combo.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 controls that allow the user
 * to choose an item from a list of items, or optionally 
 * enter a new value by typing it into an editable text
 * field. Often, <code>Combo</code>s are used in the same place
 * where a single selection <code>List</code> widget could
 * be used but space is limited. A <code>Combo</code> takes
 * less space than a <code>List</code> widget and shows
 * similar information.
 * <p>
 * Note: Since <code>Combo</code>s can contain both a list
 * and an editable text field, it is possible to confuse methods
 * which access one versus the other (compare for example,
 * <code>clearSelection()</code> and <code>deselectAll()</code>).
 * The API documentation is careful to indicate either "the
 * receiver's list" or the "the receiver's text field" to 
 * distinguish between the two cases.
 * </p><p>
 * Note that although this class is a subclass of <code>Composite</code>,
 * it does not make sense to add children to it, or set a layout on it.
 * </p>
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>DROP_DOWN, READ_ONLY, SIMPLE</dd>
 * <dt><b>Events:</b></dt>
 * <dd>DefaultSelection, Modify, Selection</dd>
 * </dl>
 * <p>
 * Note: Only one of the styles DROP_DOWN and SIMPLE 
 * may be specified.
 * </p><p>
 * IMPORTANT: This class is <em>not</em> intended to be subclassed.
 * </p>
 *
 * @see List
 */

public class Combo extends Composite {
	boolean noSelection, ignoreCharacter;
	int visibleCount = 5;
	
	/**
	 * the operating system limit for the number of characters
	 * that the text field in an instance of this class can hold
	 */
	public static final int LIMIT;
	
	/*
	 * These values can be different on different platforms.
	 * Therefore they are not initialized in the declaration
	 * to stop the compiler from inlining.
	 */
	static {
		LIMIT = OS.IsWinNT ? 0x7FFFFFFF : 0x7FFF;	
	}
	
	/*
	 * These are the undocumented control id's for the children of
	 * a combo box.  Since there are no constants for these values,
	 * they may change with different versions of Windows (but have
	 * been the same since Windows 3.0).
	 */
	static final int CBID_LIST = 1000;
	static final int CBID_EDIT = 1001;
	static int EditProc, ListProc;
	
	static final int ComboProc;
	static final TCHAR ComboClass = new TCHAR (0, "COMBOBOX", true);
	static {
		WNDCLASS lpWndClass = new WNDCLASS ();
		OS.GetClassInfo (0, ComboClass, lpWndClass);
		ComboProc = 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#DROP_DOWN
 * @see SWT#READ_ONLY
 * @see SWT#SIMPLE
 * @see Widget#checkSubclass
 * @see Widget#getStyle
 */
public Combo (Composite parent, int style) {
	super (parent, checkStyle (style));
}

/**
 * Adds the argument to the end of the receiver's list.
 *
 * @param string the new item
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string 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>
 * @exception SWTError <ul>
 *    <li>ERROR_ITEM_NOT_ADDED - if the operation fails because of an operating system failure</li>
 * </ul>
 *
 * @see #add(String,int)
 */
public void add (String string) {
	checkWidget ();
	if (string == null) error (SWT.ERROR_NULL_ARGUMENT);
	TCHAR buffer = new TCHAR (getCodePage (), string, true);
	int result = OS.SendMessage (handle, OS.CB_ADDSTRING, 0, buffer);
	if (result == OS.CB_ERR) error (SWT.ERROR_ITEM_NOT_ADDED);
	if (result == OS.CB_ERRSPACE) error (SWT.ERROR_ITEM_NOT_ADDED);
}

/**
 * Adds the argument to the receiver's list at the given
 * zero-relative index.
 * <p>
 * Note: To add an item at the end of the list, use the
 * result of calling <code>getItemCount()</code> as the
 * index or use <code>add(String)</code>.
 * </p>
 *
 * @param string the new item
 * @param index the index for the item
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the string is null</li>
 *    <li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the list (inclusive)</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>
 * @exception SWTError <ul>
 *    <li>ERROR_ITEM_NOT_ADDED - if the operation fails because of an operating system failure</li>
 * </ul>
 *
 * @see #add(String)
 */
public void add (String string, int index) {
	checkWidget ();
	if (string == null) error (SWT.ERROR_NULL_ARGUMENT);
	int count = OS.SendMessage (handle, OS.CB_GETCOUNT, 0, 0);
	if (!(0 <= index && index <= count)) {
		error (SWT.ERROR_INVALID_RANGE);
	}
	TCHAR buffer = new TCHAR (getCodePage (), string, true);
	int result = OS.SendMessage (handle, OS.CB_INSERTSTRING, index, buffer);
	if (result == OS.CB_ERRSPACE || result == OS.CB_ERR) {
		error (SWT.ERROR_ITEM_NOT_ADDED);
	}
}

