On one side of the aisle, this fall will bring a new iPhone & iPad; on the other there’s a steady flow of Android handsets and tablets and in-betweens.
One thing about the Apple mobile line had been puzzling me till recently: There are only two form factors. The prognosticators think that the next iPhone will be about the same size and shape as it is now. The same is true of the iPad, except for maybe it’ll have a double-density “Retina” display.
It couldn’t be more different on the Android side, with devices of every size and shape imaginable, some of ’em real eye-rollers. Today, I laughed at a tweet from Sascha Segan: “Samsung now has: 2.8 3.2 3.5 3.7 4 4.3 4.5 5 7 7.7 8.9 10.1 inch screen Androids. Where's the 6-incher Sammy? Get on the case!” And Samsung is just one builder.
Theories of History · There are two possible explanations for this: First, Apple has ascertained that the 3½-inch and 10-inch diagonals constitute the Platonic ideals for screen size, and no others are worth building. Second, there are technical barriers to exploring new iOS form factors.
For a long time, I didn’t believe either theory. So when in 2010 I fell in love with the original Galaxy Tab, largely on account of its size, I confidently asserted “Apple will totally do a 7" device... This argument is over”. Clearly I’m eating those words.
John Gruber asserted repeatedly that a 7-inch (or other form factor) device was not in the cards because it would screw up the screen layouts; unless of course the new screen were an exact multiple of the number of pixels on its predecessor, as with the iPhone 4’s Retina Display.
Since I work on a daily basis with at least four different screen sizes, all of which are driven reliably by Apple software, this claim baffled me. Then I noticed that none of the iOS developers were pushing back; and also Gruber is always right when it comes to Apple whys and wherefores. (But these days, bizarrely bent out of shape on the subject of Google; every action is explained by some implausible combination of malice, hypocrisy, and intellectual-property knavery. Jeepers, John, unclench a bit. But I digress.)
I still didn’t really understand the technical issue.
The Real Reason · The scales fell from my eyes when I read Nick Farina’s An iOS Developer Takes on Android, which to my mind is the single best piece of comparative writing on this subject by anyone, anywhere. In particular, scroll down to the “A Real Box Model” section. (Hey Nick, real men put hashtags on their sections so people can link to them. That’s what hashtags are for, not the horrible things that Twitter and other miscreants are doing with them. But I digress.)
When I saw Nick’s sample iOS code, I initially shook my head in
disbelief at all the little bits of hard-coded arithmetic, like
y += 7 and
MARGIN - 30. Clearly this logic is not
resilient in the face of a different-shaped screen. But I bet it’s fast.
It’s not done that way in Android-land.
Android Assumptions · Just about the first one is that you have to deal with variations in shape, size, and density, but that you get lots of help from the framework. Check out Dianne Hackborn’s monumental New Tools For Managing Screen Sizes, a comprehensive introduction to screen geometries and the mighty “dp” unit that makes it all tractable. The repertoire of Layouts also helps, and is constantly being refreshed with things like ViewPager; which mostly Just Work in the face of any old set of screen dimensions.
It’s plausible, as Nick Farina implies, that iOS’ fixed-dimensions screen model is partly responsible for the astonishingly-fast performance Apple wrings out of the underlying hardware.
And I’m not even saying that Apple’s choice here is wrong. The trade-off, if I understand it correctly, is form-factor flexibility for performance and simplicity, and so far that’s been working out pretty well for them.
I Seem To Have Been Wrong · About Apple doing a 7-inch device, I mean. But I’m sure as anything that somebody is gonna sell a buttload of tablets at that size. I’ve got probably as much experience as anyone in the world carrying around large and small tablets simultaneously, and if I had to pick just one, it wouldn’t be ten inches in any dimension.