Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2016 IBM Corporation 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: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.swt.custom; import org.eclipse.swt.*; import org.eclipse.swt.events.*; import org.eclipse.swt.graphics.*; import org.eclipse.swt.widgets.*; /** * * A TreeEditor is a manager for a Control that appears above a cell in a Tree and tracks with the * moving and resizing of that cell. It can be used to display a text widget above a cell * in a Tree so that the user can edit the contents of that cell. It can also be used to display * a button that can launch a dialog for modifying the contents of the associated cell. * * <p> Here is an example of using a TreeEditor:</p> * <pre><code> * final Tree tree = new Tree(shell, SWT.BORDER); * for (int i = 0; i < 3; i++) { * TreeItem item = new TreeItem(tree, SWT.NONE); * item.setText("item " + i); * for (int j = 0; j < 3; j++) { * TreeItem subItem = new TreeItem(item, SWT.NONE); * subItem.setText("item " + i + " " + j); * } * } * * final TreeEditor editor = new TreeEditor(tree); * //The editor must have the same size as the cell and must * //not be any smaller than 50 pixels. * editor.horizontalAlignment = SWT.LEFT; * editor.grabHorizontal = true; * editor.minimumWidth = 50; * * tree.addSelectionListener(new SelectionAdapter() { * public void widgetSelected(SelectionEvent e) { * // Clean up any previous editor control * Control oldEditor = editor.getEditor(); * if (oldEditor != null) oldEditor.dispose(); * * // Identify the selected row * TreeItem item = (TreeItem)e.item; * if (item == null) return; * * // The control that will be the editor must be a child of the Tree * Text newEditor = new Text(tree, SWT.NONE); * newEditor.setText(item.getText()); * newEditor.addModifyListener(new ModifyListener() { * public void modifyText(ModifyEvent e) { * Text text = (Text)editor.getEditor(); * editor.getItem().setText(text.getText()); * } * }); * newEditor.selectAll(); * newEditor.setFocus(); * editor.setEditor(newEditor, item); * } * }); * </code></pre> * * @see <a href="http://www.eclipse.org/swt/snippets/#treeeditor">TreeEditor snippets</a> * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a> */ public class TreeEditor extends ControlEditor { Tree tree; TreeItem item; int column = 0; ControlListener columnListener; TreeListener treeListener; Runnable timer; static final int TIMEOUT = 1500; /** * Creates a TreeEditor for the specified Tree. * * @param tree the Tree Control above which this editor will be displayed * */ public TreeEditor(Tree tree) { super(tree); this.tree = tree; columnListener = new ControlListener() { @Override public void controlMoved(ControlEvent e) { layout(); } @Override public void controlResized(ControlEvent e) { layout(); } }; timer = () -> layout(); treeListener = new TreeListener() { final Runnable runnable = () -> { if (editor == null || editor.isDisposed()) return; if (TreeEditor.this.tree.isDisposed()) return; layout(); editor.setVisible(true); }; @Override public void treeCollapsed(TreeEvent e) { if (editor == null || editor.isDisposed()) return; editor.setVisible(false); e.display.asyncExec(runnable); } @Override public void treeExpanded(TreeEvent e) { if (editor == null || editor.isDisposed()) return; editor.setVisible(false); e.display.asyncExec(runnable); } }; tree.addTreeListener(treeListener); // To be consistent with older versions of SWT, grabVertical defaults to true grabVertical = true; } @Override Rectangle computeBounds() { if (item == null || column == -1 || item.isDisposed()) return new Rectangle(0, 0, 0, 0); Rectangle cell = item.getBounds(column); Rectangle rect = item.getImageBounds(column); cell.x = rect.x + rect.width; cell.width -= rect.width; Rectangle area = tree.getClientArea(); if (cell.x < area.x + area.width) { if (cell.x + cell.width > area.x + area.width) { cell.width = area.x + area.width - cell.x; } } Rectangle editorRect = new Rectangle(cell.x, cell.y, minimumWidth, minimumHeight); if (grabHorizontal) { if (tree.getColumnCount() == 0) { // Bounds of tree item only include the text area - stretch out to include // entire client area cell.width = area.x + area.width - cell.x; } editorRect.width = Math.max(cell.width, minimumWidth); } if (grabVertical) { editorRect.height = Math.max(cell.height, minimumHeight); } if (horizontalAlignment == SWT.RIGHT) { editorRect.x += cell.width - editorRect.width; } else if (horizontalAlignment == SWT.LEFT) { // do nothing - cell.x is the right answer } else { // default is CENTER editorRect.x += (cell.width - editorRect.width) / 2; } // don't let the editor overlap with the +/- of the tree editorRect.x = Math.max(cell.x, editorRect.x); if (verticalAlignment == SWT.BOTTOM) { editorRect.y += cell.height - editorRect.height; } else if (verticalAlignment == SWT.TOP) { // do nothing - cell.y is the right answer } else { // default is CENTER editorRect.y += (cell.height - editorRect.height) / 2; } return editorRect; } /** * Removes all associations between the TreeEditor and the row in the tree. The * tree and the editor Control are <b>not</b> disposed. */ @Override public void dispose() { if (tree != null && !tree.isDisposed()) { if (this.column > -1 && this.column < tree.getColumnCount()) { TreeColumn treeColumn = tree.getColumn(this.column); treeColumn.removeControlListener(columnListener); } if (treeListener != null) tree.removeTreeListener(treeListener); } columnListener = null; treeListener = null; tree = null; item = null; column = 0; timer = null; super.dispose(); } /** * Returns the zero based index of the column of the cell being tracked by this editor. * * @return the zero based index of the column of the cell being tracked by this editor * * @since 3.1 */ public int getColumn() { return column; } /** * Returns the TreeItem for the row of the cell being tracked by this editor. * * @return the TreeItem for the row of the cell being tracked by this editor */ public TreeItem getItem() { return item; } void resize() { layout(); /* * On some platforms, the table scrolls when an item that * is partially visible at the bottom of the table is * selected. Ensure that the correct row is edited by * laying out one more time in a timerExec(). */ if (tree != null) { Display display = tree.getDisplay(); display.timerExec(-1, timer); display.timerExec(TIMEOUT, timer); } } /** * Sets the zero based index of the column of the cell being tracked by this editor. * * @param column the zero based index of the column of the cell being tracked by this editor * * @since 3.1 */ public void setColumn(int column) { int columnCount = tree.getColumnCount(); // Separately handle the case where the tree has no TreeColumns. // In this situation, there is a single default column. if (columnCount == 0) { this.column = (column == 0) ? 0 : -1; resize(); return; } if (this.column > -1 && this.column < columnCount) { TreeColumn treeColumn = tree.getColumn(this.column); treeColumn.removeControlListener(columnListener); this.column = -1; } if (column < 0 || column >= tree.getColumnCount()) return; this.column = column; TreeColumn treeColumn = tree.getColumn(this.column); treeColumn.addControlListener(columnListener); resize(); } /** * Specifies the <code>TreeItem</code> that is to be edited. * * @param item the item to be edited */ public void setItem(TreeItem item) { this.item = item; resize(); } /** * Specify the Control that is to be displayed and the cell in the tree that it is to be positioned above. * * <p>Note: The Control provided as the editor <b>must</b> be created with its parent being the Tree control * specified in the TreeEditor constructor. * * @param editor the Control that is displayed above the cell being edited * @param item the TreeItem for the row of the cell being tracked by this editor * @param column the zero based index of the column of the cell being tracked by this editor * * @since 3.1 */ public void setEditor(Control editor, TreeItem item, int column) { setItem(item); setColumn(column); setEditor(editor); } @Override public void setEditor(Control editor) { super.setEditor(editor); resize(); } /** * Specify the Control that is to be displayed and the cell in the tree that it is to be positioned above. * * <p>Note: The Control provided as the editor <b>must</b> be created with its parent being the Tree control * specified in the TreeEditor constructor. * * @param editor the Control that is displayed above the cell being edited * @param item the TreeItem for the row of the cell being tracked by this editor */ public void setEditor(Control editor, TreeItem item) { setItem(item); setEditor(editor); } @Override public void layout() { if (tree == null || tree.isDisposed()) return; if (item == null || item.isDisposed()) return; int columnCount = tree.getColumnCount(); if (columnCount == 0 && column != 0) return; if (columnCount > 0 && (column < 0 || column >= columnCount)) return; super.layout(); } }