Attachment 65206 Details for Bug 22261 – Non-Windows-specifc version of Klaus Wenger's class

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Non-Windows-specifc version of Klaus Wenger's class

TristateButton.java (text/plain), 9.10 KB, created by Mark Melvin

on 2007-04-27 09:35:45 EDT

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Creator: Mark Melvin

Created: 2007-04-27 09:35:45 EDT

Size: 9.10 KB

patch

obsolete

>package com.amis.skt.utils.ui.controls;
>
>import java.lang.reflect.Field;
>import java.lang.reflect.Method;
>
>import org.eclipse.core.runtime.IStatus;
>import org.eclipse.core.runtime.Status;
>import org.eclipse.swt.SWT;
>import org.eclipse.swt.graphics.Color;
>import org.eclipse.swt.widgets.Button;
>import org.eclipse.swt.widgets.Composite;
>import org.eclipse.swt.widgets.Event;
>import org.eclipse.swt.widgets.Listener;
>
>import com.amis.skt.ui.SKTUIPlugin;
>
>/**
> * A checkbox button with three states. To achieve the third state, this class
> * attempts to change the checkbox's colour to gray. This seems to work fine in
> * operating system's like linux, but in Windows due to the nature of the GDI,
> * this does not seem to work. However, Windows has native support for a
> * tri-state checkbox. Thus, in Windows this class attempts to hook into SWT's
> * lower level functions and make direct winapi calls to create the tri-state
> * button. If for any reason the api calls fail, this class will revert to its
> * default algorithm of colouring the button (which probably won't show up
> * properly... but at least there won't be crashes).
> * 
> * The win32 portions of this class are based off Klaus Wenger's code, which was
> * posted as a workaround for Eclipse bug #22261 
> * (https://bugs.eclipse.org/bugs/show_bug.cgi?id=22261). The code has been
> * reflected to ensure that this class will compile on non-Windows platforms.
> * 
> * @author emiranda, <a href="mailto:klaus.wenger@u14n.com">Klaus Wenger</a>
> */
>public class TristateButton extends Button {
>    private boolean grayed;        // The "gray" state flag
>    private boolean eventEn;       // Used for disabling events so that we don't self trigger them
>    private boolean allowUserGray; // Allows users to set the "gray" state by clicking on the checkbox
>    private Class   win32os;       // Reference to the Windows OS class
>    
>    public static final int WIN32_TRISTATE_FAIL = 590;
>    
>    /**
>     * Constructor.
>     */
>    public TristateButton(Composite parent, int style) {
>        this(parent,style,false);
>    }
>    
>    /**
>     * Constructor.
>     */
>    public TristateButton(Composite parent,int style,boolean allowUserGray) {
>        super(parent, style);
>        
>        try {
>            // Try to grab the win32 OS module
>            // This should always work in win32 and always fail on other platforms
>            win32os = getClass().getClassLoader().loadClass("org.eclipse.swt.internal.win32.OS"); //$NON-NLS-1$
>        }
>        catch(ClassNotFoundException ex) {
>            // Looks like we couldn't grab it, so this computer is probably not
>            // running Windows
>            win32os = null;
>        }
>        
>        this.allowUserGray = allowUserGray;
>        
>        eventEn = true;
>        
>        setGrayed(grayed = false);
>        this.addListener(SWT.Selection,new Listener () {
>            public void handleEvent(Event e) {
>                if(!eventEn)
>                    return;
>                
>                if(grayed && win32os == null)
>                    // Since Windows does this natively, we don't need to uncolour if
>                    // the user is running windows
>                    setGrayed(false);
>                else if(TristateButton.this.allowUserGray && !grayed && getSelection())
>                    setGrayed(true);
>                
>                grayed = getGrayed(); // Fix for win32 getting stuck on gray
>            }
>        });
>    }
>
>    protected void checkSubclass () {
>        // Forcing permitted subclassing
>    }
>    
>    protected void checkWidget() {
>        super.checkWidget();
>        
>        if(win32os == null)
>            return;
>        
>        try {
>            Method getWindowLong = win32os.getMethod("GetWindowLong",int.class,int.class); //$NON-NLS-1$
>            Method setWindowLong = win32os.getMethod("SetWindowLong",int.class,int.class,int.class); //$NON-NLS-1$
>            Field  handle        = getClass().getField("handle"); //$NON-NLS-1$
>            Field  gwl_style     = win32os.getField("GWL_STYLE"); //$NON-NLS-1$
>            Field  bs_checkbox   = win32os.getField("BS_CHECKBOX"); //$NON-NLS-1$
>            
>            int bits = ((Integer)getWindowLong.invoke(null,handle.get(this),gwl_style.get(null))).intValue();
>            
>            bits |= BS_3STATE;
>            bits &= ~bs_checkbox.getInt(null);
