Snapping doesn't work for a third clip moved across tracks

TRA · November 22, 2021, 1:33pm

This bug only happens when three clips are moved diagonally one by one without any space between them.
If I move three clips straight up, snapping works. If I leave a blank between the first and second clips, snapping works.

I made the following change to Shotcut\share\shotcut\qml\views\timeline\Track.js
and the problem seems to have gone away.

Line	Before	After
32	clip.trackIndex === repeater.itemAt(i).trackIndex	clip.originalTrackIndex === repeater.itemAt(i).originalTrackIndex

github.com

mltframework/shotcut/blob/master/src/qml/views/timeline/Track.js#L32

    
      
          var left = clip.x
          var right = clip.x + clip.width
          if (clip.x > -SNAP && clip.x < SNAP) {
              // Snap around origin.
              clip.x = 0
              return
          } else {
              // Snap to other clips on the same track.
              for (var i = 0; i < repeater.count; i++) {
                  // Do not snap to self.
                  if (i === clip.DelegateModel.itemsIndex && clip.trackIndex === repeater.itemAt(i).trackIndex)
                      continue
                  var itemLeft = repeater.itemAt(i).x
                  var itemRight = itemLeft + repeater.itemAt(i).width
                  // Snap to blank
                  if (right > itemLeft - SNAP && right < itemLeft + SNAP) {
                      // Snap right edge to left edge.
                      clip.x = itemLeft - clip.width
                      return
                  } else if (left > itemRight - SNAP && left < itemRight + SNAP) {
                      // Snap left edge to right edge.

I have made a pull request for this here:

github.com/mltframework/shotcut

Fix rare case of snapping not working when moving a clip cross tracks

mltframework:master ← traprog:snap_cross_track

opened 01:26PM - 22 Nov 21 UTC

traprog

+1 -1

A clip's `trackIndex` changes to the target track's index as soon as it's dragge…d to that track. `clip.trackIndex === repeater.itemAt(i).trackIndex` becomes less restrictive, and `if` clause will look for any clip that satisfy `i === clip.DelegateModel.itemsIndex` and prevents snapping to that clip. A clip's `originalTrackIndex` doesn't change to the target track's index as soon as it's dragged to that track, so `if` clause will only prevents snapping to self. For some reason, only changing `clip.trackIndex` to `originalTrackIndex` broke snapping when multiple clips are dragged across tracks. Changing `repeater.itemAt(i).trackIndex` to `originalTrackIndex` fixed it.

Tested on Windows.
Tested on v21.10.31, but it’s been a problem for a while on prior releases.

shotcut · November 22, 2021, 7:41pm

This fix is merged for the next release 21.12