Step 2: Tree Nodes


Screenshot_3

A Gantt chart consists of a left-hand side and a right-hand side. The left-hand side displays a tree table. In this step we are creating data that we use to fill the table. Any kind of object can be shown in the tree table but the easiest way to get to a working Gantt chart is to use the default model classes provided by FlexGantt. They are DefaultGanttChartModel and DefaultGanttChartNode. Since we have used the default GanttChart constructor in step 1 we already know that the model used by the Gantt chart is the default Gantt chart model, so we can retrieve it like this:

DefaultGanttChartModel model = (DefaultGanttChartModel) gc.getModel();


The root node of the default model is an instance of DefaultGanttChartNode:

DefaultGanttChartNode root = (DefaultGanttChartNode) model.getRoot();

Now we create our own nodes and add them to the root. We have to specify key values, which will show up in the key column of the tree table.

DefaultGanttChartNode node1 = new DefaultGanttChartNode("Node 1");
DefaultGanttChartNode node2 = new DefaultGanttChartNode("Node 2");
DefaultGanttChartNode node3 = new DefaultGanttChartNode("Node 3");
node1.setKey("Key 1");
node2.setKey("Key 2");
node3.setKey("Key 3");
root.add(node1);
root.add(node2);
root.add(node3);

Now we need to inform the model that the root node has changed its structure (new children). This will cause events to be fired by the model. These events are received by the tree table, which will then update itself.

model.nodeStructureChanged(root);

Let's add a few more nodes to node2 so that the example is more interesting.

DefaultGanttChartNode node21 = new DefaultGanttChartNode("Node 21");
DefaultGanttChartNode node22 = new DefaultGanttChartNode("Node 22");
DefaultGanttChartNode node23 = new DefaultGanttChartNode("Node 23");
DefaultGanttChartNode node24 = new DefaultGanttChartNode("Node 24");
DefaultGanttChartNode node25 = new DefaultGanttChartNode("Node 25");
node21.setKey("Key 21");
node22.setKey("Key 22");
node23.setKey("Key 23");
node24.setKey("Key 24");
node25.setKey("Key 25");
node2.add(node21);
node2.add(node22);
node2.add(node23);
node2.add(node24);
node2.add(node25);
model.nodeStructureChanged(node2); // another event

Our jumpstart application after step 2 now looks like this:

/**
* Copyright 2006, 2007
* Dirk Lemmermann Software & Consulting
* http://www.dlsc.com
*/
package com.dlsc.flexgantt.examples.jumpstart;

import javax.swing.JFrame;
import com.dlsc.flexgantt.model.gantt.DefaultGanttChartModel;
import com.dlsc.flexgantt.model.gantt.DefaultGanttChartNode;
import com.dlsc.flexgantt.swing.GanttChart;
import com.dlsc.flexgantt.swing.GanttChartFrame;

/**
* One of the steps used for the 'Jumpstart' tutorial. The step will create a
* couple of tree nodes and add them to the Gantt chart.
*
* @author Dirk Lemmermann
*/
public class Step2_Tree_Nodes {

    /**
     * @param args
     */
    public static void main(String[] args) {
        
        /*
         * Create a basic Gantt chart, which will use the default Gantt chart
         * model. The default model itself will use the default Gantt chart node
         * as a root object.
         */
        GanttChart gc = new GanttChart();
        
        /*
         * Retrieve the default model and node from the Gantt chart.
         */
        DefaultGanttChartModel model = (DefaultGanttChartModel) gc.getModel();
        DefaultGanttChartNode root = (DefaultGanttChartNode) model.getRoot();
        
        /*
         * Add new nodes to the model and trigger an event so that the UI will
         * update its state.
         */
        DefaultGanttChartNode node1 = new DefaultGanttChartNode("Node 1");
        DefaultGanttChartNode node2 = new DefaultGanttChartNode("Node 2");
        DefaultGanttChartNode node3 = new DefaultGanttChartNode("Node 3");
        node1.setKey("Key 1");
        node2.setKey("Key 2");
        node3.setKey("Key 3");
        root.add(node1);
        root.add(node2);
        root.add(node3);
        model.nodeStructureChanged(root); // the event

        /*
         * Add more nodes to node2.
         */
        DefaultGanttChartNode node21 = new DefaultGanttChartNode("Node 21");
        DefaultGanttChartNode node22 = new DefaultGanttChartNode("Node 22");
        DefaultGanttChartNode node23 = new DefaultGanttChartNode("Node 23");
        DefaultGanttChartNode node24 = new DefaultGanttChartNode("Node 24");
        DefaultGanttChartNode node25 = new DefaultGanttChartNode("Node 25");
        node21.setKey("Key 21");
        node22.setKey("Key 22");
        node23.setKey("Key 23");
        node24.setKey("Key 24");
        node25.setKey("Key 25");
        node2.add(node21);
        node2.add(node22);
        node2.add(node23);
        node2.add(node24);
        node2.add(node25);
        model.nodeStructureChanged(node2); // another event
                
        /*
         * Add the Gantt chart to a specialized frame class. The frame will
         * automatically add a status bar and a glass pane (used for updating
         * the cursor when commands get executed).
         */
        GanttChartFrame<GanttChart> frame = new GanttChartFrame<GanttChart>(
                "Step 2", gc);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        /*
         * Show the frame. The split panel inside the Gantt chart will adjust
         * to the preferred size of the left-hand side (the tree table).
         */
        frame.setVisible(true);
    }
}