eglfs: Fix raster windows

Also sanitize the initial WebAssembly hack. Both eglfs and wasm lack the concept
of true raster windows. A QWindow with RasterSurface is rendered with OpenGL
no matter what. The two platforms took two different approaches to work around
the rest of the machinery:

- wasm disabled the QOpenGLContext warning for non-OpenGL QWindows,

- eglfs forced the QWindow surfaceType to OpenGLSurface whenever it was
  originally set to RasterSurface.

Now, the latter breaks since c4e9eabc309a275efc222f4127f31ba4677259b7, leaving
all raster window applications failing on eglfs, because flush in the backingstore
is now checking the surface type and disallows OpenGLSurface windows. (just like
how QOpenGLContext disallows RasterSurface windows)

To solve all this correctly, introduce a new platform capability,
OpenGLOnRasterSurface, and remove the special handling in the platform plugins.

Change-Id: I7785dfb1c955577bbdccdc14ebaaac5babdec57c
Fixes: QTBUG-77100
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

3 files changed, 3 insertions, 8 deletions

diff --git a/src/plugins/platforms/eglfs/api/qeglfsintegration.cpp b/src/plugins/platforms/eglfs/api/qeglfsintegration.cpp
index c8a1ddf9b9..674f579b4f 100644
--- a/src/plugins/platforms/eglfs/api/qeglfsintegration.cpp
+++ b/src/plugins/platforms/eglfs/api/qeglfsintegration.cpp
@@ -265,6 +265,7 @@ bool QEglFSIntegration::hasCapability(QPlatformIntegration::Capability cap) cons
     case RasterGLSurface: return false;
 #endif
     case WindowManagement: return false;
+    case OpenGLOnRasterSurface: return true;
     default: return QPlatformIntegration::hasCapability(cap);
     }
 }
diff --git a/src/plugins/platforms/eglfs/api/qeglfswindow.cpp b/src/plugins/platforms/eglfs/api/qeglfswindow.cpp
index c1d5af47aa..1fed182882 100644
--- a/src/plugins/platforms/eglfs/api/qeglfswindow.cpp
+++ b/src/plugins/platforms/eglfs/api/qeglfswindow.cpp
@@ -64,7 +64,6 @@ QEglFSWindow::QEglFSWindow(QWindow *w)
       m_backingStore(0),
       m_rasterCompositingContext(0),
 #endif
-      m_raster(false),
       m_winId(0),
       m_surface(EGL_NO_SURFACE),
       m_window(0),
@@ -94,11 +93,6 @@ void QEglFSWindow::create()
 
     m_winId = newWId();
 
-    // Save the original surface type before changing to OpenGLSurface.
-    m_raster = (window()->surfaceType() == QSurface::RasterSurface);
-    if (m_raster) // change to OpenGL, but not for RasterGLSurface
-        window()->setSurfaceType(QSurface::OpenGLSurface);
-
     if (window()->type() == Qt::Desktop) {
         QRect fullscreenRect(QPoint(), screen()->availableGeometry().size());
         QWindowSystemInterface::handleGeometryChange(window(), fullscreenRect);
@@ -329,7 +323,8 @@ QEglFSScreen *QEglFSWindow::screen() const
 
 bool QEglFSWindow::isRaster() const
 {
-    return m_raster || window()->surfaceType() == QSurface::RasterGLSurface;
+    const QWindow::SurfaceType type = window()->surfaceType();
+    return type == QSurface::RasterSurface || type == QSurface::RasterGLSurface;
 }
 
 #ifndef QT_NO_OPENGL
diff --git a/src/plugins/platforms/eglfs/api/qeglfswindow_p.h b/src/plugins/platforms/eglfs/api/qeglfswindow_p.h
index b0091e2a62..be2a0630d3 100644
--- a/src/plugins/platforms/eglfs/api/qeglfswindow_p.h
+++ b/src/plugins/platforms/eglfs/api/qeglfswindow_p.h
@@ -118,7 +118,6 @@ protected:
     QOpenGLCompositorBackingStore *m_backingStore;
     QOpenGLContext *m_rasterCompositingContext;
 #endif
-    bool m_raster;
     WId m_winId;
 
     EGLSurface m_surface;