org.eclipse.swt.widgets.Button.java Source code

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/*******************************************************************************
 * Copyright (c) 2000, 2019 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
 *     Conrad Groth - Bug 23837 [FEEP] Button, do not respect foreground and background color on Windows
 *******************************************************************************/
package org.eclipse.swt.widgets;

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

/**
 * Instances of this class represent a selectable user interface object that
 * issues notification when pressed and released.
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>ARROW, CHECK, PUSH, RADIO, TOGGLE, FLAT, WRAP</dd>
 * <dd>UP, DOWN, LEFT, RIGHT, CENTER</dd>
 * <dt><b>Events:</b></dt>
 * <dd>Selection</dd>
 * </dl>
 * <p>
 * Note: Only one of the styles ARROW, CHECK, PUSH, RADIO, and TOGGLE
 * may be specified.
 * </p><p>
 * Note: Only one of the styles LEFT, RIGHT, and CENTER may be specified.
 * </p><p>
 * Note: Only one of the styles UP, DOWN, LEFT, and RIGHT may be specified
 * when the ARROW style is specified.
 * </p><p>
 * IMPORTANT: This class is <em>not</em> intended to be subclassed.
 * </p>
 *
 * @see <a href="http://www.eclipse.org/swt/snippets/#button">Button snippets</a>
 * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: ControlExample</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 * @noextend This class is not intended to be subclassed by clients.
 */
public class Button extends Control {
    String text = "", message = "";
    Image image, image2, disabledImage;
    ImageList imageList;
    boolean ignoreMouse, grayed;
    int buttonBackground = -1;
    // we need our own field, because setting Control.background causes two colored pixels around the button.
    int buttonBackgroundAlpha = 255;
    static final int MARGIN = 4;
    static final int CHECK_WIDTH, CHECK_HEIGHT;
    static final int ICON_WIDTH = 128, ICON_HEIGHT = 128;
    static /*final*/ boolean COMMAND_LINK = false;
    static final long ButtonProc;
    static final TCHAR ButtonClass = new TCHAR(0, "BUTTON", true);
    static {
        long hBitmap = OS.LoadBitmap(0, OS.OBM_CHECKBOXES);
        if (hBitmap == 0) {
            CHECK_WIDTH = OS.GetSystemMetrics(OS.SM_CXVSCROLL);
            CHECK_HEIGHT = OS.GetSystemMetrics(OS.SM_CYVSCROLL);
        } else {
            BITMAP bitmap = new BITMAP();
            OS.GetObject(hBitmap, BITMAP.sizeof, bitmap);
            OS.DeleteObject(hBitmap);
            CHECK_WIDTH = bitmap.bmWidth / 4;
            CHECK_HEIGHT = bitmap.bmHeight / 3;
        }
        WNDCLASS lpWndClass = new WNDCLASS();
        OS.GetClassInfo(0, ButtonClass, lpWndClass);
        ButtonProc = 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#ARROW
     * @see SWT#CHECK
     * @see SWT#PUSH
     * @see SWT#RADIO
     * @see SWT#TOGGLE
     * @see SWT#FLAT
     * @see SWT#UP
     * @see SWT#DOWN
     * @see SWT#LEFT
     * @see SWT#RIGHT
     * @see SWT#CENTER
     * @see Widget#checkSubclass
     * @see Widget#getStyle
     */
    public Button(Composite parent, int style) {
        super(parent, checkStyle(style));
    }

    void _setImage(Image image) {
        if ((style & SWT.COMMAND) != 0)
            return;
        if (imageList != null)
            imageList.dispose();
        imageList = null;
        if (image != null) {
            imageList = new ImageList(style & SWT.RIGHT_TO_LEFT);
            if (OS.IsWindowEnabled(handle)) {
                imageList.add(image);
            } else {
                if (disabledImage != null)
                    disabledImage.dispose();
                disabledImage = new Image(display, image, SWT.IMAGE_DISABLE);
                imageList.add(disabledImage);
            }
            BUTTON_IMAGELIST buttonImageList = new BUTTON_IMAGELIST();
            buttonImageList.himl = imageList.getHandle();
            int oldBits = OS.GetWindowLong(handle, OS.GWL_STYLE), newBits = oldBits;
            newBits &= ~(OS.BS_LEFT | OS.BS_CENTER | OS.BS_RIGHT);
            if ((style & SWT.LEFT) != 0)
                newBits |= OS.BS_LEFT;
            if ((style & SWT.CENTER) != 0)
                newBits |= OS.BS_CENTER;
            if ((style & SWT.RIGHT) != 0)
                newBits |= OS.BS_RIGHT;
            if (text.length() == 0) {
                if ((style & SWT.LEFT) != 0)
                    buttonImageList.uAlign = OS.BUTTON_IMAGELIST_ALIGN_LEFT;
                if ((style & SWT.CENTER) != 0)
                    buttonImageList.uAlign = OS.BUTTON_IMAGELIST_ALIGN_CENTER;
                if ((style & SWT.RIGHT) != 0)
                    buttonImageList.uAlign = OS.BUTTON_IMAGELIST_ALIGN_RIGHT;
            } else {
                buttonImageList.uAlign = OS.BUTTON_IMAGELIST_ALIGN_LEFT;
                buttonImageList.margin_left = computeLeftMargin();
                buttonImageList.margin_right = MARGIN;
                newBits &= ~(OS.BS_CENTER | OS.BS_RIGHT);
                newBits |= OS.BS_LEFT;
            }
            if (newBits != oldBits) {
                OS.SetWindowLong(handle, OS.GWL_STYLE, newBits);
                OS.InvalidateRect(handle, null, true);
            }
            OS.SendMessage(handle, OS.BCM_SETIMAGELIST, 0, buttonImageList);
        } else {
            OS.SendMessage(handle, OS.BCM_SETIMAGELIST, 0, 0);
        }
        /*
        * Bug in Windows.  Under certain cirumstances yet to be
        * isolated, BCM_SETIMAGELIST does not redraw the control
        * when a new image is set.  The fix is to force a redraw.
        */
        OS.InvalidateRect(handle, null, true);
    }

