[libcamera-devel] [PATCH v4 5/6] qcam: main_window: Introduce initial hotplug support

[Laurent Pinchart]

Hi Umang,

Thank you for the patch.

On Thu, Jun 11, 2020 at 05:16:07PM +0000, Umang Jain wrote:
> Hook up various QCam UI bits with hotplug support introduced
> in previous commits. This looks good-enough as first steps
> to see how the hotplugging functionality is turning out to be
> from application point-of-view.
> 
> One can still think of few edge case nuances not yet covered
> under this implementation hence, those are intentionally
> kept out of scope for now. It might require some thinking
> and/or additional time on hand.
> 
> Signed-off-by: Umang Jain <email at uajain.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

> ---
>  src/qcam/main_window.cpp | 76 ++++++++++++++++++++++++++++++++++++++++
>  src/qcam/main_window.h   |  6 ++++
>  2 files changed, 82 insertions(+)
> 
> diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp
> index 2960259..7bc1360 100644
> --- a/src/qcam/main_window.cpp
> +++ b/src/qcam/main_window.cpp
> @@ -59,6 +59,36 @@ public:
>  	}
>  };
>  
> +/**
> + * \brief Custom QEvent to signal hotplug or unplug
> + */
> +class HotplugEvent : public QEvent
> +{
> +public:
> +	enum PlugEvent {
> +		HotPlug,
> +		HotUnplug
> +	};
> +
> +	HotplugEvent(std::shared_ptr<Camera> camera, PlugEvent event)
> +		: QEvent(type()), camera_(std::move(camera)), plugEvent_(event)
> +	{
> +	}
> +
> +	static Type type()
> +	{
> +		static int type = QEvent::registerEventType();
> +		return static_cast<Type>(type);
> +	}
> +
> +	PlugEvent hotplugEvent() const { return plugEvent_; }
> +	Camera *camera() const { return camera_.get(); }
> +
> +private:
> +	std::shared_ptr<Camera> camera_;
> +	PlugEvent plugEvent_;
> +};
> +
>  MainWindow::MainWindow(CameraManager *cm, const OptionsParser::Options &options)
>  	: saveRaw_(nullptr), options_(options), cm_(cm), allocator_(nullptr),
>  	  isCapturing_(false), captureRaw_(false)
> @@ -81,6 +111,10 @@ MainWindow::MainWindow(CameraManager *cm, const OptionsParser::Options &options)
>  	setCentralWidget(viewfinder_);
>  	adjustSize();
>  
> +	/* Hotplug/unplug support */
> +	cm_->cameraAdded.connect(this, &MainWindow::addCamera);
> +	cm_->cameraRemoved.connect(this, &MainWindow::removeCamera);
> +
>  	/* Open the camera and start capture. */
>  	ret = openCamera();
>  	if (ret < 0) {
> @@ -105,6 +139,9 @@ bool MainWindow::event(QEvent *e)
>  	if (e->type() == CaptureEvent::type()) {
>  		processCapture();
>  		return true;
> +	} else if (e->type() == HotplugEvent::type()) {
> +		processHotplug(static_cast<HotplugEvent *>(e));
> +		return true;
>  	}
>  
>  	return QMainWindow::event(e);
> @@ -535,6 +572,45 @@ void MainWindow::stopCapture()
>  	setWindowTitle(title_);
>  }
>  
> +/* -----------------------------------------------------------------------------
> + * Camera hotplugging support
> + */
> +
> +void MainWindow::processHotplug(HotplugEvent *e)
> +{
> +	Camera *camera = e->camera();
> +	HotplugEvent::PlugEvent event = e->hotplugEvent();
> +
> +	if (event == HotplugEvent::HotPlug) {
> +		cameraCombo_->addItem(QString::fromStdString(camera->name()));
> +	} else if (event == HotplugEvent::HotUnplug) {
> +		/* Check if the currently-streaming camera is removed. */
> +		if (camera == camera_.get()) {
> +			toggleCapture(false);
> +			cameraCombo_->setCurrentIndex(0);
> +		}
> +
> +		int camIndex = cameraCombo_->findText(QString::fromStdString(camera->name()));
> +		cameraCombo_->removeItem(camIndex);
> +	}
> +}
> +
> +void MainWindow::addCamera(std::shared_ptr<Camera> camera)
> +{
> +	qInfo() << "Adding new camera:" << camera->name().c_str();
> +	QCoreApplication::postEvent(this,
> +				    new HotplugEvent(std::move(camera),
> +						     HotplugEvent::HotPlug));
> +}
> +
> +void MainWindow::removeCamera(std::shared_ptr<Camera> camera)
> +{
> +	qInfo() << "Removing camera:" << camera->name().c_str();
> +	QCoreApplication::postEvent(this,
> +				    new HotplugEvent(std::move(camera),
> +						     HotplugEvent::HotUnplug));
> +}
> +
>  /* -----------------------------------------------------------------------------
>   * Image Save
>   */
> diff --git a/src/qcam/main_window.h b/src/qcam/main_window.h
> index 59fa2d9..4606fe4 100644
> --- a/src/qcam/main_window.h
> +++ b/src/qcam/main_window.h
> @@ -32,6 +32,8 @@ using namespace libcamera;
>  class QAction;
>  class QComboBox;
>  
> +class HotplugEvent;
> +
>  enum {
>  	OptCamera = 'c',
>  	OptHelp = 'h',
> @@ -87,8 +89,12 @@ private:
>  	int startCapture();
>  	void stopCapture();
>  
> +	void addCamera(std::shared_ptr<Camera> camera);
> +	void removeCamera(std::shared_ptr<Camera> camera);
> +
>  	void requestComplete(Request *request);
>  	void processCapture();
> +	void processHotplug(HotplugEvent *e);
>  	void processViewfinder(FrameBuffer *buffer);
>  
>  	/* UI elements */

-- 
Regards,

Laurent Pinchart