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/*******************************************************************************
* Copyright (c) 2000, 2016 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;
/*
* example snippet: Scroll tree when mouse at top or bottom
*
* For a list of all SWT example snippets see
* http://www.eclipse.org/swt/snippets/
*/
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;
public class Snippet221 {
static Runnable Heartbeat;
static boolean Tracking;
static int ScrollSpeed = 40;
public static void main(String[] args) {
final Display display = new Display();
Shell shell = new Shell(display);
shell.setLayout(new FillLayout());
final Tree tree = new Tree(shell, SWT.FULL_SELECTION | SWT.BORDER);
tree.setHeaderVisible(true);
TreeColumn column0 = new TreeColumn(tree, SWT.LEFT);
column0.setText("Column 0");
TreeColumn column1 = new TreeColumn(tree, SWT.LEFT);
column1.setText("Column 1");
TreeColumn column2 = new TreeColumn(tree, SWT.LEFT);
column2.setText("Column 2");
for (int i = 0; i < 9; i++) {
TreeItem item = new TreeItem(tree, SWT.NONE);
item.setText("item "+i);
item.setText(1, "column 1 - "+i);
item.setText(2, "column 2 - "+i);
for (int j = 0; j < 9; j++) {
TreeItem subItem = new TreeItem(item, SWT.NONE);
subItem.setText("item "+i+" "+j);
subItem.setText(1, "column 1 - "+i+" "+j);
subItem.setText(2, "column 2 - "+i+" "+j);
for (int k = 0; k < 9; k++) {
TreeItem subsubItem = new TreeItem(subItem, SWT.NONE);
subsubItem.setText("item "+i+" "+j+" "+k);
subsubItem.setText(1, "column 1 - "+i+" "+j+" "+k);
subsubItem.setText(2, "column 2 - "+i+" "+j+" "+k);
}
}
}
column0.pack();
column1.pack();
column2.pack();
Heartbeat = () -> {
if (!Tracking || tree.isDisposed()) return;
Point cursor = display.getCursorLocation();
cursor = display.map(null, tree, cursor);
Scroll(tree, cursor.x, cursor.y);
display.timerExec(ScrollSpeed, Heartbeat);
};
Listener listener = event -> {
switch (event.type) {
case SWT.MouseEnter:
Tracking = true;
display.timerExec(0, Heartbeat);
break;
case SWT.MouseExit:
Tracking = false;
break;
}
};
tree.addListener(SWT.MouseEnter, listener);
tree.addListener(SWT.MouseExit, listener);
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch())
display.sleep();
}
display.dispose();
}
static void Scroll(Tree tree, int x, int y) {
TreeItem item = tree.getItem(new Point(x, y));
if (item == null) return;
Rectangle area = tree.getClientArea();
int headerHeight = tree.getHeaderHeight();
int itemHeight= tree.getItemHeight();
TreeItem nextItem = null;
if (y < area.y + headerHeight + 2 * itemHeight) {
nextItem = PreviousItem(tree, item);
}
if (y > area.y + area.height - 2 * itemHeight) {
nextItem = NextItem(tree, item);
}
if (nextItem != null) tree.showItem(nextItem);
}
static TreeItem PreviousItem(Tree tree, TreeItem item) {
if (item == null) return null;
TreeItem childItem = item;
TreeItem parentItem = childItem.getParentItem();
int index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
if (index == 0) {
return parentItem;
} else {
TreeItem nextItem = parentItem == null ? tree.getItem(index-1) : parentItem.getItem(index-1);
int count = nextItem.getItemCount();
while (count > 0 && nextItem.getExpanded()) {
nextItem = nextItem.getItem(count - 1);
count = nextItem.getItemCount();
}
return nextItem;
}
}
static TreeItem NextItem(Tree tree, TreeItem item) {
if (item == null) return null;
if (item.getExpanded()) {
return item.getItem(0);
} else {
TreeItem childItem = item;
TreeItem parentItem = childItem.getParentItem();
int index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
int count = parentItem == null ? tree.getItemCount() : parentItem.getItemCount();
while (true) {
if (index + 1 < count) {
return parentItem == null ? tree.getItem(index + 1) : parentItem.getItem(index + 1);
} else {
if (parentItem == null) {
return null;
} else {
childItem = parentItem;
parentItem = childItem.getParentItem();
index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
count = parentItem == null ? tree.getItemCount() : parentItem.getItemCount();
}
}
}
}
}
}
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