    void _setText(String text) {
        int oldBits = OS.GetWindowLong(handle, OS.GWL_STYLE), newBits = oldBits;
        newBits &= ~(OS.BS_LEFT | OS.BS_CENTER | OS.BS_RIGHT);
        if ((style & SWT.LEFT) != 0)
            newBits |= OS.BS_LEFT;
        if ((style & SWT.CENTER) != 0)
            newBits |= OS.BS_CENTER;
        if ((style & SWT.RIGHT) != 0)
            newBits |= OS.BS_RIGHT;
        if (imageList != null) {
            BUTTON_IMAGELIST buttonImageList = new BUTTON_IMAGELIST();
            buttonImageList.himl = imageList.getHandle();
            if (text.length() == 0) {
                if ((style & SWT.LEFT) != 0)
                    buttonImageList.uAlign = OS.BUTTON_IMAGELIST_ALIGN_LEFT;
                if ((style & SWT.CENTER) != 0)
                    buttonImageList.uAlign = OS.BUTTON_IMAGELIST_ALIGN_CENTER;
                if ((style & SWT.RIGHT) != 0)
                    buttonImageList.uAlign = OS.BUTTON_IMAGELIST_ALIGN_RIGHT;
            } else {
                buttonImageList.uAlign = OS.BUTTON_IMAGELIST_ALIGN_LEFT;
                buttonImageList.margin_left = computeLeftMargin();
                buttonImageList.margin_right = MARGIN;
                newBits &= ~(OS.BS_CENTER | OS.BS_RIGHT);
                newBits |= OS.BS_LEFT;
            }
            OS.SendMessage(handle, OS.BCM_SETIMAGELIST, 0, buttonImageList);
        }
        if (newBits != oldBits) {
            OS.SetWindowLong(handle, OS.GWL_STYLE, newBits);
            OS.InvalidateRect(handle, null, true);
        }
        /*
        * Bug in Windows.  When a Button control is right-to-left and
        * is disabled, the first pixel of the text is clipped.  The fix
        * is to append a space to the text.
        */
        if ((style & SWT.RIGHT_TO_LEFT) != 0) {
            if (!OS.IsAppThemed()) {
                text = OS.IsWindowEnabled(handle) ? text : text + " ";
            }
        }
        TCHAR buffer = new TCHAR(getCodePage(), text, true);
        OS.SetWindowText(handle, buffer);
        if ((state & HAS_AUTO_DIRECTION) != 0) {
            updateTextDirection(AUTO_TEXT_DIRECTION);
        }
    }

    /**
     * Adds the listener to the collection of listeners who will
     * be notified when the control is selected by the user, by sending
     * it one of the messages defined in the <code>SelectionListener</code>
     * interface.
     * <p>
     * <code>widgetSelected</code> is called when the control is selected by the user.
     * <code>widgetDefaultSelected</code> is not called.
     * </p>
     * <p>
     * When the <code>SWT.RADIO</code> style bit is set, the <code>widgetSelected</code> method is
     * also called when the receiver loses selection because another item in the same radio group
     * was selected by the user. During <code>widgetSelected</code> the application can use
     * <code>getSelection()</code> to determine the current selected state of the receiver.
     * </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);
    }

    @Override
    long callWindowProc(long hwnd, int msg, long wParam, long lParam) {
        if (handle == 0)
            return 0;
        return OS.CallWindowProc(ButtonProc, hwnd, msg, wParam, lParam);
    }

    static int checkStyle(int style) {
        style = checkBits(style, SWT.PUSH, SWT.ARROW, SWT.CHECK, SWT.RADIO, SWT.TOGGLE,
                COMMAND_LINK ? SWT.COMMAND : 0);
        if ((style & (SWT.PUSH | SWT.TOGGLE)) != 0) {
            return checkBits(style, SWT.CENTER, SWT.LEFT, SWT.RIGHT, 0, 0, 0);
        }
        if ((style & (SWT.CHECK | SWT.RADIO)) != 0) {
            return checkBits(style, SWT.LEFT, SWT.RIGHT, SWT.CENTER, 0, 0, 0);
        }
        if ((style & SWT.ARROW) != 0) {
            style |= SWT.NO_FOCUS;
            return checkBits(style, SWT.UP, SWT.DOWN, SWT.LEFT, SWT.RIGHT, 0, 0);
        }
        return style;
    }

    void click() {
        /*
        * Feature in Windows.  BM_CLICK sends a fake WM_LBUTTONDOWN and
        * WM_LBUTTONUP in order to click the button.  This causes the
        * application to get unexpected mouse events.  The fix is to
        * ignore mouse events when they are caused by BM_CLICK.
        */
        ignoreMouse = true;
        OS.SendMessage(handle, OS.BM_CLICK, 0, 0);
        ignoreMouse = false;
    }

    // TODO: this method ignores the style LEFT, CENTER or RIGHT
    int computeLeftMargin() {
        if ((style & (SWT.PUSH | SWT.TOGGLE)) == 0)
            return MARGIN;
        int margin = 0;
        if (image != null && text.length() != 0) {
            Rectangle bounds = image.getBoundsInPixels();
            margin += bounds.width + MARGIN * 2;
            long oldFont = 0;
            long hDC = OS.GetDC(handle);
            long newFont = OS.SendMessage(handle, OS.WM_GETFONT, 0, 0);
            if (newFont != 0)
                oldFont = OS.SelectObject(hDC, newFont);
            char[] buffer = text.toCharArray();
            RECT rect = new RECT();
            int flags = OS.DT_CALCRECT | OS.DT_SINGLELINE;
            OS.DrawText(hDC, buffer, buffer.length, rect, flags);
            margin += rect.right - rect.left;
            if (newFont != 0)
                OS.SelectObject(hDC, oldFont);
            OS.ReleaseDC(handle, hDC);
            OS.GetClientRect(handle, rect);
            margin = Math.max(MARGIN, (rect.right - rect.left - margin) / 2);
        }
        return margin;
    }

    @Override
    Point computeSizeInPixels(int wHint, int hHint, boolean changed) {
        checkWidget();
        int width = 0, height = 0, border = getBorderWidthInPixels();
        if ((style & SWT.ARROW) != 0) {
            if ((style & (SWT.UP | SWT.DOWN)) != 0) {
                width += OS.GetSystemMetrics(OS.SM_CXVSCROLL);
                height += OS.GetSystemMetrics(OS.SM_CYVSCROLL);
            } else {
                width += OS.GetSystemMetrics(OS.SM_CXHSCROLL);
                height += OS.GetSystemMetrics(OS.SM_CYHSCROLL);
            }
        } else {
            if ((style & SWT.COMMAND) != 0) {
                SIZE size = new SIZE();
                if (wHint != SWT.DEFAULT) {
                    size.cx = wHint;
                    OS.SendMessage(handle, OS.BCM_GETIDEALSIZE, 0, size);
                    width = size.cx;
                    height = size.cy;
                } else {
                    OS.SendMessage(handle, OS.BCM_GETIDEALSIZE, 0, size);
                    width = size.cy;
                    height = size.cy;
                    size.cy = 0;
                    while (size.cy != height) {
                        size.cx = width++;
                        size.cy = 0;
                        OS.SendMessage(handle, OS.BCM_GETIDEALSIZE, 0, size);
                    }
                }
            } else {
                int extra = 0;
                boolean hasImage = image != null, hasText = true;
                if (hasImage) {
                    if (image != null) {
                        Rectangle rect = image.getBoundsInPixels();
                        width = rect.width;
                        if (hasText && text.length() != 0) {
                            width += MARGIN * 2;
                        }
                        height = rect.height;
                        extra = MARGIN * 2;
                    }
                }
                if (hasText) {
                    long oldFont = 0;
                    long hDC = OS.GetDC(handle);
                    long newFont = OS.SendMessage(handle, OS.WM_GETFONT, 0, 0);
                    if (newFont != 0)
                        oldFont = OS.SelectObject(hDC, newFont);
                    TEXTMETRIC lptm = new TEXTMETRIC();
                    OS.GetTextMetrics(hDC, lptm);
                    int length = text.length();
                    if (length == 0) {
                        height = Math.max(height, lptm.tmHeight);
                    } else {
                        extra = Math.max(MARGIN * 2, lptm.tmAveCharWidth);
                        char[] buffer = text.toCharArray();
                        RECT rect = new RECT();
                        int flags = OS.DT_CALCRECT | OS.DT_SINGLELINE;
                        if ((style & SWT.WRAP) != 0 && wHint != SWT.DEFAULT) {
                            flags = OS.DT_CALCRECT | OS.DT_WORDBREAK;
                            rect.right = wHint - width - 2 * border;
                            if (isRadioOrCheck()) {
                                rect.right -= CHECK_WIDTH + 3;
                            } else {
                                rect.right -= 6;
                            }
                            if (!OS.IsAppThemed()) {
                                rect.right -= 2;
                                if (isRadioOrCheck()) {
                                    rect.right -= 2;
                                }
                            }
                        }
                        OS.DrawText(hDC, buffer, buffer.length, rect, flags);
                        width += rect.right - rect.left;
                        height = Math.max(height, rect.bottom - rect.top);
                    }
                    if (newFont != 0)
                        OS.SelectObject(hDC, oldFont);
                    OS.ReleaseDC(handle, hDC);
                }
                if (isRadioOrCheck()) {
                    width += CHECK_WIDTH + extra;
                    height = Math.max(height, CHECK_HEIGHT + 3);
                }
                if ((style & (SWT.PUSH | SWT.TOGGLE)) != 0) {
                    width += 12;
                    height += 10;
                }
            }
        }
        if (wHint != SWT.DEFAULT)
            width = wHint;
        if (hHint != SWT.DEFAULT)
            height = hHint;
        width += border * 2;
        height += border * 2;
        return new Point(width, height);
    }

