41–50 of 62 posts
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Is anybody else having problems with notifo-based comment notifications? I am receiving them, but the links stopped working sometime between Jan. 22 and March 8.
http://blog.notifo.com/notifo
This is dumb. The fact that one pixel subtends a particular visual angle does not imply that N pixels subtend N times that angle. It should be very plain to anybody implementing or using a rendering engine that pixels are intended to be linearly additive. This implies that N pixels will subtend less than N times the angle one pixel subtends. On a flat screen, this is normal and expected, because a pixel further from…
You're right, and the article linked here is wrong. The CSS spec doesn't say that px is an angular measurement, and the formula given that is supposed to convert between px and radians has no basis in the spec. The spec specifically defines px as a length; angular measurements only become relevant in calculating the reference pixel, which is a length used to define the size of 1px in circumstances where physical pixe…
> It is recommended that the reference pixel be the visual angle of one pixel on a device with a pixel density of 96dpi and a distance from the reader of an arm's length. For a nominal arm's length of 28 inches...
It would seem that the reference pixel is simply 1/2688 of the typical distance between your eyes and the device. If a device is meant to be used at half the "arm's length" distance (14 in), the reference pixel on that device would be only half as large. If a device is meant to be used at 3x times the distance (84 in), the reference pixel would be 3x larger. Much easier than angular diameters.
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The fact that this measurement is an approximation (and a very good one in fact) doesn't make it "dumb". In fact, it's flat displays that are "dumb". An optimal display would be curved so that each pixel subtends a roughly equal visual angle, and it's only the fact that most displays subtend a relatively small visual angle that allows us to approximate this with flat displays.
A curved display (let's say, spherical) centered approximately at the "primary" observer's eyeballs whose pixel elements all subtend equal solid angles would (a) lead to weird unintuitive and hard-to-program-for locations in their most natural expressions the further you wandered from the center-horizontal or center-vertical row/column of pixels; (b) make it very hard to those whose eyeballs aren't smack-dab in the c…
This is one of the more important Hacker News submissions I've seen in a long time. It seems that there is, potentially, a fundamental disconnect between what "px" is supposed to mean and what it means in practice . Given the incredible importance of the web, particularly the front-end of the web, and the extraordinary increases in screen resolution (today the iPhone 4 and iPad 3, tomorrow most computers), it's very…
I mean, think about it. Say you have a 600dpi printer. Take a typical web page that sets its body element to be 1000px wide, because the person writing it was using a 96dpi display. If "px" really meant "smallest controllable dot", that web page would print about 1.66 inches wide. Which is obviously undesirable. On the other hand, if "px" means "the length that looks about as long as one pixel on a 96dpi display" then the same web page would print about 8 inches wide, which is probably much closer to what both author and user wanted.
This is also exactly why Apple did the "pixel doubling" thing on iPhone 4 and iPad 3: it was done to prevent existing content that made certain assumptions about the visible size of "px" from breaking.
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I'm afraid this boat has long sailed. The "pixel" term is in the CSS 2.1 Spec. It's set in stone. Personally I've made peace with it. I say either "CSS pixels" or "device pixels", depending on what I want to express. And although the high resolution screens have only made the difference between the two more visible, it was there since Opera featured full pages zoom many years ago, and when Mobile Safari introduced th…
Unfortunately, redefining "px" from its original meaning as "device pixels" to a new meaning of "probably one 96th of an inch except on mobile browsers where ..." means that CSS no longer has any way to express "device pixels".
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Use em, yes, but meanwhile "px" should have continued to mean "pixel", not "96th of an inch except on mobile where ...". Occasionally you really do need to talk about pixels in CSS, and redefining "px" makes that impossible.
I was at the same time telling myself that we really need to start using em more often. I have used px so many times at this point because it's more convenient for precise aligning. This is actually going to be a problem considering retina display macbooks might be coming soon.
And that's because we've had "retina" devices for many years now, called "printers" and CSS was designed to deal with that situation from the start.
I've mentioned this before and I'm not the first to say it, but it's time to stop using px and start using in its place absolute measurements like inches or millimeters. It's the only sane approach to supporting different resolution displays.
Using absolute measurements to size things on a web page that is then viewed on a TV (viewing distance in the 5-15ft range), a tablet (viewing distance in the 1-2ft range), and an eyeglass HUD (viewing distance in the 1-3in range) would be a disaster.
The fact that people _were_ using inches and millimeters on the web and expecting them to somehow work across all these devices is why they're all now defined in terms of CSS reference pixels...
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I'm not a web designer. Can you explain to me why it's important to be able to position/size something to exactly N pixels, rather than to exactly kN pixels (where k is some integer decided by the browser implementor)?
The biggest reason is that most css properties ignore fractional px values—you can't draw a .5px border, for instance.
Gecko has supported fractional pixel values for years in general, though for borders in particular the width is clamped to integer _device_ (not CSS) pixels.
WebKit has been rounding them at parse time (even in cases when 1 CSS px is multiple device pixels) for a while, but they're about to fix that.
I believe that IE also supports subpixel layout. Not sure about Opera, offhand.
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If they had set 1 px = 1 pixel, almost all Web pages would be unreadably small. AFAIK, Web designers don't use pt.
And people would have quickly learned to not use "pixel" unless they really mean "pixel".
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That's actually a very good point, don't know why you're being downvoted.
I find it interesting that I was downvoted to the negatives, then you posted this reply, and then I got upvoted to the top. I wonder what the causation is there. I suspect I know why I was downvoted; I used unnecessary emotive language ("dumb") and didn't explain my point clearly. Most of the rest of the commenters were focused on one part of the article's point, which is very relevant -- the idea that a pixel is no…
Of course, when you complain about being downvoted it shames people into upvoting you (sort of like when adults bully children into fake-apologizing for something they're not sorry about).