RFR: 8254569: Remove hard dependency on Dispman in Monocle fb rendering

[Kevin Rushforth]

On Fri, 30 Oct 2020 15:09:49 GMT, Johan Vos <jvos at openjdk.org> wrote:

> Allow the EGL functionality in monocle to leverage EGL-based systems. The low-level specific details about how the EGL calls should be constructed are left out, and a native interface (egl_ext.h) is created that can be mapped to any low-level system.

Looks OK as near as I can tell. I left a few questions along with a comment about a missing copyright header (that's the only thing that definitely needs to be fixed).

modules/javafx.graphics/src/main/java/com/sun/glass/ui/monocle/EGLAcceleratedScreen.java line 45:

> 43:      *        implementation to get the best matching configuration.
> 44:      */
> 45:     EGLAcceleratedScreen(int[] attributes) throws GLException {

I presume you intended to call the (newly added) default `super` method and not `super(int[])`?

modules/javafx.graphics/src/main/java/com/sun/glass/ui/monocle/EGLPlatform.java line 37:

> 35:         String lib = System.getProperty("monocle.egl.lib");
> 36:         if (lib != null) {
> 37:             LinuxSystem.getLinuxSystem().dlopen(lib, LinuxSystem.RTLD_LAZY | LinuxSystem.RTLD_GLOBAL);

Do you need to check the return value (and maybe throw an Exception)?

modules/javafx.graphics/src/main/java/com/sun/glass/ui/monocle/EGLPlatform.java line 43:

> 41:     @Override
> 42:     public synchronized AcceleratedScreen getAcceleratedScreen(int[] attributes) throws GLException {
> 43:         return new EGLAcceleratedScreen(attributes);

Should this method cache the result so it returns a singleton (not sure, but the other `NativePlatform` subclasses, including `Dispman` do)?

modules/javafx.graphics/src/main/native-glass/monocle/egl/eglBridge.c line 56:

> 54: JNIEXPORT jlong JNICALL Java_com_sun_glass_ui_monocle_EGLAcceleratedScreen_nEglChooseConfig
> 55:     (JNIEnv *env, jclass clazz, jlong eglDisplay, jintArray attribs) {
> 56:     jint *attrArray = (*env)->GetIntArrayElements(env, attribs, JNI_FALSE);

Should this check the return value in case it fails (returns NULL)?

modules/javafx.graphics/src/main/native-glass/monocle/egl/egl_ext.h line 1:

> 1: #include <jni.h>

This needs a standard copyright header.

Also should it have a guard to prevent including it more than once?

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PR: https://git.openjdk.java.net/jfx/pull/343