    @Override
    void createHandle() {
        /*
        * Feature in Windows.  When a button is created,
        * it clears the UI state for all controls in the
        * shell by sending WM_CHANGEUISTATE with UIS_SET,
        * UISF_HIDEACCEL and UISF_HIDEFOCUS to the parent.
        * This is undocumented and unexpected.  The fix
        * is to ignore the WM_CHANGEUISTATE, when sent
        * from CreateWindowEx().
        */
        parent.state |= IGNORE_WM_CHANGEUISTATE;
        super.createHandle();
        parent.state &= ~IGNORE_WM_CHANGEUISTATE;

        if (OS.IsAppThemed()) {
            /* Set the theme background.
            *
            * NOTE: On Vista this causes problems when the tab
            * key is pressed for push buttons so disable the
            * theme background drawing for these widgets for
            * now.
            */
            if ((style & (SWT.PUSH | SWT.TOGGLE)) == 0) {
                state |= THEME_BACKGROUND;
            }

            /*
            * Bug in Windows.  For some reason, the HBRUSH that
            * is returned from WM_CTRLCOLOR is misaligned when
            * the button uses it to draw.  If the brush is a solid
            * color, this does not matter.  However, if the brush
            * contains an image, the image is misaligned.  The
            * fix is to draw the background in WM_CTRLCOLOR.
            *
            * NOTE: For comctl32.dll 6.0 with themes disabled,
            * drawing in WM_ERASEBKGND will draw on top of the
            * text of the control.
            */
            if ((style & SWT.RADIO) != 0) {
                state |= DRAW_BACKGROUND;
            }
        }
    }

    private boolean customBackgroundDrawing() {
        return buttonBackground != -1 && !isRadioOrCheck();
    }

    private boolean customDrawing() {
        return customBackgroundDrawing() || customForegroundDrawing();
    }

    private boolean customForegroundDrawing() {
        return foreground != -1 && !text.isEmpty() && OS.IsWindowEnabled(handle);
    }

    @Override
    int defaultBackground() {
        if ((style & (SWT.PUSH | SWT.TOGGLE)) != 0) {
            return OS.GetSysColor(OS.COLOR_BTNFACE);
        }
        return super.defaultBackground();
    }

    @Override
    int defaultForeground() {
        return OS.GetSysColor(OS.COLOR_BTNTEXT);
    }

    @Override
    void enableWidget(boolean enabled) {
        super.enableWidget(enabled);
        /*
        * Bug in Windows.  When a Button control is right-to-left and
        * is disabled, the first pixel of the text is clipped.  The fix
        * is to append a space to the text.
        */
        if ((style & SWT.RIGHT_TO_LEFT) != 0) {
            if (!OS.IsAppThemed()) {
                int bits = OS.GetWindowLong(handle, OS.GWL_STYLE);
                boolean hasImage = (bits & (OS.BS_BITMAP | OS.BS_ICON)) != 0;
                if (!hasImage) {
                    String string = enabled ? text : text + " ";
                    TCHAR buffer = new TCHAR(getCodePage(), string, true);
                    OS.SetWindowText(handle, buffer);
                }
            }
        }
        /*
        * Bug in Windows.  When a button has the style BS_CHECKBOX
        * or BS_RADIOBUTTON, is checked, and is displaying both an
        * image and some text, when BCM_SETIMAGELIST is used to
        * assign an image list for each of the button states, the
        * button does not draw properly.  When the user drags the
        * mouse in and out of the button, it draws using a blank
        * image.  The fix is to set the complete image list only
        * when the button is disabled.
        */
        updateImageList();
    }

    /**
     * Returns a value which describes the position of the
     * text or image in the receiver. The value will be one of
     * <code>LEFT</code>, <code>RIGHT</code> or <code>CENTER</code>
     * unless the receiver is an <code>ARROW</code> button, in
     * which case, the alignment will indicate the direction of
     * the arrow (one of <code>LEFT</code>, <code>RIGHT</code>,
     * <code>UP</code> or <code>DOWN</code>).
     *
     * @return the alignment
     *
     * @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 getAlignment() {
        checkWidget();
        if ((style & SWT.ARROW) != 0) {
            if ((style & SWT.UP) != 0)
                return SWT.UP;
            if ((style & SWT.DOWN) != 0)
                return SWT.DOWN;
            if ((style & SWT.LEFT) != 0)
                return SWT.LEFT;
            if ((style & SWT.RIGHT) != 0)
                return SWT.RIGHT;
            return SWT.UP;
        }
        if ((style & SWT.LEFT) != 0)
            return SWT.LEFT;
        if ((style & SWT.CENTER) != 0)
            return SWT.CENTER;
        if ((style & SWT.RIGHT) != 0)
            return SWT.RIGHT;
        return SWT.LEFT;
    }

    @Override
    public Color getBackground() {
        if (isRadioOrCheck()) {
            return super.getBackground();
        }
        checkWidget();
        if (buttonBackground != -1) {
            return Color.win32_new(display, buttonBackground, buttonBackgroundAlpha);
        }
        return Color.win32_new(display, defaultBackground());
    }

    boolean getDefault() {
        if ((style & SWT.PUSH) == 0)
            return false;
        int bits = OS.GetWindowLong(handle, OS.GWL_STYLE);
        return (bits & OS.BS_DEFPUSHBUTTON) != 0;
    }

