On Sat, 5 Jun 2021 15:07:27 GMT, Phil Race <p...@openjdk.org> wrote: > There are two issues here, both macOS specific. > First the original reported one that occurs when running on a shared remote > VNC type desktop on macOS. > Only a single supported display mode is returned and it is also the current > mode. > A program that simply enumerates the reported modes and tries to set them, if > it reaches the native layer, > will fail because macOS reports the same display mode it returned as valid as > now being illegal. > It does not appear to be as simple as a user's permission level since it > occurs with an admin user as well > so it probably is the case that macOS simply does not allow this shared > desktop to be changed although > there's no docs I can find > Ordinarily we would not have tried this since we test if the requested > display mode is the same as the native > one and skip it, but the provided test used REFRESH_RATE_UNKNOWN which is > allowed as meaning match > any mode that satisfies W,H,BPP. But this caused it to fail the equals test > so the code is enhanced to check for that > > Second, when creating a test it was discovered that *at least* on the > built-in retina display of a 16" macbook pro, > the system default contig is never in the list of available modes and can be > discovered only by querying the *current* mode > before any modes are changed. This beheaviour is 100% consistent no matter if > the system was just rebooted, has > an external monitor attached as well, or not, activates the discrete card, or > not. > > Since we've had code since at least 2013 that added the default mode I > suspect this has been seen before but nowhere > can I find an explanation. > > It has odd consequences like after you change the display mode, you will no > longer see the default display mode reported, > so the list of available modes is reduced by one. > But for a typical use case which doesn't re-query or more typically caches > the original display mode in order to restore it, it presents a bigger > problem that trying to restore will always fail. > > So the other thing this fix does is detect when we fail to restore the > initial mode and try again in a different way. > Only if that fails do we then throw an exception.
src/java.desktop/macosx/native/libawt_lwawt/awt/CGraphicsDevice.m line 266: > 264: /* > 265: * Class: sun_awt_CGraphicsDevice > 266: * Method: nativeSetDisplayMode `nativeResetDisplayMode`? ------------- PR: https://git.openjdk.java.net/jdk/pull/4373
