Minimap: scrolling up in large file makes the slider jump a little bit

[bpasero]

Steps to Reproduce:

1. macOS with zoom mode 1
2. large file with 30k lines scrolled all the way down
3. use mouse wheel to scroll up

=> at some point the thumb jumps up and then on the next scroll jumps down again
=> the other scrollbar does not show this behaviour

[alexdima]

I've tried to work around this tremor in some cases, but there are still cases where it occurs.

The root cause is:

• the minimap does not render partial lines. i.e. if a line is painted with 2px height, at y = 0 in the minimap there will always be a full line starting
• the viewport renders partial lines
• depending on the scrollTop, the viewport can contain N or N + 1 lines (where the first and last lines are only partially visible)
• in such cases the minimap slider has this tremor.

Very annoying indeed.

[levani]

Not sure if it's the same problem but the slider also jumps when dragging by cursor.

[jens1o]

does f5e4e4f closes this issue? @alexandrudima

[alexdima]

6df8165 should hopefully fix it