RFR: 8255240: Mobile builds need to exclude some modules [v3]

[Magnus Ihse Bursie]

On Tue, 3 Nov 2020 13:56:34 GMT, Johan Vos <jvos at openjdk.org> wrote:

>> See. https://bugs.openjdk.java.net/browse/JDK-8255785
>
> Thanks for the suggestion.
> `NEEDS_LIB_X11` was already false for ios/android (same file, in the if clause) but there were a few places where an X11 header was still required. I could easily fix those, but there are more issues when building libawt.a. For example, font.c relies on fontconfig/fontconfig.h which we don't have on android.
> Actually, the whole font handling is something that is already done in JavaFX (in OpenJFX), and for Android we leverage freetype. 
> I'm a bit puzzled, as I think it would be a huge overkill to somehow port the font code from OpenJDK to android, but never using it as it is already done in OpenJFX. 
> Another area is the dependency on X11 in the java2d/opengl/J2D_GL files.
> 
> To me, it seems the main issue is that I don't think this code belongs in the core of OpenJDK.

Fine. If you don't need or want java.desktop, then I suggest you exclude that module for iOS/Android.

I still agree with Bob that keeping java.desktop but not building the native libs sounds problematic, since it will make stuff fail surprisingly at runtime.

If you need part, but not all, of java.desktop, then for this patch I don't really care, but if so, that is something that needs to be discussed seriously on how to handle before we can start thinking about upstreaming mobile into mainline.

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PR: https://git.openjdk.java.net/mobile/pull/10