> On Feb 10, 2015, at 12:20, Quincey Morris > <quinceymor...@rivergatesoftware.com> wrote: > > On Feb 10, 2015, at 11:23 , Jerry Krinock <je...@ieee.org> wrote: >> >> I’ve always wondered why, when you’re dragging a window around a non-Retina >> screen, the anti-aliasing doesn’t show a “comb filter” kind of effect, with >> different lines getting fuzzy and sharp as they are dragged on and off their >> pixels. Looking at this closely today, I think the explanation may be that >> >> (1) Although you need to look carefully, Apple has constrained >> dragging windows to “snap" to the grid of backing pixels. >> You cannot move a window by one half pixel. >> (2) A window’s intrinsic scrollers, title bars, etc. are also >> on a 1-pixel grid. >> (3) Any control or view that you place into Interface Builder >> must be on a 1-pixel grid. I just tried entering a decimal >> fraction, 139.5, and after I ended editing, it was rounded >> down to 139. > > Case #3 is actually points, not pixels. Cases #1 and #2 may be points, too, > but I don’t know. > > Then there’s #1A and #3A — meaning: positioning those elements > programmatically. Even though you can’t place a button off the 1-point grid > in IB, you might be able to do it programmatically. Or not. > > Also, be careful about conceptualizing backing “pixels”. On an iPhone 6+, the > backing store is 2x, but the hardware is 3x. (Let’s hope I got that the right > way round.)
You got it backwards :) The app renders into a 3x backing store (i.e. each point is represented by a 3x3 grid of pixels). As far as the app is concerned, it is rendering to a 1242 x 2208 pixel (414x736 point) screen, but that is scaled down to the hardware resolution of 1080x1920 pixels. > Something similar is true of the Retina iMac/MacBook, too, though it’s > complicated by having multiple logical resolutions. > > > > _______________________________________________ > > Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) > > Please do not post admin requests or moderator comments to the list. > Contact the moderators at cocoa-dev-admins(at)lists.apple.com > > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/cocoa-dev/clarkcox3%40gmail.com > > This email sent to clarkc...@gmail.com
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