[libcamera-devel] [PATCH v3 20/30] py: cam: Drop PIL dependency

[Laurent Pinchart]

Hi Tomi,

Thank you for the patch.

On Fri, May 27, 2022 at 05:44:37PM +0300, Tomi Valkeinen wrote:
> We can use Qt directly to accomplish the same as we do with PIL.
> 
> A minor downside is that loading MJPEG frame with Qt produces a "Corrupt
> JPEG data" warning. The resulting picture looks fine, though. So add a
> message handler to ignore that warning.

What's the exact message being printed ?

> Signed-off-by: Tomi Valkeinen <tomi.valkeinen at ideasonboard.com>
> ---
>  src/py/cam/cam_qt.py | 30 ++++++++++++++++++++++--------
>  1 file changed, 22 insertions(+), 8 deletions(-)
> 
> diff --git a/src/py/cam/cam_qt.py b/src/py/cam/cam_qt.py
> index af4b0f86..b6412bdf 100644
> --- a/src/py/cam/cam_qt.py
> +++ b/src/py/cam/cam_qt.py
> @@ -2,17 +2,32 @@
>  # Copyright (C) 2022, Tomi Valkeinen <tomi.valkeinen at ideasonboard.com>
>  
>  from helpers import mfb_to_rgb
> -from io import BytesIO
> -from PIL import Image
> -from PIL.ImageQt import ImageQt
>  from PyQt5 import QtCore, QtGui, QtWidgets
>  import libcamera as libcam
>  import libcamera.utils
>  import sys
>  
> +
> +# Loading MJPEG to a QPixmap produces corrupt JPEG data warnings. Ignore these.
> +def qt_message_handler(msg_type, msg_log_context, msg_string):
> +    if msg_string.startswith("Corrupt JPEG data"):
> +        return
> +
> +    # For some reason qInstallMessageHandler returns None, so we won't
> +    # call the old handler

Have you seen that happening ? If that's the case, do we really need to
call print(), or is it a sign that there should be no logging ?

> +    if old_msg_handler is not None:
> +        old_msg_handler(msg_type, msg_log_context, msg_string)
> +    else:
> +        print(msg_string)
> +
> +
> +old_msg_handler = QtCore.qInstallMessageHandler(qt_message_handler)

Quite a bit of a hack, but I don't really see another viable option.

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

> +
> +
>  def rgb_to_pix(rgb):
> -    img = Image.frombuffer('RGB', (rgb.shape[1], rgb.shape[0]), rgb)
> -    qim = ImageQt(img).copy()
> +    w = rgb.shape[1]
> +    h = rgb.shape[0]
> +    qim = QtGui.QImage(rgb, w, h, QtGui.QImage.Format.Format_RGB888)
>      pix = QtGui.QPixmap.fromImage(qim)
>      return pix
>  
> @@ -135,9 +150,8 @@ class MainWindow(QtWidgets.QWidget):
>              cfg = stream.configuration
>  
>              if cfg.pixel_format == libcam.formats.MJPEG:
> -                img = Image.open(BytesIO(mfb.planes[0]))
> -                qim = ImageQt(img).copy()
> -                pix = QtGui.QPixmap.fromImage(qim)
> +                pix = QtGui.QPixmap(cfg.size.width, cfg.size.height)
> +                pix.loadFromData(mfb.planes[0])
>              else:
>                  rgb = mfb_to_rgb(mfb, cfg)
>                  if rgb is None:

-- 
Regards,

Laurent Pinchart