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 * Lars Vogel <Lars.Vogel@vogella.com> - Bug 507339, 508155 *******************************************************************************/ package org.eclipse.swt.snippets; /* * SWT accessibility snippet: respond to text-based questions from an AT * * For a list of all SWT example snippets see * http://www.eclipse.org/swt/snippets/ * * @since 3.6 */ import static org.eclipse.swt.events.FocusListener.*; import static org.eclipse.swt.events.KeyListener.*; import static org.eclipse.swt.events.MouseListener.*; import org.eclipse.swt.*; import org.eclipse.swt.accessibility.*; import org.eclipse.swt.graphics.*; import org.eclipse.swt.layout.*; import org.eclipse.swt.widgets.*; public class Snippet334 { final static String text = "line one\nline two\nline three"; static Display display; static Shell shell; static Canvas canvas; public static void main(String[] arg) { display = new Display(); shell = new Shell(display); shell.setText("Snippet 334"); shell.setLayout(new GridLayout(2, false)); Label label = new Label(shell, SWT.NONE); label.setText("Test:"); canvas = new Canvas(shell, SWT.MULTI | SWT.BORDER); final Caret caret = new Caret(canvas, SWT.NONE); canvas.addPaintListener(e -> { GC gc = e.gc; gc.drawText(text, 10, 10); caret.setBounds(10, 10, 2, gc.getFontMetrics().getHeight()); Rectangle rect = canvas.getClientArea(); if (canvas.isFocusControl()) { gc.drawFocus(rect.x, rect.y, rect.width, rect.height); } }); canvas.addTraverseListener(e -> { switch (e.detail) { case SWT.TRAVERSE_TAB_NEXT: case SWT.TRAVERSE_TAB_PREVIOUS: e.doit = true; // enable traversal break; } }); // key listener enables traversal out) canvas.addKeyListener(keyPressedAdapter(e -> { })); canvas.addFocusListener(focusGainedAdapter(event -> canvas.redraw())); canvas.addFocusListener(focusLostAdapter(event -> canvas.redraw())); canvas.addMouseListener(mouseDownAdapter(e -> canvas.setFocus())); Accessible acc = canvas.getAccessible(); acc.addRelation(ACC.RELATION_LABELLED_BY, label.getAccessible()); acc.addAccessibleControlListener(new AccessibleControlAdapter() { @Override public void getRole(AccessibleControlEvent e) { e.detail = ACC.ROLE_TEXT; } @Override public void getLocation(AccessibleControlEvent e) { Rectangle rect = canvas.getBounds(); Point pt = shell.toDisplay(rect.x, rect.y); e.x = pt.x; e.y = pt.y; e.width = rect.width; e.height = rect.height; } @Override public void getValue(AccessibleControlEvent e) { e.result = text; } @Override public void getFocus(AccessibleControlEvent e) { e.childID = ACC.CHILDID_SELF; } @Override public void getChildCount(AccessibleControlEvent e) { e.detail = 0; } @Override public void getState(AccessibleControlEvent e) { e.detail = ACC.STATE_NORMAL | ACC.STATE_FOCUSABLE; if (canvas.isFocusControl()) e.detail |= ACC.STATE_FOCUSED | ACC.STATE_SELECTABLE; } }); acc.addAccessibleTextListener(new AccessibleTextExtendedAdapter() { @Override public void getSelectionRange(AccessibleTextEvent e) { // select the first 4 characters for testing e.offset = 0; e.length = 4; } @Override public void getCaretOffset(AccessibleTextEvent e) { e.offset = 0; } @Override public void getTextBounds(AccessibleTextEvent e) { // for now, assume that start = 0 and end = text.length GC gc = new GC(canvas); Point extent = gc.textExtent(text); gc.dispose(); Rectangle rect = display.map(canvas, null, 10, 10, extent.x, extent.y); e.x = rect.x; e.y = rect.y; e.width = rect.width; e.height = rect.height; } @Override public void getText(AccessibleTextEvent e) { int start = 0, end = text.length(); switch (e.type) { case ACC.TEXT_BOUNDARY_ALL: start = e.start; end = e.end; break; case ACC.TEXT_BOUNDARY_CHAR: start = e.count >= 0 ? e.start + e.count : e.start - e.count; start = Math.max(0, Math.min(end, start)); end = start; e.count = start - e.start; e.start = start; e.end = start; break; case ACC.TEXT_BOUNDARY_LINE: int offset = e.count <= 0 ? e.start : e.end; offset = Math.min(offset, text.length()); int lineCount = 0; int index = 0; while (index != -1) { lineCount++; index = text.indexOf("\n", index); if (index != -1) index++; } e.count = e.count < 0 ? Math.max(e.count, -lineCount) : Math.min(e.count, lineCount); index = 0; int lastIndex = 0; String[] lines = new String[lineCount]; for (int i = 0; i < lines.length; i++) { index = text.indexOf("\n", index); lines[i] = index != -1 ? text.substring(lastIndex, index) : text.substring(lastIndex); lastIndex = index; index++; } int len = 0; int lineAtOffset = 0; for (int i = 0; i < lines.length; i++) { len += lines[i].length(); if (len >= e.offset) { lineAtOffset = i; break; } } int result = Math.max(0, Math.min(lineCount - 1, lineAtOffset + e.count)); e.count = result - lineAtOffset; e.result = lines[result]; break; } e.result = text.substring(start, end); } @Override public void getSelectionCount(AccessibleTextEvent e) { e.count = 1; } @Override public void getSelection(AccessibleTextEvent e) { // there is only 1 selection, so index = 0 getSelectionRange(e); e.start = e.offset; e.end = e.offset + e.length; } @Override public void getRanges(AccessibleTextEvent e) { // for now, ignore bounding box e.start = 0; e.end = text.length() - 1; } @Override public void getCharacterCount(AccessibleTextEvent e) { e.count = text.length(); } @Override public void getVisibleRanges(AccessibleTextEvent e) { e.start = 0; e.end = text.length() - 1; } }); Button button = new Button(shell, SWT.PUSH); button.setText("Button"); button.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, false, false, 2, 1)); shell.pack(); shell.open(); while (!shell.isDisposed()) { if (!display.readAndDispatch()) display.sleep(); } display.dispose(); } }