Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2018 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.accessibility.*; import org.eclipse.swt.events.*; import org.eclipse.swt.graphics.*; import org.eclipse.swt.widgets.*; /** * A Label which supports aligned text and/or an image and different border styles. * <p> * If there is not enough space a CLabel uses the following strategy to fit the * information into the available space: * <pre> * ignores the indent in left align mode * ignores the image and the gap * shortens the text by replacing the center portion of the label with an ellipsis * shortens the text by removing the center portion of the label * </pre> * <dl> * <dt><b>Styles:</b> * <dd>LEFT, RIGHT, CENTER, SHADOW_IN, SHADOW_OUT, SHADOW_NONE</dd> * <dt><b>Events:</b> * <dd>(NONE)</dd> * </dl> * *<p> * This class may be subclassed for the purpose of overriding the default string * shortening algorithm that is implemented in method <code>shortenText()</code>. * </p> * * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: CustomControlExample</a> * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a> * @see CLabel#shortenText(GC, String, int) */ public class CLabel extends Canvas { /** Gap between icon and text */ private static final int GAP = 5; /** Left and right margins */ private static final int DEFAULT_MARGIN = 3; /** a string inserted in the middle of text that has been shortened */ private static final String ELLIPSIS = "..."; //$NON-NLS-1$ // could use the ellipsis glyph on some platforms "\u2026" /** the alignment. Either CENTER, RIGHT, LEFT. Default is LEFT*/ private int align = SWT.LEFT; private int leftMargin = DEFAULT_MARGIN; private int topMargin = DEFAULT_MARGIN; private int rightMargin = DEFAULT_MARGIN; private int bottomMargin = DEFAULT_MARGIN; /** the current text */ private String text; /** the current icon */ private Image image; // The tooltip is used for two purposes - the application can set // a tooltip or the tooltip can be used to display the full text when the // the text has been truncated due to the label being too short. // The appToolTip stores the tooltip set by the application. Control.tooltiptext // contains whatever tooltip is currently being displayed. private String appToolTipText; private boolean ignoreDispose; private Image backgroundImage; private Color[] gradientColors; private int[] gradientPercents; private boolean gradientVertical; private Color background; private static int DRAW_FLAGS = SWT.DRAW_MNEMONIC | SWT.DRAW_TAB | SWT.DRAW_TRANSPARENT | SWT.DRAW_DELIMITER; /** * 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 widget which will be the parent of the new instance (cannot be null) * @param style the style of widget 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> * </ul> * * @see SWT#LEFT * @see SWT#RIGHT * @see SWT#CENTER * @see SWT#SHADOW_IN * @see SWT#SHADOW_OUT * @see SWT#SHADOW_NONE * @see #getStyle() */ public CLabel(Composite parent, int style) { super(parent, checkStyle(style)); if ((style & (SWT.CENTER | SWT.RIGHT)) == 0) style |= SWT.LEFT; if ((style & SWT.CENTER) != 0) align = SWT.CENTER; if ((style & SWT.RIGHT) != 0) align = SWT.RIGHT; if ((style & SWT.LEFT) != 0) align = SWT.LEFT; addPaintListener(event -> onPaint(event)); addTraverseListener(event -> { if (event.detail == SWT.TRAVERSE_MNEMONIC) { onMnemonic(event); } }); addListener(SWT.Dispose, event -> onDispose(event)); initAccessible(); } /** * Check the style bits to ensure that no invalid styles are applied. */ private static int checkStyle(int style) { if ((style & SWT.BORDER) != 0) style |= SWT.SHADOW_IN; int mask = SWT.SHADOW_IN | SWT.SHADOW_OUT | SWT.SHADOW_NONE | SWT.LEFT_TO_RIGHT | SWT.RIGHT_TO_LEFT; style = style & mask; return style |= SWT.NO_FOCUS | SWT.DOUBLE_BUFFERED; } @Override public Point computeSize(int wHint, int hHint, boolean changed) { checkWidget(); Point e = getTotalSize(image, text); if (wHint == SWT.DEFAULT) { e.x += leftMargin + rightMargin; } else { e.x = wHint; } if (hHint == SWT.DEFAULT) { e.y += topMargin + bottomMargin; } else { e.y = hHint; } return e; } /** * Draw a rectangle in the given colors. */ private void drawBevelRect(GC gc, int x, int y, int w, int h, Color topleft, Color bottomright) { gc.setForeground(bottomright); gc.drawLine(x + w, y, x + w, y + h); gc.drawLine(x, y + h, x + w, y + h); gc.setForeground(topleft); gc.drawLine(x, y, x + w - 1, y); gc.drawLine(x, y, x, y + h - 1); } /* * Return the lowercase of the first non-'&' character following * an '&' character in the given string. If there are no '&' * characters in the given string, return '\0'. */ char _findMnemonic(String string) { if (string == null) return '\0'; int index = 0; int length = string.length(); do { while (index < length && string.charAt(index) != '&') index++; if (++index >= length) return '\0'; if (string.charAt(index) != '&') return Character.toLowerCase(string.charAt(index)); index++; } while (index < length); return '\0'; } /** * Returns the horizontal alignment. * The alignment style (LEFT, CENTER or RIGHT) is returned. * * @return SWT.LEFT, SWT.RIGHT or SWT.CENTER */ public int getAlignment() { /* * This call is intentionally commented out, to allow this getter method to be * called from a thread which is different from one that created the widget. */ //checkWidget(); return align; } /** * Return the CLabel's bottom margin. * * @return the bottom margin of the label * * @since 3.6 */ public int getBottomMargin() { /* * This call is intentionally commented out, to allow this getter method to be * called from a thread which is different from one that created the widget. */ //checkWidget(); return bottomMargin; } /** * Return the CLabel's image or <code>null</code>. * * @return the image of the label or null */ public Image getImage() { /* * This call is intentionally commented out, to allow this getter method to be * called from a thread which is different from one that created the widget. */ //checkWidget(); return image; } /** * Return the CLabel's left margin. * * @return the left margin of the label * * @since 3.6 */ public int getLeftMargin() { /* * This call is intentionally commented out, to allow this getter method to be * called from a thread which is different from one that created the widget. */ //checkWidget(); return leftMargin; } /** * Return the CLabel's right margin. * * @return the right margin of the label * * @since 3.6 */ public int getRightMargin() { /* * This call is intentionally commented out, to allow this getter method to be * called from a thread which is different from one that created the widget. */ //checkWidget(); return rightMargin; } /** * Compute the minimum size. */ private Point getTotalSize(Image image, String text) { Point size = new Point(0, 0); if (image != null) { Rectangle r = image.getBounds(); size.x += r.width; size.y += r.height; } GC gc = new GC(this); if (text != null && text.length() > 0) { Point e = gc.textExtent(text, DRAW_FLAGS); size.x += e.x; size.y = Math.max(size.y, e.y); if (image != null) size.x += GAP; } else { size.y = Math.max(size.y, gc.getFontMetrics().getHeight()); } gc.dispose(); return size; } @Override public int getStyle() { int style = super.getStyle(); switch (align) { case SWT.RIGHT: style |= SWT.RIGHT; break; case SWT.CENTER: style |= SWT.CENTER; break; case SWT.LEFT: style |= SWT.LEFT; break; } return style; } /** * Return the Label's text. * * @return the text of the label or null */ public String getText() { /* * This call is intentionally commented out, to allow this getter method to be * called from a thread which is different from one that created the widget. */ //checkWidget(); return text; } @Override public String getToolTipText() { checkWidget(); return appToolTipText; } /** * Return the CLabel's top margin. * * @return the top margin of the label * * @since 3.6 */ public int getTopMargin() { /* * This call is intentionally commented out, to allow this getter method to be * called from a thread which is different from one that created the widget. */ //checkWidget(); return topMargin; } private void initAccessible() { Accessible accessible = getAccessible(); accessible.addAccessibleListener(new AccessibleAdapter() { @Override public void getName(AccessibleEvent e) { e.result = getText(); } @Override public void getHelp(AccessibleEvent e) { e.result = getToolTipText(); } @Override public void getKeyboardShortcut(AccessibleEvent e) { char mnemonic = _findMnemonic(CLabel.this.text); if (mnemonic != '\0') { e.result = "Alt+" + mnemonic; //$NON-NLS-1$ } } }); accessible.addAccessibleControlListener(new AccessibleControlAdapter() { @Override public void getChildAtPoint(AccessibleControlEvent e) { e.childID = ACC.CHILDID_SELF; } @Override public void getLocation(AccessibleControlEvent e) { Rectangle rect = getDisplay().map(getParent(), null, getBounds()); e.x = rect.x; e.y = rect.y; e.width = rect.width; e.height = rect.height; } @Override public void getChildCount(AccessibleControlEvent e) { e.detail = 0; } @Override public void getRole(AccessibleControlEvent e) { e.detail = ACC.ROLE_LABEL; } @Override public void getState(AccessibleControlEvent e) { e.detail = ACC.STATE_READONLY; } }); } void onDispose(Event event) { /* make this handler run after other dispose listeners */ if (ignoreDispose) { ignoreDispose = false; return; } ignoreDispose = true; notifyListeners(event.type, event); event.type = SWT.NONE; gradientColors = null; gradientPercents = null; backgroundImage = null; text = null; image = null; appToolTipText = null; } void onMnemonic(TraverseEvent event) { char mnemonic = _findMnemonic(text); if (mnemonic == '\0') return; if (Character.toLowerCase(event.character) != mnemonic) return; Composite control = this.getParent(); while (control != null) { Control[] children = control.getChildren(); int index = 0; while (index < children.length) { if (children[index] == this) break; index++; } index++; if (index < children.length) { if (children[index].setFocus()) { event.doit = true; event.detail = SWT.TRAVERSE_NONE; } } control = control.getParent(); } } void onPaint(PaintEvent event) { Rectangle rect = getClientArea(); if (rect.width == 0 || rect.height == 0) return; boolean shortenText = false; String t = text; Image img = image; int availableWidth = Math.max(0, rect.width - (leftMargin + rightMargin)); Point extent = getTotalSize(img, t); if (extent.x > availableWidth) { img = null; extent = getTotalSize(img, t); if (extent.x > availableWidth) { shortenText = true; } } GC gc = event.gc; String[] lines = text == null ? null : splitString(text); // shorten the text if (shortenText) { extent.x = 0; for (int i = 0; i < lines.length; i++) { Point e = gc.textExtent(lines[i], DRAW_FLAGS); if (e.x > availableWidth) { lines[i] = shortenText(gc, lines[i], availableWidth); extent.x = Math.max(extent.x, getTotalSize(null, lines[i]).x); } else { extent.x = Math.max(extent.x, e.x); } } if (appToolTipText == null) { super.setToolTipText(text); } } else { super.setToolTipText(appToolTipText); } // determine horizontal position int x = rect.x + leftMargin; if (align == SWT.CENTER) { x = (rect.width - extent.x) / 2; } if (align == SWT.RIGHT) { x = rect.width - rightMargin - extent.x; } // draw a background image behind the text try { if (backgroundImage != null) { // draw a background image behind the text Rectangle imageRect = backgroundImage.getBounds(); // tile image to fill space gc.setBackground(getBackground()); gc.fillRectangle(rect); int xPos = 0; while (xPos < rect.width) { int yPos = 0; while (yPos < rect.height) { gc.drawImage(backgroundImage, xPos, yPos); yPos += imageRect.height; } xPos += imageRect.width; } } else if (gradientColors != null) { // draw a gradient behind the text final Color oldBackground = gc.getBackground(); if (gradientColors.length == 1) { if (gradientColors[0] != null) gc.setBackground(gradientColors[0]); gc.fillRectangle(0, 0, rect.width, rect.height); } else { final Color oldForeground = gc.getForeground(); Color lastColor = gradientColors[0]; if (lastColor == null) lastColor = oldBackground; int pos = 0; for (int i = 0; i < gradientPercents.length; ++i) { gc.setForeground(lastColor); lastColor = gradientColors[i + 1]; if (lastColor == null) lastColor = oldBackground; gc.setBackground(lastColor); if (gradientVertical) { final int gradientHeight = (gradientPercents[i] * rect.height / 100) - pos; gc.fillGradientRectangle(0, pos, rect.width, gradientHeight, true); pos += gradientHeight; } else { final int gradientWidth = (gradientPercents[i] * rect.width / 100) - pos; gc.fillGradientRectangle(pos, 0, gradientWidth, rect.height, false); pos += gradientWidth; } } if (gradientVertical && pos < rect.height) { gc.setBackground(getBackground()); gc.fillRectangle(0, pos, rect.width, rect.height - pos); } if (!gradientVertical && pos < rect.width) { gc.setBackground(getBackground()); gc.fillRectangle(pos, 0, rect.width - pos, rect.height); } gc.setForeground(oldForeground); } gc.setBackground(oldBackground); } else { if ((background != null || (getStyle() & SWT.DOUBLE_BUFFERED) == 0) && background.getAlpha() > 0) { gc.setBackground(getBackground()); gc.fillRectangle(rect); } } } catch (SWTException e) { if ((getStyle() & SWT.DOUBLE_BUFFERED) == 0) { gc.setBackground(getBackground()); gc.fillRectangle(rect); } } // draw