Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2017 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 PopupList is a list of selectable items that appears in its own shell positioned above * its parent shell. It is used for selecting items when editing a Table cell (similar to the * list that appears when you open a Combo box). * * The list will be positioned so that it does not run off the screen and the largest number of items * are visible. It may appear above the current cursor location or below it depending how close you * are to the edge of the screen. * * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a> */ public class PopupList { Shell shell; List list; int minimumWidth; /** * Creates a PopupList above the specified shell. * * @param parent a Shell control which will be the parent of the new instance (cannot be null) */ public PopupList(Shell parent) { this(parent, 0); } /** * Creates a PopupList above the specified shell. * * @param parent a widget which will be the parent of the new instance (cannot be null) * @param style the style of widget to construct * * @since 3.0 */ public PopupList(Shell parent, int style) { int listStyle = SWT.SINGLE | SWT.V_SCROLL; if ((style & SWT.H_SCROLL) != 0) listStyle |= SWT.H_SCROLL; shell = new Shell(parent, checkStyle(style)); list = new List(shell, listStyle); // close dialog if user selects outside of the shell shell.addListener(SWT.Deactivate, e -> shell.setVisible(false)); // resize shell when list resizes shell.addControlListener(ControlListener.controlResizedAdapter(e -> { Rectangle shellSize = shell.getClientArea(); list.setSize(shellSize.width, shellSize.height); })); // return list selection on Mouse Up or Carriage Return list.addMouseListener(new MouseListener() { @Override public void mouseDoubleClick(MouseEvent e) { } @Override public void mouseDown(MouseEvent e) { } @Override public void mouseUp(MouseEvent e) { shell.setVisible(false); } }); list.addKeyListener(new KeyListener() { @Override public void keyReleased(KeyEvent e) { } @Override public void keyPressed(KeyEvent e) { if (e.character == '\r') { shell.setVisible(false); } } }); } private static int checkStyle(int style) { int mask = SWT.LEFT_TO_RIGHT | SWT.RIGHT_TO_LEFT; return style & mask; } /** * Gets the widget font. * <p> * @return the widget font * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public Font getFont() { return list.getFont(); } /** * Gets the items. * <p> * This operation will fail if the items cannot * be queried from the OS. * * @return the items in the widget * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public String[] getItems() { return list.getItems(); } /** * Gets the minimum width of the list. * * @return the minimum width of the list */ public int getMinimumWidth() { return minimumWidth; } /** * Launches the Popup List, waits for an item to be selected and then closes the PopupList. * * @param rect the initial size and location of the PopupList; the dialog will be * positioned so that it does not run off the screen and the largest number of items are visible * * @return the text of the selected item or null if no item is selected */ public String open(Rectangle rect) { Point listSize = list.computeSize(rect.width, SWT.DEFAULT, false); Rectangle screenSize = shell.getDisplay().getBounds(); // Position the dialog so that it does not run off the screen and the largest number of items are visible int spaceBelow = screenSize.height - (rect.y + rect.height) - 30; int spaceAbove = rect.y - 30; int y = 0; if (spaceAbove > spaceBelow && listSize.y > spaceBelow) { // place popup list above table cell if (listSize.y > spaceAbove) { listSize.y = spaceAbove; } else { listSize.y += 2; } y = rect.y - listSize.y; } else { // place popup list below table cell if (listSize.y > spaceBelow) { listSize.y = spaceBelow; } else { listSize.y += 2; } y = rect.y + rect.height; } // Make dialog as wide as the cell listSize.x = rect.width; // dialog width should not be less than minimumWidth if (listSize.x < minimumWidth) listSize.x = minimumWidth; // Align right side of dialog with right side of cell int x = rect.x + rect.width - listSize.x; shell.setBounds(x, y, listSize.x, listSize.y); shell.open(); list.setFocus(); Display display = shell.getDisplay(); while (!shell.isDisposed() && shell.isVisible()) { if (!display.readAndDispatch()) display.sleep(); } String result = null; if (!shell.isDisposed()) { String[] strings = list.getSelection(); shell.dispose(); if (strings.length != 0) result = strings[0]; } return result; } /** * Selects an item with text that starts with specified String. * <p> * If the item is not currently selected, it is selected. * If the item at an index is selected, it remains selected. * If the string is not matched, it is ignored. * * @param string the text of the item * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public void select(String string) { String[] items = list.getItems(); // find the first entry in the list that starts with the // specified string if (string != null) { for (int i = 0; i < items.length; i++) { if (items[i].startsWith(string)) { int index = list.indexOf(items[i]); list.select(index); break; } } } } /** * Sets the widget font. * <p> * When new font is null, the font reverts * to the default system font for the widget. * * @param font the new font (or null) * * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public void setFont(Font font) { list.setFont(font); } /** * Sets all items. * <p> * The previous selection is cleared. * The previous items are deleted. * The new items are added. * The top index is set to 0. * * @param strings the array of items * * This operation will fail when an item is null * or could not be added in the OS. * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the items array is null</li> * <li>ERROR_INVALID_ARGUMENT - if an item in the items array is null</li> * </ul> * @exception SWTException <ul> * <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> * </ul> */ public void setItems(String[] strings) { list.setItems(strings); } /** * Sets the minimum width of the list. * * @param width the minimum width of the list */ public void setMinimumWidth(int width) { if (width < 0) SWT.error(SWT.ERROR_INVALID_ARGUMENT); minimumWidth = width; } }