Consolidate context creation failure handling in Quick.

Add QQuickWidget::sceneGraphError() equivalent to
QQuickWindow::sceneGraphError(), move message formatting code
to QQuickWindowPrivate.

Change-Id: I18cd4d7e0f6ee1011c29375218dc6a044b0d2cf2
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

9 files changed, 122 insertions, 49 deletions

diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index d7a6f071c6..6a56a5dc82 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -65,6 +65,7 @@
 #include <QtGui/qstylehints.h>
 #include <QtCore/qvarlengtharray.h>
 #include <QtCore/qabstractanimation.h>
+#include <QtCore/QLibraryInfo>
 #include <QtQml/qqmlincubator.h>
 
 #include <QtQuick/private/qquickpixmapcache_p.h>
@@ -2303,6 +2304,36 @@ bool QQuickWindowPrivate::isRenderable() const
     return ((q->isExposed() && q->isVisible())) && q->geometry().isValid();
 }
 
+void QQuickWindowPrivate::contextCreationFailureMessage(const QSurfaceFormat &format,
+                                                        QString *translatedMessage,
+                                                        QString *untranslatedMessage,
+                                                        bool isEs)
+{
+    const QString contextType = QLatin1String(isEs ? "EGL" : "OpenGL");
+    QString formatStr;
+    QDebug(&formatStr) << format;
+#if defined(Q_OS_WIN32)
+    const bool isDebug = QLibraryInfo::isDebugBuild();
+    const QString eglLibName = QLatin1String(isDebug ? "libEGLd.dll" : "libEGL.dll");
+    const QString glesLibName = QLatin1String(isDebug ? "libGLESv2d.dll" : "libGLESv2.dll");
+     //: %1 Context type (Open GL, EGL), ANGLE %2, %3 library names
+    const char msg[] = QT_TRANSLATE_NOOP("QQuickWindow",
+        "Failed to create %1 context for format %2."
+        "This is most likely caused by not having the necessary graphics drivers installed.\n\n"
+        "Install a driver providing OpenGL 2.0 or higher, or, if this is not possible, "
+        "make sure the ANGLE Open GL ES 2.0 emulation libraries (%3, %4 and d3dcompiler_*.dll) "
+        "are available in the application executable's directory or in a location listed in PATH.");
+    *translatedMessage = QQuickWindow::tr(msg).arg(contextType, formatStr, eglLibName, glesLibName);
+    *untranslatedMessage = QString::fromLatin1(msg).arg(contextType, formatStr, eglLibName, glesLibName);
+#else // Q_OS_WIN32
+    //: %1 Context type (Open GL, EGL), %2 format specification
+    const char msg[] = QT_TRANSLATE_NOOP("QQuickWindow",
+                                         "Failed to create %1 context for format %2");
+    *translatedMessage = QQuickWindow::tr(msg).arg(contextType, formatStr);
+    *untranslatedMessage = QString::fromLatin1(msg).arg(contextType, formatStr);
+#endif // !Q_OS_WIN32
+}
+
 /*!
     Propagates an event \a e to a QQuickItem \a item on the window.
 
diff --git a/src/quick/items/qquickwindow_p.h b/src/quick/items/qquickwindow_p.h
index e78f00c22f..421651b483 100644
--- a/src/quick/items/qquickwindow_p.h
+++ b/src/quick/items/qquickwindow_p.h
@@ -242,6 +242,11 @@ public:
     static QObject *data_at(QQmlListProperty<QObject> *, int);
     static void data_clear(QQmlListProperty<QObject> *);
 
+    static void contextCreationFailureMessage(const QSurfaceFormat &format,
+                                              QString *translatedMessage,
+                                              QString *untranslatedMessage,
+                                              bool isEs);
+
 private:
     static void cleanupNodesOnShutdown(QQuickItem *);
 };
diff --git a/src/quick/scenegraph/qsgrenderloop.cpp b/src/quick/scenegraph/qsgrenderloop.cpp
index 644a674749..6647ec83d0 100644
--- a/src/quick/scenegraph/qsgrenderloop.cpp
+++ b/src/quick/scenegraph/qsgrenderloop.cpp
@@ -46,6 +46,7 @@
 #include <QtCore/QCoreApplication>
 #include <QtCore/QTime>
 #include <QtCore/QScopedPointer>
+#include <QtCore/QLibraryInfo>
 #include <QtCore/private/qabstractanimation_p.h>
 
