Add an error signal to QQuickWindow

When nothing is connected to this signal, an error will be printed or,
in case of Windows, a message box will be shown. If there is something
connected, it is up to the application to handle the error.

[ChangeLog] Added a new sceneGraphError() signal to QQuickWindow
which applications can use to detect errors like OpenGL context creation
failures and react in their own custom ways.

Task-number: QTBUG-36138
Change-Id: I33b1e5e0e3f25872af67c5bb5ae937e3470b25f3
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/src/quick/scenegraph/qsgrenderloop.cpp b/src/quick/scenegraph/qsgrenderloop.cpp
index 50c5b141c3..08ab3809b3 100644
--- a/src/quick/scenegraph/qsgrenderloop.cpp
+++ b/src/quick/scenegraph/qsgrenderloop.cpp
@@ -281,9 +281,18 @@ void QSGGuiThreadRenderLoop::renderWindow(QQuickWindow *window)
         if (QSGContext::sharedOpenGLContext())
             gl->setShareContext(QSGContext::sharedOpenGLContext());
         if (!gl->create()) {
-            qWarning("QtQuick: failed to create OpenGL context");
             delete gl;
             gl = 0;
+            QString formatStr;
+            QDebug(&formatStr) << window->requestedFormat();
+            QString contextType = QLatin1String(QOpenGLFunctions::isES() ? "EGL" : "OpenGL");
+            const char *msg = QT_TRANSLATE_NOOP("QSGGuiThreadRenderLoop", "Failed to create %1 context for format %2");
+            QString translatedMsg = tr(msg).arg(contextType).arg(formatStr);
+            QString nonTranslatedMsg = QString(QLatin1String(msg)).arg(contextType).arg(formatStr);
+            bool signalEmitted = QQuickWindowPrivate::get(window)->emitError(QQuickWindow::ContextNotAvailable,
+                                                                             translatedMsg);
+            if (!signalEmitted)
+                qFatal("%s", qPrintable(nonTranslatedMsg));
         } else {
             current = gl->makeCurrent(window);
         }