Move legacy rendercontrol example into a subdirectory

...called rendercontrol_opengl under examples/quick/rendercontrol. This
example is going to be migrated to support operating with RHI-on-OpenGL
later on.

Additionally, we can this way introduce more rendercontrol examples in
the future, for example to show how to do things with Vulkan, Metal,
D3D.

Task-number: QTBUG-78595
Change-Id: I7f5243b1f86e62949400107bf12bfa07b17b1031
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>

1 files changed, 352 insertions, 0 deletions

diff --git a/examples/quick/rendercontrol/rendercontrol_opengl/window_singlethreaded.cpp b/examples/quick/rendercontrol/rendercontrol_opengl/window_singlethreaded.cpp
new file mode 100644
index 0000000000..ddbbfe4b52
--- /dev/null
+++ b/examples/quick/rendercontrol/rendercontrol_opengl/window_singlethreaded.cpp
@@ -0,0 +1,352 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, 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 The Qt Company Ltd 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."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "window_singlethreaded.h"
+#include "cuberenderer.h"
+#include <QOpenGLContext>
+#include <QOpenGLFunctions>
+#include <QOpenGLFramebufferObject>
+#include <QOpenGLShaderProgram>
+#include <QOpenGLVertexArrayObject>
+#include <QOpenGLBuffer>
+#include <QOpenGLVertexArrayObject>
+#include <QOffscreenSurface>
+#include <QScreen>
+#include <QQmlEngine>
+#include <QQmlComponent>
+#include <QQuickItem>
+#include <QQuickWindow>
+#include <QQuickRenderControl>
+#include <QCoreApplication>
+
+class RenderControl : public QQuickRenderControl
+{
+public:
+    RenderControl(QWindow *w) : m_window(w) { }
+    QWindow *renderWindow(QPoint *offset) override;
+
+private:
+    QWindow *m_window;
+};
+
+QWindow *RenderControl::renderWindow(QPoint *offset)
+{
+    if (offset)
+        *offset = QPoint(0, 0);
+    return m_window;
+}
+
+WindowSingleThreaded::WindowSingleThreaded()
+    : m_rootItem(nullptr),
+      m_fbo(nullptr),
+      m_quickInitialized(false),
+      m_quickReady(false),
+      m_dpr(0)
+{
+    setSurfaceType(QSurface::OpenGLSurface);
+
+    // The rendercontrol does not necessarily need an FBO. Demonstrate this
+    // when requested.
+    m_onscreen = QCoreApplication::arguments().contains(QStringLiteral("--onscreen"));
+
+    QSurfaceFormat format;
+    // Qt Quick may need a depth and stencil buffer. Always make sure these are available.
+    format.setDepthBufferSize(16);
+    format.setStencilBufferSize(8);
+    setFormat(format);
+
+    m_context = new QOpenGLContext;
+    m_context->setFormat(format);
+    m_context->create();
+
+    m_offscreenSurface = new QOffscreenSurface;
+    // Pass m_context->format(), not format. Format does not specify and color buffer
+    // sizes, while the context, that has just been created, reports a format that has
+    // these values filled in. Pass this to the offscreen surface to make sure it will be
+    // compatible with the context's configuration.
+    m_offscreenSurface->setFormat(m_context->format());
+    m_offscreenSurface->create();
+
+    m_cubeRenderer = new CubeRenderer(m_offscreenSurface);
+
+    m_renderControl = new RenderControl(this);
+
+    // Create a QQuickWindow that is associated with out render control. Note that this
+    // window never gets created or shown, meaning that it will never get an underlying
+    // native (platform) window.
+    m_quickWindow = new QQuickWindow(m_renderControl);
+
+    // Create a QML engine.
+    m_qmlEngine = new QQmlEngine;
+    if (!m_qmlEngine->incubationController())
+        m_qmlEngine->setIncubationController(m_quickWindow->incubationController());
+
+    // When Quick says there is a need to render, we will not render immediately. Instead,
