[news.eclipse.platform.swt] Re: Snippet234, synchronized table scroll pr

[wim.jongman@xxxxxxxxx (Wim Jongman)]

Hi Grant, 

I have a huge problem getting this to work in combination with the 
SWT.VIRTUAL style and a jface lazytree contentprovider. I tried SWT.VIRTUAL 
in combination with an SWT.SetData event listener which works great. However, 
when I wrap a TreeViewer around the tree, I get a lot of errors. 

Any ideas on this or should I try the JFACE newsgroup. 

Here is your snippet with the SWT.VIRTUAL and with a gridlayout for sizing. 
Please note that the SWT.NO_SCROLL eliminates the need for the expand 
listeners. 

Thanks, 

Wim 


/******************************************************************************* 
* Copyright (c) 2000, 2008 IBM Corporation and others. 
* All rights reserved. This program and the accompanying materials 
* are made available under the terms of the Eclipse Public License v1.0 
* which accompanies this distribution, and is available at 
* http://www.eclipse.org/legal/epl-v10.html 
* 
* Contributors: 
* IBM Corporation - initial API and implementation 

*******************************************************************************/ 
package org.eclipse.swt.snippets; 

/* 
* ScrolledComposite snippet: use a ScrolledComposite to scroll a virtual Tree 
vertically 
* 
* For a list of all SWT example snippets see 
* http://www.eclipse.org/swt/snippets/ 
*/ 
import org.eclipse.swt.SWT; 
import org.eclipse.swt.custom.ScrolledComposite; 
import org.eclipse.swt.events.SelectionAdapter; 
import org.eclipse.swt.events.SelectionEvent; 
import org.eclipse.swt.graphics.Point; 
import org.eclipse.swt.graphics.Rectangle; 
import org.eclipse.swt.layout.GridData; 
import org.eclipse.swt.layout.GridLayout; 
import org.eclipse.swt.widgets.Button; 
import org.eclipse.swt.widgets.Display; 
import org.eclipse.swt.widgets.Event; 
import org.eclipse.swt.widgets.Listener; 
import org.eclipse.swt.widgets.Shell; 
import org.eclipse.swt.widgets.Tree; 
import org.eclipse.swt.widgets.TreeItem; 

public class Snippet296Virtual { 

	public static void main(String[] args) { 
		final Display display = new Display(); 
		Shell shell = new Shell(display); 
		shell.setBounds(10, 10, 300, 300); 
		shell.setLayout(new GridLayout(1, true)); 
		final ScrolledComposite sc = new ScrolledComposite(shell, SWT.VERTICAL); 
		sc.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true)); 
		// sc.setBounds (10, 10, 280, 200); 

		final Tree tree = new Tree(sc, SWT.VIRTUAL | SWT.NO_SCROLL); 
		tree.addListener(SWT.SetData, new Listener() { 

			public void handleEvent(Event event) { 
				TreeItem item = (TreeItem) event.item; 
				System.out.println(tree.indexOf(item)); 
				TreeItem parentItem = item.getParentItem(); 
				String text = null; 
				if (parentItem == null) { 
					text = "node " + tree.indexOf(item); 
				} else { 
					text = parentItem.getText() + " - " 
							+ parentItem.indexOf(item); 
				} 
				item.setText(text); 
				System.out.println(text); 
				item.setItemCount(10); 
			} 
		}); 
		 
		tree.setItemCount(100); 
		sc.setContent(tree); 
		sc.setExpandHorizontal(true); 
		//sc.setExpandVertical(true); 
		final int clientWidth = shell.getClientArea().width; 
		System.out.println("clientwidth " + clientWidth); 
		int prefHeight = tree.computeSize(SWT.DEFAULT, SWT.DEFAULT).y; 
		System.out.println("prefHeight " + prefHeight); 
		tree.setSize(clientWidth, prefHeight); 

