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PeekMessage changed in Windows 10?

ProgrammerDX · 2015-08-14T06:54:54

Hey all, I noticed in Windows 10 some oddities with PeekMessage. It's doing undocumented things. One PeekMessage call would send MULTIPLE messages to the WndProc and then return zero (no messages according to msdn). That's weird because: 1. It's processing more than one message in one PeekMessage call 2. It's returning zero You can test this by creating a default Win32 app in Visual Studio, and then making the following simple changes: /*(global var)*/ bool exitapp = false; //.... in _tWinMain // Main message loop: while( !exitapp ) { OutputDebugStringA( "CALL 1\n" ); if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) { if( msg.message == WM_QUIT ) { return msg.wParam; } char tmp[256]; wsprintfA( tmp, "PEEKED %d\n", msg.message ); OutputDebugStringA( tmp ); if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg)) { TranslateMessage(&msg); DispatchMessage(&msg); } } else { OutputDebugStringA( "none\n" ); } OutputDebugStringA( "CALL 2\n" ); } //... //... in WndProc at the top char tmp[256]; wsprintfA( tmp, "WndProc %d\n", message ); OutputDebugStringA( tmp ); //... case WM_CLOSE: exitapp = true; break; Anyone know what's going on? it messes with my engine that expects PeekMessage to process only one message. Greetings,

General and Gameplay Programming Programming

Started by ProgrammerDX August 13, 2015 11:55 AM

12 comments, last by rave3d 8 years, 8 months ago

Erik Rufelt

5,903

August 13, 2015 05:47 PM

I think you misunderstood samoth's post.. at least unless I completely missed the point. He says it's easy to get an impression from MSDN that couldn't possibly be true..

SmkViper

5,396

August 13, 2015 09:39 PM

I think you misunderstood samoth's post.. at least unless I completely missed the point. He says it's easy to get an impression from MSDN that couldn't possibly be true..

If so then my sarcasm meter is broken today... (which is entirely possible, it's been a long week)

Brain

19,059

August 13, 2015 11:42 PM

whereas the ones sent on starting the app for example are probably sent by a separate thread that handles the starting of that particular program (cursor turns to hour-glass and the app has 10 seconds I think to set up properly and become response, and otherwise you get "unresponsive" notifications if there's a window and waiting is stopped).

In my experience the hung app notification is triggered if an app hasn't responded to any posted message within around 10 seconds.

You'll also notice that C++ programs built with the debug profile in visual studio may not trigger the hung app notification whilst release mode programs do.

This is again one of those things that are undocumented and I noticed this whilst debugging a badly behaved loading screen.

Just thought you might find this useful! :)

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Khatharr

8,814

August 14, 2015 01:34 AM

I initially encountered this behavior in Win7 when I found that I couldn't catch certain messages outside of the proc. (It looks like you may be trying to do the same thing I was trying to do, actually.)

void hurrrrrrrr() {__asm sub [ebp+4],5;}

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rave3d

691

August 14, 2015 06:54 AM

I can understand how this confusion can be happen.

There are lots of tutorials out in the internet using PeekMessage just as the OP does. Most of them never mention that PeekMessage automatically dispatches the messages.

So someone start as a little programmer having even difficulties with the language itself and relies on the tutorial and it just works.

If you use something for years in a specific way and it works, you are never going to read API documentation until the first time it fails.

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