Matthew Flatt 45b1b8419c Mac OS X: support Retina mode ... Seems to work for Mac OS X 10.9 (Mavericks), at least. In Retina mode, a drawing unit corresponds to two pixels on the screen or in a bitmap created by `make-screen-bitmap'. In particular, a bitmap created by `make-screen-bitmap' is actually twice as big in each dimension as requested, and the bitmap is scaled when transferring to other drawing contexts. When transferring onto the screen, scalings cancel so that the result looks right. Adds `get-display-backing-scale` to `racket/gui/base`, and also `get-backing-scale` to `bitmap%`. To do: add a way to set the backing scale of a bitmap. That option will provide a way to give controls higher-resolution bitmaps as labels. original commit: fac247d340455328ab7e18db10546939bb067f4a		2013-10-31 08:50:22 -06:00
pkgs	Mac OS X: support Retina mode	2013-10-31 08:50:22 -06:00