Panning goes in the wrong (opposite) direction

[HunterGraubard]

• URL to reproduce the issue: http://desmonding.me/zooming/
• OS: Windows 10 Pro
• Browser and version: Chrome 65.0.3325.181, Firefox 61.0a1.

Steps to reproduce:

1. Open a full size image in the viewer.
2. Click down with the mouse, or touch down with a finger.
3. Drag the mouse cursor or finger while still holding down.

The expected result is that the image will move as if fixed to the cursor or finger. For example, if you touch down on somebody's head, their head should remain under the cursor or finger at all times while dragging. If you move the cursor/finger to the left, then the image should move to the left. Instead, the image moves in the opposite direction, which is very unintuitive and confusing.

For an example of the expected result, see PhotoSwipe's demo page: http://photoswipe.com

[kingdido999]

Although one can argue this is not simulating a grab behavior, I admit this is not very intuitive. I will try to experiment with the opposite direction.