Big Tree Example with static model

examples/org.eclipse.jface.snippets/Eclipse JFace Snippets/org/eclipse/jface/snippets/viewers/Snippet047VirtualBigTreeViewer.java

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+/*******************************************************************************
+ * Copyright (c) 2006, 2016 Tom Schindl and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Tom Schindl - initial API and implementation
+ *     Lars Vogel <Lars.Vogel@vogella.com> - Bug 486603
+ *     Wim Jongman <wim.jongman@remainsoftware.com> - Overhaul without preloading model
+ *******************************************************************************/
+
+package org.eclipse.jface.snippets.viewers;
+
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLong;
+
+import org.eclipse.jface.layout.GridDataFactory;
+import org.eclipse.jface.viewers.ILazyTreeContentProvider;
+import org.eclipse.jface.viewers.LabelProvider;
+import org.eclipse.jface.viewers.TreeViewer;
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.layout.GridData;
+import org.eclipse.swt.layout.GridLayout;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Shell;
+import org.eclipse.swt.widgets.Text;
+
+/**
+ * A simple TreeViewer example to demonstrate the usage of an
+ * ILazyContentProvider.
+ *
+ */
+public class Snippet047VirtualBigTreeViewer {
+
+	private static final int MODEL_DEEP = 1;
+	private static final int MODEL_MAX_CHILD_COUNT = 20_000;
+	private static final int MODEL_MIN_CHILDS = 10;
+	private static final Random RANDOM = new Random();
+	private static AtomicLong rendered = new AtomicLong();
+	private static AtomicLong updated = new AtomicLong();
+	private static AtomicLong childcount = new AtomicLong();
+	private final TreeViewer fViewer;
+	private final Text fText;
+
+	private class MyContentProvider implements ILazyTreeContentProvider {
+
+		@Override
+		public Object getParent(Object element) {
+
+			return ((Node) element).getParent();
+		}
+
+		@Override
+		public void updateChildCount(Object element, int currentChildCount) {
+
+			childcount.incrementAndGet();
+			int cc = ((Node) element).getChildCount();
+			if (cc != currentChildCount) {
+				fViewer.setChildCount(element, cc);
+			}
+		}
+
+		@Override
+		public void updateElement(Object parent, int index) {
+
+			updated.incrementAndGet();
+			Node element = ((Node) parent).getChild(index);
+			fViewer.replace(parent, index, element);
+			fViewer.setChildCount(element, element.getChildCount());
+		}
+	}
+
+	public class Node {
+
+		private Node[] fChildren;
+		private final int fCounter;
+		private final Node fParent;
+
+		public Node(int counter, Node parent) {
+
+			fCounter = counter;
+			fParent = parent;
+		}
+
+		public Node getParent() {
+
+			return fParent;
+		}
+
+		public Node[] getChildren() {
+
+			return fChildren;
+		}
+
+		public Node getChild(int index) {
+
+			if (fChildren == null) {
+				return null;
+			}
+			return fChildren[index];
+		}
+
+		public int getChildCount() {
+
+			if (fChildren == null) {
+				return 0;
+			}
+			return fChildren.length;
+		}
+
+		@Override
+		public String toString() {
+
+			Node parent = getParent();
+			String type = parent == null ? "Root" : parent.getParent() == null ? "Node" : "Leaf";
+			return type + " " + this.fCounter + " of " + (parent == null ? "" : String.valueOf(parent.getChildCount()))
+					+ " with " + getChildCount() + " childs";
+		}
+	}
+
+	public Snippet047VirtualBigTreeViewer(Shell shell) {
+
+		System.out.println("Create large model...");
+		Node root = createModel();
+		System.out.println("Show UI");
+		fText = new Text(shell, SWT.SINGLE | SWT.LEAD | SWT.BORDER);
+		fText.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));
+		fText.setEnabled(false);
+		fViewer = new TreeViewer(shell, SWT.VIRTUAL | SWT.BORDER);
+		fViewer.setLabelProvider(new LabelProvider() {
+
+			@Override
+			public String getText(Object element) {
+
+				rendered.incrementAndGet();
+				return super.getText(element);
+			}
+		});
+		fViewer.setContentProvider(new MyContentProvider());
+		fViewer.setUseHashlookup(true);
+		fViewer.setInput(root);
+		fViewer.getTree().setLayoutData(GridDataFactory.fillDefaults().create());
+		fViewer.setChildCount(root, root.getChildCount());
+		fViewer.getTree().setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+		// at this point the model only contains what is visible on the screen.
+	}
+
+	private Node createModel() {
+
+		Node root = new Node(-1, null);
+		createChilds(root, 0);
+		return root;
+	}
+
+	private void createChilds(Node parent, int i) {
+
+		if (i > MODEL_DEEP) {
+			return;
+		}
+		int childs = RANDOM.nextInt(MODEL_MIN_CHILDS, MODEL_MAX_CHILD_COUNT);
+		parent.fChildren = new Node[childs];
+		for (int j = 0; j < childs; j++) {
+			parent.fChildren[j] = new Node(j, parent);
+			createChilds(parent.fChildren[j], i + 1);
+		}
+	}
+
+	/**
+	 * @param args
+	 */
+	public static void main(String[] args) {
+
+		Thread thread = new Thread(new Runnable() {
+
+			@Override
+			public void run() {
+
+				try {
+					long last = 0;
+					while (true) {
+						TimeUnit.SECONDS.sleep(1);
+						long current = rendered.get();
+						if (current != last) {
+							last = current;
+							System.out.println("Total render requests: " + current + ", " + updated.get()
+									+ " update elements, " + childcount.get() + " update childcounts");
+						}
+					}
+				} catch (InterruptedException e) {
+					return;
+				}
+			}
+		});
+		thread.setDaemon(true);
+		thread.start();
+		Display display = new Display();
+		Shell shell = new Shell(display);
+		shell.setLayout(new GridLayout());
+		new Snippet047VirtualBigTreeViewer(shell);
+		shell.setSize(800, 600);
+		shell.open();
+		while (!shell.isDisposed()) {
+			if (!display.readAndDispatch()) {
+				display.sleep();
+			}
+		}
+		display.dispose();
+	}
+}