Well, thanks. I'll wait a few days, if nobody give a sample code I accept your comment as answer.
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WM_DEVICECHANGE does not want to work
[env: Win2k, MS Visual C++ 7.0, Borland C++ Builder 5.0]
Hi,
I can't get working WM_DEVICECHANGE message. I've found number of samples in MSDN and other places. But this message does not seem to arrive neither to my applications nor samples I've found around the Internet..
I've discovered that there is RegisterDeviceNotification
Thanks in advance.
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Answers
I get WM_DEVICECHANGE messages for a custom USB device without calling RegisterDeviceNotification
a) you get more than one, and I didn't find the additional info meaningful (however, USB documentation was still scarce when I implemented that)
b) while processing the message, I cannot find the device even when it's there. a simple PostMessage - decoupling solved this even with all "evil timing" attempts on all systems
however, for me it was enough to know that "something" happened, and to re-enumerate devices after that.
I should clarify...
You have to register for device notification on 2000 and XP. Windows 95/98/Me seem to send this message without notification. (I don't believe they support the RegisterDeviceNotifcation API anyway)
On XP you'll receive a message with wParam=7 and lParam=0 when there is some type of change, but you don't know what it is.
Hi Alisher,
Problem is my application does not get WM_DEVICECHANGE message when user insert/removes CD under Win2k/XP. So I need to use RegisterDeviceNotification
http://msdn.microsoft.com/
I woould be happy to look at your code - if it will help I accept your comment as answer. If you could, please send sample to mikle@tomsk.net.
Thanks.
I just checked my all code... there is a bad news and good news ;-)
the bad news is that delphi doesn't need any registration for message handlers (it is done on startup internally)
so I declare my handler like:
procedure WMDeviceChange(var msg: TWMDeviceChange); message WM_DEVICECHANGE;
and then write my code in procedure (this is a test):
...
memo1.Lines.Add( 'got WM_DEVICECHANGE message!' );
...
there is nothing else I have to do! no register notification etc etc...
the good news - it works just fine ;-), I checked my USB mouse removal/plug and CD disk change, it works on my system perfectly (w2k)...
what I suggest - I am sending you this my test program compiled with delphi, it shows you in memo area all messages, try to run it and remove/insert CD and look if it works on your system... then we can go further to understand your registration problem...
and about your question 'how to get GIUD' I think this an appropriate function
http://msdn.microsoft.com/
and this a full code example doing what you need and it does not mention any special registration function to be used
http://msdn.microsoft.com/
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by: djdjPosted on 2002-11-11 at 19:48:32ID: 7436425
The problem with WM_DEVICECHANGE on W2K/WXP is that you have to register for the devices you want notification for using the RegisterDeviceNotification
Unfortunately I've never gotten it to work myself. But that should point you in the general direction you need to go.