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>

4 files changed, 11 insertions, 4 deletions

diff --git a/src/gui/kernel/qopenglcontext.cpp b/src/gui/kernel/qopenglcontext.cpp
index 499d16c109..e8c64bdc01 100644
--- a/src/gui/kernel/qopenglcontext.cpp
+++ b/src/gui/kernel/qopenglcontext.cpp
@@ -977,11 +977,8 @@ bool QOpenGLContext::makeCurrent(QSurface *surface)
     if (!surface->surfaceHandle())
         return false;
     if (!surface->supportsOpenGL()) {
-#ifndef Q_OS_WASM // ### work around the WASM platform plugin using QOpenGLContext with raster surfaces.
-        // see QTBUG-70076
         qWarning() << "QOpenGLContext::makeCurrent() called with non-opengl surface" << surface;
         return false;
-#endif
     }
 
     if (!d->platformGLContext->makeCurrent(surface->surfaceHandle()))
diff --git a/src/gui/kernel/qplatformintegration.cpp b/src/gui/kernel/qplatformintegration.cpp
index ac4d12b024..258d214c7a 100644
--- a/src/gui/kernel/qplatformintegration.cpp
+++ b/src/gui/kernel/qplatformintegration.cpp
@@ -244,6 +244,9 @@ QPlatformServices *QPlatformIntegration::services() const
     \value TopStackedNativeChildWindows The platform supports native child windows via
     QWindowContainer without having to punch a transparent hole in the
     backingstore. (since 5.10)
+
+    \value OpenGLOnRasterSurface The platform supports making a QOpenGLContext current
+    in combination with a QWindow of type RasterSurface.
  */
 
 /*!
diff --git a/src/gui/kernel/qplatformintegration.h b/src/gui/kernel/qplatformintegration.h
index 1179daeb32..0b999de264 100644
--- a/src/gui/kernel/qplatformintegration.h
+++ b/src/gui/kernel/qplatformintegration.h
@@ -103,7 +103,8 @@ public:
         AllGLFunctionsQueryable,
         ApplicationIcon,
         SwitchableWidgetComposition,
-        TopStackedNativeChildWindows
+        TopStackedNativeChildWindows,
+        OpenGLOnRasterSurface
     };
 
     virtual ~QPlatformIntegration() { }
diff --git a/src/gui/kernel/qsurface.cpp b/src/gui/kernel/qsurface.cpp
index 415e64b39c..709f28d431 100644
--- a/src/gui/kernel/qsurface.cpp
+++ b/src/gui/kernel/qsurface.cpp
@@ -39,6 +39,8 @@
 
 #include "qsurface.h"
 #include "qopenglcontext.h"
+#include <qpa/qplatformintegration.h>
+#include <QtGui/private/qguiapplication_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -103,6 +105,10 @@ QT_BEGIN_NAMESPACE
 bool QSurface::supportsOpenGL() const
 {
     SurfaceType type = surfaceType();
+    if (type == RasterSurface) {
+        QPlatformIntegration *integ = QGuiApplicationPrivate::instance()->platformIntegration();
+        return integ->hasCapability(QPlatformIntegration::OpenGLOnRasterSurface);
+    }
     return type == OpenGLSurface || type == RasterGLSurface;
 }