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Learn more about: CWaitCursor Class |
CWaitCursor Class |
11/04/2016 |
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5dfae2ff-d7b6-4383-b0ad-91e0868c67b3 |
Provides a one-line way to show a wait cursor, which is usually displayed as an hourglass, while you're doing a lengthy operation.
class CWaitCursor
| Name | Description |
|---|---|
| CWaitCursor::CWaitCursor | Constructs a CWaitCursor object and displays the wait cursor. |
| Name | Description |
|---|---|
| CWaitCursor::Restore | Restores the wait cursor after it's been changed. |
CWaitCursor does not have a base class.
Good Windows programming practices require that you display a wait cursor whenever you're performing an operation that takes a noticeable amount of time.
To display a wait cursor, just define a CWaitCursor variable before the code that performs the lengthy operation. The object's constructor automatically causes the wait cursor to be displayed.
When the object goes out of scope (at the end of the block in which the CWaitCursor object is declared), its destructor sets the cursor to the previous cursor. In other words, the object performs the necessary clean-up automatically.
Note
Because of how their constructors and destructors work, CWaitCursor objects are always declared as local variables — they're never declared as global variables nor are they allocated with new.
If you perform an operation which might cause the cursor to be changed, such as displaying a message box or dialog box, call the Restore member function to restore the wait cursor. It is okay to call Restore even when a wait cursor is currently displayed.
Another way to display a wait cursor is to use the combination of CCmdTarget::BeginWaitCursor, CCmdTarget::EndWaitCursor, and perhaps CCmdTarget::RestoreWaitCursor. However, CWaitCursor is easier to use because you don't need to set the cursor to the previous cursor when you're done with the lengthy operation.
Note
MFC sets and restores the cursor using the CWinApp::DoWaitCursor virtual function. You can override this function to provide custom behavior.
CWaitCursor
Header: afxwin.h
[!code-cppNVC_MFCWindowing#62]
To display a wait cursor, just declare a CWaitCursor object before the code that performs the lengthy operation.
CWaitCursor();
The constructor automatically causes the wait cursor to be displayed.
When the object goes out of scope (at the end of the block in which the CWaitCursor object is declared), its destructor sets the cursor to the previous cursor. In other words, the object performs the necessary clean-up automatically.
You can take advantage of the fact that the destructor is called at the end of the block (which might be before the end of the function) to make the wait cursor active in only part of your function. This technique is shown in the second example below.
Note
Because of how their constructors and destructors work, CWaitCursor objects are always declared as local variables — they're never declared as global variables, nor are they allocated with new.
[!code-cppNVC_MFCWindowing#63]
To restore the wait cursor, call this function after performing an operation, such as displaying a message box or dialog box, which might change the wait cursor to another cursor.
void Restore();It is OK to call Restore even when the wait cursor is currently displayed.
If you need to restore the wait cursor while in a function other than the one in which the CWaitCursor object is declared, you can call CCmdTarget::RestoreWaitCursor.
[!code-cppNVC_MFCWindowing#64]
Hierarchy Chart
CCmdTarget::BeginWaitCursor
CCmdTarget::EndWaitCursor
CCmdTarget::RestoreWaitCursor
CWinApp::DoWaitCursor
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