+    // a timer with a small interval is used to get better performance.
+    m_updateTimer.setSingleShot(true);
+    m_updateTimer.setInterval(5);
+    connect(&m_updateTimer, &QTimer::timeout, this, &WindowSingleThreaded::render);
+
+    // Now hook up the signals. For simplicy we don't differentiate between
+    // renderRequested (only render is needed, no sync) and sceneChanged (polish and sync
+    // is needed too).
+    connect(m_quickWindow, &QQuickWindow::sceneGraphInitialized, this, &WindowSingleThreaded::createFbo);
+    connect(m_quickWindow, &QQuickWindow::sceneGraphInvalidated, this, &WindowSingleThreaded::destroyFbo);
+    connect(m_renderControl, &QQuickRenderControl::renderRequested, this, &WindowSingleThreaded::requestUpdate);
+    connect(m_renderControl, &QQuickRenderControl::sceneChanged, this, &WindowSingleThreaded::requestUpdate);
+
+    // Just recreating the FBO on resize is not sufficient, when moving between screens
+    // with different devicePixelRatio the QWindow size may remain the same but the FBO
+    // dimension is to change regardless.
+    connect(this, &QWindow::screenChanged, this, &WindowSingleThreaded::handleScreenChange);
+}
+
+WindowSingleThreaded::~WindowSingleThreaded()
+{
+    // Make sure the context is current while doing cleanup. Note that we use the
+    // offscreen surface here because passing 'this' at this point is not safe: the
+    // underlying platform window may already be destroyed. To avoid all the trouble, use
+    // another surface that is valid for sure.
+    m_context->makeCurrent(m_offscreenSurface);
+
+    // Delete the render control first since it will free the scenegraph resources.
+    // Destroy the QQuickWindow only afterwards.
+    delete m_renderControl;
+
+    delete m_qmlComponent;
+    delete m_quickWindow;
+    delete m_qmlEngine;
+    delete m_fbo;
+
+    m_context->doneCurrent();
+
+    delete m_cubeRenderer;
+
+    delete m_offscreenSurface;
+    delete m_context;
+}
+
+void WindowSingleThreaded::createFbo()
+{
+    // The scene graph has been initialized. It is now time to create an FBO and associate
+    // it with the QQuickWindow.
+    m_dpr = devicePixelRatio();
+    if (!m_onscreen) {
+        m_fbo = new QOpenGLFramebufferObject(size() * m_dpr, QOpenGLFramebufferObject::CombinedDepthStencil);
+        m_quickWindow->setRenderTarget(m_fbo);
+    } else {
+        // Special case: No FBO. Render directly to the window's default framebuffer.
+        m_onscreenSize = size() * m_dpr;
+        m_quickWindow->setRenderTarget(0, m_onscreenSize);
+    }
+}
+
+void WindowSingleThreaded::destroyFbo()
+{
+    delete m_fbo;
+    m_fbo = nullptr;
+}
+
+void WindowSingleThreaded::render()
+{
+    QSurface *surface = m_offscreenSurface;
+    if (m_onscreen)
+        surface = this;
+    if (!m_context->makeCurrent(surface))
+        return;
+
+    // Polish, synchronize and render the next frame (into our fbo).  In this example
+    // everything happens on the same thread and therefore all three steps are performed
+    // in succession from here. In a threaded setup the render() call would happen on a
+    // separate thread.
+    m_renderControl->polishItems();
+    m_renderControl->sync();
+    m_renderControl->render();
+
+    m_quickWindow->resetOpenGLState();
+    QOpenGLFramebufferObject::bindDefault();
+
+    m_context->functions()->glFlush();
+
+    m_quickReady = true;
+
+    // Get something onto the screen.
+    if (!m_onscreen)
+        m_cubeRenderer->render(this, m_context, m_quickReady ? m_fbo->texture() : 0);
+    else
+        m_context->swapBuffers(this);
+}
+
+void WindowSingleThreaded::requestUpdate()
+{
+    if (!m_updateTimer.isActive())
+        m_updateTimer.start();
+}
+
+void WindowSingleThreaded::run()
+{
+    disconnect(m_qmlComponent, &QQmlComponent::statusChanged, this, &WindowSingleThreaded::run);
