ask the user whether to stop a rendering process when accidentally dragging the mouse in an ongoing rendering session

include/mitsuba/render/renderjob.h

@@ -98,6 +98,15 @@ public:
 	/// Get a pointer to the underlying scene (const version)
 	inline const Scene *getScene() const { return m_scene.get(); }
 
+	/// Get a pointer to the underlying render queue
+	inline RenderQueue *getRenderQueue() { return m_queue.get(); }
+
+	/// Get a pointer to the underlying render queue (const version)
+	inline const RenderQueue *getRenderQueue() const { return m_queue.get(); }
+
+	/// Return the amount of time spent rendering the given job (in seconds)
+	inline Float getRenderTime() const { return m_queue->getRenderTime(this); }
+
 	MTS_DECLARE_CLASS()
 protected:
 	/// Virtual destructor

src/libpython/render.cpp

@@ -362,12 +362,14 @@ void export_render() {
 		.staticmethod("loadScene");
 
  	Scene *(RenderJob::*renderJob_getScene)(void) = &RenderJob::getScene;
+ 	RenderQueue *(RenderJob::*renderJob_getRenderQueue)(void) = &RenderJob::getRenderQueue;
 	BP_CLASS(RenderJob, Thread, (bp::init<const std::string &, Scene *, RenderQueue *>()))
 		.def(bp::init<const std::string &, Scene *, RenderQueue *, int, bp::optional<int, int> >())
 		.def("flush", &RenderJob::flush)
 		.def("cancel", renderJob_cancel)
 		.def("wait", &RenderJob::wait)
- 		.def("getScene", renderJob_getScene, BP_RETURN_VALUE);
+ 		.def("getScene", renderJob_getScene, BP_RETURN_VALUE)
+ 		.def("getRenderQueue", renderJob_getRenderQueue, BP_RETURN_VALUE);
 
 	BP_CLASS(RenderQueue, Object, bp::init<>())
 		.def("getJobCount", &RenderQueue::getJobCount)

src/mtsgui/glwidget.cpp

@@ -386,13 +386,11 @@ void GLWidget::focusOutEvent(QFocusEvent *event) {
 		m_movementTimer->stop();
 }
 
-
 void GLWidget::timerImpulse() {
 	if (!m_context || !m_context->scene || !m_preview->isRunning()) {
 		m_movementTimer->stop();
 		return;
 	}
-
 	if (m_animation) {
 		Float x = std::min(m_animationTimer->getMilliseconds() / 500.0f, 1.0f);
 		Float t = x*x*x*(x*(x*6-15)+10); // smootherstep by Ken Perlin
@@ -453,6 +451,23 @@ void GLWidget::timerImpulse() {
 	resetPreview();
 }
 
+bool GLWidget::askReallyCancelRendering() {
+	try {
+		Float renderTime = m_context->renderJob->getRenderTime();
+
+		if (renderTime < 10) /* Only ask for jobs that have been rendering for a bit */
+			return true;
+	} catch (...) {
+		return true;
+	}
+
+	bool cancel = QMessageBox::question(this,
+		"Really cancel rendering?", "Camera motion detected. Do you really want to cancel the rendering?",
+		QMessageBox::Yes | QMessageBox::No) == QMessageBox::Yes;
+
+	return cancel;
+}
+
 void GLWidget::resetPreview() {
 	if (!m_context || !m_context->scene || !m_preview->isRunning())
 		return;
@@ -543,6 +558,12 @@ void GLWidget::keyPressEvent(QKeyEvent *event) {
 	}
 	if (!m_movementTimer->isActive() && (m_leftKeyDown || m_rightKeyDown
 			|| m_upKeyDown || m_downKeyDown)) {
+
+		if (m_context->renderJob && !askReallyCancelRendering()) {
+			m_leftKeyDown = m_rightKeyDown = m_upKeyDown = m_downKeyDown = false;
+			return;
+		}
+
 		m_clock->reset();
 		m_movementTimer->start();
 	}
@@ -615,6 +636,12 @@ void GLWidget::mouseMoveEvent(QMouseEvent *event) {
 		nearClip = camera->getNearClip(),
 		farClip = camera->getFarClip();
 
+	bool setCursor = true;
+	if (m_context->renderJob) {
+		if (!askReallyCancelRendering())
+			return;
+		setCursor = false;
+	}
 	if (focusDistance <= nearClip || focusDistance >= farClip) {
 		focusDistance = autoFocus();
 		camera->setFocusDistance(focusDistance);
@@ -623,7 +650,7 @@ void GLWidget::mouseMoveEvent(QMouseEvent *event) {
 	Point target = p + d * focusDistance;
 	Vector up = m_context->up;
 
-	if (!m_didSetCursor) {
+	if (!m_didSetCursor && setCursor) {
 		QApplication::setOverrideCursor(Qt::BlankCursor);
 		m_didSetCursor = true;
 	}
@@ -828,11 +855,13 @@ void GLWidget::wheelEvent(QWheelEvent *event) {
 	} else {
 		if (!m_preview->isRunning() || m_context == NULL || m_context->scene == NULL || m_animation)
 			return;
-
 		PerspectiveCamera *camera = getPerspectiveCamera();
 		if (!camera)
 			return;
 
+		if (m_context->renderJob && !askReallyCancelRendering())
+			return;
+
 		Float focusDistance = camera->getFocusDistance(),
 			nearClip = camera->getNearClip(),
 			farClip = camera->getFarClip();

src/mtsgui/glwidget.h

@@ -127,6 +127,7 @@ protected:
 	Point2i upperLeft(bool flipY = false) const;
 	void reveal(const AABB &aabb);
 	Float autoFocus() const;
+	bool askReallyCancelRendering();
 
 	inline ProjectiveCamera *getProjectiveCamera() {
 		Sensor *sensor = m_context->scene->getSensor();