/**
 * Adds the listener to the collection of listeners who will
 * be notified when the receiver's text is modified, by sending
 * it one of the messages defined in the <code>ModifyListener</code>
 * interface.
 *
 * @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 ModifyListener
 * @see #removeModifyListener
 */
public void addModifyListener (ModifyListener listener) {
	checkWidget ();
	if (listener == null) error (SWT.ERROR_NULL_ARGUMENT);
	TypedListener typedListener = new TypedListener (listener);
	addListener (SWT.Modify, typedListener);
}

/**
 * Adds the listener to the collection of listeners who will
 * be notified when the receiver's selection changes, by sending
 * it one of the messages defined in the <code>SelectionListener</code>
 * interface.
 * <p>
 * <code>widgetSelected</code> is called when the combo's list selection changes.
 * <code>widgetDefaultSelected</code> is typically called when ENTER is pressed the combo's text area.
 * </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;
	return OS.CallWindowProc (ComboProc, handle, msg, wParam, lParam);
}

protected void checkSubclass () {
	if (!isValidSubclass ()) error (SWT.ERROR_INVALID_SUBCLASS);
}

static int checkStyle (int style) {
	/*
	 * Feature in Windows.  It is not possible to create
	 * a combo box that has a border using Windows style
	 * bits.  All combo boxes draw their own border and
	 * do not use the standard Windows border styles.
	 * Therefore, no matter what style bits are specified,
	 * clear the BORDER bits so that the SWT style will
	 * match the Windows widget.
	 *
	 * The Windows behavior is currently implemented on
	 * all platforms.
	 */
	style &= ~SWT.BORDER;
	
	/*
	 * Even though it is legal to create this widget
	 * with scroll bars, they serve no useful purpose
	 * because they do not automatically scroll the
	 * widget's client area.  The fix is to clear
	 * the SWT style.
	 */
	style &= ~(SWT.H_SCROLL | SWT.V_SCROLL);
	style = checkBits (style, SWT.DROP_DOWN, SWT.SIMPLE, 0, 0, 0, 0);
	if ((style & SWT.SIMPLE) != 0) return style & ~SWT.READ_ONLY;
	return style;
}

/**
 * Sets the selection in the receiver's text field to an empty
 * selection starting just before the first character. If the
 * text field is editable, this has the effect of placing the
 * i-beam at the start of the text.
 * <p>
 * Note: To clear the selected items in the receiver's list, 
 * use <code>deselectAll()</code>.
 * </p>
 *
 * @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 #deselectAll
 */
public void clearSelection () {
	checkWidget ();
	OS.SendMessage (handle, OS.CB_SETEDITSEL, 0, -1);
}