border int style = getStyle(); if ((style & SWT.SHADOW_IN) != 0 || (style & SWT.SHADOW_OUT) != 0) { paintBorder(gc, rect); } /* * Compute text height and image height. If image height is more than * the text height, draw image starting from top margin. Else draw text * starting from top margin. */ Rectangle imageRect = null; int lineHeight = 0, textHeight = 0, imageHeight = 0; if (img != null) { imageRect = img.getBounds(); imageHeight = imageRect.height; } if (lines != null) { lineHeight = gc.getFontMetrics().getHeight(); textHeight = lines.length * lineHeight; } int imageY = 0, midPoint = 0, lineY = 0; if (imageHeight > textHeight) { if (topMargin == DEFAULT_MARGIN && bottomMargin == DEFAULT_MARGIN) imageY = rect.y + (rect.height - imageHeight) / 2; else imageY = topMargin; midPoint = imageY + imageHeight / 2; lineY = midPoint - textHeight / 2; } else { if (topMargin == DEFAULT_MARGIN && bottomMargin == DEFAULT_MARGIN) lineY = rect.y + (rect.height - textHeight) / 2; else lineY = topMargin; midPoint = lineY + textHeight / 2; imageY = midPoint - imageHeight / 2; } // draw the image if (img != null) { gc.drawImage(img, 0, 0, imageRect.width, imageHeight, x, imageY, imageRect.width, imageHeight); x += imageRect.width + GAP; extent.x -= imageRect.width + GAP; } // draw the text if (lines != null) { gc.setForeground(getForeground()); for (int i = 0; i < lines.length; i++) { int lineX = x; if (lines.length > 1) { if (align == SWT.CENTER) { int lineWidth = gc.textExtent(lines[i], DRAW_FLAGS).x; lineX = x + Math.max(0, (extent.x - lineWidth) / 2); } if (align == SWT.RIGHT) { int lineWidth = gc.textExtent(lines[i], DRAW_FLAGS).x; lineX = Math.max(x, rect.x + rect.width - rightMargin - lineWidth); } } gc.drawText(lines[i], lineX, lineY, DRAW_FLAGS); lineY += lineHeight; } } } /** * Paint the Label's border. */ private void paintBorder(GC gc, Rectangle r) { Display disp = getDisplay(); Color c1 = null; Color c2 = null; int style = getStyle(); if ((style & SWT.SHADOW_IN) != 0) { c1 = disp.getSystemColor(SWT.COLOR_WIDGET_NORMAL_SHADOW); c2 = disp.getSystemColor(SWT.COLOR_WIDGET_HIGHLIGHT_SHADOW); } if ((style & SWT.SHADOW_OUT) != 0) { c1 = disp.getSystemColor(SWT.COLOR_WIDGET_LIGHT_SHADOW); c2 = disp.getSystemColor(SWT.COLOR_WIDGET_NORMAL_SHADOW); } if (c1 != null && c2 != null) { gc.setLineWidth(1); drawBevelRect(gc, r.x, r.y, r.width - 1, r.height - 1, c1, c2); } } /** * Set the horizontal alignment of the CLabel. * Use the values LEFT, CENTER and RIGHT to align image and text within the available space. * * @param align the alignment style of LEFT, RIGHT or CENTER * * @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> * <li>ERROR_INVALID_ARGUMENT - if the value of align is not one of SWT.LEFT, SWT.RIGHT or SWT.CENTER</li> * </ul> */ public void setAlignment(int align) { checkWidget(); if (align != SWT.LEFT && align != SWT.RIGHT && align != SWT.CENTER) { SWT.error(SWT.ERROR_INVALID_ARGUMENT); } if (this.align != align) { this.align = align; redraw(); } } @Override public void setBackground(Color color) { super.setBackground(color); // Are these settings the same as before? if (backgroundImage == null && gradientColors == null && gradientPercents == null) { if (color == null) { if (background == null) return; } else { if (color.equals(background)) return; } } background = color; backgroundImage = null; gradientColors = null; gradientPercents = null; redraw(); } /** * Specify a gradient of colours to be drawn in the background of the CLabel. * <p>For example, to draw a gradient that varies from dark blue to blue and then to * white and stays white for the right half of the label, use the following call * to setBackground:</p> * <pre> * clabel.setBackground(new Color[]{display.getSystemColor(SWT.COLOR_DARK_BLUE), * display.getSystemColor(SWT.COLOR_BLUE), * display.getSystemColor(SWT.COLOR_WHITE), * display.getSystemColor(SWT.COLOR_WHITE)}, * new int[] {25, 50, 100}); * </pre> * * @param colors an array of Color that specifies the colors to appear in the gradient * in order of appearance from left to right; The value <code>null</code> * clears the background gradient; the value <code>null</code> can be used * inside the array of Color to specify the background color. * @param percents an array of integers between 0 and 100 specifying the percent of the width * of the widget at which the color should change; the size of the percents * array must be one