Brief thoughts on right to repair issues people don’t think about

While making devices more repairable is pretty much seen as universally a good thing, right? Unfortunately, engineering involves tradeoffs, but some of those tradeoffs that are seen as bad for repair (or are actually desirable in spite of it), or actually improves reliability. These are some things I suspect right to repair advocates forget.

This article is intended to unify some disparate thoughts on the subject I’ve had on Lobsters comment, this blog (i.e. the ThinkPad one), etc. as one post. I intend to do this more often for other things…

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What systems and applications do I (cb) use?

This is a stream of consciousness (so don’t expect my usual polish) based off of some friends’ musings on the tools they use. I’m doing this to explain some of the tools I use, in the hopes of conveying my feelings on them. I doubt (and sometimes probably hope I won’t) I’ll convince you on the merits or if you should use any of these tools, but you’ll at least know why I care. As I write this, I consider the tools I use to be fairly pedestrian, but perhaps this document might have sentimental or historic interest later. Consider it like usesthis.com – and I also use a Mac!

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Scaling images with alpha blending properly with PHP gd

I had some code trying to scale an image in gd using the imagescale function, that looked something like this:

/* makes a copy of the image, instead of modifying in place */
$target = imagescale($image, $width, $height);

However, the images it created were heavily distorted when using bilinear filtering, and didn’t quite look right with neared neighbour either. For example, with bilinear filtering…

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Portable software is more complex than you think

I’m someone who cares about making software portable. In fact, I actually have a job basically doing so. For most Unix-shaped things (better known as things, since Unix destroyed all competition), the POSIX standard exists to codify common attributes and provide a common ground. Unfortunately, this is made far more complicated by systems both doing many things outside of POSIX’s lowest common denominator, and systems just not implementing POSIX correctly. People tend to think “portability” is whatever operating systems they use, and assuming the lowest common denominator is that. While many guides recommend writing software in a disciplined (or tortured, if you disagree) manner with separate compilation units for platform differences when possible, the reality is your codebase will have #ifdefs and a configure script if it does anything useful. Not to mention the increasing irrelevance of the standard itself.

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Quick and dirty subclassing in Win32

Context: So I wanted to implement drag and drop with files the quick and dirty way; specifically, WM_DROPFILES. (You can also do this with COM, but it’s a bit more involved, especially from raw C. I haven’t written about drag and drop yet, so the comparison is covered elsewhere for now.) My use case is simple, so I didn’t need the benefits or complexity of COM drag and drop. Turns out it’s just marking it as having the extended style in the resource editor or calling DragAcceptFiles, or so I thought. While I could get my dialog to accept the files, I couldn’t get the list view to do so. It turns out that the list view doesn’t handle these messages, nor does it send a notification back to the parent.

One strategy to deal with this is subclassing, although we aren’t going through the formal channels to do. That’s trickier, because it involves using things like CreateWindowEx, and might be a pain with dialog resources that already have a list view. Instead, we’ll actually replace the window procedure out from under the already materialized dialog control – basically monkey patching. In fact, Microsoft’s own documentation mentions this (and a better way with caveats). However, it doesn’t provide a concrete example. This article will quickly show you how, and provides an interesting, if brief example of Windows API principles.

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Notes on the system image list

If you need the icons for files in a Windows program, the easiest way to do so is with the system image list. This is an image list (a resource containing icons, mapped by index) that caches those system icons. The advantage of being an image list is you can easily associate it with a control (like a ListView) and pick out the images by their index, or draw out of it.

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UTF-8 conversion issues on legacy Windows

Short post: On Windows, UTF-16 was the dominant locale, and UTF-8 was something only to convert to and from. (Microsoft jumped the gun before Unicode expanded the address space.) While it got better (Windows 10 can use UTF-8 as an MBCS locale with ANSI APIs), it was historically a lot worse.

For converting, you’d use the MultiByteToWideChar and its opposite WideCharToMultiByte. On legacy Windows, they have slightly confusing semantics. Specifically, with flags. While Vista on introduced many flags that can be used with the UTF-8 codepage (to deal with the quirks of conversion, like invalid characters), previously only MB_ERR_INVALID_CHARS was allowed, and only if you were running XP or 2000 SP4. Before that, you can’t have any flags if you’re converting to or from UTF-16 and UTF-8. It’s unfortunately a little dangerous, but that’s the rub.