An example of JavaFX

This is a really simple thing I wrapped up in a couple of minutes. It doesn't show much, and certainly isn't very flashy, but it does show some main points I wanted to share about my 5-minutes experience with JFX. By the way, this code can be just taken as is and put directly into the JavaFX Pad.

import javafx.ui.*;
import javafx.ui.canvas.*;

class Person {
    attribute name:String ;
    attribute parent:Person inverse Person.children;
    attribute children:Person* inverse Person.parent;
    attribute gender:String;
}

Canvas {
    var father = Person { name:"George", gender:"Male" }
    var jen = Person {name:"Jennifer", parent:father, gender: "Female" }
    var matt = Person { name:"Matt", parent:father, gender:"Male" }
    var lara = Person {name:"Lara", parent:father, gender: "Female" }
    
    content: select Text {content: p.name y:indexof p * 15} 
                    from p in father.children 
                    where p.gender == "Female"
}

The points I want to show off:

• No need to update the "children" attribute: Notice that I do not update the children attribute of dad. Since children and parent are defined to be inverse to one another, just specifying who the parent is is enough.
• Creating graphical elements is easy: I can create graphical elements using a select statement on the array of items I have in my data model, and use their attributes as values to the elements. It's that simple - I create three elements here with one line of code, and I could create complex queries using joins and where clauses.

The annoying part was when I tried to give some behavior to the generated Text elements. I changed the creation to be like this:

Text {
        var x1:Number = 0
        var y1:Number = indexof p * 15 + 20
        content: p.name
        x:bind x1
        y:bind y1
        cursor:HAND
        onMouseDragged:operation(e:CanvasMouseEvent) {
            x1 += e.localDragTranslation.x;
            y1 += e.localDragTranslation.y;
        }

But, it didn't work! It did change the cursor to "Hand" when the mouse was over an element, but it didn't make the drag work. I can't imagine why - In an example on the openjfx.org site something similar was made, but there they used subclassing and adding attributes instead of adding variables dynamically like I chose to do here. Maybe that's the case; but it really isn't clear. If anyone has an idea, please let me know!