less than the size of the colors array. * * @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> * <li>ERROR_INVALID_ARGUMENT - if the values of colors and percents are not consistent</li> * </ul> */ public void setBackground(Color[] colors, int[] percents) { setBackground(colors, percents, false); } /** * Specify a gradient of colours to be drawn in the background of the CLabel. * <p>For example, to draw a gradient that varies from dark blue to white in the vertical, * direction use the following call * to setBackground:</p> * <pre> * clabel.setBackground(new Color[]{display.getSystemColor(SWT.COLOR_DARK_BLUE), * display.getSystemColor(SWT.COLOR_WHITE)}, * new int[] {100}, true); * </pre> * * @param colors an array of Color that specifies the colors to appear in the gradient * in order of appearance from left/top to right/bottom; The value <code>null</code> * clears the background gradient; the value <code>null</code> can be used * inside the array of Color to specify the background color. * @param percents an array of integers between 0 and 100 specifying the percent of the width/height * of the widget at which the color should change; the size of the percents * array must be one less than the size of the colors array. * @param vertical indicate the direction of the gradient. True is vertical and false is horizontal. * * @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> * <li>ERROR_INVALID_ARGUMENT - if the values of colors and percents are not consistent</li> * </ul> * * @since 3.0 */ public void setBackground(Color[] colors, int[] percents, boolean vertical) { checkWidget(); if (colors != null) { if (percents == null || percents.length != colors.length - 1) { SWT.error(SWT.ERROR_INVALID_ARGUMENT); } if (getDisplay().getDepth() < 15) { // Don't use gradients on low color displays colors = new Color[] { colors[colors.length - 1] }; percents = new int[] {}; } for (int i = 0; i < percents.length; i++) { if (percents[i] < 0 || percents[i] > 100) { SWT.error(SWT.ERROR_INVALID_ARGUMENT); } if (i > 0 && percents[i] < percents[i - 1]) { SWT.error(SWT.ERROR_INVALID_ARGUMENT); } } } // Are these settings the same as before? final Color background = getBackground(); if (backgroundImage == null) { if ((gradientColors != null) && (colors != null) && (gradientColors.length == colors.length)) { boolean same = false; for (int i = 0; i < gradientColors.length; i++) { same = (gradientColors[i] == colors[i]) || ((gradientColors[i] == null) && (colors[i] == background)) || ((gradientColors[i] == background) && (colors[i] == null)); if (!same) break; } if (same) { for (int i = 0; i < gradientPercents.length; i++) { same = gradientPercents[i] == percents[i]; if (!same) break; } } if (same && this.gradientVertical == vertical) return; } } else { backgroundImage = null; } // Store the new settings if (colors == null) { gradientColors = null; gradientPercents = null; gradientVertical = false; } else { gradientColors = new Color[colors.length]; for (int i = 0; i < colors.length; ++i) gradientColors[i] = (colors[i] != null) ? colors[i] : background; gradientPercents = new int[percents.length]; for (int i = 0; i < percents.length; ++i) gradientPercents[i] = percents[i]; gradientVertical = vertical; } // Refresh with the new settings redraw(); } /** * Set the image to be drawn in the background of the label. * * @param image the image to be drawn in the background * * @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 setBackground(Image image) { checkWidget(); if (image == backgroundImage) return; if (image != null) { gradientColors = null; gradientPercents = null; } backgroundImage = image; redraw(); } /** * Set the label's bottom margin, in points. * * @param bottomMargin the bottom margin of the label, which must be equal to or greater than zero * * @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> * * @since 3.6 */ public void setBottomMargin(int bottomMargin) { checkWidget(); if (this.bottomMargin == bottomMargin || bottomMargin < 0) return; this.bottomMargin = bottomMargin; redraw(); } @Override public void setFont(Font font) { super.setFont(font); redraw(); } /** * Set the label's Image. * The value <code>null</code> clears it. * * @param image the image to be displayed in the label 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 setImage(Image image) { checkWidget(); if (image != this.image) { this.image = image; redraw(); } } /** * Set the label's