In Cocoa application I've got 16x16 and 32x32 @2x
version of an image: . When the image is displayed in NSImageView Mac OS X always picks higher-resolution version (i.e. downscales the @2x
image on non-retina displays instead of using the 1:1 version).
(IB on the left = good, running app on the right = downscaled mess)
Of course I've got both images added to the project (as image.png
and image@2x.png
).
If I delete the @2x
image from app bundle then OS X will display the lower-resolution image.
The bug happens regardless whether Xcode (4.6.2) combines them into a .tiff or not (and I've checked that the combined .tiff contains both images).
Oddly this happens only with this particular image. Other 1x/2x images in the same project are displayed correctly matching screen DPI.
How is that possible?! Do images have to meet some special criteria other than size and filename pattern?
It turns out to be the
NSImage
’sprefersColorMatch
property [1]:It is possible to set to
NO
in User Defined Runtime Attributes in Interface Builder [2].[1] https://developer.apple.com/documentation/appkit/nsimage/1520010-preferscolormatch
[2] Are specific PNG compression types incompatible with macOS Cocoa apps?
Mystery solved: OS X doesn't like mixed types of PNGs.
if both files are forced to use same color mode (i.e. both gray or both paletted) then OS X selects images correctly.