+
+    if (m_qmlComponent->isError()) {
+        const QList<QQmlError> errorList = m_qmlComponent->errors();
+        for (const QQmlError &error : errorList)
+            qWarning() << error.url() << error.line() << error;
+        return;
+    }
+
+    QObject *rootObject = m_qmlComponent->create();
+    if (m_qmlComponent->isError()) {
+        const QList<QQmlError> errorList = m_qmlComponent->errors();
+        for (const QQmlError &error : errorList)
+            qWarning() << error.url() << error.line() << error;
+        return;
+    }
+
+    m_rootItem = qobject_cast<QQuickItem *>(rootObject);
+    if (!m_rootItem) {
+        qWarning("run: Not a QQuickItem");
+        delete rootObject;
+        return;
+    }
+
+    // The root item is ready. Associate it with the window.
+    m_rootItem->setParentItem(m_quickWindow->contentItem());
+
+    // Update item and rendering related geometries.
+    updateSizes();
+
+    // Initialize the render control and our OpenGL resources.
+    QSurface *surface = m_offscreenSurface;
+    if (m_onscreen)
+        surface = this;
+    m_context->makeCurrent(surface);
+    m_renderControl->initialize(m_context);
+    m_quickInitialized = true;
+}
+
+void WindowSingleThreaded::updateSizes()
+{
+    // Behave like SizeRootObjectToView.
+    m_rootItem->setWidth(width());
+    m_rootItem->setHeight(height());
+
+    m_quickWindow->setGeometry(0, 0, width(), height());
+
+    m_cubeRenderer->resize(width(), height());
+}
+
+void WindowSingleThreaded::startQuick(const QString &filename)
+{
+    m_qmlComponent = new QQmlComponent(m_qmlEngine, QUrl(filename));
+    if (m_qmlComponent->isLoading())
+        connect(m_qmlComponent, &QQmlComponent::statusChanged, this, &WindowSingleThreaded::run);
+    else
+        run();
+}
+
+void WindowSingleThreaded::exposeEvent(QExposeEvent *)
+{
+    if (isExposed()) {
+        if (!m_quickInitialized) {
+            if (!m_onscreen)
+                m_cubeRenderer->render(this, m_context, m_quickReady ? m_fbo->texture() : 0);
+            startQuick(QStringLiteral("qrc:/rendercontrol/demo.qml"));
+        }
+    }
+}
+
+void WindowSingleThreaded::resizeFbo()
+{
+    QSurface *surface = m_offscreenSurface;
+    if (m_onscreen)
+        surface = this;
+    if (m_rootItem && m_context->makeCurrent(surface)) {
+        delete m_fbo;
+        createFbo();
+        m_context->doneCurrent();
+        updateSizes();
+        render();
+    }
+}
+
+void WindowSingleThreaded::resizeEvent(QResizeEvent *)
+{
+    // If this is a resize after the scene is up and running, recreate the fbo and the
+    // Quick item and scene.
+    if (!m_onscreen) {
+        if (m_fbo && m_fbo->size() != size() * devicePixelRatio())
+            resizeFbo();
+    } else {
+        if (m_onscreenSize != size() * devicePixelRatio())
+            resizeFbo();
+    }
+}
+
+void WindowSingleThreaded::handleScreenChange()
+{
+    if (m_dpr != devicePixelRatio())
+        resizeFbo();
+}
+
+void WindowSingleThreaded::mousePressEvent(QMouseEvent *e)
+{
+    // Use the constructor taking localPos and screenPos. That puts localPos into the
+    // event's localPos and windowPos, and screenPos into the event's screenPos. This way
+    // the windowPos in e is ignored and is replaced by localPos. This is necessary
+    // because QQuickWindow thinks of itself as a top-level window always.
+    QMouseEvent mappedEvent(e->type(), e->localPos(), e->screenPos(), e->button(), e->buttons(), e->modifiers());
+    QCoreApplication::sendEvent(m_quickWindow, &mappedEvent);
+}
+
+void WindowSingleThreaded::mouseReleaseEvent(QMouseEvent *e)
+{
+    QMouseEvent mappedEvent(e->type(), e->localPos(), e->screenPos(), e->button(), e->buttons(), e->modifiers());
+    QCoreApplication::sendEvent(m_quickWindow, &mappedEvent);
+}