Support threading with QQuickRenderControl

Reorganize the rendercontrol example to demonstrate both the single
and multi threaded approaches.

A small helper function is introduced to the QQuickRenderControl API:
The QSGRenderContext has to live on the render thread. Previously there
was no way for applications to move it to the desired thread. This is
now possible.

Pass --threaded to the rendercontrol example to use a separate render thread.

[ChangeLog][QtQuick] QQuickRenderControl can now be used to render the Qt Quick
scene on a dedicated render thread, similarly to how the built-in threaded render
loop operates.

Task-number: QTBUG-42813
Change-Id: I01c3b2ffca8a174d9d2c267a51f2e484ed7b34b3
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>
Reviewed-by: Jørgen Lind <jorgen.lind@theqtcompany.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/examples/quick/rendercontrol/cuberenderer.h b/examples/quick/rendercontrol/cuberenderer.h
new file mode 100644
index 0000000000..8f98376fdf
--- /dev/null
+++ b/examples/quick/rendercontrol/cuberenderer.h
@@ -0,0 +1,73 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** You may use this file under the terms of the BSD license as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
+**     of its contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef CUBERENDERER_H
+#define CUBERENDERER_H
+
+#include <QMatrix4x4>
+
+QT_FORWARD_DECLARE_CLASS(QOpenGLContext)
+QT_FORWARD_DECLARE_CLASS(QOpenGLShaderProgram)
+QT_FORWARD_DECLARE_CLASS(QOpenGLBuffer)
+QT_FORWARD_DECLARE_CLASS(QOpenGLVertexArrayObject)
+QT_FORWARD_DECLARE_CLASS(QWindow)
+
+class CubeRenderer
+{
+public:
+    CubeRenderer();
+    ~CubeRenderer();
+
+    void resize(int w, int h);
+    void render(QWindow *w, QOpenGLContext *share, uint texture);
+
+private:
+    void init(QWindow *w, QOpenGLContext *share);
+    void setupVertexAttribs();
+
+    QOpenGLContext *m_context;
+    QOpenGLShaderProgram *m_program;
+    QOpenGLBuffer *m_vbo;
+    QOpenGLVertexArrayObject *m_vao;
+    int m_matrixLoc;
+    QMatrix4x4 m_proj;
+};
+
+#endif