November 2006 | Page 2 of 3 | The Old New Thing

The window manager moves the mouse; applications choose the cursor

Raymond ChenNovember 17, 2006Nov 17, 200611/17/06

You can sometimes narrow down the source of a problem just by looking at the screen and moving the mouse. When you move the mouse, the cursor on the screen moves to match. This work is done in the window manager in kernel mode. The mouse hardware notifies the window manager, "Hey, I moved left twenty units." The window manager takes this ...

Using DIB sections to perform bulk color mapping

Raymond ChenNovember 16, 2006Nov 16, 200611/16/06

When doing dithering, one operation you have to do for every pixel is map it (more accurately, map a modified version of it) to the nearest color in your available palette. Since this is part of the dithering inner loop, you need this operation to be as fast as possible.¹ A common technique for this is to precompute the nearest palette ...

Manipulating the DIB color table for fun and profit

Raymond ChenNovember 15, 2006Nov 15, 200611/15/06

If you create a DIB section at 8bpp or lower, then it will come with a color table. Pixels in the bitmap are represented not by their red/blue/green component values, but are instead indices into the color table. For example, a 4bpp DIB section can have up to sixteen colors in its color table. Although displays that use 8bpp or lower are ...

Keeping classic hardware alive through emulation

Raymond ChenNovember 14, 2006Nov 14, 200611/14/06

At the Windows 2000 Conference and Expo which coincided with the operating system's launch, I paid a visit to the emulators.com booth, where they were excitedly showing off SoftMac 2000, a Mac emulator that ran on Windows 2000. Emulator trivia: MacOS booted in five seconds under Windows 2000, which was faster than the real ...

Blitting between color and monochrome DCs

Raymond ChenNovember 14, 2006Nov 14, 200611/14/06

When blitting between color and monochrome DCs, The text foreground and background colors play a role. We saw earlier that when blitting from a monochrome DC to a color DC, the color black in the source turns into the destination's text color, and the color white in the source turns into the destination's background color. This came in handy...

New dessert lounge: Coco la ti da

Raymond ChenNovember 13, 2006Nov 13, 200611/13/06

After a Seattle Symphony concert, it has long been a tradition among my friends to walk the three blocks from Benaroya Hall, up University Street, past Luly Yang Couture to gawk at the jaw-dropping gowns in the window (the pictures on the web site fail to capture their fabulousness), arriving at the W Hotel, home of Earth & Ocean, where...

What do bitwise operations mean for colors?

Raymond ChenNovember 13, 2006Nov 13, 200611/13/06

Someday, you're going to pass a raster operation to the BitBlt function that entails bit manipulation. Something like SRCAND perhaps, or possibly the dreaded SRCINVERT. These bitwise operations make perfect sense for monochrome bitmaps, since those are one bit per pixel anyway. But what does it mean for color bitmaps? What do you get when you...

Converting an HRESULT to a Win32 error code: Diagram and answer to exercise

Raymond ChenNovember 10, 2006Nov 10, 200611/10/06

Here's the diagram from How do I convert an HRESULT to a Win32 error code?. If you are offended by VML, cover your ears and hum for a while. The little sliver at the top is the mapping of zero to zero. The big white box at the bottom is the mapping of all negative numbers to corresponding negative numbers. And the rainbow represents the...

A modest proposal: Solving the problem of steroids in baseball

Raymond ChenNovember 9, 2006Nov 9, 200611/9/06

In recent years, the issue of steroids in baseball has been the source of much hand-wringing. Some people argue that steroids are ruining the game. Others say that you can't go around trampling the Bill of Rights and punishing people for doing things that are perfectly legal anyway. To resolve this issue, I present this modest proposal...

Why can't you use the Tab key to select items from the auto-complete drop-down?