    /**
     * Returns <code>true</code> if the receiver is grayed,
     * and false otherwise. When the widget does not have
     * the <code>CHECK</code> style, return false.
     *
     * @return the grayed state of the checkbox
     *
     * @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 3.4
     */
    public boolean getGrayed() {
        checkWidget();
        if ((style & SWT.CHECK) == 0)
            return false;
        return grayed;
    }

    /**
     * Returns the receiver's image if it has one, or null
     * if it does not.
     *
     * @return the receiver's image
     *
     * @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 Image getImage() {
        checkWidget();
        return image;
    }

    /**
     * Returns the widget message. When the widget is created
     * with the style <code>SWT.COMMAND</code>, the message text
     * is displayed to provide further information for the user.
     *
     * @return the widget message
     *
     * @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 3.3
     */
    /*public*/ String getMessage() {
        checkWidget();
        return message;
    }

    @Override
    String getNameText() {
        return getText();
    }

    /**
     * Returns <code>true</code> if the receiver is selected,
     * and false otherwise.
     * <p>
     * When the receiver is of type <code>CHECK</code> or <code>RADIO</code>,
     * it is selected when it is checked. When it is of type <code>TOGGLE</code>,
     * it is selected when it is pushed in. If the receiver is of any other type,
     * this method returns false.
     *
     * @return the selection 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 getSelection() {
        checkWidget();
        if ((style & (SWT.CHECK | SWT.RADIO | SWT.TOGGLE)) == 0)
            return false;
        return isChecked();
    }

    /**
     * Returns the receiver's text, which will be an empty
     * string if it has never been set or if the receiver is
     * an <code>ARROW</code> button.
     *
     * @return the receiver's text
     *
     * @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 String getText() {
        checkWidget();
        if ((style & SWT.ARROW) != 0)
            return "";
        return text;
    }

    private boolean isChecked() {
        long flags = OS.SendMessage(handle, OS.BM_GETCHECK, 0, 0);
        return flags != OS.BST_UNCHECKED;
    }

    private boolean isRadioOrCheck() {
        return (style & (SWT.RADIO | SWT.CHECK)) != 0;
    }

    @Override
    boolean isTabItem() {
        if ((style & SWT.PUSH) != 0)
            return isTabGroup();
        return super.isTabItem();
    }

    @Override
    boolean mnemonicHit(char ch) {
        if (!setFocus())
            return false;
        /*
        * Feature in Windows.  When a radio button gets focus,
        * it selects the button in WM_SETFOCUS.  Therefore, it
        * is not necessary to click the button or send events
        * because this has already happened in WM_SETFOCUS.
        */
        if ((style & SWT.RADIO) == 0)
            click();
        return true;
    }

    @Override
    boolean mnemonicMatch(char key) {
        char mnemonic = findMnemonic(getText());
        if (mnemonic == '\0')
            return false;
        return Character.toUpperCase(key) == Character.toUpperCase(mnemonic);
    }

    @Override
    void releaseWidget() {
        super.releaseWidget();
        if (imageList != null)
            imageList.dispose();
        imageList = null;
        if (disabledImage != null)
            disabledImage.dispose();
        disabledImage = null;
        if (image2 != null)
            image2.dispose();
        image2 = null;
        text = null;
        image = null;
    }

    /**
     * Removes the listener from the collection of listeners who will
     * be notified when the control is selected by the user.
     *
     * @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);
    }

    @Override
    int resolveTextDirection() {
        return (style & SWT.ARROW) != 0 ? SWT.NONE : BidiUtil.resolveTextDirection(text);
    }

    void selectRadio() {
        /*
        * This code is intentionally commented.  When two groups
        * of radio buttons with the same parent are separated by
        * another control, the correct behavior should be that
        * the two groups act independently.  This is consistent
        * with radio tool and menu items.  The commented code
        * implements this behavior.
        */
        //   int index = 0;
        //   Control [] children = parent._getChildren ();
        //   while (index < children.length && children [index] != this) index++;
        //   int i = index - 1;
        //   while (i >= 0 && children [i].setRadioSelection (false)) --i;
        //   int j = index + 1;
        //   while (j < children.length && children [j].setRadioSelection (false)) j++;
        //   setSelection (true);
        Control[] children = parent._getChildren();
        for (int i = 0; i < children.length; i++) {
            Control child = children[i];
            if (this != child)
                child.setRadioSelection(false);
        }
        setSelection(true);
    }

    /**
     * Controls how text, images and arrows will be displayed
     * in the receiver. The argument should be one of
     * <code>LEFT</code>, <code>RIGHT</code> or <code>CENTER</code>
     * unless the receiver is an <code>ARROW</code> button, in
     * which case, the argument indicates the direction of
     * the arrow (one of <code>LEFT</code>, <code>RIGHT</code>,
     * <code>UP</code> or <code>DOWN</code>).
     *
     * @param alignment the new alignment
     *
     * @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 setAlignment(int alignment) {
        checkWidget();
        if ((style & SWT.ARROW) != 0) {
            if ((style & (SWT.UP | SWT.DOWN | SWT.LEFT | SWT.RIGHT)) == 0)
                return;
            style &= ~(SWT.UP | SWT.DOWN | SWT.LEFT | SWT.RIGHT);
            style |= alignment & (SWT.UP | SWT.DOWN | SWT.LEFT | SWT.RIGHT);
            OS.InvalidateRect(handle, null, true);
            return;
        }
        if ((alignment & (SWT.LEFT | SWT.RIGHT | SWT.CENTER)) == 0)
            return;
        style &= ~(SWT.LEFT | SWT.RIGHT | SWT.CENTER);
        style |= alignment & (SWT.LEFT | SWT.RIGHT | SWT.CENTER);
        int oldBits = OS.GetWindowLong(handle, OS.GWL_STYLE), newBits = oldBits;
        newBits &= ~(OS.BS_LEFT | OS.BS_CENTER | OS.BS_RIGHT);
        if ((style & SWT.LEFT) != 0)
            newBits |= OS.BS_LEFT;
        if ((style & SWT.CENTER) != 0)
            newBits |= OS.BS_CENTER;
        if ((style & SWT.RIGHT) != 0)
            newBits |= OS.BS_RIGHT;
        if (imageList != null) {
            BUTTON_IMAGELIST buttonImageList = new BUTTON_IMAGELIST();
            buttonImageList.himl = imageList.getHandle();
            if (text.length() == 0) {
                if ((style & SWT.LEFT) != 0)
                    buttonImageList.uAlign = OS.BUTTON_IMAGELIST_ALIGN_LEFT;
                if ((style & SWT.CENTER) != 0)
                    buttonImageList.uAlign = OS.BUTTON_IMAGELIST_ALIGN_CENTER;
                if ((style & SWT.RIGHT) != 0)
                    buttonImageList.uAlign = OS.BUTTON_IMAGELIST_ALIGN_RIGHT;
            } else {
                buttonImageList.uAlign = OS.BUTTON_IMAGELIST_ALIGN_LEFT;
                buttonImageList.margin_left = computeLeftMargin();
                buttonImageList.margin_right = MARGIN;
                newBits &= ~(OS.BS_CENTER | OS.BS_RIGHT);
                newBits |= OS.BS_LEFT;
            }
            OS.SendMessage(handle, OS.BCM_SETIMAGELIST, 0, buttonImageList);
        }
        if (newBits != oldBits) {
            OS.SetWindowLong(handle, OS.GWL_STYLE, newBits);
            OS.InvalidateRect(handle, null, true);
        }
    }