>            
>            setWindowLong.invoke(null,handle.get(this),gwl_style.get(this),new Integer(bits));
>        }
>        catch(Exception ex) {
>            // Adds a warning to SKT UI's log
>            SKTUIPlugin.log(new Status(IStatus.WARNING, SKTUIPlugin.PLUGIN_SKTUI,
>                    WIN32_TRISTATE_FAIL,"Exception occurred calling native win32 tri-state button",ex)); //$NON-NLS-1$
>            win32os = null;
>        }
>    }
>
>    /**
>     * Allows or disallows the user from setting the "gray" state.
>     */
>    public void setAllowUserGray(boolean allowUserGray) {
>        this.allowUserGray = allowUserGray;
>    }
>    
>    /**
>     * Sets the button into / out of the "gray" state.
>     */
>    public void setGrayed(boolean grayed) {
>        if((getStyle() & SWT.CHECK) == 0)
>            return;
>            
>        if(win32os != null) {
>            try {
>                Method getWindowLong = win32os.getMethod("GetWindowLong",int.class,int.class); //$NON-NLS-1$
>                Method setWindowLong = win32os.getMethod("SetWindowLong",int.class,int.class,int.class); //$NON-NLS-1$
>                Method sendMessage   = win32os.getMethod("SendMessage",int.class,int.class,int.class,int.class); //$NON-NLS-1$
>                Field  handle        = getClass().getField("handle"); //$NON-NLS-1$
>                Field  bst_checked   = win32os.getField("BST_CHECKED"); //$NON-NLS-1$
>                Field  bst_unchecked = win32os.getField("BST_UNCHECKED"); //$NON-NLS-1$
>                Field  gwl_style     = win32os.getField("GWL_STYLE"); //$NON-NLS-1$
>                Field  bm_setcheck   = win32os.getField("BM_SETCHECK"); //$NON-NLS-1$
>            
>                checkWidget();
>                
>                int flags = grayed ? BST_INDETERMINATE : getSelection()
>                        ? bst_checked.getInt(null) : bst_unchecked.getInt(null);
>                
>                /*
>                 * Feature in Windows. When BM_SETCHECK is used
>                 * to set the checked state of a radio or check
>                 * button, it sets the WM_TABSTOP style. This
>                 * is undocumented and unwanted. The fix is
>                 * to save and restore the window style bits.
>                 */
>                int bits = ((Integer)getWindowLong.invoke(null,handle.get(this),gwl_style.get(null))).intValue();
>                sendMessage.invoke(null,handle.get(this),bm_setcheck.get(null),new Integer(flags),new Integer(0));
>                setWindowLong.invoke(null,handle.get(this),gwl_style.get(this),new Integer(bits));
>            }
>            catch(Exception ex) {
>                // Adds a warning to SKT UI's log
>                SKTUIPlugin.log(new Status(IStatus.WARNING, SKTUIPlugin.PLUGIN_SKTUI,
>                        WIN32_TRISTATE_FAIL,"Exception occurred calling native win32 tri-state button",ex)); //$NON-NLS-1$
>                win32os = null;
>                setGrayed(grayed);
>            }
>            return;         
>        }
>        
>        Color c = grayed ? new Color(null,192,192,192) : new Color(null,0,0,0);
>        setForeground(c);
>        
>        this.grayed = grayed;
>        
>        eventEn = false;
>        // Prevent event from being handled locally so we don't get stuct in
>        // a firing / handling loop
>        setSelection(true);
>        eventEn = true;
>    }
>    
>    /**
>     * Checks if the button is in the "gray" state.
>     */
>    public boolean getGrayed() {
>        if((getStyle() & SWT.CHECK) == 0)
>            return false;
>        
>        if(win32os != null) {
>            try {
>                Method sendMessage = win32os.getMethod("SendMessage",int.class,int.class,int.class,int.class); //$NON-NLS-1$
>                Field  handle      = getClass().getField("handle"); //$NON-NLS-1$
>                Field  bm_getcheck = win32os.getField("BM_GETCHECK"); //$NON-NLS-1$
>                
>                checkWidget();
>                
>                int state = ((Integer)sendMessage.invoke(null,handle.get(this),bm_getcheck.get(null),new Integer(0),new Integer(0))).intValue();
>                
>                return (state & BST_INDETERMINATE) != 0;
>            }
>            catch(Exception ex) {
>                // Adds a warning to SKT UI's log
>                SKTUIPlugin.log(new Status(IStatus.WARNING, SKTUIPlugin.PLUGIN_SKTUI,
>                        WIN32_TRISTATE_FAIL,"Exception occurred calling native win32 tri-state button",ex)); //$NON-NLS-1$
>                win32os = null;
>                setGrayed(false);
>            }
>        }
>        
>        return grayed;
>    }
>    
>    private static final int BS_3STATE = 0x00000005;
>    private static final int BST_INDETERMINATE = 0x0002;
>}
>

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Attachments on bug 22261: 27940 | 27941 | 27942 | 45177 | 65176 | 65206