Image.FromFile() or FromStream() hangs on GdiplusStartup

Question

I have a simple C# Application containing this line:

var mImage = System.Drawing.Image.FromFile(filename);

When running this code on Windows (.NET), the image is loaded correctly. When running the same code on OS X (Mono), the application just hangs. The debugger stays in that call forever. No exception no nothing.

The callstack shows the application hangs at:

System.Drawing.GDIPlus.GdiplusStartup ()

What could go wrong here?

PS: I have the latest versions of Xamarin Studio and Mono installed.

Answer 1

1) Not only check you have the latest Xamarin Studio version but check you have the latest build!!!

Bug report:

This problem was reported by Troy Dawson using Xamarin Studio Version 5.5 (build 198), just over a month ago: https://bugzilla.xamarin.com/show_bug.cgi?id=23444

"With the latest Mono from the alpha release channel, attached project should raise an typenotfound exception when run at:

var image = Image.FromStream(content);

Because GDIPlus can't be initialized or something.

This is similar to another bug I filed where Image.FromStream() takes a very long time to return when Mono is first run."

Full exception:

An exception was thrown by the type initializer for System.Drawing.GDIPlus ---> System.Exception: GdiplusStartup

Solution:

A day after the bug was reported on 2014-09-29 Sadik Ali confirms he can reproduce the problem Comment 1, then 4 days later Troy Dawson confirms that Xamarin Studio Version 5.5 (build 227) fixes the issue Comment 2.

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2) If it still fails with the latest build I suggest you go through the limitations and make sure the image(s) you're loading are supported: https://github.com/mono/libgdiplus/blob/master/TODO

Answer 2

The problem is MonoMac GDI's way of interfacing with Mac fonts. The first time it is launched, it builds a font-cache it needs, and this actually takes a few minutes. Just let it run for a while. This delay goes away once the font cache is built.

If you kill it, it never finishes building the cache, and it'll happen every time. It's a shame they don't even yet have any kind of dialog or message printed that this is happening.

In rare situations, your font-cache directory may not be writable by mono. In this case, you can either run the app as root once, or you can follow the instructions here.