Re: help needed with custom drawing in SWT.Tree

From:
Jeff Higgins <oohiggins@yahoo.com>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 06 Jul 2010 05:31:57 -0400
Message-ID:
<i0ut6v$kpq$1@news.eternal-september.org>
On 7/6/2010 4:22 AM, Tech Id wrote:

Hello,

In the tiny piece of code below, I am not able to figure out whats
wrong with the custom drawing of code.
I want it to use for displaying text that spans multiple columns
(starting from column 0)

Thanks a lot in advance.
Techie

class test {

    Display display;
    Shell shell;

    public test () {
        display = new Display ();
        shell = new Shell (display);

        text_spanning_all_columns ();

        shell.pack ();
        shell.open ();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch ()) display.sleep ();
        }
        display.dispose ();
    }

    void text_spanning_all_columns () {
        shell.setLayout (new FillLayout());
        final Tree table = new Tree(shell, SWT.MULTI | SWT.FULL_SELECTION);
        table.setHeaderVisible(true);
        int columnCount = 4;
        for (int i=0; i<columnCount; i++) {
            TreeColumn column = new TreeColumn(table, SWT.NONE);
            column.setText("Column " + i);
        }
        int itemCount = 8;
        for (int i = 0; i< itemCount; i++) {
            TreeItem item = new TreeItem(table, SWT.NONE);
            item.setText(0, "item "+i+" a");
            item.setText(3, "item "+i+" d");
            TreeItem subItem = new TreeItem (item, SWT.NONE);
        }
        /*
         * NOTE: MeasureItem, PaintItem and EraseItem are called repeatedly.
         * Therefore, it is critical for performance that these methods be
         * as efficient as possible.
         */
        final String string = "text that spans two columns and much much
more";
        GC gc = new GC(table);
        final Point extent = gc.stringExtent(string);
        gc.dispose();
        final Color red = display.getSystemColor(SWT.COLOR_RED);
        Listener paintListener = new Listener() {
            public void handleEvent(Event event) {
                switch(event.type) {
                    case SWT.MeasureItem: {
                        TreeItem item = (TreeItem) event.item;
                        if (item.getParentItem() != null) {
                            //event.width = extent.x/2;
                            //event.height = Math.max(event.height, extent.y + 2);
                        }
                        break;
                    }
                    case SWT.PaintItem: {

                        TreeItem item = (TreeItem) event.item;
                        if (item.getParentItem() != null) {
                            int offset = 0;
                            for (int i=0; i<event.index; i++)
                                offset += table.getColumn(i).getWidth();

                            event.gc.setForeground(red);
                            int y = event.y + (event.height - extent.y)/2;
                            event.gc.drawString(string, event.x - offset, y, true);
                        }
                        break;
                    }
                }
            }
        };
        table.addListener(SWT.MeasureItem, paintListener);
        table.addListener(SWT.PaintItem, paintListener);
        for (int i = 0; i< columnCount; i++) {
            table.getColumn(i).pack();
        }
    }
}

public class abc {

    public static void main(String [] args) {
        new test();
    }
}


class test {

   Display display;
   Shell shell;

   public test() {
     display = new Display();
     shell = new Shell(display);
     text_spanning_all_columns();
     shell.pack();
     shell.open();
     while (!shell.isDisposed()) {
       if (!display.readAndDispatch()) {
         display.sleep();
       }
     }
     display.dispose();
   }

   void text_spanning_all_columns () {
     shell.setLayout (new FillLayout());
     final Tree table = new Tree(shell, SWT.MULTI | SWT.FULL_SELECTION);
     table.setHeaderVisible(true);
     int columnCount = 4;
     for (int i=0; i<columnCount; i++) {
       TreeColumn column = new TreeColumn(table, SWT.NONE);
       column.setText("Column " + i);
     }
     int itemCount = 8;
     for (int i = 0; i < itemCount; i++) {
       TreeItem item = new TreeItem(table, SWT.NONE);
       item.setText(0, "item "+i+" a");
       item.setText(3, "item "+i+" d");
       TreeItem subItem = new TreeItem (item, SWT.NONE);
     }
     /*
      * NOTE: MeasureItem, PaintItem and EraseItem are called repeatedly.
      * Therefore, it is critical for performance that these methods be
      * as efficient as possible.
      */
     final String string =
       "text that spans two columns and much much more";
     GC gc = new GC(table);
     final Point extent = gc.stringExtent(string);
     gc.dispose();
     final Color red = display.getSystemColor(SWT.COLOR_RED);
     Listener paintListener = new Listener() {
       public void handleEvent(Event event) {
         switch(event.type) {
           case SWT.MeasureItem: {
             TreeItem item = (TreeItem) event.item;
             if (item.getParentItem() != null) {
               //event.width = extent.x/2;
               //event.height = Math.max(event.height, extent.y + 2);
             }
             break;
           }
           case SWT.PaintItem: {
             TreeItem item = (TreeItem) event.item;
             if (item.getParentItem() != null) {
               int offset = 0;
               for (int i=0; i<event.index; i++) {
                 offset += table.getColumn(i).getWidth();
               }
               event.gc.setForeground(red);
               int y = event.y + (event.height - extent.y)/2;
               event.gc.drawString(string, event.x - offset, y, true);
             }
             break;
           }
         }
       }
     };
     table.addListener(SWT.MeasureItem, paintListener);
     table.addListener(SWT.PaintItem, paintListener);
     for (int i = 0; i < columnCount; i++) {
       table.getColumn(i).pack();
     }
   }
}

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