Java tutorial
/******************************************************************************* * Copyright (c) 2002, 2016 Innoopract Informationssysteme GmbH 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: * Innoopract Informationssysteme GmbH - initial API and implementation * EclipseSource - ongoing development ******************************************************************************/ package org.eclipse.swt.widgets; import static org.eclipse.rap.rwt.internal.textsize.TextSizeUtil.textExtent; import static org.eclipse.swt.internal.widgets.MarkupUtil.isMarkupEnabledFor; import static org.eclipse.swt.internal.widgets.MarkupValidator.isValidationDisabledFor; import org.eclipse.rap.rwt.RWT; import org.eclipse.rap.rwt.internal.lifecycle.WidgetLCA; import org.eclipse.rap.rwt.internal.textsize.TextSizeUtil; import org.eclipse.rap.rwt.internal.theme.ThemeAdapter; import org.eclipse.rap.rwt.theme.BoxDimensions; import org.eclipse.swt.SWT; import org.eclipse.swt.SWTException; import org.eclipse.swt.graphics.Image; import org.eclipse.swt.graphics.Point; import org.eclipse.swt.graphics.Rectangle; import org.eclipse.swt.internal.widgets.MarkupValidator; import org.eclipse.swt.internal.widgets.labelkit.LabelLCA; import org.eclipse.swt.internal.widgets.labelkit.LabelThemeAdapter; /** * Instances of this class represent a non-selectable * user interface object that displays a string or image. * When SEPARATOR is specified, displays a single * vertical or horizontal line. * <p> * Shadow styles are hints and may not be honoured * by the platform. To create a separator label * with the default shadow style for the platform, * do not specify a shadow style. * </p> * <dl> * <dt><b>Styles:</b></dt> * <dd>SEPARATOR, HORIZONTAL, VERTICAL</dd> * <dd>SHADOW_IN, SHADOW_OUT, SHADOW_NONE</dd> * <dd>CENTER, LEFT, RIGHT, WRAP</dd> * <dt><b>Events:</b></dt> * <dd>(none)</dd> * </dl> * <p> * Note: Only one of SHADOW_IN, SHADOW_OUT and SHADOW_NONE may be specified. * SHADOW_NONE is a HINT. Only one of HORIZONTAL and VERTICAL may be specified. * Only one of CENTER, LEFT and RIGHT may be specified. * </p><p> * IMPORTANT: This class is intended to be subclassed <em>only</em> * within the SWT implementation. * </p> * * <hr /> * <strong>Note:</strong> Unlike in SWT, setting an image clears the text of the * label and vice versa. Thus, after calling <code>setText()</code>, the method * <code>getImage()</code> will return <code>null</code>, and after calling * <code>setImage()</code>, <code>getText</code> will return the empty string. * </p> * @since 1.0 */ // TODO [rh] check what should happen with style == SEPARATOR and setForeground public class Label extends Control { private String text = ""; private Image image; /** * Constructs a new instance of this class given its parent * and a style value describing its behavior and appearance. * <p> * The style value is either one of the style constants defined in * class <code>SWT</code> which is applicable to instances of this * class, or must be built by <em>bitwise OR</em>'ing together * (that is, using the <code>int</code> "|" operator) two or more * of those <code>SWT</code> style constants. The class description * lists the style constants that are applicable to the class. * Style bits are also inherited from superclasses. * </p> * * @param parent a composite control which will be the parent of the new instance (cannot be null) * @param style the style of control to construct * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the parent is null</li> * </ul> * @exception SWTException <ul> * <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li> * <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li> * </ul> * * @see SWT#SEPARATOR * @see SWT#HORIZONTAL * @see SWT#VERTICAL * @see SWT#SHADOW_IN * @see SWT#SHADOW_OUT * @see SWT#SHADOW_NONE * @see SWT#CENTER * @see SWT#LEFT * @see SWT#RIGHT * @see SWT#WRAP * @see Widget#checkSubclass * @see Widget#getStyle */ public Label(Composite parent, int style) { super(parent, checkStyle(style)); } @Override void initState() { addState(THEME_BACKGROUND); } /** * Sets the receiver's text. * <p> * This method sets the widget label. The label may include * the mnemonic character and line delimiters. * </p> * <p> * Mnemonics are indicated by an '&' that causes the next * character to be the mnemonic. When the user presses a * key sequence that matches the mnemonic, focus is assigned * to the control that follows the label. On most platforms, * the mnemonic appears underlined but may be emphasised in a * platform specific manner. The mnemonic indicator character * '&' can be escaped by doubling it in the string, causing * a single '&' to be displayed. * </p> * * @param text the new text * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the