Port the threadedqopenglwidget example

Task-number: PYSIDE-841
Pick-to: 6.2
Change-Id: Ia394ab350ab04281e2227dc3af950913f44c6564
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>

1 files changed, 115 insertions, 0 deletions

diff --git a/examples/opengl/threadedqopenglwidget/glwidget.py b/examples/opengl/threadedqopenglwidget/glwidget.py
new file mode 100644
index 000000000..b9a1091c9
--- /dev/null
+++ b/examples/opengl/threadedqopenglwidget/glwidget.py
@@ -0,0 +1,115 @@
+#############################################################################
+##
+## Copyright (C) 2022 The Qt Company Ltd.
+## Contact: http://www.qt.io/licensing/
+##
+## This file is part of the Qt for Python 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 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."
+##
+## $QT_END_LICENSE$
+##
+#############################################################################
+
+
+from PySide6.QtOpenGLWidgets import QOpenGLWidget
+from PySide6.QtCore import QMutexLocker, QSize, QThread, Slot, Signal
+
+from renderer import Renderer
+
+
+class GLWidget(QOpenGLWidget):
+
+    render_requested = Signal()
+
+    def __init__(self, parent=None):
+        super().__init__(parent)
+
+        self.aboutToCompose.connect(self.on_about_to_compose)
+        self.frameSwapped.connect(self.on_frame_swapped)
+        self.aboutToResize.connect(self.on_about_to_resize)
+        self.resized.connect(self.on_resized)
+
+        self._thread = QThread()
+        self._renderer = Renderer(self)
+        self._renderer.moveToThread(self._thread)
+        self._thread.finished.connect(self._renderer.deleteLater)
+
+        self.render_requested.connect(self._renderer.render)
+        self._renderer.context_wanted.connect(self.grab_context)
+
+        self._thread.start()
+
+    def stop_rendering(self):
+        self._renderer.prepare_exit()
+        self._thread.quit()
+        self._thread.wait()
+        self._thread = None
+        self._renderer = None
+
+    def closeEvent(self, event):
+        self.stop_rendering()
+        event.accept()
+
+    def paintEvent(self, event):
+        pass
+
+    def sizeHint(self):
+        return QSize(200, 200)
+
+    @Slot()
+    def on_about_to_compose(self):
+        # We are on the gui thread here. Composition is about to
+        # begin. Wait until the render thread finishes.
+        self._renderer.lock_renderer()
+
+    @Slot()
+    def on_frame_swapped(self):
+        self._renderer.unlock_renderer()
+        # Assuming a blocking swap, our animation is driven purely by the
+        # vsync in self example.
+        self.render_requested.emit()
+
+    @Slot()
+    def on_about_to_resize(self):
+        self._renderer.lock_renderer()
+
+    @Slot()
+    def on_resized(self):
+        self._renderer.unlock_renderer()
+
+    def grab_context(self):
+        if not self._renderer:
+            return
+        self._renderer.lock_renderer()
+        with QMutexLocker(self._renderer.grab_mutex()):
+            self.context().moveToThread(self._thread)
+            self._renderer.grab_condition().wakeAll()
+            self._renderer.unlock_renderer()