 #include <QtGui/QOpenGLContext>
@@ -59,6 +60,10 @@
 #include <QtQuick/private/qsgcontext_p.h>
 #include <private/qquickprofiler_p.h>
 
+#ifdef Q_OS_WIN
+#  include <QtCore/qt_windows.h>
+#endif
+
 QT_BEGIN_NAMESPACE
 
 DEFINE_BOOL_CONFIG_OPTION(qsg_render_timing, QSG_RENDER_TIMING)
@@ -208,6 +213,32 @@ void QSGRenderLoop::setInstance(QSGRenderLoop *instance)
     s_renderLoopInstance->reset(instance);
 }
 
+void QSGRenderLoop::handleContextCreationFailure(QQuickWindow *window,
+                                                 bool isEs)
+{
+    QString translatedMessage;
+    QString untranslatedMessage;
+    QQuickWindowPrivate::contextCreationFailureMessage(window->requestedFormat(),
+                                                       &translatedMessage,
+                                                       &untranslatedMessage,
+                                                       isEs);
+    // If there is a slot connected to the error signal, emit it and leave it to
+    // the application to do something with the message. If nothing is connected,
+    // show a message on our own and terminate.
+    const bool signalEmitted =
+        QQuickWindowPrivate::get(window)->emitError(QQuickWindow::ContextNotAvailable,
+                                                    translatedMessage);
+#if defined(Q_OS_WIN) && !defined(Q_OS_WINCE) && !defined(Q_OS_WINRT)
+    if (!signalEmitted && !QLibraryInfo::isDebugBuild() && !GetConsoleWindow()) {
+        MessageBox(0, (LPCTSTR) translatedMessage.utf16(),
+                   (LPCTSTR)(QCoreApplication::applicationName().utf16()),
+                   MB_OK | MB_ICONERROR);
+    }
+#endif // Q_OS_WIN && !Q_OS_WINCE && !Q_OS_WINRT
+    if (!signalEmitted)
+        qFatal("%s", qPrintable(untranslatedMessage));
+}
+
 QSGGuiThreadRenderLoop::QSGGuiThreadRenderLoop()
     : gl(0)
     , eventPending(false)
@@ -283,18 +314,10 @@ void QSGGuiThreadRenderLoop::renderWindow(QQuickWindow *window)
         if (QSGContext::sharedOpenGLContext())
             gl->setShareContext(QSGContext::sharedOpenGLContext());
         if (!gl->create()) {
+            const bool isEs = gl->isES();
             delete gl;
             gl = 0;
-            QString formatStr;
-            QDebug(&formatStr) << window->requestedFormat();
-            QString contextType = QLatin1String("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));
+            handleContextCreationFailure(window, isEs);
         } else {
             cd->fireOpenGLContextCreated(gl);
             current = gl->makeCurrent(window);
diff --git a/src/quick/scenegraph/qsgrenderloop_p.h b/src/quick/scenegraph/qsgrenderloop_p.h
index 46edd77eda..2418af4157 100644
--- a/src/quick/scenegraph/qsgrenderloop_p.h
+++ b/src/quick/scenegraph/qsgrenderloop_p.h
@@ -88,6 +88,9 @@ public:
 
 Q_SIGNALS:
     void timeToIncubate();
+
+protected:
+    void handleContextCreationFailure(QQuickWindow *window, bool isEs);
 };
 
