The Old New Thing

Filtering the folders that appear in the Browse for Folder dialog

October 14, 2013 Oct 14, 2013 10/14/13

Raymond Chen

IFolderFilter.

C++ corner case: You can implement pure virtual functions in the base class

October 11, 2013 Oct 11, 2013 10/11/13

Raymond Chen

In our discussion , we saw that you can declare a pure virtual function with the syntax, and if you try to call one of these functions from the base class, you will get the dreaded R6025 - pure virtual function call error. In that article, I wrote that a pure virtual function is "a method which is declared by the base class, but for which...

How do I find out what size the window manager would have chosen for my window?

October 10, 2013 Oct 10, 2013 10/10/13

Raymond Chen

We saw some time ago how the window manager decides where to place a newly-created window if you pass the values when creating the window. But what if you want to filter the values first? If you pass an explicit upper left corner but pass for the width and height, then the bottom right corner will be down near the bottom right corner of the...

Using the TAB key to navigate in non-dialogs, redux

October 9, 2013 Oct 9, 2013 10/9/13

Raymond Chen

You want to use the TAB key to navigate through a non-dialog, so you call in your message loop, but it doesn't work! The problem here is that you are passing the wrong window handle to . The first parameter to is the dialog-like window you want to be able to navigate through. But the code above passes the window that received the ...

Printing the contents of the clipboard as text to stdout

October 7, 2013 Oct 7, 2013 10/7/13

Raymond Chen

The takes its stdin and puts it on the clipboard. But how do you get it out? That's today's Little Program. (I guess we could call it .) Okay, what do we have here? We open the clipboard and try to get the Unicode text on it. We then look for the null terminator within the first 0x10000000 bytes. Why do I stop at 256MB? Because I'm lazy...

What's the difference between CopyIcon and DuplicateIcon?

October 4, 2013 Oct 4, 2013 10/4/13

Raymond Chen

There are two functions that can be used to create one icon that is identical to another. One of them is . The other is . What's the difference? There isn't any difference. Both functions clone an icon. In fact, their implementations are basically line-for-line identical. Originally, there was just one function to clone an icon: . Windows&...

The relationship between module resources and resource-derived objects in 32-bit Windows

October 3, 2013 Oct 3, 2013 10/3/13

Raymond Chen

Last time, we saw how 16-bit Windows converted resources attached to an EXE or DLL file (which I called module resources for lack of a better term) to user interface resources. As a refresher: During the conversion from 16-bit Windows to 32-bit Windows, some of these rules changed. Specifically, icons, cursors, and accelerator tables are no...

The relationship between module resources and resource-derived objects in 16-bit Windows

October 2, 2013 Oct 2, 2013 10/2/13

Raymond Chen

As we saw last time, in 16-bit Windows, resources attached to an EXE or DLL file (which I called module resources for lack of a better term) were recorded in memory as discardable global memory blocks, and the window manager accessed them directly as needed. For example, if you had an icon or a cursor, the or was really a resource handle, ...

Playing a sound every time the foreground window changes

September 30, 2013 Sep 30, 2013 09/30/13

Raymond Chen

Today's Little Program plays a little sound every time the foreground window changes. One of my colleagues wondered if such a program was possible, "so that I stop accidentally typing the second halves of paragraphs into windows that pop up and steal focus." It's not clear whether this program will actually solve the bigger problem, but it ...

How can I determine how responsive my application is to input?

September 27, 2013 Sep 27, 2013 09/27/13

Raymond Chen

A customer was adding diagnostics to their application and wanted to know if there was a way to detect that the application was being slow in processing its input. These sorts of delays manifest themselves to the end user as a sluggish application which is slow to respond to input events. They already had a watchdog timer that was reset every...