This case is really prevalent there clearly was a work entitled PostQuitMessage so you can article WM_Prevent. PostMessage always works more effectively when you wish so you’re able to replicate a demand otherwise input feel from the post WM_Demand otherwise among the piano otherwise mouse messages (that is always dicey, in addition). So it holds true since “real” input situations always have been in sequences from relevant messages (like keydown/keyup pairs) and your app could get befuddled if you try to help you processes another type of enter in content in the middle of one of these sequences. Article works more effectively when simulating input. Often you must have fun with PostMessage to acquire as much as a beneficial quirk otherwise bug to prevent unlimited recursion. Like, guess your own WM_SETFOCUS handler (OnSetFocus) establishes that the new desire windows isn’t perfect for particular reasoning and you have to change the main focus to another windows.

For those who name SetFocus from the inside your OnSetFocus handler, Screen immediately directs another WM_SETFOCUS messagea€”when you are nonetheless processing the original you to!

The result is unlimited regress up until your stack blows right up. To get rid of this infelicity, you could blog post a contact to yourselfa€”MYWM_SWITCHFOCUSa€”so OnSetFocus can be end one which just process the content to alter the main focus. This is exactly those types of instances that’s more straightforward to see when you look at the habit than just on paper. It is essential to keep in mind would be the fact Windows wouldn’t enable you to SetFocus contained in this a good WM_SETFOCUS handler. Because SendMessage calls brand new window proc individually, it will require an enthusiastic HWND. How else can it understand hence message proc to mention? But PostMessage adds the content on the content queue, that’s regarding the a bond otherwise processes, perhaps not a screen.

// blog post message to me 
PostMessage(NULL, WM_HI_THERE_Handsome, . ); 

Which is, they tries to be nice by providing per software a chance so you’re able to perish gracefully, but if a software does not behave in time, ExitWindowsEx eliminates the app anyway

If your HWND was NULL, PostMessage postings the content to the current running thread’s message waiting line. In practice, this particular aspect actually badly beneficial because most moments we should blog post a message to another thread (perhaps that have PostThreadMessage); but there are constantly unusual points when it’s simpler to create so you’re able to yourself instead of a window. (If you think of every, excite tell me.) In case you think you happen to be beginning to discover when you should use SendMessage and you may PostMessage, you can find around three much more content-sending properties you should know on the: SendMessageCallback, SendNotifyMessage, and you will SendMessageTimeout. Such services are of help about heady realm of Win32A® and you may multithreading. During the Win32, for individuals who name SendMessage their bond was banned until the address bond procedure the content. If the address bond try in itself banned for some most other reasoning, SendMessage never ever yields. Oops. SendNotifyMessage, SendMessageTimeout, and you will SendMessageCallback was indeed designed to work with this condition. SendNotifyMessage functions such as SendMessage in the event your target window is part of (was made by the) the present day thread; it functions including PostMessage when your windows is part of a special thread. SendMessageTimeout is comparable, nevertheless enables you to identify a maximum time for you anticipate the other bond to react. As well crappy, so unfortunate. SendMessageTimeout delays, yet not forever. Since you you are going to imagine, SendMessageCallback takes an effective callback function. They directs the message and production quickly; in the event the content might have been processed, Windows calls your own setting. SendMessageCallback comes in handy when you may like to fool around with PostMessage, however you want to know when the content might have been addressed. Consider it just like the PostMessage which have income acknowledgment. PostMessage, SendMessageTimeout, and SendNotifyMessage all are good candidates to utilize if you would like so you’re able to shown an email to any or all top-level window that with HWND_TOPMOST since the HWND. It is a bad idea to utilize HWND_TOPMOST with SendMessage given that you to dry techniques may bring your app to help you a stop. Profile 2 sumong the different content-sending properties. Whew!