On Dec 17, 2014, at 6:52 AM, Jerry Krinock <je...@ieee.org> wrote: > I think I did what the "High Resolution Guidelines for OS X” document > suggested for drawing offscreen vector images. See code snip below. > > The result looks the same to me. It’s OK with the old code, and OK with the > new code. > > To help me understand what I’m doing, I would appreciate if someone please > elaborate on this quote from the documeent: > > “If your app uses -lockFocus: … either you’ll get a low resolution NSImage > object that looks incorrect when drawn, or you’ll get a 2x image that has > more pixels in its bitmap than you are expecting” > > • Are these “either” the only two possible results, or is there a third > possibility, that it will work properly? > > • Regarding "a low resolution NSImage object that looks incorrect when > drawn”, does that mean that it looks grossly incorrect, like, say, the image > is scaled down and squashed into one quadrant, or does it just mean that it > will look fuzzy on a Retina display? > > • What does "a 2x image that has more pixels in its bitmap” mean? I thought > that a 2x image is expected to have more pixels in its bitmap.
All of this is about living in an environment where your app's windows can be displayed on a high-resolution (a.k.a. high-DPI or Retina) screen and/or move back and forth between such a screen and a standard-resolution screen. When you draw a single time using -lockFocus, your image can only be appropriate for one or the other. So, it will either be drawn at standard resolution, in which case it will look fuzzy or blocky on a high-resolution screen; or it will be drawn at high resolution, in which case it will waste RAM/VRAM and rendering work if it's only going to be displayed on a standard-resolution screen. It might also be very slightly less sharp than it would otherwise have been. It will be down-sampled to display on the standard-resolution screen, which usually works pretty well (especially at a 2:1 ratio) but does have some effect. The image will not be grossly incorrect. Regards, Ken _______________________________________________ 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/archive%40mail-archive.com This email sent to arch...@mail-archive.com
