RGB Curve: Area picker misbehaves (multiple versions).

Is there an existing issue for this?

• I checked and did not find my issue in the already reported ones

Describe the bug

It is no longer possible to use the area picker in RGB independent channels mode.

The curve misbehaves (mainly shown in the shadows part) and the nodes are no longer connected to the shown curve.

Steps to reproduce

1. open any raw file
2. activate the RGB curve module, set the method to RGB, Independent channels.
3. click on the area picker (no need to actually select a part of the image)

See the malformed curve

Try to set a node and see it is no longer connected to the curve.

Expected behavior

It should work as the point picker.

Logfile | Screenshot | Screencast

Result of the above mentioned steps:

Commit

Don't know. Just noticed it the previous dev version but haven't used the area picker for a while (5.4.1 is ok)

Where did you obtain darktable from?

darktable.org / GitHub release

darktable version

5.5.0+348~g98b939b7c8

What OS are you using?

Linux

What is the version of your OS?

Debian 13 (latest + all updates)

Describe your system

X11
libgtk 3.24.49-3

Compile options:
Bit depth -> 64 bit
Exiv2 -> 0.28.5
Lensfun -> 0.3.4
Debug -> DISABLED
SSE2 optimizations -> ENABLED
OpenMP -> ENABLED
OpenCL -> ENABLED
Lua -> ENABLED - API version 9.6.0
Colord -> ENABLED
gPhoto2 -> ENABLED
OSMGpsMap -> ENABLED - map view is available
GMIC -> ENABLED - Compressed LUTs are supported
GraphicsMagick -> ENABLED
ImageMagick -> DISABLED
libavif -> ENABLED
libheif -> ENABLED
libjxl -> ENABLED
LibRaw -> ENABLED - Version 0.22.0-Release
OpenJPEG -> ENABLED
OpenEXR -> ENABLED
WebP -> ENABLED

32Gb ram

Are you using OpenCL GPU in darktable?

Yes, but this is not opencl related. Same behaviour is seen when opencl is turned off.

If yes, what is the GPU card and driver?

Nvidia GeForce RTX 2060 SUPER + propriety driver version 550.163.01-2

Please provide additional context if applicable. You can attach files too, but might need to rename to .txt or .zip

This behaviour is not shown with the latest stable version (5.4.1).

• It does not matter which workflow you use,
• Other modules do not seem to be the problem.
• Not brand specific (tried a nef, cr3 and cr2).
• Interpolation method used also does not matter.

Reproduce the problem in the RGB curve module using RGB, Independent channels, and the area picker, then compare its malformed curve and disconnected nodes with the point picker and stable 5.4.1. Done means the area picker produces a valid curve and newly set nodes remain connected to it.