[libcamera-devel] [PATCH 6/6] qcam: Provide save image functionality

[Kieran Bingham]

Hi All,

This one is a bit of an RFC due to comments in the patch:

On 06/02/2020 15:05, Kieran Bingham wrote:
> Implement a save image button on the toolbar which will take a current
> viewfinder image and present the user with a QFileDialog to allow them
> to choose where to save the image.
> 
> Utilise the QImageWriter to perform the output task.
> 
> Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> ---
>  src/qcam/main_window.cpp | 22 ++++++++++++++++++++++
>  src/qcam/main_window.h   |  1 +
>  src/qcam/viewfinder.cpp  |  7 +++++++
>  src/qcam/viewfinder.h    |  2 ++
>  4 files changed, 32 insertions(+)
> 
> diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp
> index 0ae4c60b8699..0e994b1e9197 100644
> --- a/src/qcam/main_window.cpp
> +++ b/src/qcam/main_window.cpp
> @@ -11,7 +11,10 @@
>  #include <sys/mman.h>
>  
>  #include <QCoreApplication>
> +#include <QFileDialog>
>  #include <QIcon>
> +#include <QImage>
> +#include <QImageWriter>
>  #include <QInputDialog>
>  #include <QTimer>
>  #include <QToolBar>
> @@ -89,6 +92,9 @@ int MainWindow::createToolbars(CameraManager *cm)
>  	action = toolbar_->addAction(QIcon(":stop-circle.svg"), "stop");
>  	connect(action, &QAction::triggered, this, &MainWindow::stopCapture);
>  
> +	action = toolbar_->addAction(QIcon(":save.svg"), "save");
> +	connect(action, &QAction::triggered, this, &MainWindow::saveImage);
> +
>  	return 0;
>  }
>  
> @@ -339,6 +345,22 @@ void MainWindow::stopCapture()
>  	setWindowTitle(title_);
>  }
>  
> +void MainWindow::saveImage()
> +{
> +	/* Take a lock to prevent updating the backed image, copy,
> +	 * then ask where to save with lock released */
> +
> +	QImage image = viewfinder_->getCurrentImage();
> +
> +	QString filename = QFileDialog::getSaveFileName(this, "Save Image", "",
> +							"Image Files (*.png *.jpg *.jpeg)");
> +
> +	std::cerr << "Save jpeg to " << filename.toStdString() << std::endl;

I think that can be removed now :-)

> +
> +	QImageWriter writer(filename);
> +	writer.write(image);
> +}
> +
>  void MainWindow::requestComplete(Request *request)
>  {
>  	if (request->status() == Request::RequestCancelled)
> diff --git a/src/qcam/main_window.h b/src/qcam/main_window.h
> index b0bf16dd2a09..fc85b6a46491 100644
> --- a/src/qcam/main_window.h
> +++ b/src/qcam/main_window.h
> @@ -48,6 +48,7 @@ private Q_SLOTS:
>  
>  	int startCapture();
>  	void stopCapture();
> +	void saveImage();
>  
>  private:
>  	int createToolbars(CameraManager *cm);
> diff --git a/src/qcam/viewfinder.cpp b/src/qcam/viewfinder.cpp
> index 6de284d1b782..3fa4a326c342 100644
> --- a/src/qcam/viewfinder.cpp
> +++ b/src/qcam/viewfinder.cpp
> @@ -6,6 +6,7 @@
>   */
>  
>  #include <QImage>
> +#include <QImageWriter>
>  #include <QPainter>
>  
>  #include "format_converter.h"
> @@ -27,6 +28,12 @@ void ViewFinder::display(const unsigned char *raw, size_t size)
>  	update();
>  }
>  
> +QImage ViewFinder::getCurrentImage()
> +{
> +	/* Ideally need to lock, return/copy, then unlock... Can a scoped lock work? */

So I 'think' that this might actually be saved from races by the QT
threading. But I'm not entirely sure...

Thoughts anyone?

> +	return *image_;

And of course a "memcpy" here isn't ideal either - but I anticipate this
could all get changed to create a new stream to perform a
StreamRole::StillCapture type capture ...


> +}
> +
>  int ViewFinder::setFormat(unsigned int format, unsigned int width,
>  			  unsigned int height)
>  {
> diff --git a/src/qcam/viewfinder.h b/src/qcam/viewfinder.h
> index ef5fd45b264a..1da79d3e67aa 100644
> --- a/src/qcam/viewfinder.h
> +++ b/src/qcam/viewfinder.h
> @@ -23,6 +23,8 @@ public:
>  		      unsigned int height);
>  	void display(const unsigned char *rgb, size_t size);
>  
> +	QImage getCurrentImage();
> +
>  protected:
>  	void paintEvent(QPaintEvent *) override;
>  	QSize sizeHint() const override;
> 

-- 
Regards
--
Kieran