    /**
     * Sets the button's background color to the color specified
     * by the argument, or to the default system color for the control
     * if the argument is null.
     * <p>
     * Note: This is custom paint operation and only affects {@link SWT#PUSH} and {@link SWT#TOGGLE} buttons. If the native button
     * has a 3D look an feel (e.g. Windows 7), this method will cause the button to look FLAT irrespective of the state of the
     * {@link SWT#FLAT} style.
     * For {@link SWT#CHECK} and {@link SWT#RADIO} buttons, this method delegates to {@link Control#setBackground(Color)}.
     * </p>
     * @param color the new color (or null)
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_INVALID_ARGUMENT - if the argument has been disposed</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>
     */
    @Override
    public void setBackground(Color color) {
        checkWidget();
        if (isRadioOrCheck()) {
            super.setBackground(color);
        } else {
            setButtonBackground(color);
        }
    }

    private void setButtonBackground(Color color) {
        int pixel = -1;
        int alpha = 255;
        if (color != null) {
            if (color.isDisposed())
                error(SWT.ERROR_INVALID_ARGUMENT);
            pixel = color.handle;
            alpha = color.getAlpha();
        }
        if (pixel == buttonBackground && alpha == buttonBackgroundAlpha)
            return;
        buttonBackground = pixel;
        buttonBackgroundAlpha = alpha;
        updateBackgroundColor();
    }

    void setDefault(boolean value) {
        if ((style & SWT.PUSH) == 0)
            return;
        long hwndShell = menuShell().handle;
        int bits = OS.GetWindowLong(handle, OS.GWL_STYLE);
        if (value) {
            bits |= OS.BS_DEFPUSHBUTTON;
            OS.SendMessage(hwndShell, OS.DM_SETDEFID, handle, 0);
        } else {
            bits &= ~OS.BS_DEFPUSHBUTTON;
            OS.SendMessage(hwndShell, OS.DM_SETDEFID, 0, 0);
        }
        OS.SendMessage(handle, OS.BM_SETSTYLE, bits, 1);
    }

    @Override
    public boolean setFocus() {
        checkWidget();
        /*
        * Feature in Windows.  When a radio button gets focus,
        * it selects the button in WM_SETFOCUS.  The fix is to
        * not assign focus to an unselected radio button.
        */
        if ((style & SWT.RADIO) != 0 && !isChecked() && display.fixFocus)
            return false;
        return super.setFocus();
    }

    /**
     * Sets the receiver's image to the argument, which may be
     * <code>null</code> indicating that no image should be displayed.
     * <p>
     * Note that a Button can display an image and text simultaneously
     * on Windows (starting with XP), GTK+ and OSX.  On other platforms,
     * a Button that has an image and text set into it will display the
     * image or text that was set most recently.
     * </p>
     * @param image the image to display on the receiver (may be <code>null</code>)
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_INVALID_ARGUMENT - if the image has been disposed</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>
     */
    public void setImage(Image image) {
        checkWidget();
        if (image != null && image.isDisposed())
            error(SWT.ERROR_INVALID_ARGUMENT);
        if ((style & SWT.ARROW) != 0)
            return;
        this.image = image;
        /* This code is intentionally commented */
        //   if (OS.COMCTL32_MAJOR < 6) {
        //      if (image == null || text.length () != 0) {
        //         _setText (text);
        //         return;
        //      }
        //   }
        _setImage(image);
    }

    /**
     * Sets the grayed state of the receiver.  This state change
     * only applies if the control was created with the SWT.CHECK
     * style.
     *
     * @param grayed the new grayed 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>
     *
     * @since 3.4
     */
    public void setGrayed(boolean grayed) {
        checkWidget();
        if ((style & SWT.CHECK) == 0)
            return;
        this.grayed = grayed;
        long flags = OS.SendMessage(handle, OS.BM_GETCHECK, 0, 0);
        if (grayed) {
            if (flags == OS.BST_CHECKED)
                updateSelection(OS.BST_INDETERMINATE);
        } else {
            if (flags == OS.BST_INDETERMINATE)
                updateSelection(OS.BST_CHECKED);
        }
    }

    /**
     * Sets the widget message. When the widget is created
     * with the style <code>SWT.COMMAND</code>, the message text
     * is displayed to provide further information for the user.
     *
     * @param message the new message
     *
     * @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>
     *
     * @since 3.3
     */
    /*public*/ void setMessage(String message) {
        checkWidget();
        if (message == null)
            error(SWT.ERROR_NULL_ARGUMENT);
        this.message = message;
        if ((style & SWT.COMMAND) != 0) {
            int length = message.length();
            char[] chars = new char[length + 1];
            message.getChars(0, length, chars, 0);
            OS.SendMessage(handle, OS.BCM_SETNOTE, 0, chars);
        }
    }

    @Override
    boolean setRadioFocus(boolean tabbing) {
        if ((style & SWT.RADIO) == 0 || !getSelection())
            return false;
        return tabbing ? setTabItemFocus() : setFocus();
    }

    @Override
    boolean setRadioSelection(boolean value) {
        if ((style & SWT.RADIO) == 0)
            return false;
        if (getSelection() != value) {
            setSelection(value);
            sendSelectionEvent(SWT.Selection);
        }
        return true;
    }

    /**
     * Sets the selection state of the receiver, if it is of type <code>CHECK</code>,
     * <code>RADIO</code>, or <code>TOGGLE</code>.
     *
     * <p>
     * When the receiver is of type <code>CHECK</code> or <code>RADIO</code>,
     * it is selected when it is checked. When it is of type <code>TOGGLE</code>,
     * it is selected when it is pushed in.
     *
     * @param selected the new selection 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 setSelection(boolean selected) {
        checkWidget();
        if ((style & (SWT.CHECK | SWT.RADIO | SWT.TOGGLE)) == 0)
            return;
        int flags = selected ? OS.BST_CHECKED : OS.BST_UNCHECKED;
        if ((style & SWT.CHECK) != 0) {
            if (selected && grayed)
                flags = OS.BST_INDETERMINATE;
        }
        updateSelection(flags);
    }

