Wayland rendering issues regression

The map application is an IVI application that is drawn to a Wayland Compositor. The map rendering is based on the QtQuick textureinthread example, qt5/qtdeclarative/examples/quick/scenegraph/textureinthread

The map rendering runs on its own thread.

It has its own QOpenGLContext similar to qt5/qtdeclarative/examples/quick/scenegraph/textureinthread/threadrenderer.cpp.html#247

It has its own QOffscreenSurface similar to qt5/qtdeclarative/examples/quick/scenegraph/textureinthread/threadrenderer.cpp.html#233

When time to render, the map rendering calls “context->makeCurrent(surface);”that is it makes its own QOpenGLContext current in its own thread, against its own QOffscreenSurface similar to
qt5/qtdeclarative/examples/quick/scenegraph/textureinthread/threadrenderer.cpp.html#91

The issue is tracked down to line 410 of change list https://github.com/qt/qtwayland/commit/bf09c7a1493c01a65ee0f110b37a04e653edc08e

Line 410 changes from “window->updateSurface(true);” to (window->updateSurface(window->isExposed());”, see below.

if (eglSurface == EGL_NO_SURFACE) {
- window->updateSurface(true);
+ window->updateSurface(window->isExposed());
eglSurface = window->eglSurface();
}

The “window->isExposed()” always return false because the window is from a QOffscreenSurface:

QWaylandEglWindow *window = static_cast<QWaylandEglWindow *>(surface);

Since the “window->isExposed();” always returns false, the eglSurface of the window will not get created, or in another word, it always has the value of EGL_NO_SURFACE.

With eglSurface has no surface, the call to eglMakeCurrent(m_eglDisplay, eglSurface, eglSurface, m_context) will create a EGL_KHR_surfaceless_context, https://www.khronos.org/registry/EGL/extensions/KHR/EGL_KHR_surfaceless_context.txt

if (!eglMakeCurrent(m_eglDisplay, eglSurface, eglSurface, m_context)) {
qWarning("QWaylandGLContext::makeCurrent: eglError: %x, this: %p \n", eglGetError(), this);
window->setCanResize(true);
return false;
}

This is where the map render goes wrong. The map does get render but it is rendered incorrectly.

This was working correctly with Qt 5.9.4.