[libcamera-devel] [PATCH v2 7/7] qcam: Provide save image functionality

[Laurent Pinchart]

Hi Kieran,

Thank you for the patch.

On Fri, Feb 14, 2020 at 12:18:10AM +0000, 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>
> 
> ---
> v2:
>  - Rename save to saveAs
>  - Add empty file check
>  - Lock concurrent access to the ViewFinder image
> 
>  src/qcam/assets/feathericons/feathericons.qrc |  1 +
>  src/qcam/main_window.cpp                      | 22 +++++++++++++++++++
>  src/qcam/main_window.h                        |  1 +
>  src/qcam/viewfinder.cpp                       | 11 ++++++++++
>  src/qcam/viewfinder.h                         |  5 +++++
>  5 files changed, 40 insertions(+)
> 
> diff --git a/src/qcam/assets/feathericons/feathericons.qrc b/src/qcam/assets/feathericons/feathericons.qrc
> index b8e5c2266408..6ca3a846803c 100644
> --- a/src/qcam/assets/feathericons/feathericons.qrc
> +++ b/src/qcam/assets/feathericons/feathericons.qrc
> @@ -1,6 +1,7 @@
>  <!DOCTYPE RCC><RCC version="1.0">
>  <qresource>
>  <file>./play-circle.svg</file>
> +<file>./save.svg</file>
>  <file>./stop-circle.svg</file>
>  <file>./x-circle.svg</file>
>  </qresource>
> diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp
> index ec93e0177b41..8ee2a7d68c96 100644
> --- a/src/qcam/main_window.cpp
> +++ b/src/qcam/main_window.cpp
> @@ -12,7 +12,10 @@
>  
>  #include <QComboBox>
>  #include <QCoreApplication>
> +#include <QFileDialog>
>  #include <QIcon>
> +#include <QImage>
> +#include <QImageWriter>
>  #include <QInputDialog>
>  #include <QTimer>
>  #include <QToolBar>
> @@ -88,6 +91,9 @@ int MainWindow::createToolbars()
>  	action = toolbar_->addAction(QIcon(":stop-circle.svg"), "stop");
>  	connect(action, &QAction::triggered, this, &MainWindow::stopCapture);
>  
> +	action = toolbar_->addAction(QIcon(":save.svg"), "saveAs");
> +	connect(action, &QAction::triggered, this, &MainWindow::saveImageAs);
> +
>  	return 0;
>  }
>  
> @@ -339,6 +345,22 @@ void MainWindow::stopCapture()
>  	setWindowTitle(title_);
>  }
>  
> +void MainWindow::saveImageAs()
> +{
> +	QImage image = viewfinder_->getCurrentImage();
> +
> +	QString filename = QFileDialog::getSaveFileName(this, "Save Image", "",
> +							"Image Files (*.png *.jpg *.jpeg)");
> +
> +	std::cerr << "Save image to " << filename.toStdString() << std::endl;

Should this be cout ? It's not an error.

> +
> +	if (filename == "")

	if (filename.isEmpty())

is slightly more efficient.

> +		return;
> +
> +	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 27ceed611d59..dcc39d7de948 100644
> --- a/src/qcam/main_window.h
> +++ b/src/qcam/main_window.h
> @@ -48,6 +48,7 @@ private Q_SLOTS:
>  
>  	int startCapture();
>  	void stopCapture();

I'd add a blank line here as it's unrelated.

> +	void saveImageAs();
>  
>  private:
>  	int createToolbars();
> diff --git a/src/qcam/viewfinder.cpp b/src/qcam/viewfinder.cpp
> index 6de284d1b782..211926e185d3 100644
> --- a/src/qcam/viewfinder.cpp
> +++ b/src/qcam/viewfinder.cpp
> @@ -6,6 +6,8 @@
>   */
>  
>  #include <QImage>
> +#include <QImageWriter>
> +#include <QMutexLocker>
>  #include <QPainter>
>  
>  #include "format_converter.h"
> @@ -23,10 +25,19 @@ ViewFinder::~ViewFinder()
>  
>  void ViewFinder::display(const unsigned char *raw, size_t size)
>  {
> +	QMutexLocker locker(&mutex_);
> +
>  	converter_.convert(raw, size, image_);
>  	update();
>  }
>  
> +QImage ViewFinder::getCurrentImage()
> +{
> +	QMutexLocker locker(&mutex_);
> +
> +	return *image_;

I'm afraid this is still unsafe despite the lock as QImage using
implicit data sharing. You can return image_->copy() instead as a first
step.

> +}
> +
>  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..06e8034fce1d 100644
> --- a/src/qcam/viewfinder.h
> +++ b/src/qcam/viewfinder.h
> @@ -7,6 +7,7 @@
>  #ifndef __QCAM_VIEWFINDER_H__
>  #define __QCAM_VIEWFINDER_H__
>  
> +#include <QMutex>
>  #include <QWidget>
>  
>  #include "format_converter.h"
> @@ -23,6 +24,8 @@ public:
>  		      unsigned int height);
>  	void display(const unsigned char *rgb, size_t size);
>  
> +	QImage getCurrentImage();
> +
>  protected:
>  	void paintEvent(QPaintEvent *) override;
>  	QSize sizeHint() const override;
> @@ -33,7 +36,9 @@ private:
>  	unsigned int height_;
>  
>  	FormatConverter converter_;
> +
>  	QImage *image_;
> +	QMutex mutex_; // Prevent concurrent access to image_

C-style comments as in the rest of the code base ?

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

>  };
>  
>  #endif /* __QCAM_VIEWFINDER__ */

-- 
Regards,

Laurent Pinchart