text 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 setText(String text) { checkWidget(); if (text == null) { SWT.error(SWT.ERROR_NULL_ARGUMENT); } if ((style & SWT.SEPARATOR) == 0) { if (isMarkupEnabledFor(this) && !isValidationDisabledFor(this)) { MarkupValidator.getInstance().validate(text); } this.text = text; image = null; } } /** * Returns the receiver's text, which will be an empty * string if it has never been set or if the receiver is * a <code>SEPARATOR</code> label. * * @return the receiver's text * * @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 getText() { checkWidget(); return text; } /** * Sets the receiver's image to the argument, which may be * null indicating that no image should be displayed. * * @param image the image to display on the receiver (may be null) * * @exception IllegalArgumentException <ul> * <li>ERROR_INVALID_ARGUMENT - if the image has been disposed</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> */ // TODO [rst] Clarify or remove this comment: // TODO: The LCA does not yet handle images. So, setting an image currently public void setImage(Image image) { checkWidget(); if ((style & SWT.SEPARATOR) == 0) { this.image = image; text = ""; } } /** * Returns the receiver's image if it has one, or null * if it does not. * * @return the receiver's image * * @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 Image getImage() { checkWidget(); return image; } /** * Controls how text and images will be displayed in the receiver. * The argument should be one of <code>LEFT</code>, <code>RIGHT</code> * or <code>CENTER</code>. If the receiver is a <code>SEPARATOR</code> * label, the argument is ignored and the alignment is not changed. * * @param alignment the new alignment * * @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 setAlignment(int alignment) { checkWidget(); if ((style & SWT.SEPARATOR) == 0 && (alignment & (SWT.LEFT | SWT.RIGHT | SWT.CENTER)) != 0) { style &= ~(SWT.LEFT | SWT.RIGHT | SWT.CENTER); style |= alignment & (SWT.LEFT | SWT.RIGHT | SWT.CENTER); } } /** * Returns a value which describes the position of the * text or image in the receiver. The value will be one of * <code>LEFT</code>, <code>RIGHT</code> or <code>CENTER</code> * unless the receiver is a <code>SEPARATOR</code> label, in * which case, <code>NONE</code> is returned. * * @return the alignment * * @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 int getAlignment() { checkWidget(); int result; if ((style & SWT.SEPARATOR) != 0) { result = 0; } else if ((style & SWT.LEFT) != 0) { result = SWT.LEFT; } else if ((style & SWT.CENTER) != 0) { result = SWT.CENTER; } else if ((style & SWT.RIGHT) != 0) { result = SWT.RIGHT; } else { result = SWT.LEFT; } return result; } @Override public Point computeSize(int wHint, int hHint, boolean changed) { checkWidget(); int width = 0; int height = 0; if ((style & SWT.SEPARATOR) != 0) { int lineWidth = getSeparatorLineWidth(); if ((style & SWT.HORIZONTAL) != 0) { width = DEFAULT_WIDTH; height = lineWidth; } else { width = lineWidth; height = DEFAULT_HEIGHT; } } else if (image != null) { Rectangle rect = image.getBounds(); width = rect.width; height = rect.height; } else if (text.length() > 0) { int wrapWidth = 0; if ((style & SWT.WRAP) != 0 && wHint != SWT.DEFAULT) { wrapWidth = wHint; } Point extent = textExtent(getFont(), text, wrapWidth, isMarkupEnabledFor(this)); width = extent.x; height = extent.y + 2; } else { height = TextSizeUtil.getCharHeight(getFont()); } if (wHint != SWT.DEFAULT) { width = wHint; } if (hHint != SWT.DEFAULT) { height = hHint; } BoxDimensions border = getBorder(); BoxDimensions padding = getPadding(); width += border.left + border.right + padding.left + padding.right; height += border.top + border.bottom + padding.top + padding.bottom; return new Point(width, height); } @Override String getNameText() { return getText(); } @Override public void setData(String key, Object value) { if (!RWT.MARKUP_ENABLED.equals(key) || !isMarkupEnabledFor(this)) { super.setData(key, value); } } @Override @SuppressWarnings("unchecked") public <T> T getAdapter(Class<T> adapter) { if (adapter == WidgetLCA.class) { return (T) LabelLCA.INSTANCE; } return super.getAdapter(adapter); } private static int checkStyle(int style) { int result = style; result |= SWT.NO_FOCUS; if ((style & SWT.SEPARATOR) != 0) { result = checkBits(result, SWT.VERTICAL, SWT.HORIZONTAL, 0, 0, 0, 0); result = checkBits(result, SWT.SHADOW_OUT, SWT.SHADOW_IN, SWT.SHADOW_NONE, 0, 0, 0); } result = checkBits(result, SWT.LEFT, SWT.CENTER, SWT.RIGHT, 0, 0, 0); return result; } private int getSeparatorLineWidth() { LabelThemeAdapter themeAdapter = (LabelThemeAdapter) getAdapter(ThemeAdapter.class); return themeAdapter.getSeparatorLineWidth(this); } }