5 files changed, 59 insertions, 1 deletions
diff --git a/src/gui/kernel/qopenglcontext.cpp b/src/gui/kernel/qopenglcontext.cpp
index f6273fc6dd..71a1d1e074 100644
--- a/src/gui/kernel/qopenglcontext.cpp
+++ b/src/gui/kernel/qopenglcontext.cpp
@@ -489,6 +489,12 @@ QOpenGLContext::QOpenGLContext(QObject *parent)
 /*!
     Sets the \a format the OpenGL context should be compatible with. You need
     to call create() before it takes effect.
+
+    When the format is not explicitly set via this function, the format returned
+    by QSurfaceFormat::defaultFormat() will be used. This means that when having
+    multiple contexts, individual calls to this function can be replaced by one
+    single call to QSurfaceFormat::setDefaultFormat() before creating the first
+    context.
 */
 void QOpenGLContext::setFormat(const QSurfaceFormat &format)
 {
diff --git a/src/gui/kernel/qopenglcontext_p.h b/src/gui/kernel/qopenglcontext_p.h
index 4447df5294..46e1572376 100644
--- a/src/gui/kernel/qopenglcontext_p.h
+++ b/src/gui/kernel/qopenglcontext_p.h
@@ -211,6 +211,7 @@ public:
         , workaround_missingPrecisionQualifiers(false)
         , active_engine(0)
     {
+        requestedFormat = QSurfaceFormat::defaultFormat();
     }
 
     virtual ~QOpenGLContextPrivate()
diff --git a/src/gui/kernel/qsurfaceformat.cpp b/src/gui/kernel/qsurfaceformat.cpp
index 2b8e611dff..f077abc6a2 100644
--- a/src/gui/kernel/qsurfaceformat.cpp
+++ b/src/gui/kernel/qsurfaceformat.cpp
@@ -196,6 +196,9 @@ public:
 
 /*!
     Constructs a default initialized QSurfaceFormat.
+
+    \note By default OpenGL 2.0 is requested since this provides the highest
+    grade of portability between platforms and OpenGL implementations.
 */
 QSurfaceFormat::QSurfaceFormat() : d(new QSurfaceFormatPrivate)
 {
@@ -730,6 +733,43 @@ int QSurfaceFormat::swapInterval() const
     return d->swapInterval;
 }
 
+Q_GLOBAL_STATIC(QSurfaceFormat, qt_default_surface_format)
+
+/*!
+    Sets the global default surface \a format.
+
+    This format is used by default in QOpenGLContext, QWindow, QOpenGLWidget and
+    similar classes.
+
+    It can always be overridden on a per-instance basis by using the class in
+    question's own setFormat() function. However, it is often more convenient to
+    set the format for all windows once at the start of the application. It also
+    guarantees proper behavior in cases where shared contexts are required,
+    because settings the format via this function guarantees that all contexts
+    and surfaces, even the ones created internally by Qt, will use the same
+    format.
+
+    \since 5.4
+    \sa defaultFormat()
+ */
+void QSurfaceFormat::setDefaultFormat(const QSurfaceFormat &format)
+{
+    *qt_default_surface_format() = format;
+}
+
+/*!
+    Returns the global default surface format.
+
+    When setDefaultFormat() is not called, this is a default-constructed QSurfaceFormat.
+
+    \since 5.4
+    \sa setDefaultFormat()
+ */
+QSurfaceFormat QSurfaceFormat::defaultFormat()
+{
+    return *qt_default_surface_format();
+}
+
 /*!
     Returns \c true if all the options of the two QSurfaceFormat objects
     \a a and \a b are equal.
diff --git a/src/gui/kernel/qsurfaceformat.h b/src/gui/kernel/qsurfaceformat.h
index 453beac5cd..05aba2f83c 100644
--- a/src/gui/kernel/qsurfaceformat.h
+++ b/src/gui/kernel/qsurfaceformat.h
@@ -138,6 +138,9 @@ public:
     int swapInterval() const;
     void setSwapInterval(int interval);
 
+    static void setDefaultFormat(const QSurfaceFormat &format);
+    static QSurfaceFormat defaultFormat();
+
 private:
     QSurfaceFormatPrivate *d;
 
diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index 8159b7746e..8c0db2c0c7 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -224,6 +224,8 @@ void QWindowPrivate::init()
         exit(1);
     }
     QGuiApplicationPrivate::window_list.prepend(q);
+
+    requestedFormat = QSurfaceFormat::defaultFormat();
 }
 
 /*!
@@ -672,7 +674,13 @@ void QWindow::setModality(Qt::WindowModality modality)
     this function after create() has been called will not re-resolve the
     surface format of the native surface.
 
-    \sa create(), destroy()
+    When the format is not explicitly set via this function, the format returned
+    by QSurfaceFormat::defaultFormat() will be used. This means that when having
+    multiple windows, individual calls to this function can be replaced by one
+    single call to QSurfaceFormat::setDefaultFormat() before creating the first
+    window.
+
+    \sa create(), destroy(), QSurfaceFormat::setDefaultFormat()
 */
 void QWindow::setFormat(const QSurfaceFormat &format)
 {