File indexing completed on 2024-04-28 04:20:14

0001 
0002 /*
0003    Copyright (c) 2003-2007 Clarence Dang <dang@kde.org>
0004    All rights reserved.
0005 
0006    Redistribution and use in source and binary forms, with or without
0007    modification, are permitted provided that the following conditions
0008    are met:
0009 
0010    1. Redistributions of source code must retain the above copyright
0011       notice, this list of conditions and the following disclaimer.
0012    2. Redistributions in binary form must reproduce the above copyright
0013       notice, this list of conditions and the following disclaimer in the
0014       documentation and/or other materials provided with the distribution.
0015 
0016    THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
0017    IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
0018    OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
0019    IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
0020    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
0021    NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
0022    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
0023    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
0024    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
0025    THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
0026 */
0027 
0028 
0029 #ifndef kpSetOverrideCursorSaver_H
0030 #define kpSetOverrideCursorSaver_H
0031 
0032 
0033 class QCursor;
0034 
0035 
0036 //
0037 // A less error-prone way of setting the override cursor, compared to
0038 // the QApplication::{set,restore}OverrideCursor() pair.
0039 //
0040 // To use this class, allocate it on the stack with the desired cursor.
0041 //
0042 // This class sets the application's override cursor to <cursor> on
0043 // construction.  It restores the cursor on destruction.
0044 //
0045 // Example Usage 1 - Cursor active during the entire method:
0046 //
0047 //     void method ()
0048 //     {
0049 //         kpSetOverrideCursorSaver cursorSaver (Qt::WaitCursor);
0050 //
0051 //         <potentially time-consuming operation>
0052 //
0053 //     }   // Stack unwinds, calling cursorSaver's destructor,
0054 //         // which restores the cursor
0055 //
0056 // Example Usage 2 - Cursor active during part of the method:
0057 //
0058 //     void method ()
0059 //     {
0060 //         <some code>
0061 //
0062 //         {
0063 //             kpSetOverrideCursorSaver cursorSaver (Qt::WaitCursor);
0064 //
0065 //             <potentially time-consuming operation>
0066 //
0067 //         }   // Stack unwinds, calling cursorSaver's destructor,
0068 //             // which restores the cursor
0069 //
0070 //         // (cursor is restored before this code executes)
0071 //         <more code>
0072 //     }
0073 //
0074 // Note that the kpSetOverrideCursorSaver must be defined as a local
0075 // variable inside -- not outside --- the braces containing the code the
0076 // cursor can be active over, else the destruction and cursor restoration
0077 // might not occur at the right time.  In other words, the following usage
0078 // is wrong:
0079 //
0080 // INCORRECT Example Usage 2:
0081 //
0082 //     void method ()
0083 //     {
0084 //         <some code>
0085 //
0086 //         kpSetOverrideCursorSaver cursorSaver (Qt::WaitCursor);
0087 //         // BUG: These braces do nothing to limit the effect of cursorSaver.
0088 //         {
0089 //             <potentially time-consuming operation>
0090 //         }
0091 //
0092 //         // BUG: cursorSaver has not yet restored the cursor before this
0093 //         //      code executes.
0094 //         <more code>
0095 //
0096 //     }   // Stack unwinds, calling cursorSaver's destructor,
0097 //         // which restores the cursor
0098 //
0099 class kpSetOverrideCursorSaver
0100 {
0101 public:
0102     kpSetOverrideCursorSaver (const QCursor &cursor);
0103     ~kpSetOverrideCursorSaver ();
0104 };
0105 
0106 
0107 #endif  // kpSetOverrideCursorSaver_H