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 c4e9eabc30, 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>
(cherry picked from commit 53a6f7b783)
Reviewed-by: Jukka Jokiniva <jukka.jokiniva@qt.io>

src/gui/kernel/qopenglcontext.cpp

@@ -976,11 +976,8 @@ 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()))

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.
  */
 
 /*!

src/gui/kernel/qplatformintegration.h

@@ -105,7 +105,8 @@ public:
         AllGLFunctionsQueryable,
         ApplicationIcon,
         SwitchableWidgetComposition,
-        TopStackedNativeChildWindows
+        TopStackedNativeChildWindows,
+        OpenGLOnRasterSurface
     };
 
     virtual ~QPlatformIntegration() { }

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;
 }
 

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);
     }
 }

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

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;

src/plugins/platforms/wasm/qwasmintegration.cpp

@@ -168,6 +168,7 @@ bool QWasmIntegration::hasCapability(QPlatformIntegration::Capability cap) const
     case RasterGLSurface: return false; // to enable this you need to fix qopenglwidget and quickwidget for wasm
     case MultipleWindows: return true;
     case WindowManagement: return true;
+    case OpenGLOnRasterSurface: return true;
     default: return QPlatformIntegration::hasCapability(cap);
     }
 }