Java tutorial
/******************************************************************************* * Copyright (c) 2002, 2015 Innoopract Informationssysteme GmbH. * 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 org.eclipse.rap.rwt.internal.lifecycle.WidgetLCA; import org.eclipse.rap.rwt.internal.theme.ThemeAdapter; import org.eclipse.swt.SWT; import org.eclipse.swt.SWTException; import org.eclipse.swt.events.SelectionEvent; import org.eclipse.swt.events.SelectionListener; import org.eclipse.swt.graphics.Point; import org.eclipse.swt.internal.widgets.scrollbarkit.ScrollBarLCA; import org.eclipse.swt.internal.widgets.scrollbarkit.ScrollBarThemeAdapter; /** * Instances of this class are selectable user interface * objects that represent a range of positive, numeric values. * <p> * At any given moment, a given scroll bar will have a * single 'selection' that is considered to be its * value, which is constrained to be within the range of * values the scroll bar represents (that is, between its * <em>minimum</em> and <em>maximum</em> values). * </p><p> * Typically, scroll bars will be made up of five areas: * <ol> * <li>an arrow button for decrementing the value</li> * <li>a page decrement area for decrementing the value by a larger amount</li> * <li>a <em>thumb</em> for modifying the value by mouse dragging</li> * <li>a page increment area for incrementing the value by a larger amount</li> * <li>an arrow button for incrementing the value</li> * </ol> * Based on their style, scroll bars are either <code>HORIZONTAL</code> * (which have a left facing button for decrementing the value and a * right facing button for incrementing it) or <code>VERTICAL</code> * (which have an upward facing button for decrementing the value * and a downward facing buttons for incrementing it). * </p><p> * On some platforms, the size of the scroll bar's thumb can be * varied relative to the magnitude of the range of values it * represents (that is, relative to the difference between its * maximum and minimum values). Typically, this is used to * indicate some proportional value such as the ratio of the * visible area of a document to the total amount of space that * it would take to display it. SWT supports setting the thumb * size even if the underlying platform does not, but in this * case the appearance of the scroll bar will not change. * </p><p> * Scroll bars are created by specifying either <code>H_SCROLL</code>, * <code>V_SCROLL</code> or both when creating a <code>Scrollable</code>. * They are accessed from the <code>Scrollable</code> using * <code>getHorizontalBar</code> and <code>getVerticalBar</code>. * </p><p> * Note: Scroll bars are not Controls. On some platforms, scroll bars * that appear as part of some standard controls such as a text or list * have no operating system resources and are not children of the control. * For this reason, scroll bars are treated specially. To create a control * that looks like a scroll bar but has operating system resources, use * <code>Slider</code>. * </p> * <dl> * <dt><b>Styles:</b></dt> * <dd>HORIZONTAL, VERTICAL</dd> * <dt><b>Events:</b></dt> * <dd>Selection</dd> * </dl> * <p> * Note: Only one of the styles HORIZONTAL and VERTICAL may be specified. * </p><p> * IMPORTANT: This class is <em>not</em> intended to be subclassed. * </p> * * <!--@see Slider--> * @see Scrollable * @see Scrollable#getHorizontalBar * @see Scrollable#getVerticalBar * * <p>(current) limitations:</p> * <ul> * <li>minimum, maximum, thumb, increment and pageIncrement properties are not * rendered (no corresponding client-side property)</li> * </ul> * * @since 1.0 */ public class ScrollBar extends Widget { private final Scrollable parent; private int thumb; private int selection; private int minimum; private int maximum; /** * 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> * * <p><strong>IMPORTANT:</strong> This method is <em>not</em> part of the RWT * public API. It is marked public only so that it can be shared * within the packages provided by RWT. It should never be accessed * from application code. * </p> * * @see SWT#HORIZONTAL * @see SWT#VERTICAL * @see Widget#checkSubclass * @see Widget#getStyle */ ScrollBar(Scrollable parent, int style) { super(parent, checkStyle(style)); this.parent = parent; } /** * Returns the receiver's parent, which must be a Scrollable. * * @return the receiver's parent * * @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 Scrollable getParent() { checkWidget(); return parent; } ///////////// // Visibility /** * Marks the receiver as visible if the argument is <code>true</code>, * and marks it invisible otherwise. * <p> * If one of the receiver's ancestors is not visible or some * other condition makes the receiver not visible, marking * it visible may not actually cause it to be displayed. * </p> * * @param visible the new visibility state * * @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 setVisible(boolean visible) { checkWidget(); boolean isVisible = !hasState(HIDDEN); if (isVisible != visible) { if (visible) { removeState(HIDDEN); } else { addState(HIDDEN); } } } /** * Returns <code>true</code> if the receiver is visible, and * <code>false</code> otherwise. * <p> * If one of the receiver's ancestors is not visible or some * other condition makes the receiver not visible, this method * may still indicate that it is considered visible even though * it may not actually be showing. * </p> * * @return the receiver's visibility state * * @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 boolean getVisible() { checkWidget(); return !hasState(HIDDEN); } /** * Returns <code>true</code> if the receiver is visible and all * of the receiver's ancestors are visible and <code>false</code> * otherwise. * * @return the receiver's visibility state * * @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> * * @see #getVisible */ public boolean isVisible() { checkWidget(); return getVisible() && parent.isVisible(); } ///////////// // Enablement /** * Enables the receiver if the argument is <code>true</code>, * and disables it otherwise. A disabled control is typically * not selectable from the user interface and draws with an * inactive or "grayed" look. * * @param enabled the new enabled state * * @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 setEnabled(boolean enabled) { checkWidget(); if (enabled) { removeState(DISABLED); } else { addState(DISABLED); } } /** * Returns <code>true</code> if the receiver is enabled, and * <code>false</code> otherwise. A disabled control is typically * not selectable from the user interface and draws with an * inactive or "grayed" look. * * @return the receiver's enabled state * * @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> * * @see #isEnabled */ public boolean getEnabled() { checkWidget(); return !hasState(DISABLED); } /** * Returns <code>true</code> if the receiver is enabled and all * of the receiver's ancestors are enabled, and <code>false</code> * otherwise. A disabled control is typically not selectable from the * user interface and draws with an inactive or "grayed" look. * * @return the receiver's enabled state * * @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> * * @see #getEnabled */ public boolean isEnabled() { checkWidget(); return getEnabled() && parent.isEnabled(); } /** * Returns a point describing the receiver's size. The * x coordinate of the result is the width of the receiver. * The y coordinate of the result is the height of the * receiver. * * @return the receiver's size * * @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 Point getSize() { Point result = parent.getSize(); if ((style & SWT.HORIZONTAL) != 0) { result.y = getScrollBarWidth(); } else { result.x = getScrollBarWidth(); } return result; } /** * Returns the size of the receiver's thumb relative to the * difference between its maximum and minimum values. * * @return the thumb value * * @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> * * @see ScrollBar */ public int getThumb() { checkWidget(); return thumb; } /** * Sets the size of the receiver's thumb relative to the * difference between its maximum and minimum values. This new * value will be ignored if it is less than one, and will be * clamped if it exceeds the receiver's current range. * * @param thumb the new thumb value, which must be at least one and not * larger than the size of the current range * * @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 setThumb(int thumb) { checkWidget(); this.thumb = thumb; } /** * Returns the maximum value which the receiver will allow. * * @return the maximum * * @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 getMaximum() { checkWidget(); return maximum; } /** * Sets the maximum. If this value is negative or less than or * equal to the minimum, the value is ignored. If necessary, first * the thumb and then the selection are adjusted to fit within the * new range. * * @param maximum the new maximum * * @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 setMaximum(int maximum) { checkWidget(); this.maximum = maximum; } /** * Returns the minimum value which the receiver will allow. * * @return the minimum * * @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 getMinimum() { checkWidget(); return minimum; } /** * Sets the minimum value. If this value is negative or greater * than or equal to the maximum, the value is ignored. If necessary, * first the thumb and then the selection are adjusted to fit within * the new range. * * @param minimum the new minimum * * @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 setMinimum(int minimum) { checkWidget(); this.minimum = minimum; } /** * Sets the single <em>selection</em> that is the receiver's * value to the argument which must be greater than or equal * to zero. * * @param selection the new selection (must be zero or greater) * * @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 setSelection(int selection) { checkWidget(); if (this.selection != selection) { this.selection = selection; } } /** * Returns the single 'selection' that is the receiver's value. * * @return the selection * * @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 getSelection() { checkWidget(); return selection; } //////////////////// // SelectionListener /** * Adds the listener to the collection of listeners who will * be notified when the receiver's value changes, by sending * it one of the messages defined in the <code>SelectionListener</code> * interface. * <p> * When <code>widgetSelected</code> is called, the event object detail field contains one of the following values: * <code>SWT.NONE</code> - for the end of a drag. * <code>SWT.DRAG</code>. * <code>SWT.HOME</code>. * <code>SWT.END</code>. * <code>SWT.ARROW_DOWN</code>. * <code>SWT.ARROW_UP</code>. * <code>SWT.PAGE_DOWN</code>. * <code>SWT.PAGE_UP</code>. * <code>widgetDefaultSelected</code> is not called. * </p> * * @param listener the listener which should be notified * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the listener 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> * * @see SelectionListener * @see #removeSelectionListener * @see SelectionEvent */ public void addSelectionListener(SelectionListener listener) { checkWidget(); if (listener == null) { SWT.error(SWT.ERROR_NULL_ARGUMENT); } TypedListener typedListener = new TypedListener(listener); addListener(SWT.Selection, typedListener); addListener(SWT.DefaultSelection, typedListener); } /** * Removes the listener from the collection of listeners who will * be notified when the receiver's value changes. * * @param listener the listener which should no longer be notified * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the listener 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> * * @see SelectionListener * @see #addSelectionListener */ public void removeSelectionListener(SelectionListener listener) { checkWidget(); if (listener == null) { SWT.error(SWT.ERROR_NULL_ARGUMENT); } removeListener(SWT.Selection, listener); removeListener(SWT.DefaultSelection, listener); } @Override @SuppressWarnings("unchecked") public <T> T getAdapter(Class<T> adapter) { if (adapter == WidgetLCA.class) { return (T) ScrollBarLCA.INSTANCE; } return super.getAdapter(adapter); } @Override void releaseParent() { super.releaseParent(); if (parent.horizontalBar == this) { parent.horizontalBar = null; } if (parent.verticalBar == this) { parent.verticalBar = null; } } ////////////////// // Helping methods private static int checkStyle(int style) { return checkBits(style, SWT.HORIZONTAL, SWT.VERTICAL, 0, 0, 0, 0); } private int getScrollBarWidth() { ScrollBarThemeAdapter themeAdapter = (ScrollBarThemeAdapter) getAdapter(ThemeAdapter.class); return themeAdapter.getScrollBarWidth(this); } }