The Old New Thing

October 2010 - The Old New Thing

It's the Great Pumpkin, Charlie Brown: The world of competitive pumpkin-growing

October 29, 2010 Oct 29, 2010 10/29/10
Raymond Chen
Bill Littlefield of NPR's sports program Only a Game interviews Susan Warren about competitive pumpkin-growing. [Direct link - Real format] An excerpt from her book Backyard Giants was printed in The Wall Street Journal: The Race to Break the Squash Barrier, the quest to grow a one-ton pumpkin. I'm fascinated by these subcultures of ...

Debugging walkthrough: Diagnosing a __purecall failure

October 29, 2010 Oct 29, 2010 10/29/10
Raymond Chen
Prerequisite: Understanding what __purecall means. I was asked to help diagnose an issue in which a program managed to stumble into the __purecall function. The stack at the point of failure looked like this: The line at XYZ!CViewFrame::SetFrame that called the mystic __purecall was a simple AddRef: From what we know of __purecall...

Why is there an LVN_ODSTATECHANGED notification when there's already a perfectly good LVN_ITEMCHANGED notification?

October 28, 2010 Oct 28, 2010 10/28/10
Raymond Chen
If you work with owner-data listviews, you take the responsibility for managing the data associated with each item in the list view. The list view control itself only knows how many items there are; when it needs information about an item, it asks you for it. It's the fancy name for a "virtual list view" control. When you use an ownerdata ...
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How do I programmatically invoke Aero Peek on a window?

October 27, 2010 Oct 27, 2010 10/27/10
Raymond Chen
A customer wanted to know if there was a way for their application to invoke the Aero Peek feature so that their window appeared and all the other windows on the system turned transparent. No, there is no such programmatic interface exposed. Aero Peek is a feature for the user to invoke, not a feature for applications to invoke so they can ...

Belated happy first birthday, Windows 7

October 25, 2010 Oct 25, 2010 10/25/10
Raymond Chen
On Friday, the marketing folks informed me that they decided to put me on the Microsoft Careers United States home page in recognition of Windows 7's first birthday. It's an honor and to be honest a bit scary to be chosen to be the face of Windows on a day of such significance. (They told me that had narrowed it down to me and "some ...

When you call a function, your code doesn't resume execution until that function returns

October 25, 2010 Oct 25, 2010 10/25/10
Raymond Chen
Consider this code fragment: When foo calls bar(), and bar has not yet returned, does foo continue executing? Does baz get called before bar returns? No, it does not. The basic structure of the C/C++ language imposes sequential execution. Control does not return to the foo function until bar returns control, either by reaching the end ...
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The evolution of the ICO file format, part 4: PNG images

October 22, 2010 Oct 22, 2010 10/22/10
Raymond Chen
We finish our tour of the evolution of the ICO file format with the introduction of PNG-compressed images in Windows Vista. The natural way of introducing PNG support for icon images would be to allow the biCompression field of the BITMAP­INFO­HEADER to take the value BI_PNG, in which case the image would be represented not by a ...

The evolution of the ICO file format, part 3: Alpha-blended images

October 21, 2010 Oct 21, 2010 10/21/10
Raymond Chen
Windows XP introduced the ability to provide icon images which contain an 8-bit alpha channel. Up until this point, you had only a 1-bit alpha channel, represented by a mask. The representation of an alpha-blended image in your ICO file is pretty straightforward. Recall that the old ICO format supports 0RGB 32bpp bitmaps. To use an alpha...

How do I get the dimensions of a cursor or icon?

October 20, 2010 Oct 20, 2010 10/20/10
Raymond Chen
Given a HICON or a HCURSOR, how do you get the dimensions of the icon or cursor? The GetIconInfo function gets you most of the way there, returning you an ICONINFO structure which gives you the mask and color bitmaps (and the hotspot, if a cursor). You can then use the GetObject function to get the attributes of the bitmap. And then here's ...
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