    /**
     * Sets the receiver's text.
     * <p>
     * This method sets the button label.  The label may include
     * the mnemonic character but must not contain line delimiters.
     * </p>
     * <p>
     * Mnemonics are indicated by an '&amp;' that causes the next
     * character to be the mnemonic.  When the user presses a
     * key sequence that matches the mnemonic, a selection
     * event occurs. On most platforms, the mnemonic appears
     * underlined but may be emphasized in a platform specific
     * manner.  The mnemonic indicator character '&amp;' can be
     * escaped by doubling it in the string, causing a single
     * '&amp;' to be displayed.
     * </p><p>
     * Note that a Button can display an image and text simultaneously
     * on Windows (starting with XP), GTK+ and OSX.  On other platforms,
     * a Button that has an image and text set into it will display the
     * image or text that was set most recently.
     * </p><p>
     * Also note, if control characters like '\n', '\t' etc. are used
     * in the string, then the behavior is platform dependent.
     * </p>
     * @param string the new text
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the text 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>
     */
    public void setText(String string) {
        checkWidget();
        if (string == null)
            error(SWT.ERROR_NULL_ARGUMENT);
        if ((style & SWT.ARROW) != 0)
            return;
        text = string;
        /* This code is intentionally commented */
        //   if (OS.COMCTL32_MAJOR < 6) {
        //      if (text.length () == 0 && image != null) {
        //         _setImage (image);
        //         return;
        //      }
        //   }
        _setText(string);
    }

    @Override
    boolean updateTextDirection(int textDirection) {
        if (super.updateTextDirection(textDirection)) {
            // TODO: Keep for now, to follow up
            //      int flags = SWT.RIGHT_TO_LEFT | SWT.LEFT_TO_RIGHT;
            //      style &= ~SWT.MIRRORED;
            //      style &= ~flags;
            //      style |= textDirection & flags;
            //      updateOrientation ();
            //      checkMirrored ();
            return true;
        }
        return false;
    }

    void updateImageList() {
        if (imageList != null) {
            BUTTON_IMAGELIST buttonImageList = new BUTTON_IMAGELIST();
            OS.SendMessage(handle, OS.BCM_GETIMAGELIST, 0, buttonImageList);
            if (imageList != null)
                imageList.dispose();
            imageList = new ImageList(style & SWT.RIGHT_TO_LEFT);
            if (OS.IsWindowEnabled(handle)) {
                imageList.add(image);
            } else {
                if (disabledImage != null)
                    disabledImage.dispose();
                disabledImage = new Image(display, image, SWT.IMAGE_DISABLE);
                imageList.add(disabledImage);
            }
            buttonImageList.himl = imageList.getHandle();
            OS.SendMessage(handle, OS.BCM_SETIMAGELIST, 0, buttonImageList);
            /*
            * Bug in Windows.  Under certain cirumstances yet to be
            * isolated, BCM_SETIMAGELIST does not redraw the control
            * when an image is set.  The fix is to force a redraw.
            */
            OS.InvalidateRect(handle, null, true);
        }
    }

    @Override
    void updateOrientation() {
        super.updateOrientation();
        updateImageList();
    }

    void updateSelection(int flags) {
        if (flags != OS.SendMessage(handle, OS.BM_GETCHECK, 0, 0)) {
            /*
            * Feature in Windows. When BM_SETCHECK is used
            * to set the checked state of a radio or check
            * button, it sets the WS_TABSTOP style.  This
            * is undocumented and unwanted.  The fix is
            * to save and restore the window style bits.
            */
            int bits = OS.GetWindowLong(handle, OS.GWL_STYLE);
            if ((style & SWT.CHECK) != 0) {
                if (flags == OS.BST_INDETERMINATE) {
                    bits &= ~OS.BS_CHECKBOX;
                    bits |= OS.BS_3STATE;
                } else {
                    bits |= OS.BS_CHECKBOX;
                    bits &= ~OS.BS_3STATE;
                }
                if (bits != OS.GetWindowLong(handle, OS.GWL_STYLE)) {
                    OS.SetWindowLong(handle, OS.GWL_STYLE, bits);
                }
            }
            OS.SendMessage(handle, OS.BM_SETCHECK, flags, 0);
            if (bits != OS.GetWindowLong(handle, OS.GWL_STYLE)) {
                OS.SetWindowLong(handle, OS.GWL_STYLE, bits);
            }
        }
    }

    @Override
    int widgetStyle() {
        int bits = super.widgetStyle();
        if ((style & SWT.FLAT) != 0)
            bits |= OS.BS_FLAT;
        if ((style & SWT.ARROW) != 0)
            return bits | OS.BS_OWNERDRAW;
        if ((style & SWT.LEFT) != 0)
            bits |= OS.BS_LEFT;
        if ((style & SWT.CENTER) != 0)
            bits |= OS.BS_CENTER;
        if ((style & SWT.RIGHT) != 0)
            bits |= OS.BS_RIGHT;
        if ((style & SWT.WRAP) != 0)
            bits |= OS.BS_MULTILINE;
        if ((style & SWT.PUSH) != 0)
            return bits | OS.BS_PUSHBUTTON | OS.WS_TABSTOP;
        if ((style & SWT.CHECK) != 0)
            return bits | OS.BS_CHECKBOX | OS.WS_TABSTOP;
        if ((style & SWT.RADIO) != 0)
            return bits | OS.BS_RADIOBUTTON;
        if ((style & SWT.TOGGLE) != 0)
            return bits | OS.BS_PUSHLIKE | OS.BS_CHECKBOX | OS.WS_TABSTOP;
        if ((style & SWT.COMMAND) != 0)
            return bits | OS.BS_COMMANDLINK | OS.WS_TABSTOP;
        return bits | OS.BS_PUSHBUTTON | OS.WS_TABSTOP;
    }

    @Override
    TCHAR windowClass() {
        return ButtonClass;
    }

    @Override
    long windowProc() {
        return ButtonProc;
    }

    @Override
    LRESULT WM_GETDLGCODE(long wParam, long lParam) {
        LRESULT result = super.WM_GETDLGCODE(wParam, lParam);
        if (result != null)
            return result;
        if ((style & SWT.ARROW) != 0) {
            return new LRESULT(OS.DLGC_STATIC);
        }
        return result;
    }

    @Override
    LRESULT WM_GETOBJECT(long wParam, long lParam) {
        /*
        * Ensure that there is an accessible object created for this
        * control because support for radio button position in group
        * accessibility is implemented in the accessibility package.
        */
        if ((style & SWT.RADIO) != 0) {
            if (accessible == null)
                accessible = new_Accessible(this);
        }
        return super.WM_GETOBJECT(wParam, lParam);
    }

    @Override
    LRESULT WM_KILLFOCUS(long wParam, long lParam) {
        LRESULT result = super.WM_KILLFOCUS(wParam, lParam);
        if ((style & SWT.PUSH) != 0 && getDefault()) {
            menuShell().setDefaultButton(null, false);
        }
        return result;
    }

    @Override
    LRESULT WM_LBUTTONDOWN(long wParam, long lParam) {
        if (ignoreMouse)
            return null;
        return super.WM_LBUTTONDOWN(wParam, lParam);
    }

