fixed NPE
[phpeclipse.git] / net.sourceforge.phpeclipse / src / net / sourceforge / phpdt / internal / ui / util / SWTUtil.java
1 /*******************************************************************************
2  * Copyright (c) 2000, 2003 IBM Corporation and others.
3  * All rights reserved. This program and the accompanying materials 
4  * are made available under the terms of the Common Public License v1.0
5  * which accompanies this distribution, and is available at
6  * http://www.eclipse.org/legal/cpl-v10.html
7  * 
8  * Contributors:
9  *     IBM Corporation - initial API and implementation
10  *******************************************************************************/
11 package net.sourceforge.phpdt.internal.ui.util;
12
13
14 import org.eclipse.swt.SWT;
15 import org.eclipse.swt.dnd.DragSource;
16 import org.eclipse.swt.dnd.DropTarget;
17 import org.eclipse.swt.layout.GridData;
18 import org.eclipse.swt.widgets.Button;
19 import org.eclipse.swt.widgets.Caret;
20 import org.eclipse.swt.widgets.Control;
21 import org.eclipse.swt.widgets.Display;
22 import org.eclipse.swt.widgets.Menu;
23 import org.eclipse.swt.widgets.ScrollBar;
24 import org.eclipse.swt.widgets.Shell;
25 import org.eclipse.swt.widgets.Table;
26 import org.eclipse.swt.widgets.Widget;
27
28 import org.eclipse.jface.dialogs.IDialogConstants;
29 import org.eclipse.jface.resource.JFaceResources;
30 import org.eclipse.jface.util.Assert;
31
32 /**
33  * Utility class to simplify access to some SWT resources. 
34  */
35 public class SWTUtil {
36         
37         /**
38          * Returns the standard display to be used. The method first checks, if
39          * the thread calling this method has an associated disaply. If so, this
40          * display is returned. Otherwise the method returns the default display.
41          */
42         public static Display getStandardDisplay() {
43                 Display display;
44                 display= Display.getCurrent();
45                 if (display == null)
46                         display= Display.getDefault();
47                 return display;         
48         }
49         
50         /**
51          * Returns the shell for the given widget. If the widget doesn't represent
52          * a SWT object that manage a shell, <code>null</code> is returned.
53          * 
54          * @return the shell for the given widget
55          */
56         public static Shell getShell(Widget widget) {
57                 if (widget instanceof Control)
58                         return ((Control)widget).getShell();
59                 if (widget instanceof Caret)
60                         return ((Caret)widget).getParent().getShell();
61                 if (widget instanceof DragSource)
62                         return ((DragSource)widget).getControl().getShell();
63                 if (widget instanceof DropTarget)
64                         return ((DropTarget)widget).getControl().getShell();
65                 if (widget instanceof Menu)
66                         return ((Menu)widget).getParent().getShell();
67                 if (widget instanceof ScrollBar)
68                         return ((ScrollBar)widget).getParent().getShell();
69                                                         
70                 return null;    
71         }
72
73
74         /**
75          * Returns a width hint for a button control.
76          */
77         public static int getButtonWidthHint(Button button) {
78                 if (button.getFont().equals(JFaceResources.getDefaultFont()))
79                         button.setFont(JFaceResources.getDialogFont());
80                 PixelConverter converter= new PixelConverter(button);
81                 int widthHint= converter.convertHorizontalDLUsToPixels(IDialogConstants.BUTTON_WIDTH);
82                 return Math.max(widthHint, button.computeSize(SWT.DEFAULT, SWT.DEFAULT, true).x);
83         }
84
85         /**
86          * Returns a height hint for a button control.
87          */             
88         public static int getButtonHeigthHint(Button button) {
89                 if (button.getFont().equals(JFaceResources.getDefaultFont()))
90                         button.setFont(JFaceResources.getDialogFont());
91                 PixelConverter converter= new PixelConverter(button);
92                 return converter.convertVerticalDLUsToPixels(IDialogConstants.BUTTON_HEIGHT);
93         }       
94
95         
96         /**
97          * Sets width and height hint for the button control.
98          * <b>Note:</b> This is a NOP if the button's layout data is not
99          * an instance of <code>GridData</code>.
100          * 
101          * @param       the button for which to set the dimension hint
102          */             
103         public static void setButtonDimensionHint(Button button) {
104                 Assert.isNotNull(button);
105                 Object gd= button.getLayoutData();
106                 if (gd instanceof GridData) {
107                         ((GridData)gd).heightHint= getButtonHeigthHint(button);
108                         ((GridData)gd).widthHint= getButtonWidthHint(button);            
109                 }
110         }
111         
112         public static int getTableHeightHint(Table table, int rows) {
113                 if (table.getFont().equals(JFaceResources.getDefaultFont()))
114                         table.setFont(JFaceResources.getDialogFont());
115                 int result= table.getItemHeight() * rows + table.getHeaderHeight();
116                 if (table.getLinesVisible())
117                         result+= table.getGridLineWidth() * (rows - 1);
118                 return result;          
119         }
120         
121
122 }