public Point computeSize (int wHint, int hHint, boolean changed) {
	checkWidget ();
	int width = 0, height = 0, tmInternalLeading = 0;
	if (wHint == SWT.DEFAULT) {
		int newFont, oldFont = 0;
		int hDC = OS.GetDC (handle);
		newFont = OS.SendMessage (handle, OS.WM_GETFONT, 0, 0);
		if (newFont != 0) oldFont = OS.SelectObject (hDC, newFont);
		int count = OS.SendMessage (handle, OS.CB_GETCOUNT, 0, 0);
		RECT rect = new RECT ();
		int flags = OS.DT_CALCRECT | OS.DT_NOPREFIX;
		if ((style & SWT.READ_ONLY) == 0) flags |= OS.DT_EDITCONTROL;
		int length = OS.GetWindowTextLength (handle);
		int cp = getCodePage ();
		TCHAR buffer = new TCHAR (cp, length + 1);
		OS.GetWindowText (handle, buffer, length + 1);
		OS.DrawText (hDC, buffer, length, rect, flags);
		width = Math.max (width, rect.right - rect.left);
		for (int i=0; i<count; i++) {
			length = OS.SendMessage (handle, OS.CB_GETLBTEXTLEN, i, 0);
			if (length != OS.CB_ERR) {
				if (length + 1 > buffer.length ()) buffer = new TCHAR (cp, length + 1);
				int result = OS.SendMessage (handle, OS.CB_GETLBTEXT, i, buffer);
				if (result != OS.CB_ERR) {
					OS.DrawText (hDC, buffer, length, rect, flags);
					width = Math.max (width, rect.right - rect.left);
				}
			}
		}
		if ((style & SWT.READ_ONLY) != 0) {
			TEXTMETRIC tm = OS.IsUnicode ? (TEXTMETRIC) new TEXTMETRICW () : new TEXTMETRICA ();
			OS.GetTextMetrics (hDC, tm);
			tmInternalLeading = tm.tmInternalLeading;
		}
		if (newFont != 0) OS.SelectObject (hDC, oldFont);
		OS.ReleaseDC (handle, hDC);
	}
	if (hHint == SWT.DEFAULT) {
		if ((style & SWT.SIMPLE) != 0) {
			int count = OS.SendMessage (handle, OS.CB_GETCOUNT, 0, 0);
			int itemHeight = OS.SendMessage (handle, OS.CB_GETITEMHEIGHT, 0, 0);
			height = count * itemHeight;
		}
	}	
	if (width == 0) width = DEFAULT_WIDTH;
	if (height == 0) height = DEFAULT_HEIGHT;
	if (wHint != SWT.DEFAULT) width = wHint;
	if (hHint != SWT.DEFAULT) height = hHint;
	if ((style & SWT.READ_ONLY) != 0) {
		width += tmInternalLeading * 2;
	} else {
		int hwndText = OS.GetDlgItem (handle, CBID_EDIT);
		if (hwndText != 0) {
			int margins = OS.SendMessage (hwndText, OS.EM_GETMARGINS, 0, 0);
			int marginWidth = (margins & 0xFFFF) + ((margins >> 16) & 0xFFFF);
			width += marginWidth + 3;
		}
	}
	int border = OS.GetSystemMetrics (OS.SM_CXEDGE);
	width += OS.GetSystemMetrics (OS.SM_CXVSCROLL) + border * 2;
	int textHeight = OS.SendMessage (handle, OS.CB_GETITEMHEIGHT, -1, 0);
	if ((style & SWT.DROP_DOWN) != 0) {
		height = textHeight + 6;
	} else {
		height += textHeight + 10;
	}
	return new Point (width, height);
}

/**
 * Copies the selected text.
 * <p>
 * The current selection is copied to the clipboard.
 * </p>
 *
 * @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 2.1
 */
public void copy () {
	checkWidget ();
	OS.SendMessage (handle, OS.WM_COPY, 0, 0);
}

void createHandle () {
	super.createHandle ();
	state &= ~CANVAS;

	/* Get the text and list window procs */
	int hwndText = OS.GetDlgItem (handle, CBID_EDIT);
	if (hwndText != 0 && EditProc == 0) {
		EditProc = OS.GetWindowLong (hwndText, OS.GWL_WNDPROC);
	}
	int hwndList = OS.GetDlgItem (handle, CBID_LIST);
	if (hwndList != 0 && ListProc == 0) {
		ListProc = OS.GetWindowLong (hwndList, OS.GWL_WNDPROC);
	}

	/*
	* Bug in Windows.  If the combo box has the CBS_SIMPLE style,
	* the list portion of the combo box is not drawn correctly the
	* first time, causing pixel corruption.  The fix is to ensure
	* that the combo box has been resized more than once.
	*/
	if ((style & SWT.SIMPLE) != 0) {
		int flags = OS.SWP_NOZORDER | OS.SWP_DRAWFRAME | OS.SWP_NOACTIVATE;
		SetWindowPos (handle, 0, 0, 0, 0x3FFF, 0x3FFF, flags);
		SetWindowPos (handle, 0, 0, 0, 0, 0, flags);
	}
}

/**