    @Override
    LRESULT WM_LBUTTONUP(long wParam, long lParam) {
        if (ignoreMouse)
            return null;
        return super.WM_LBUTTONUP(wParam, lParam);
    }

    @Override
    LRESULT WM_SETFOCUS(long wParam, long lParam) {
        /*
        * Feature in Windows. When Windows sets focus to
        * a radio button, it sets the WS_TABSTOP style.
        * This is undocumented and unwanted.  The fix is
        * to save and restore the window style bits.
        */
        int bits = 0;
        if ((style & SWT.RADIO) != 0) {
            bits = OS.GetWindowLong(handle, OS.GWL_STYLE);
        }
        LRESULT result = super.WM_SETFOCUS(wParam, lParam);
        if ((style & SWT.RADIO) != 0) {
            OS.SetWindowLong(handle, OS.GWL_STYLE, bits);
        }
        if ((style & SWT.PUSH) != 0) {
            menuShell().setDefaultButton(this, false);
        }
        return result;
    }

    @Override
    LRESULT WM_SIZE(long wParam, long lParam) {
        LRESULT result = super.WM_SIZE(wParam, lParam);
        if (result != null)
            return result;
        if ((style & (SWT.PUSH | SWT.TOGGLE)) != 0) {
            if (imageList != null && text.length() != 0) {
                BUTTON_IMAGELIST buttonImageList = new BUTTON_IMAGELIST();
                OS.SendMessage(handle, OS.BCM_GETIMAGELIST, 0, buttonImageList);
                buttonImageList.uAlign = OS.BUTTON_IMAGELIST_ALIGN_LEFT;
                buttonImageList.margin_left = computeLeftMargin();
                buttonImageList.margin_right = MARGIN;
                OS.SendMessage(handle, OS.BCM_SETIMAGELIST, 0, buttonImageList);
            }
        }
        return result;
    }

    @Override
    LRESULT WM_SYSCOLORCHANGE(long wParam, long lParam) {
        LRESULT result = super.WM_SYSCOLORCHANGE(wParam, lParam);
        if (result != null)
            return result;
        if (image2 != null)
            _setImage(image);
        return result;
    }

    @Override
    LRESULT WM_UPDATEUISTATE(long wParam, long lParam) {
        LRESULT result = super.WM_UPDATEUISTATE(wParam, lParam);
        if (result != null)
            return result;
        /*
        * Feature in Windows.  When WM_UPDATEUISTATE is sent to
        * a button, it sends WM_CTLCOLORBTN to get the foreground
        * and background.  If drawing happens in WM_CTLCOLORBTN,
        * it will overwrite the contents of the control.  The
        * fix is draw the button without drawing the background
        * and avoid the button window proc.
        *
        * NOTE:  This only happens for radio, check and toggle
        * buttons.
        */
        if ((style & (SWT.RADIO | SWT.CHECK | SWT.TOGGLE)) != 0) {
            boolean redraw = findImageControl() != null;
            if (!redraw) {
                if ((state & THEME_BACKGROUND) != 0) {
                    if (OS.IsAppThemed()) {
                        redraw = findThemeControl() != null;
                    }
                }
                if (!redraw)
                    redraw = findBackgroundControl() != null;
            }
            if (redraw) {
                OS.InvalidateRect(handle, null, false);
                long code = OS.DefWindowProc(handle, OS.WM_UPDATEUISTATE, wParam, lParam);
                return new LRESULT(code);
            }
        }
        /*
        * Feature in Windows.  Push and toggle buttons draw directly
        * in WM_UPDATEUISTATE rather than damaging and drawing later
        * in WM_PAINT.  This means that clients who hook WM_PAINT
        * expecting to get all the drawing will not.  The fix is to
        * redraw the control when paint events are hooked.
        */
        if ((style & (SWT.PUSH | SWT.TOGGLE)) != 0) {
            if (hooks(SWT.Paint) || filters(SWT.Paint) || customDrawing()) {
                OS.InvalidateRect(handle, null, true);
            }
        }
        return result;
    }

    @Override
    LRESULT wmCommandChild(long wParam, long lParam) {
        int code = OS.HIWORD(wParam);
        switch (code) {
        case OS.BN_CLICKED:
        case OS.BN_DOUBLECLICKED:
            if ((style & (SWT.CHECK | SWT.TOGGLE)) != 0) {
                setSelection(!getSelection());
            } else {
                if ((style & SWT.RADIO) != 0) {
                    if ((parent.getStyle() & SWT.NO_RADIO_GROUP) != 0) {
                        setSelection(!getSelection());
                    } else {
                        selectRadio();
                    }
                }
            }
            sendSelectionEvent(SWT.Selection);
        }
        return super.wmCommandChild(wParam, lParam);
    }

    @Override
    LRESULT wmNotifyChild(NMHDR hdr, long wParam, long lParam) {
        switch (hdr.code) {
        case OS.NM_CUSTOMDRAW:
            // this message will not appear for owner-draw buttons (currently the ARROW button).

            NMCUSTOMDRAW nmcd = new NMCUSTOMDRAW();
            OS.MoveMemory(nmcd, lParam, NMCUSTOMDRAW.sizeof);

            switch (nmcd.dwDrawStage) {
            case OS.CDDS_PREPAINT: {
                // buttons are ignoring SetBkColor, SetBkMode and SetTextColor
                if (customBackgroundDrawing()) {
                    int pixel = buttonBackground;
                    if ((nmcd.uItemState & OS.CDIS_SELECTED) != 0) {
                        pixel = getDifferentColor(buttonBackground);
                    } else if ((nmcd.uItemState & OS.CDIS_HOT) != 0) {
                        pixel = getSlightlyDifferentColor(buttonBackground);
                    }
                    if ((style & SWT.TOGGLE) != 0 && isChecked()) {
                        pixel = getDifferentColor(buttonBackground);
                    }
                    RECT rect = new RECT();
                    OS.SetRect(rect, nmcd.left + 2, nmcd.top + 2, nmcd.right - 2, nmcd.bottom - 2);
                    long brush = OS.CreateSolidBrush(pixel);
                    OS.FillRect(nmcd.hdc, rect, brush);
                    OS.DeleteObject(brush);
                }
                if (customForegroundDrawing()) {
                    /*
                     * Check-box/Radio buttons are native widget which honors
                     * the Win OS zoom level for both 'Square' and 'Text' part
                     * [Note: By-design SWT doesn't control native auto-scaling]
                     * Hence, custom fore-ground draw logic should auto-scale
                     * text-padding as per OS Native DPI level to fix bug 506371
                     */
                    int radioOrCheckTextPadding = DPIUtil.autoScaleUpUsingNativeDPI(16);
                    int border = isRadioOrCheck() ? 0 : 3;
                    int left = nmcd.left + border;
                    int right = nmcd.right - border;
                    if (image != null) {
                        GCData data = new GCData();
                        data.device = display;
                        GC gc = GC.win32_new(nmcd.hdc, data);

