The WH_MSGFILTER hook lets you snoop on messages as they travel through modal loops.
A sample program that loses thread messages.
Thread messages (as generated by the function) do not go anywhere when passed to the function. This is obvious if you think about it, because there is no window handle associated with a thread message. has no idea what to do with a message with no associated window. It has no choice but to throw the message away. This has dire consequences ...
The function accepts a parameter. The documentation explains that it is a handle to the DLL containing the hook procedure. Why does the window manager need to have this handle? It needs the handle so it knows which DLL to load into each process when the hook fires. It injects the DLL you pass, then calls the function you pass. Clearly the fu...
I think it's time to update the scratch program we've been using for the past year. I hear there's this new language called C++ that's going to become really popular any day now, so let's hop on the bandwagon! The basic idea of this program is the same as our old scratch program, but now it has that fresh lemony C++ scent. Instead of keeping ou...
Last year I alluded to the fact that the Itanium processor has two stacks. The one that is traditionally thought of as "the stack" (and the one that the register refers to) is a manually managed block of memory from which a function can carve out space to use during its execution. For example, if you declare a local variable like then that buf...
The DC brush is a stock brush associated with the device context. Like the system color brushes, the color of the DC brush changes dynamically, but whereas the system color brushes change color based on the system colors, the color of the DC brush changes at your command. The DC brush is handy when you need a solid color brush for a very shor...
One of the less-understood parameters to the function and the function is the (either passed as a parameter or as part of the structure). The window class name is not sufficient to identify the class uniquely. Each process has its own window class list, and each entry in the window class list consists of an instance handle and a class nam...
We can take our computation of the interval between two moments in time and combine it with the trick we developed for using the powers of mathematics to simplify multi-level comparisons to reduce the amount of work we impose upon the time/date engine. Observe that we avoided a call to the method (which is presumably rather complicated becau...
Computing the interval between two moments in time is easy: It's just subtraction, but subtraction may not be what you want. If you are displaying time units on the order of months and years, then you run into the problem that a month is of variable length. some people just take the value relative to a base date of January 1 and extract the yea...
