[libcamera-devel] [PATCH v2] qcam: viewfinder: Maintain aspect ratio

[Laurent Pinchart]

Hi Kieran,

On Tue, Jun 15, 2021 at 01:32:16AM +0300, Laurent Pinchart wrote:
> Hi Kieran,
> 
> Thank you for the patch.
> 
> On Mon, Jun 14, 2021 at 12:11:10PM +0100, Kieran Bingham wrote:
> > Keep the image aspect ratio when displaying in the viewfinder.
> > 
> > When the window is adjusted to a size that differs in aspect ratio to
> > the image, keep the image centered in the main viewpoint.
> > 
> > Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> 
> > ---
> > 
> > v2: (fixed up from Laurent's review comments)
> > 
> >  - No longer accept event on an invalid size.
> >  - centering simplifed
> > 
> > 
> >  src/qcam/viewfinder_qt.cpp | 16 ++++++++++++++--
> >  src/qcam/viewfinder_qt.h   |  2 ++
> >  2 files changed, 16 insertions(+), 2 deletions(-)
> > 
> > diff --git a/src/qcam/viewfinder_qt.cpp b/src/qcam/viewfinder_qt.cpp
> > index e436714c6bdb..08ac29e9fa99 100644
> > --- a/src/qcam/viewfinder_qt.cpp
> > +++ b/src/qcam/viewfinder_qt.cpp
> > @@ -15,6 +15,7 @@
> >  #include <QMap>
> >  #include <QMutexLocker>
> >  #include <QPainter>
> > +#include <QResizeEvent>
> >  #include <QtDebug>
> >  
> >  #include <libcamera/formats.h>
> > @@ -34,7 +35,7 @@ static const QMap<libcamera::PixelFormat, QImage::Format> nativeFormats
> >  };
> >  
> >  ViewFinderQt::ViewFinderQt(QWidget *parent)
> > -	: QWidget(parent), buffer_(nullptr)
> > +	: QWidget(parent), place_(rect()), buffer_(nullptr)
> >  {
> >  	icon_ = QIcon(":camera-off.svg");
> >  }
> > @@ -146,7 +147,7 @@ void ViewFinderQt::paintEvent(QPaintEvent *)
> >  
> >  	/* If we have an image, draw it. */
> >  	if (!image_.isNull()) {
> > -		painter.drawImage(rect(), image_, image_.rect());
> > +		painter.drawImage(place_, image_, image_.rect());
> >  		return;
> >  	}
> >  
> > @@ -179,3 +180,14 @@ QSize ViewFinderQt::sizeHint() const
> >  {
> >  	return size_.isValid() ? size_ : QSize(640, 480);
> >  }
> > +
> > +void ViewFinderQt::resizeEvent(QResizeEvent *event)
> > +{
> > +	if (!size_.isValid())
> > +		return;
> > +
> > +	place_.setSize(size_.scaled(event->size(), Qt::KeepAspectRatio));
> > +	place_.moveCenter(rect().center());
> > +
> > +	event->accept();

As far as I can tell, event->accept() isn't needed. It's however a good
practice to call the base object's resizeEvent() function. I'd thus
replace this with

	QWidget::resizeEvent(event);

> > +}
> > diff --git a/src/qcam/viewfinder_qt.h b/src/qcam/viewfinder_qt.h
> > index d755428887c0..bf31b81b3437 100644
> > --- a/src/qcam/viewfinder_qt.h
> > +++ b/src/qcam/viewfinder_qt.h
> > @@ -42,6 +42,7 @@ Q_SIGNALS:
> >  
> >  protected:
> >  	void paintEvent(QPaintEvent *) override;
> > +	void resizeEvent(QResizeEvent *) override;
> >  	QSize sizeHint() const override;
> >  
> >  private:
> > @@ -49,6 +50,7 @@ private:
> >  
> >  	libcamera::PixelFormat format_;
> >  	QSize size_;
> > +	QRect place_;
> >  
> >  	/* Camera stopped icon */
> >  	QSize vfSize_;

-- 
Regards,

Laurent Pinchart