                        int margin = computeLeftMargin();
                        int imageWidth = image.getBoundsInPixels().width;
                        left += (imageWidth + (isRadioOrCheck() ? 2 * MARGIN : MARGIN)); // for SWT.RIGHT_TO_LEFT right and left are inverted

                        int x = margin + (isRadioOrCheck() ? radioOrCheckTextPadding : 3);
                        int y = Math.max(0, (nmcd.bottom - image.getBoundsInPixels().height) / 2);
                        gc.drawImage(image, DPIUtil.autoScaleDown(x), DPIUtil.autoScaleDown(y));
                        gc.dispose();
                    }

                    left += isRadioOrCheck() ? radioOrCheckTextPadding : 0;
                    RECT textRect = new RECT();
                    OS.SetRect(textRect, left, nmcd.top + border, right, nmcd.bottom - border);

                    // draw text
                    char[] buffer = text.toCharArray();
                    int flags = 0;
                    if ((style & SWT.WRAP) != 0) {
                        flags |= OS.DT_WORDBREAK;
                        if (!isRadioOrCheck() && image != null) {
                            textRect.right -= MARGIN;
                        }
                    } else {
                        flags |= OS.DT_SINGLELINE; // TODO: this always draws the prefix
                    }
                    OS.DrawText(nmcd.hdc, buffer, buffer.length, textRect, flags | OS.DT_CALCRECT);
                    OS.OffsetRect(textRect, 0, Math.max(0, (nmcd.bottom - textRect.bottom - border) / 2));
                    if (image != null) {
                        // The default button with an image doesn't respect the text alignment. So we do the same for styled buttons.
                        flags |= OS.DT_LEFT;
                        if (!isRadioOrCheck()) {
                            OS.OffsetRect(textRect, Math.max(MARGIN, (right - textRect.right) / 2 + 1), 0);
                        }
                    } else if ((style & SWT.LEFT) != 0) {
                        flags |= OS.DT_LEFT;
                    } else if ((style & SWT.RIGHT) != 0) {
                        flags |= OS.DT_RIGHT;
                        OS.OffsetRect(textRect, right - textRect.right, 0);
                    } else {
                        flags |= OS.DT_CENTER;
                        OS.OffsetRect(textRect, (right - textRect.right) / 2, 0);
                    }
                    OS.SetBkMode(nmcd.hdc, OS.TRANSPARENT);
                    OS.SetTextColor(nmcd.hdc, foreground);
                    OS.DrawText(nmcd.hdc, buffer, buffer.length, textRect, flags);

                    // draw focus rect
                    if ((nmcd.uItemState & OS.CDIS_FOCUS) != 0) {
                        RECT focusRect = new RECT();
                        if (isRadioOrCheck()) {
                            if (text.length() > 0) {
                                OS.SetRect(focusRect, textRect.left - 1, textRect.top,
                                        Math.min(nmcd.right, textRect.right + 1),
                                        Math.min(nmcd.bottom, textRect.bottom + 1));
                            } else {
                                /*
                                 * With custom foreground, draw focus rectangle for CheckBox
                                 * and Radio buttons considering the native text padding
                                 * value(which is DPI aware). See bug 508141 for details.
                                 */
                                OS.SetRect(focusRect, nmcd.left + 1 + radioOrCheckTextPadding, nmcd.top,
                                        nmcd.right - 2, nmcd.bottom - 1);
                            }
                        } else {
                            OS.SetRect(focusRect, nmcd.left + 2, nmcd.top + 3, nmcd.right - 2, nmcd.bottom - 3);
                        }
                        OS.DrawFocusRect(nmcd.hdc, focusRect);
                    }
                    return new LRESULT(OS.CDRF_SKIPDEFAULT);
                }
                return new LRESULT(OS.CDRF_DODEFAULT);
            }
            }
            break;
        }
        return super.wmNotifyChild(hdr, wParam, lParam);
    }

    @Override
    LRESULT wmDrawChild(long wParam, long lParam) {
        if ((style & SWT.ARROW) == 0)
            return super.wmDrawChild(wParam, lParam);
        DRAWITEMSTRUCT struct = new DRAWITEMSTRUCT();
        OS.MoveMemory(struct, lParam, DRAWITEMSTRUCT.sizeof);
        RECT rect = new RECT();
        OS.SetRect(rect, struct.left, struct.top, struct.right, struct.bottom);
        if (OS.IsAppThemed()) {
            int iStateId = OS.ABS_LEFTNORMAL;
            switch (style & (SWT.UP | SWT.DOWN | SWT.LEFT | SWT.RIGHT)) {
            case SWT.UP:
                iStateId = OS.ABS_UPNORMAL;
                break;
            case SWT.DOWN:
                iStateId = OS.ABS_DOWNNORMAL;
                break;
            case SWT.LEFT:
                iStateId = OS.ABS_LEFTNORMAL;
                break;
            case SWT.RIGHT:
                iStateId = OS.ABS_RIGHTNORMAL;
                break;
            }
            /*
            * Feature in Windows.  DrawThemeBackground() does not mirror the drawing.
            * The fix is switch left to right and right to left.
            */
            if ((style & SWT.MIRRORED) != 0) {
                if ((style & (SWT.LEFT | SWT.RIGHT)) != 0) {
                    iStateId = iStateId == OS.ABS_RIGHTNORMAL ? OS.ABS_LEFTNORMAL : OS.ABS_RIGHTNORMAL;
                }
            }
            /*
            * NOTE: The normal, hot, pressed and disabled state is
            * computed relying on the fact that the increment between
            * the direction states is invariant (always separated by 4).
            */
            if (!getEnabled())
                iStateId += OS.ABS_UPDISABLED - OS.ABS_UPNORMAL;
            if ((struct.itemState & OS.ODS_SELECTED) != 0)
                iStateId += OS.ABS_UPPRESSED - OS.ABS_UPNORMAL;
            OS.DrawThemeBackground(display.hScrollBarTheme(), struct.hDC, OS.SBP_ARROWBTN, iStateId, rect, null);
        } else {
            int uState = OS.DFCS_SCROLLLEFT;
            switch (style & (SWT.UP | SWT.DOWN | SWT.LEFT | SWT.RIGHT)) {
            case SWT.UP:
                uState = OS.DFCS_SCROLLUP;
                break;
            case SWT.DOWN:
                uState = OS.DFCS_SCROLLDOWN;
                break;
            case SWT.LEFT:
                uState = OS.DFCS_SCROLLLEFT;
                break;
            case SWT.RIGHT:
                uState = OS.DFCS_SCROLLRIGHT;
                break;
            }
            if (!getEnabled())
                uState |= OS.DFCS_INACTIVE;
            if ((style & SWT.FLAT) == SWT.FLAT)
                uState |= OS.DFCS_FLAT;
            if ((struct.itemState & OS.ODS_SELECTED) != 0)
                uState |= OS.DFCS_PUSHED;
            OS.DrawFrameControl(struct.hDC, rect, OS.DFC_SCROLL, uState);
        }
        return null;
    }

}