進度條 vc

The progress dialog

It's one of those boring tasks we all hate to do: writing a progress dialog. It ranks right up there with typing "ListView_SetExtendedListViewStyleEx". And even if you're able to reuse an existing dialog, it might not look just the way you want it to, or it might be tough to integrate into your code.

Fortunately, IE 5 saves us from having to build a dialog or write code to handle a Cancel button ever again! The BROWSEUI.DLL file implements a COM interface called IProgressDialog that provides a dialog that looks like the one displayed by Explorer and SHFileOperation().

The progress dialog has these features:

The AVI file should be 272x60 and is subject to the normal restrictions of the animation common control. If you don't have an AVI of your own, MSVC comes with some sample ones (in the /common/graphics/avis directory on the CD), or you can open up shell32.dll in the resource editor and swipe one from there. (If you were wondering, I snagged the AVI in the screen shot above from Internet FastFind.)

Even though the documentation states that you can remove the minimize button from the dialog, this appears to be broken, even in build 2195 of Windows 2000. The dialog will always have a minimize button (for the time being, until Microsoft fixes it).

Since the COM methods have several flags and reserved parameters, I wrote a thin MFC wrapper class, CSHProgressWnd, that makes your code much more readable. The MFC class is not derived from CWnd since the COM interface doesn't provide access to the progress window directly. That means you can use the wrapper even in console apps or other situations where you don't use the CWnd framework. I don't use much MFC stuff (the features I use most are memory validation routines like AfxIsValidString()), so you can very easily remove the dependency on MFC if you so desire.

If you're wondering about the name, I put the "SH" in the class name because MSDN states that the IProgressDialog interface is actually part of shell32.dll (and only available on Windows 2000!), and I used "SH" to indicate that it was a shell feature. I later discovered that the dialog works fine on older versions of Windows, but by that time I'd finished the code.

CSHProgressWnd Functions

Construction/destruction

The CSHProgressWnd constructor creates an IProgressDialog object. On a properly-working system, this will always succeed. However, you can call the IsValid() function if you want to double-check that everything worked. Note that you must initialize OLE (such as with AfxOleInit()) before constructing a CSHProgressWnd object.

The CSHProgressWnd destructor destroys the dialog and releases the COM interface.

Dialog setup

Call these functions to determine how the dialog will look.

void SetTitle ( LPCTSTR szTitle )
Sets the text that appears in the caption bar of the progress dialog.

void SetAnimation ( HINSTANCE hinst, UINT uRsrcID )
void SetAnimation ( UINT uRsrcID )
Specifies a resource containing an AVI that will be shown in the dialog. The first function takes the HINSTANCE of the module containing the resource. The second form uses the return from AfxGetResourceHandle() as the module.

void SetCancelMessage ( LPCTSTR szMessage )
Sets the text that is shown on line 3 when the user clicks the Cancel button.

void SetCalculateTime ( bool bCalculate = true )
Sets whether the progress dialog shows an estimate of the time remaining on line 3. If you don't call SetCalculateTime(), the dialog defaults to showing the time remaining.

void SetAllowMinimize ( bool bAllow = true )
Sets whether the progress dialog includes a minimize button. If you don't call SetAllowMinimize(), the dialog defaults to having a minimize button. NOTE: Calling SetAllowMinimize(false) will not remove the minimize button; this appears to be a bug in the dialog implementation.

void SetShowProgressBar ( bool bShow = true )
Sets whether the progress dialog shows a progress bar. If you don't call SetShowProgressBar(), the dialog defaults to having a progress bar.

Showing the dialog

The progress dialog can be modal or modeless. Call one of these two functions to display the dialog.

HRESULT ShowModal ( CWnd* pwndParent )
Displays the dialog as a modal dialog. pwndParent is a pointer to the parent window. Test the return value with the SUCCEEDED() macro to determine if the dialog was created successfully. If the dialog is not created, the return value is the error returned by the IProgressDialog::StartProgressDialog() method.

HRESULT ShowModeless ( CWnd* pwndParent )
Same as ShowModal(), but the progress dialog is modeless instead of modal.

Updating the progress

void SetLineText ( DWORD dwLine, LPCTSTR szText, bool bCompactPath = false )
Sets one of the three lines of text in the dialog. dwLine can be 1, 2, or 3. Lines 1 and 2 appear between the AVI and the progress bar, and line 3 appears under the progress bar. If you have the dialog calculate the time remaining (by calling SetCalculateTime(true)), the dialog uses line 3 to display the estimated time remaining, and that line is unavailable to SetLineText(). If you are displaying a file name or path, pass true for the third parameter to have the dialog shorten the path so it fits in the dialog.

void UpdateProgress ( DWORD dwProgress, DWORD dwMax )
void UpdateProgress ( DWORD dwProgress )
UpdateProgress() sets the dialog's progress indicator. The first form of the function sets the current and maximum progress values. These may be, for example, 0 and 100, but the exact values are up to you. You must call the first form the first time, then afterwards you can call the second form as long as your maximum progress value does not change. You may freely change the maximum value if you need to, as long as you call the first form whenever the maximum value changes.

void UpdateProgress ( ULONGLONG u64Progress, ULONGLONG u64ProgressMax )
void UpdateProgress ( ULONGLONG u64Progress )
These two functions work like the previous two, except they take 64-bit numbers instead of DWORDs.

Other functions

bool HasUserCanceled()
You should call HasUserCanceled() periodically during your processing, and break out if the function returns true.

void EndDialog()
Call EndDialog() to close the progress dialog. The CSHProgressWnd destructor will also close the dialog if it is still visible.

void ResetTimer()
If you want to reset the timer used by the dialog to estimate the time remaining, call ResetTimer() at the beginning of your processing loop. The dialog uses the time between calls to ResetTimer() and UpdateProgress() to calculate the time remaining. Normally you won't need to call this function; if you don't call it, the dialog will base its estimate on the time elapsed between creation of the dialog (via ShowModal() or ShowModeless()) and the first call to UpdateProgress().

Sample code that uses CSHProgressWnd

Collapse Copy Code

void CMyDialog::ProcessSomeStuff()
{
CSHProgressWnd dlg;
const DWORD    dwMax = 100;
TCHAR          szMsg[256];

    dlg.SetTitle ( _T("Hang on a sec...") );
    dlg.SetAnimation ( IDR_PROGRESS_AVI );
    dlg.SetCancelMessage ( _T("Cancelling this operation...") );
    dlg.SetLineText ( 1, _T("Unzipping files...") );

    if ( FAILED( dlg.ShowModal ( this )))
        return;

    dlg.UpdateProgress ( 0, dwMax );

    for ( DWORD dwProgress = 0;
          dwProgress < dwMax && !dlg.HasUserCanceled();
          dwProgress += 5 )
        {
        DoSomeSlowProcessing();

        wsprintf ( szMsg, _T("I'm %lu%% done"), dwProgress );

        dlg.SetLineText ( 2, szMsg );
        dlg.UpdateProgress ( dwProgress );
        }

    dlg.EndDialog();
}

You can get updates to this and my other articles at http://home.inreach.com/mdunn/code/