Java tutorial
/******************************************************************************* * Copyright (c) 2008, 2015 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 org.eclipse.rap.rwt.internal.lifecycle.WidgetLCA; import org.eclipse.rap.rwt.theme.BoxDimensions; 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.sliderkit.SliderLCA; /** * Instances of this class are selectable user interface * objects that represent a range of positive, numeric values. * <p> * At any given moment, a given slider will have a * single 'selection' that is considered to be its * value, which is constrained to be within the range of * values the slider represents (that is, between its * <em>minimum</em> and <em>maximum</em> values). * </p><p> * Typically, sliders 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, sliders 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 slider'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 slider will not change. * </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 ScrollBar * @since 1.2 */ public class Slider extends Control { private final Point PREFERRED_SIZE = new Point(170, 16); private int increment; private int maximum; private int minimum; private int pageIncrement; private int selection; private int thumb; /** * 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#HORIZONTAL * @see SWT#VERTICAL * @see Widget#checkSubclass * @see Widget#getStyle */ public Slider(Composite parent, int style) { super(parent, checkStyle(style)); increment = 1; maximum = 100; minimum = 0; pageIncrement = 10; selection = 0; thumb = 10; } /** * Adds the listener to the collection of listeners who will * be notified when the user changes the receiver's value, 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 when the user changes the receiver's value * * @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 user changes the receiver's value. * * @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); } static int checkStyle(int style) { return checkBits(style, SWT.HORIZONTAL, SWT.VERTICAL, 0, 0, 0, 0); } @Override public Point computeSize(int wHint, int hHint, boolean changed) { checkWidget(); int width, height; if ((style & SWT.HORIZONTAL) != 0) { width = PREFERRED_SIZE.x; height = PREFERRED_SIZE.y; } else { width = PREFERRED_SIZE.y; height = PREFERRED_SIZE.x; } if (wHint != SWT.DEFAULT) { width = wHint; } if (hHint != SWT.DEFAULT) { height = hHint; } BoxDimensions border = getBorder(); width += border.left + border.right; height += border.top + border.bottom; return new Point(width, height); } @Override void createWidget() { super.createWidget(); increment = 1; pageIncrement = 10; maximum = 100; thumb = 10; } /** * Returns the amount that the receiver's value will be * modified by when the up/down (or right/left) arrows * are pressed. * * @return the increment * * @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 getIncrement() { checkWidget(); return increment; } /** * 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; } /** * 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; } /** * Returns the amount that the receiver's value will be * modified by when the page increment/decrement areas * are selected. * * @return the page increment * * @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 getPageIncrement() { checkWidget(); return pageIncrement; } /** * Returns the 'selection', which 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; } /** * 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> */ public int getThumb() { checkWidget(); return thumb; } /** * Sets the amount that the receiver's value will be * modified by when the up/down (or right/left) arrows * are pressed to the argument, which must be at least * one. * * @param value the new increment (must be 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> */ public void setIncrement(int value) { checkWidget(); if (value >= 1 && value <= maximum - minimum) { increment = value; } } /** * 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 value the new maximum, which must be greater than the current 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 setMaximum(int value) { checkWidget(); if (0 <= minimum && minimum < value) { maximum = value; if (selection > maximum - thumb) { selection = maximum - thumb; } } if (thumb >= maximum - minimum) { thumb = maximum - minimum; selection = 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 value 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 value) { checkWidget(); if (0 <= value && value < maximum) { minimum = value; if (selection < minimum) { selection = minimum; } } if (thumb >= maximum - minimum) { thumb = maximum - minimum; selection = minimum; } } /** * Sets the amount that the receiver's value will be * modified by when the page increment/decrement areas * are selected to the argument, which must be at least * one. * * @param value the page increment (must be 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> */ public void setPageIncrement(int value) { checkWidget(); if (value >= 1 && value <= maximum - minimum) { pageIncrement = value; } } /** * Sets the 'selection', which is the receiver's * value, to the argument which must be greater than or equal * to zero. * * @param value 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 value) { checkWidget(); if (value < minimum) { selection = minimum; } else if (value > maximum - thumb) { selection = maximum - thumb; } else { selection = value; } } /** * 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 value 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 value) { checkWidget(); if (value >= 1) { thumb = value; } if (value >= maximum - minimum) { thumb = maximum - minimum; selection = minimum; } } /** * Sets the receiver's selection, minimum value, maximum * value, thumb, increment and page increment all at once. * <p> * Note: This is similar to setting the values individually * using the appropriate methods, but may be implemented in a * more efficient fashion on some platforms. * </p> * * @param selection the new selection value * @param minimum the new minimum value * @param maximum the new maximum value * @param thumb the new thumb value * @param increment the new increment value * @param pageIncrement the new pageIncrement 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> */ public void setValues(int selection, int minimum, int maximum, int thumb, int increment, int pageIncrement) { checkWidget(); if (selection >= minimum && selection <= maximum) { this.selection = selection; } if (0 <= minimum && minimum < maximum) { this.minimum = minimum; if (selection < minimum) { this.selection = minimum; } } if (0 <= minimum && minimum < maximum) { this.maximum = maximum; if (selection > maximum - thumb) { this.selection = maximum - thumb; } } if (thumb >= 1) { this.thumb = thumb; } if (increment >= 1 && increment <= (maximum - minimum)) { this.increment = increment; } if (pageIncrement >= 1 && pageIncrement <= (maximum - minimum)) { this.pageIncrement = pageIncrement; } if (thumb >= maximum - minimum) { this.thumb = maximum - minimum; this.selection = minimum; } } @Override @SuppressWarnings("unchecked") public <T> T getAdapter(Class<T> adapter) { if (adapter == WidgetLCA.class) { return (T) SliderLCA.INSTANCE; } return super.getAdapter(adapter); } @Override boolean isTabGroup() { return true; } }