		/* 
		 * The following listener ensures that a newly-selected item in the Tree 
		 * is always visible. 
		 */ 
		tree.addSelectionListener(new SelectionAdapter() { 
			public void widgetSelected(SelectionEvent e) { 
				TreeItem[] selectedItems = tree.getSelection(); 
				if (selectedItems.length > 0) { 
					Rectangle itemRect = selectedItems[0].getBounds(); 
					Rectangle area = sc.getClientArea(); 
					Point origin = sc.getOrigin(); 
					if (itemRect.x < origin.x 
							|| itemRect.y < origin.y 
							|| itemRect.x + itemRect.width > origin.x 
									+ area.width 
							|| itemRect.y + itemRect.height > origin.y 
									+ area.height) { 
						sc.setOrigin(itemRect.x, itemRect.y); 
					} 
				} 
			} 
		}); 
		/* 
		 * The following listener scrolls the Tree one item at a time in 
		 * response to MouseWheel events. 
		 */ 
		tree.addListener(SWT.MouseWheel, new Listener() { 
			public void handleEvent(Event event) { 
				Point origin = sc.getOrigin(); 
				if (event.count < 0) { 
					origin.y = Math.min(origin.y + tree.getItemHeight(), tree 
							.getSize().y); 
				} else { 
					origin.y = Math.max(origin.y - tree.getItemHeight(), 0); 
				} 
				sc.setOrigin(origin); 
			} 
		}); 

		Button downButton = new Button(shell, SWT.PUSH); 
		downButton.setBounds(10, 220, 120, 30); 
		downButton.setText("Down 10px"); 
		downButton.addListener(SWT.Selection, new Listener() { 
			public void handleEvent(Event event) { 
				sc.setOrigin(0, sc.getOrigin().y + 10); 
			} 
		}); 
		Button upButton = new Button(shell, SWT.PUSH); 
		upButton.setBounds(140, 220, 120, 30); 
		upButton.setText("Up 10px"); 
		upButton.addListener(SWT.Selection, new Listener() { 
			public void handleEvent(Event event) { 
				sc.setOrigin(0, sc.getOrigin().y - 10); 
			} 
		}); 
		shell.open(); 
		while (!shell.isDisposed()) { 
			if (!display.readAndDispatch()) 
				display.sleep(); 
		} 
		display.dispose(); 
	} 
} 


> Hi, 
> 
> This can probably be made to work by putting each of the Tables into a 
> ScrolledComposite, and scrolling the ScrolledComposites with setOrigin() 
> since this is pixel-based. For an example that does something like this see 
> 
http://dev.eclipse.org/viewcvs/index.cgi/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet296.java?view=co 
 
> Note that I just added a listener to this snippet that makes using the 
> scroll wheel work, but snippet changes sometimes take a while to replicate 
> on the eclipse.org servers, so if the scroll wheel does not work for you 
> then add the following to the snippet: 
> 
> /* 
> * The following listener scrolls the Tree one item at a time 
> * in response to MouseWheel events. 
> */ 
> tree.addListener(SWT.MouseWheel, new Listener() { 
> public void handleEvent(Event event) { 
> Point origin = sc.getOrigin(); 
> if (event.count < 0) { 
> origin.y = Math.min(origin.y + tree.getItemHeight(), 
> tree.getSize().y); 
> } else { 
> origin.y = Math.max(origin.y - tree.getItemHeight(), 0); 
> } 
> sc.setOrigin(origin); 
> } 
> }); 
> 
> HTH, 
> Grant 
> 
> 
> "Wim Jongman" <wim.jongman@xxxxxxxxx> wrote in message 
> news:h7f2em$2r8$1@xxxxxxxxxxxxxxxxxxxx 
>> Hi, 
>> 
>> This snippet 
>> 
>> 
>> 
> 
http://dev.eclipse.org/viewcvs/index.cgi/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet234.java?view=co 
>> 
>> The problem is that we can pixel scroll the table but that will not be 
>> detected because the scroll appears to be by item as vbar.getSelection() 
>> indicates. If you drag the thumb pixel by pixel, the second table will 
> only 
>> jump every $itemHeight$ pixels. 
>> 
>> Also the left table snippet does not react on mouse scroll in osx 
> snippet167 
>> uses an alternative listener which does react on mouse scroll. 
>> 
>> Is there a way to get this going neatly on OSx? Blocking the pixel 
> scrolling 
>> capabilities could be one solution. Is that possible? 
>> 
>> Regards, 
>> 
>> Wim Jongman