TableColumnExt not respecting prototype value

I'm trying to use SwingX's TableColumnExt class to set a prototype value for the column's width in the hierarchical column of a JXTreeTable. After I initialize the model and table I do this:

TableColumnExt column = dataTable.getColumnExt(0);            
column.setPrototypeValue(500);

When my table is rendered, all columns are equally sized. These are the methods I'm using on the JXTreeTable instance.

dataTable.setRowHeight(28);
dataTable.setFillsViewportHeight(true);
dataTable.setHorizontalScrollEnabled(true);

What am I doing wrong here?

Solution

As already mentioned in my comments, it's a bug. The issues are many-fold:

the code responsible for measuring the prototype size requirements is ColumnFactory.calcPrototypeWidth
it's doing so by configuring the renderer as returned by the table with the given prototype and measuring its prefSize
the rendering of the hierarchical column is delegated to a JTree, using black magic
the default factory is unaware of that black magic, thus querying the JTree's prefSize which is independent of the prototype
the first idea: make the factory aware of the special rendering of the hierarchical column and walk down to the real - underlying treeCellRenderer - doesn't work, again due to some other internal black magic
automatic column re-sizing due to setting the prototype is broken in JXTable (Issue #1510)

A workaround involves

a custom ColumnFactory which is aware of the special renderer (== JXTree) of the hierarchical column)
for the hierarchical column, configure and measure a TreeCellRenderer - not the one used by the tree itself, but a unrelated dummy
after setting the prototype, manually trigger a size evaluation of the column

Below is a custom ColumnFactory and its usage (not formally tested, so take it with a grain of salt :-).

// a custom factory
ColumnFactory factory = new ColumnFactory() {

    @Override
    protected int calcPrototypeWidth(JXTable table,
            TableColumnExt columnExt) {
        if (isHierarchicalPrototype(table, columnExt))  {
            return calcHierarchicalPrototypeWidth((JXTreeTable) table, columnExt);
        }
        return super.calcPrototypeWidth(table, columnExt);
    }

    protected boolean isHierarchicalPrototype(JXTable table,
            TableColumnExt columnExt) {
        return (table instanceof JXTreeTable) 
                && ((JXTreeTable) table).getTreeTableModel().getHierarchicalColumn() == 
                         columnExt.getModelIndex()
                && columnExt.getPrototypeValue() != null;
    }

    TreeCellRenderer dummy = new DefaultTreeCellRenderer();
    protected int calcHierarchicalPrototypeWidth(JXTreeTable table,
            TableColumnExt columnExt) {
        JXTree renderer = (JXTree) getCellRenderer(table, columnExt);
        // commented lines would be the obvious step down into the "real" sizing
        // requirements, but giving reasonable result due to internal black magic
        // TreeCellRenderer treeRenderer = renderer.getCellRenderer();
        // Component comp = treeRenderer.getTreeCellRendererComponent(renderer, 
              columnExt.getPrototypeValue(), false, false, false, -1, false);
        // instead, measure a dummy
        Component comp = dummy.getTreeCellRendererComponent(renderer, 
                columnExt.getPrototypeValue(), false, false, false, -1, false);

        return Math.max(renderer.getPreferredSize().width, comp.getPreferredSize().width);
    }

};

// usage: first create the treeTable, set the factory and set the model
JXTreeTable table = new JXTreeTable();
table.setColumnFactory(factory);
table.setTreeTableModel(new FileSystemModel());
// set the prototype
table.getColumnExt(0).setPrototypeValue("long longer longest still not enough to really see" +
           " some effect of the prototype if available");
// Issue #1510: prototype value handling broken in underlying JXTable
// need to manually force the config
table.getColumnFactory().configureColumnWidths(table, table.getColumnExt(0));