 QT_END_NAMESPACE
diff --git a/src/quick/scenegraph/qsgthreadedrenderloop.cpp b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
index f639841588..ba8c3a7fce 100644
--- a/src/quick/scenegraph/qsgthreadedrenderloop.cpp
+++ b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
@@ -946,19 +946,10 @@ void QSGThreadedRenderLoop::handleExposure(Window *w)
                 w->thread->gl->setShareContext(QSGContext::sharedOpenGLContext());
             w->thread->gl->setFormat(w->window->requestedFormat());
             if (!w->thread->gl->create()) {
+                const bool isEs = w->thread->gl->isES();
                 delete w->thread->gl;
                 w->thread->gl = 0;
-                QString formatStr;
-                QDebug(&formatStr) << w->window->requestedFormat();
-                QString contextType = QLatin1String("OpenGL");
-                const char *msg = QT_TRANSLATE_NOOP("QSGThreadedRenderLoop",
-                                                    "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(w->window)->emitError(QQuickWindow::ContextNotAvailable,
-                                                                                    translatedMsg);
-                if (!signalEmitted)
-                    qFatal("%s", qPrintable(nonTranslatedMsg));
+                handleContextCreationFailure(w->window, isEs);
                 return;
             }
 
diff --git a/src/quick/scenegraph/qsgwindowsrenderloop.cpp b/src/quick/scenegraph/qsgwindowsrenderloop.cpp
index 31012c7589..913b737798 100644
--- a/src/quick/scenegraph/qsgwindowsrenderloop.cpp
+++ b/src/quick/scenegraph/qsgwindowsrenderloop.cpp
@@ -183,35 +183,10 @@ void QSGWindowsRenderLoop::show(QQuickWindow *window)
             m_gl->setShareContext(QSGContext::sharedOpenGLContext());
         bool created = m_gl->create();
         if (!created) {
-            const bool isDebug = QLibraryInfo::isDebugBuild();
-            QString eglLibName = QLatin1String(isDebug ? "libEGLd.dll" : "libEGL.dll");
-            QString glesLibName = QLatin1String(isDebug ? "libGLESv2d.dll" : "libGLESv2.dll");
-            QString contextType = QLatin1String("OpenGL");
-            const char *msg = QT_TRANSLATE_NOOP(
-                "QSGWindowsRenderLoop",
-                "Failed to create %1 context. "
-                "This is most likely caused by not having the necessary graphics drivers installed.\n\n"
-                "Install a driver providing OpenGL 2.0 or higher, or, if this is not possible, "
-                "make sure the Angle Open GL ES 2.0 emulation libraries (%2, %3 and d3dcompiler_*.dll) "
-                "are available in the application executable's directory or in a location listed in PATH.");
-            QString translatedMsg = tr(msg).arg(contextType).arg(eglLibName).arg(glesLibName);
-            QString nonTranslatedMsg = QString(QLatin1String(msg)).arg(contextType).arg(eglLibName).arg(glesLibName);
-            // If there is a slot connected to the error signal, emit it and leave it to
-            // the application to do something with the message. If nothing is connected,
-            // show a message on our own and terminate.
-            bool signalEmitted = QQuickWindowPrivate::get(window)->emitError(QQuickWindow::ContextNotAvailable,
-                                                                             translatedMsg);
-#if defined(Q_OS_WIN) && !defined(Q_OS_WINCE) && !defined(Q_OS_WINRT)
-            if (!signalEmitted && !isDebug && !GetConsoleWindow()) {
-                MessageBox(0, (LPCTSTR) translatedMsg.utf16(),
-                           (LPCTSTR)(QCoreApplication::applicationName().utf16()),
-                           MB_OK | MB_ICONERROR);
-            }
-#endif // !Q_OS_WINCE && !Q_OS_WINRT
+            const bool isEs = m_gl->isES();
             delete m_gl;
             m_gl = 0;
-            if (!signalEmitted)
-                qFatal("%s", qPrintable(nonTranslatedMsg));
+            handleContextCreationFailure(window, isEs);
             return;
         }
 
diff --git a/src/quickwidgets/qquickwidget.cpp b/src/quickwidgets/qquickwidget.cpp
index dbc7d6c21a..46db2ddfeb 100644
--- a/src/quickwidgets/qquickwidget.cpp
+++ b/src/quickwidgets/qquickwidget.cpp
@@ -56,6 +56,12 @@
 #include <QtCore/qbasictimer.h>
 #include <QtGui/QOffscreenSurface>
 
