with the other alternatives?

[caalador]

Nothing blocking having them require the portlet either e.g. WindowStateHandler<MySecondPortlet>

[Legioth]

Nothing blocking having them require the portlet either e.g. WindowStateHandler<MySecondPortlet>

That approach does on the other hand cause some boilerplate if there's only one portlet since you cannot omit the type parameter without getting IDE warnings about using raw types.

[caalador]

Well this has been turned around as things have been progressing as we have more need to know the PortletView in the portlet instance than knowing the portlet in the view instance.