RFR: 8092439: [Monocle] Refactor monocle SPI to allow support for multiple screens

[Kevin Rushforth]

On Tue, 16 Mar 2021 14:24:19 GMT, Johan Vos <jvos at openjdk.org> wrote:

> Fix for JDK-8092439 and JDK-8092064
> Monocle currently hard-codes a single Screen, and the `staticScreen_getScreens()` method will never return more than 1 Screen.
> 
> This PR introduces the possibility to deal with multiple screens, which is not uncommon on embedded systems. By default, the `staticScreen_getScreens()` method will still return a single screen, but the sub-platforms can now return multiple screens.
> 
> The EGL subplatform will now query the low-level drivers, and if they detect multiple displays, multiple `Screen` instances will be configured.
> The low-level native implementation for getting the number of physical screens and there characteristics is deferred to the real low-level libraries (for example, an X11 based approach can do it in a different way then a DRM based approach).

Looks good. I left one comment that you might want to look at (probably for a follow-up issue, since it doesn't seem to be causing problems).

modules/javafx.graphics/src/main/native-glass/monocle/egl/eglBridge.c line 92:

> 90: 
> 91: JNIEXPORT jlong JNICALL Java_com_sun_glass_ui_monocle_EGLScreen_nGetHandle
> 92: (JNIEnv *env, jclass clazz, jint idx)  {

Since the JNI parameters are unused, it may not matter, but since this is an instance method, the second argument is a `jobject` not a `jclass`. The same issue applies to the rest. I see that you just copied a preexisting issue, so you might or might not want to fix it, or maybe just file a follow-on cleanup issue if you like.

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Marked as reviewed by kcr (Lead).

PR: https://git.openjdk.java.net/jfx/pull/426