[libcamera-devel] [PATCH v2 1/5] qcam: viewfinder: Pass stride value to viewfinder

[Kieran Bingham]

Hi Laurent,

On 07/09/2021 01:20, Laurent Pinchart wrote:
> qcam currently assumes that no padding is used at end of lines, and uses
> the image width as the stride. This leads to rendering failures with
> some formats on some platforms. To prepare for stride support, add a
> stride parameter to the ViewFinder::setFormat() function to pass the
> stride from the stream configuration to the viewfinder.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  src/qcam/main_window.cpp   | 3 ++-
>  src/qcam/viewfinder.h      | 3 ++-
>  src/qcam/viewfinder_gl.cpp | 7 ++-----
>  src/qcam/viewfinder_gl.h   | 3 ++-
>  src/qcam/viewfinder_qt.cpp | 3 ++-
>  src/qcam/viewfinder_qt.h   | 3 ++-
>  6 files changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp
> index 168dd5ce30e3..bb6b03993add 100644
> --- a/src/qcam/main_window.cpp
> +++ b/src/qcam/main_window.cpp
> @@ -448,7 +448,8 @@ int MainWindow::startCapture()
>  
>  	/* Configure the viewfinder. */
>  	ret = viewfinder_->setFormat(vfConfig.pixelFormat,
> -				     QSize(vfConfig.size.width, vfConfig.size.height));
> +				     QSize(vfConfig.size.width, vfConfig.size.height),
> +				     vfConfig.stride);
>  	if (ret < 0) {
>  		qInfo() << "Failed to set viewfinder format";
>  		return ret;
> diff --git a/src/qcam/viewfinder.h b/src/qcam/viewfinder.h
> index fb462835fb5f..4c2102a6ed04 100644
> --- a/src/qcam/viewfinder.h
> +++ b/src/qcam/viewfinder.h
> @@ -23,7 +23,8 @@ public:
>  
>  	virtual const QList<libcamera::PixelFormat> &nativeFormats() const = 0;
>  
> -	virtual int setFormat(const libcamera::PixelFormat &format, const QSize &size) = 0;
> +	virtual int setFormat(const libcamera::PixelFormat &format, const QSize &size,
> +			      unsigned int stride) = 0;
>  	virtual void render(libcamera::FrameBuffer *buffer, Image *image) = 0;
>  	virtual void stop() = 0;
>  
> diff --git a/src/qcam/viewfinder_gl.cpp b/src/qcam/viewfinder_gl.cpp
> index 32232faa2ad8..aeb1ea02d2d5 100644
> --- a/src/qcam/viewfinder_gl.cpp
> +++ b/src/qcam/viewfinder_gl.cpp
> @@ -72,7 +72,7 @@ const QList<libcamera::PixelFormat> &ViewFinderGL::nativeFormats() const
>  }
>  
>  int ViewFinderGL::setFormat(const libcamera::PixelFormat &format,
> -			    const QSize &size)
> +			    const QSize &size, unsigned int stride)
>  {
>  	if (format != format_) {
>  		/*
> @@ -92,6 +92,7 @@ int ViewFinderGL::setFormat(const libcamera::PixelFormat &format,
>  	}
>  
>  	size_ = size;
> +	stride_ = stride;
>  
>  	updateGeometry();
>  	return 0;
> @@ -119,10 +120,6 @@ void ViewFinderGL::render(libcamera::FrameBuffer *buffer, Image *image)
>  		renderComplete(buffer_);
>  
>  	image_ = image;
> -	/*
> -	 * \todo Get the stride from the buffer instead of computing it naively
> -	 */

We're getting it from the StreamConfiguration instead of the
PixelFormatInfo, or the buffer ... Are they (sufficiently) equivalent?

The documentation suggests subtle differences.

Is this patch 'all' that is required to ensure the strides are passed
correctly, or do we need to keep/add a todo to make it clear that there
is further work up at "Configure the viewfinder" to handle plane
specific strides?

I guess that would become evident if StreamConfiguration::stride became
a span of strides... so perhaps the compiler will act as a todo if that
ever happens.


I don't want to complain too much though..

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>


> -	stride_ = buffer->metadata().planes()[0].bytesused / size_.height();
>  	update();
>  	buffer_ = buffer;
>  }
> diff --git a/src/qcam/viewfinder_gl.h b/src/qcam/viewfinder_gl.h
> index 72a60ecb9159..2b2b1e86035a 100644
> --- a/src/qcam/viewfinder_gl.h
> +++ b/src/qcam/viewfinder_gl.h
> @@ -38,7 +38,8 @@ public:
>  
>  	const QList<libcamera::PixelFormat> &nativeFormats() const override;
>  
> -	int setFormat(const libcamera::PixelFormat &format, const QSize &size) override;
> +	int setFormat(const libcamera::PixelFormat &format, const QSize &size,
> +		      unsigned int stride) override;
>  	void render(libcamera::FrameBuffer *buffer, Image *image) override;
>  	void stop() override;
>  
> diff --git a/src/qcam/viewfinder_qt.cpp b/src/qcam/viewfinder_qt.cpp
> index 0d357d860014..cd051760160c 100644
> --- a/src/qcam/viewfinder_qt.cpp
> +++ b/src/qcam/viewfinder_qt.cpp
> @@ -52,7 +52,8 @@ const QList<libcamera::PixelFormat> &ViewFinderQt::nativeFormats() const
>  }
>  
>  int ViewFinderQt::setFormat(const libcamera::PixelFormat &format,
> -			    const QSize &size)
> +			    const QSize &size,
> +			    [[maybe_unused]] unsigned int stride)
>  {
>  	image_ = QImage();
>  
> diff --git a/src/qcam/viewfinder_qt.h b/src/qcam/viewfinder_qt.h
> index 6b48ef48a7d1..756f3fa33055 100644
> --- a/src/qcam/viewfinder_qt.h
> +++ b/src/qcam/viewfinder_qt.h
> @@ -31,7 +31,8 @@ public:
>  
>  	const QList<libcamera::PixelFormat> &nativeFormats() const override;
>  
> -	int setFormat(const libcamera::PixelFormat &format, const QSize &size) override;
> +	int setFormat(const libcamera::PixelFormat &format, const QSize &size,
> +		      unsigned int stride) override;
>  	void render(libcamera::FrameBuffer *buffer, Image *image) override;
>  	void stop() override;
>  
>