Re: [Gimp-user] Image doesn't move smoothly

[Øyvind Kolås <pippin gimp org>]

On Sat, Apr 21, 2018 at 8:52 PM, Steve Kinney <admin pilobilus net> wrote:
> > Some caveats I noticed:
> >
> > - The size of the image canvas, layer in question, and current zoom level seem to have no impact on redraw 
> > times; only the actual size of the image window whose area is being redrawn.
> >
> > - Visual artifacts are most noticeable when moving the object upwards.
> >
> > - Using the Pan function (Spacebar) always results in smooth movement as it is not actually making changes 
> > to the image, just scrolling its position within the image window.
> >
> >
> > I do notice that during the move operation all visual redraws originate from the upper-left of the moved 
> > object.  Not necessarily a bad choice, but could the redraw perhaps originate from the cursor's current 
> > location within the image window, redrawing outwards?  After all, when you're clicking and dragging 
> > something, the area around the cursor is generally what your vision is focused on....

Updating the display as quick as possible after receiving motion
events, rather than rendering everything and updating at a low
frame-rate, is a known feature - not a bug. Until things are fast
enough to do 15fps of the entire viewport - for instance with GIMP
integrating with and using the mipmap based preview-rendering
infrastructure in GEGL, always waiting until we have a full "frame" to
present will significantly increase latency leading to a worse user
experience than presenting as much rendered content as soon as
possible.

/pippin