Handle offscreen surfaces

Implement createPlatformOffscreenSurface(). This way a QOffscreenSurface
will not lead to creating a QWindow. Fairly dummy, and may need amending
later, but fixes the immediate problem with the - still default - direct
OpenGL code path of Qt Quick.

Task-number: QTBUG-76993
Change-Id: Ia4198163fc91d3f353d0067a2a807ec075168ace
Reviewed-by: Jesus Fernandez <[email protected]>

Author: alpqr

src/plugins/platforms/webgl/qwebglintegration.cpp

@@ -253,6 +253,12 @@ QPlatformWindow *QWebGLIntegration::createPlatformWindow(QWindow *window) const
     return platformWindow;
 }
 
+QPlatformOffscreenSurface *QWebGLIntegration::createPlatformOffscreenSurface(QOffscreenSurface *surface) const
+{
+    qCDebug(lcWebGL, "New offscreen surface %p", surface);
+    return new QWebGLOffscreenSurface(surface);
+}
+
 QPlatformOpenGLContext *QWebGLIntegration::createPlatformOpenGLContext(QOpenGLContext *context)
     const
 {

src/plugins/platforms/webgl/qwebglintegration.h

@@ -59,6 +59,7 @@ class QWebGLIntegration : public QPlatformIntegration, public QPlatformNativeInt
     QPlatformInputContext *inputContext() const override;
     QPlatformTheme *createPlatformTheme(const QString &name) const override;
     QPlatformWindow *createPlatformWindow(QWindow *window) const override;
+    QPlatformOffscreenSurface *createPlatformOffscreenSurface(QOffscreenSurface *surface) const;
     QPlatformBackingStore *createPlatformBackingStore(QWindow *window) const override;
     QPlatformOpenGLContext *createPlatformOpenGLContext(QOpenGLContext *context) const override;
 

src/plugins/platforms/webgl/qwebglwindow.cpp

@@ -40,6 +40,7 @@
 #include <QtGui/qpa/qwindowsysteminterface.h>
 #include <QtGui/qpa/qplatformintegration.h>
 #include <QtGui/qopenglcontext.h>
+#include <QtGui/qoffscreensurface.h>
 
 #include "qwebglwindow.h"
 
@@ -170,4 +171,19 @@ WId QWebGLWindow::winId() const
     return d->id;
 }
 
+QWebGLOffscreenSurface::QWebGLOffscreenSurface(QOffscreenSurface *offscreenSurface)
+    : QPlatformOffscreenSurface(offscreenSurface)
+{
+}
+
+QSurfaceFormat QWebGLOffscreenSurface::format() const
+{
+    return offscreenSurface()->format();
+}
+
+bool QWebGLOffscreenSurface::isValid() const
+{
+    return true;
+}
+
 QT_END_NAMESPACE

src/plugins/platforms/webgl/qwebglwindow.h

@@ -35,6 +35,7 @@
 
 #include <QtCore/qscopedpointer.h>
 #include <QtGui/qpa/qplatformwindow.h>
+#include <QtGui/qpa/qplatformoffscreensurface.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -72,6 +73,15 @@ class QWebGLWindow : public QPlatformWindow
     QScopedPointer<QWebGLWindowPrivate> d_ptr;
 };
 
+class QWebGLOffscreenSurface : public QPlatformOffscreenSurface
+{
+public:
+    QWebGLOffscreenSurface(QOffscreenSurface *offscreenSurface);
+
+    QSurfaceFormat format() const override;
+    bool isValid() const override;
+};
+
 QT_END_NAMESPACE
 
 #endif // QWEBGLWINDOW_H