I've pushed a fix to 3-22. I'll cherry-pick it to master later.

thanks

many thanks!

After applying this patch to gtk 3.22.12 all text has become really big. I am attaching a screenshot

Created attachment 349718 [details]
Screenshot demonstrating big text

Your screen-shot doesn't really show anything out of the ordinary; perhaps if you include some other application's window in the shot?

Why did you backport it to 3.22.12 instead of compiling and testing gtk-3-22 HEAD?

Attaching a screenshot of the way it looked before.

I was trying to update the gtk+3 Homebrew formula for 3.22.12, as I figured that applying your patch would be sufficient to get that release working properly.

Created attachment 349731 [details]
Screenshot demonstrating how it was (and should still be?)

Created attachment 349835 [details]
Showing gtk3-demo before and after the patch.

I don't see anything like such a dramatic difference. I've attached a screenshot showing the two side-by-side; the left view is compiled from 8074626fc, immediately before changing the resolution settings and the right image from gtk-3-22 HEAD, after fixing the resolution setting. Xcode 8.2, MacOS 10.12.3, late 2013 Mac Pro, 1920x1080 monitor. There's no apparent difference on the 2560x1440 monitor.

Note that that's not a retina display and that I don't have one to test with.

The screenshots I uploaded were indeed made on an iMac with retina display. In my case the difference is dramatic: it looks like it went into vision impaired mode.

This is already apparent by looking at the difference in file size and image dimensions (taking into account I did not manually resize the window): both parameters blow up with the latest gtk 3.22.12 release.

I am wondering why you didn't replace userSpaceScaleFactor by 1, as explained in https://bugzilla.gnome.org/show_bug.cgi?id=765883. This would have continued to provide proper support for retina and non-retina screens, while getting rid of the deprecation warning.

I'd forgotten about bug 765883. (BTW you don't need to copy the URI for bugs unless they're from a different bug tracker.) There was another discussion somewhere (sorry, don't remember where and I can't find it) pointing out that hardcoding the pixels isn't the right thing to do, we should be asking the display for its resolution and using that. That's very much the advertised intent of "get_mm_from_pixels" and that's exactly what my change does. That it causes text (and only text!) to blow up on HiDPI suggests that fixing this has exposed problems elsewhere.

Fair enough.

Until the underlying cause of the text blowing up is found, would it be possible to revert b6aaae7dea8e574f3e8da1e2a25997ea3d10f05e for the next gtk+3 bug fix release? Same request for gtk+4 if it would have been cherrypicked into master.

Thanks

Created attachment 349915 [details]
Gtk3-demo on a retina MacBookPro

So I borrowed a retina MBP, bundled up gtk3-demo and copied it over, and as you can see it looks fine.

I can't find anything that looks like your example in gtk3-demo. What are you using? Does gtk3-demo look similarly borked on your system? What MacOS version?

I disagree that it looks fine. The grainy nature of gtk3-demo compared to the smooth appearance of the text app points to something being wrong with the retina support. 

Apart from the text blowing up on my machine, I do get the smooth appearance, and I believe it has always been there for gtk+3 with quartz backend.

Oh and I am using gtk3-widget-factory instead of gtk3-demo, which indeed looks equally blown up...

I can report that the text is incredibly large now on 3.22.15. :(

Note that I'm on a MacBook Pro (Retina, 15-inch, Mid 2015) running 10.12.4

I use the following patch to get 3.12.15 working properly:

diff --git a/gdk/quartz/gdkscreen-quartz.c b/gdk/quartz/gdkscreen-quartz.c
index 586f7af..d032643 100644
--- a/gdk/quartz/gdkscreen-quartz.c
+++ b/gdk/quartz/gdkscreen-quartz.c
@@ -79,7 +79,7 @@ gdk_quartz_screen_init (GdkQuartzScreen *quartz_screen)
   NSDictionary *dd = [[[NSScreen screens] objectAtIndex:0] deviceDescription];
   NSSize size = [[dd valueForKey:NSDeviceResolution] sizeValue];

-  _gdk_screen_set_resolution (screen, size.width);
+  _gdk_screen_set_resolution (screen, 72.0);

   gdk_quartz_screen_calculate_layout (quartz_screen);

@@ -334,11 +334,8 @@ gdk_quartz_screen_get_height (GdkScreen *screen)
 static gint
 get_mm_from_pixels (NSScreen *screen, int pixels)
 {
-  const float mm_per_inch = 25.4;
-  NSDictionary *dd = [[[NSScreen screens] objectAtIndex:0] deviceDescription];
-  NSSize size = [[dd valueForKey:NSDeviceResolution] sizeValue];
-  float dpi = size.width;
-  return (pixels / dpi) * mm_per_inch;
+  const float dpi = 72.0;
+  return (pixels / dpi) * 25.4;
 }

 static gchar *

Christoph opened bug 782393 to address directly the font-size issue, so let's please continue the discussion there.

I'm re-resolving this as the original problem, the crash, is fixed.