+#ifdef Q_OS_WIN
+#  include <QtWidgets/QMessageBox>
+#  include <QtCore/QLibraryInfo>
+#  include <QtCore/qt_windows.h>
+#endif
+
 QT_BEGIN_NAMESPACE
 
 extern Q_GUI_EXPORT QImage qt_gl_read_framebuffer(const QSize &size, bool alpha_format, bool include_alpha);
@@ -387,6 +393,21 @@ QQmlContext* QQuickWidget::rootContext() const
 */
 
 /*!
+    \fn void QQuickWidget::sceneGraphError(QQuickWindow::SceneGraphError error, const QString &message)
+
+    This signal is emitted when an error occurred during scene graph initialization.
+
+    Applications should connect to this signal if they wish to handle errors,
+    like OpenGL context creation failures, in a custom way. When no slot is
+    connected to the signal, the behavior will be different: Quick will print
+    the message, or show a message box, and terminate the application.
+
+    This signal will be emitted from the gui thread.
+
+    \sa QQuickWindow::sceneGraphError()
+ */
+
+/*!
     \property QQuickWidget::status
     The component's current \l{QQuickWidget::Status} {status}.
 */
@@ -510,6 +531,27 @@ QSize QQuickWidgetPrivate::rootObjectSize() const
     return rootObjectSize;
 }
 
+void QQuickWidgetPrivate::handleContextCreationFailure(const QSurfaceFormat &format, bool isEs)
+{
+    Q_Q(QQuickWidget);
+
+    QString translatedMessage;
+    QString untranslatedMessage;
+    QQuickWindowPrivate::contextCreationFailureMessage(format, &translatedMessage, &untranslatedMessage, isEs);
+
+    static const QMetaMethod errorSignal = QMetaMethod::fromSignal(&QQuickWidget::sceneGraphError);
+    const bool signalConnected = q->isSignalConnected(errorSignal);
+    if (signalConnected)
+        emit q->sceneGraphError(QQuickWindow::ContextNotAvailable, translatedMessage);
+
+#if defined(Q_OS_WIN) && !defined(Q_OS_WINCE) && !defined(Q_OS_WINRT)
+    if (!signalConnected && !QLibraryInfo::isDebugBuild() && !GetConsoleWindow())
+        QMessageBox::critical(q, QCoreApplication::applicationName(), translatedMessage);
+#endif // Q_OS_WIN && !Q_OS_WINCE && !Q_OS_WINRT
+    if (!signalConnected)
+        qFatal("%s", qPrintable(untranslatedMessage));
+}
+
 void QQuickWidgetPrivate::createContext()
 {
     if (context)
@@ -521,9 +563,10 @@ void QQuickWidgetPrivate::createContext()
     if (QSGContext::sharedOpenGLContext())
         context->setShareContext(QSGContext::sharedOpenGLContext()); // ??? is this correct
     if (!context->create()) {
-        qWarning("QQuickWidget: failed to create OpenGL context");
+        const bool isEs = context->isES();
         delete context;
         context = 0;
+        handleContextCreationFailure(offscreenWindow->requestedFormat(), isEs);
         return;
     }
 
diff --git a/src/quickwidgets/qquickwidget.h b/src/quickwidgets/qquickwidget.h
index 614d5b82a6..2c021c85fb 100644
--- a/src/quickwidgets/qquickwidget.h
+++ b/src/quickwidgets/qquickwidget.h
@@ -95,6 +95,7 @@ public Q_SLOTS:
 
 Q_SIGNALS:
     void statusChanged(QQuickWidget::Status);
+    void sceneGraphError(QQuickWindow::SceneGraphError error, const QString &message);
 
 private Q_SLOTS:
     void continueExecute();
diff --git a/src/quickwidgets/qquickwidget_p.h b/src/quickwidgets/qquickwidget_p.h
index 2d2d6500b2..1ba06162f9 100644
--- a/src/quickwidgets/qquickwidget_p.h
+++ b/src/quickwidgets/qquickwidget_p.h
@@ -86,6 +86,7 @@ public:
     void renderSceneGraph();
     void createContext();
     void destroyContext();
+    void handleContextCreationFailure(const QSurfaceFormat &format, bool isEs);
 
     GLuint textureId() const Q_DECL_OVERRIDE;