horizontal left margin, in points. * * @param leftMargin the left margin of the label, which must be equal to or greater than zero * * @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> * * @since 3.6 */ public void setLeftMargin(int leftMargin) { checkWidget(); if (this.leftMargin == leftMargin || leftMargin < 0) return; this.leftMargin = leftMargin; redraw(); } /** * Set the label's margins, in points. * * @param leftMargin the left margin. * @param topMargin the top margin. * @param rightMargin the right margin. * @param bottomMargin the bottom margin. * @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> * * @since 3.6 */ public void setMargins(int leftMargin, int topMargin, int rightMargin, int bottomMargin) { checkWidget(); this.leftMargin = Math.max(0, leftMargin); this.topMargin = Math.max(0, topMargin); this.rightMargin = Math.max(0, rightMargin); this.bottomMargin = Math.max(0, bottomMargin); redraw(); } /** * Set the label's right margin, in points. * * @param rightMargin the right margin of the label, which must be equal to or greater than zero * * @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> * * @since 3.6 */ public void setRightMargin(int rightMargin) { checkWidget(); if (this.rightMargin == rightMargin || rightMargin < 0) return; this.rightMargin = rightMargin; redraw(); } /** * Set the label's text. * The value <code>null</code> clears it. * <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><p> * Note: If control characters like '\n', '\t' etc. are used * in the string, then the behavior is platform dependent. * </p> * * @param text the text to be displayed in the label 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 setText(String text) { checkWidget(); if (text == null) text = ""; //$NON-NLS-1$ if (!text.equals(this.text)) { this.text = text; redraw(); } } @Override public void setToolTipText(String string) { super.setToolTipText(string); appToolTipText = super.getToolTipText(); } /** * Set the label's top margin, in points. * * @param topMargin the top margin of the label, which must be equal to or greater than zero * * @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> * * @since 3.6 */ public void setTopMargin(int topMargin) { checkWidget(); if (this.topMargin == topMargin || topMargin < 0) return; this.topMargin = topMargin; redraw(); } /** * Shorten the given text <code>t</code> so that its length doesn't exceed * the given width. The default implementation replaces characters in the * center of the original string with an ellipsis ("..."). * Override if you need a different strategy. * * @param gc the gc to use for text measurement * @param t the text to shorten * @param width the width to shorten the text to, in points * @return the shortened text */ protected String shortenText(GC gc, String t, int width) { if (t == null) return null; int w = gc.textExtent(ELLIPSIS, DRAW_FLAGS).x; if (width <= w) return t; int l = t.length(); int max = l / 2; int min = 0; int mid = (max + min) / 2 - 1; if (mid <= 0) return t; TextLayout layout = new TextLayout(getDisplay()); layout.setText(t); mid = validateOffset(layout, mid); while (min < mid && mid < max) { String s1 = t.substring(0, mid); String s2 = t.substring(validateOffset(layout, l - mid), l); int l1 = gc.textExtent(s1, DRAW_FLAGS).x; int l2 = gc.textExtent(s2, DRAW_FLAGS).x; if (l1 + w + l2 > width) { max = mid; mid = validateOffset(layout, (max + min) / 2); } else if (l1 + w + l2 < width) { min = mid; mid = validateOffset(layout, (max + min) / 2); } else { min = max; } } String result = mid == 0 ? t : t.substring(0, mid) + ELLIPSIS + t.substring(validateOffset(layout, l - mid), l); layout.dispose(); return result; } int validateOffset(TextLayout layout, int offset) { int nextOffset = layout.getNextOffset(offset, SWT.MOVEMENT_CLUSTER); if (nextOffset != offset) return layout.getPreviousOffset(nextOffset, SWT.MOVEMENT_CLUSTER); return offset; } private String[] splitString(String text) { String[] lines = new String[1]; int start = 0, pos; do { pos = text.indexOf('\n', start); if (pos == -1) { lines[lines.length - 1] = text.substring(start); } else { boolean crlf = (pos > 0) && (text.charAt(pos - 1) == '\r'); lines[lines.length - 1] = text.substring(start, pos - (crlf ? 1 : 0)); start = pos + 1; String[] newLines = new String[lines.length + 1]; System.arraycopy(lines, 0, newLines, 0, lines.length); lines = newLines; } } while (pos != -1); return lines; } }