slider.java

源码为Eclipse开源开发平台桌面开发工具SWT的源代码,

/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.widgets;


import org.eclipse.swt.internal.win32.*;
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.events.*;

/**
 * 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 <em>selection</em> 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
 */
public class Slider extends Control {
	int increment, pageIncrement;
	static final int ScrollBarProc;
	static final TCHAR ScrollBarClass = new TCHAR (0, "SCROLLBAR", true);
	static {
		WNDCLASS lpWndClass = new WNDCLASS ();
		OS.GetClassInfo (0, ScrollBarClass, lpWndClass);
		ScrollBarProc = lpWndClass.lpfnWndProc;
	}

/**
 * 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));
}

/**
 * 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>0</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) error (SWT.ERROR_NULL_ARGUMENT);
	TypedListener typedListener = new TypedListener(listener);
	addListener (SWT.Selection,typedListener);
	addListener (SWT.DefaultSelection,typedListener);
}

int callWindowProc (int msg, int wParam, int lParam) {
	if (handle == 0) return 0;
	/*
	* Feature in Windows.  Windows runs a modal message
	* loop when the user drags a scroll bar.  This means
	* that mouse down events won't get delivered until
	* after the loop finishes.  The fix is to run any
	* deferred messages, including mouse down messages
	* before calling the scroll bar window proc.
	*/
	switch (msg) {
		case OS.WM_LBUTTONDOWN:
		case OS.WM_LBUTTONDBLCLK: 
			display.runDeferredEvents ();
	}
	return OS.CallWindowProc (ScrollBarProc, handle, msg, wParam, lParam);
}

static int checkStyle (int style) {
	return checkBits (style, SWT.HORIZONTAL, SWT.VERTICAL, 0, 0, 0, 0);
}

public Point computeSize (int wHint, int hHint, boolean changed) {
	checkWidget ();
	int border = getBorderWidth ();
	int width = border * 2, height = border * 2;
	if ((style & SWT.HORIZONTAL) != 0) {
		width += OS.GetSystemMetrics (OS.SM_CXHSCROLL) * 10;
		height += OS.GetSystemMetrics (OS.SM_CYHSCROLL);
	} else {
		width += OS.GetSystemMetrics (OS.SM_CXVSCROLL);
		height += OS.GetSystemMetrics (OS.SM_CYVSCROLL) * 10;
	}
	if (wHint != SWT.DEFAULT) width = wHint + (border * 2);
	if (hHint != SWT.DEFAULT) height = hHint + (border * 2);
	return new Point (width, height);
}

void createWidget () {
	super.createWidget ();
	increment = 1;
	pageIncrement = 10;
	/*
	* Set the intial values of the maximum
	* to 100 and the thumb to 10.  Note that
	* info.nPage needs to be 11 in order to
	* get a thumb that is 10.
	*/
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	info.fMask = OS.SIF_ALL;
	info.nMax = 100;
	info.nPage = 11;
	OS.SetScrollInfo (handle, OS.SB_CTL, info, true);
}

int defaultBackground () {
	return OS.GetSysColor (OS.COLOR_SCROLLBAR);
}

int defaultForeground () {
	return OS.GetSysColor (OS.COLOR_BTNFACE);
}

void enableWidget (boolean enabled) {
	if (OS.IsWinCE) {
		super.enableWidget (enabled);
	} else {
		int flags = enabled ? OS.ESB_ENABLE_BOTH : OS.ESB_DISABLE_BOTH;
		OS.EnableScrollBar (handle, OS.SB_CTL, flags);
	}
	state &= ~DISABLED;
	if (!enabled) state |= DISABLED;
}

public boolean getEnabled () {
	checkWidget ();
	return (state & DISABLED) == 0;
}

/**
 * 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 ();
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	info.fMask = OS.SIF_RANGE;
	OS.GetScrollInfo (handle, OS.SB_CTL, info);
	return info.nMax;
}

/**
 * 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 ();
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	info.fMask = OS.SIF_RANGE;
	OS.GetScrollInfo (handle, OS.SB_CTL, info);
	return info.nMin;
}

/**
 * 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 single <em>selection</em> 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 ();
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	info.fMask = OS.SIF_POS;
	OS.GetScrollInfo (handle, OS.SB_CTL, info);
	return info.nPos;
}

/**
 * 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 ();
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	info.fMask = OS.SIF_PAGE;
	OS.GetScrollInfo (handle, OS.SB_CTL, info);
	if (info.nPage != 0) --info.nPage;
	return info.nPage;
}

/**
 * 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) error (SWT.ERROR_NULL_ARGUMENT);
	if (eventTable == null) return;
	eventTable.unhook (SWT.Selection, listener);
	eventTable.unhook (SWT.DefaultSelection,listener);	
}

void setBounds (int x, int y, int width, int height, int flags) {
	super.setBounds (x, y, width, height, flags);
	/*
	* Bug in Windows.  If the scroll bar is resized when it has focus,
	* the flashing cursor that is used to show that the scroll bar has
	* focus is not moved.  The fix is to post a fake WM_SETFOCUS to
	* get the scroll bar to recompute the size of the flashing cursor.
	*/
	if (OS.GetFocus () == handle) {
		OS.PostMessage (handle, OS.WM_SETFOCUS, 0, 0);
	}
}

/**
 * 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) return;
	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 (value < 0) return;
	SCROLLINFO info = new SCROLLINFO ();
	info.cbSize = SCROLLINFO.sizeof;
	info.fMask = OS.SIF_RANGE | OS.SIF_DISABLENOSCROLL;
	OS.GetScrollInfo (handle, OS.SB_CTL, info);
	if (value - info.nMin - info.nPage < 1) return;
	info.nMax = value;
	OS.SetScrollInfo (handle, OS.SB_CTL, info, (state & DISABLED) == 0);
		
	/*
	* Feature in Windows.  Using SIF_DISABLENOSCROLL,
	* SetScrollInfo () can change enabled and disabled
	* state of the scroll bar causing a scroll bar that
	* was disabled by the application to become enabled.
	* The fix is to disable the scroll bar (again) when
	* the application has disabled the scroll bar.
	*/