UI: RGB parade, waveform and histogram drag behavior on black point

[sergiks]

Is there an existing issue for this?

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

Describe the bug

Black point drag behavior has changed in a bad way lately (Darktable 5.4.0) in the "RGB parade", "Waveform" and "Histogram" views in Darktable.

Previously: dragging the "shadows" part direction would match the effective underlying waveform move. And the move was smooth, slow and accurate.

Currently (bad): dragging over the bottom part of the waveform UP rapidly jumps the waveform DOWN in big steps. Same in RGB parade. Same in Histogram (but in horizontal axis).

Opposed to the top part of the waveform, where the behavior remained as previously: drag direction matches the waveform change direction, and the move is smooth.

Steps to reproduce

Open any photo in the Darkroom module, Open any of the three tools: RGB Parade, Waveform, Histogram.

Place mouse cursor over the "shadows" part of the waveform/histogram. Click and drag.

Expected behavior

Slow changes in displayed waveform, matching the direction of the mouse move.

Logfile | Screenshot | Screencast

Darktable-bug-waveform.mp4

Commit

No response

Where did you obtain darktable from?

darktable.org / GitHub release

darktable version

5.4.0

What OS are you using?

Mac

What is the version of your OS?

Mac OS Tahoe 26.2 (25C56)

Describe your system

Mac Mini 2023 on Apple M2 Pro

Are you using OpenCL GPU in darktable?

None

If yes, what is the GPU card and driver?

No response

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

No response