Own-thread Win32 splash screen
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Implementation of an own-thread splash screen, with a progress indicator using Win32 and GDI+.
Introduction
Using MFC-based classes -- even with your own threads -- may lead to hang-up of the splash screen repainting while loading the application. This is because MFC has synchronization on the message queue level. So, the application stops responding to the user. CSplashWnd is a class that makes it easy to use splash screens that can always paint themselves. It is implemented using the Win32 API, but you can use it in MFC applications, as well.
How to Use the Class
The CSplashWnd uses GDI+ to show images. It allows you to use a variety of image types including BMP, GIF, JPEG, PNG, TIFF and EMF. However, you have to initialize the GDI+ library:
// Before using CSplashWnd
GdiplusStartupInput gdiplusStartupInput;
ULONG_PTR gdiplusToken;
GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);
...
// Somewhere in the end of your program
GdiplusShutdown(gdiplusToken);
The use of CSplashWnd is very simple. Just add SplashWnd.cpp and SplashWnd.h into your project and then include SplashWnd.h in your program. To initialize the splash screen, use CSplashWnd::SetImage. This method sets the image you want to see while loading the application. It can look like this:
...
CSplashWnd splash;
splash.SetImage(pImage);
splash.Show();
// ... Some long operation
splash.Hide();
...
The splash screen can have a button on the taskbar. It is created only if CSplashWnd::SetWindowName is invoked before CSplashWnd::Show. A button on the taskbar may be useful if the splash screen appears before any window is created. In that case, the user can easily find the application. You can indicate the loading progress using the CSplashWnd::SetProgress method. The first call of CSplashWnd::SetProgress leads to creating a progress control at the bottom of the splash window. It also sets the progress control to the initial state. All subsequent calls just update the progress state.
You could show more details of loading or computing process by passing text description of progress stage to CSplashWnd::SetProgress method using text string or string resource ID as additional input parameter.
...
splash.Show()
splash.SetProgress(0, L"Loading...");
for (int i =0; i < 100; ++i)
{
// compute something
// ...
splash.SetProgress(i);
}
splash.SetProgress(100, L"Done.");
...
If the length of the loading operation is known, you'll want to use the CSplashWnd::SetAutoProgress method. It automatically updates the progress state using its own timer. At the moment, it updates the state one step per second. The previous code will now look like:
...
splash.Show()
splash.SetAutoProgress(0, 100, 100);
for (int i =0; i < 100; ++i)
{
// compute something
// here we know that one loop takes one second
}
...
History
- August 9, 2006 - The class was written.
- May 25, 2007 - Some synchronization has been added and the timer message ID has been fixed.
- June 20, 2008 - New features: multimonitor support, text progress status, support for external resource handles.