add directmode streaming to ncplayer

[dankamongmen]

We supposedly added direct mode streaming support in #1346, but we haven't yet extended ncplayer to stream when -k is provided. It ought be thus augmented.

[dankamongmen]

we should probably disable the cursor when doing this.

[dankamongmen]

I've got initial support for ncplayer -k with multiframe media using the new streamfile function. Some problems:

• frames ought be printed over one another (probably following a clear), not successively
• we've lost our ability to interpret horizontal margins
• haven't tested with sixel yet, only kitty

so don't go merging that branch just yet.

[dankamongmen]

using sc and rc, we correctly return to the origin after each frame, when we're high enough that the entire graphic fits. otherwise, we return to a position mid-graphic. we can probably deal with this pretty easily if we know the graphic height.

[dankamongmen]

seems to work fine on sixel, btw.

[dankamongmen]

we should probably handle input now in perframe_direct(), certainly at least 'q' to exit.

[dankamongmen]

I think I've got margins fixed back up, huzzah. Just need to handle the multiframe-at-bottom case, and this ought be ready to merge.

[dankamongmen]

So to handle the bottom case, I think it would be sufficient to figure out the number of rows and columns we printed, and undo those with moves. We then don't even require cursor push/pop support. That information ought be available from ncvisual_blitter_geom() if nothing else; we just need hit it from the directmode context.

[dankamongmen]

yeah we can get the columns+rows from the ncdirectv, which is just a neutered ncplane.

[dankamongmen]

Yep, that works, at least for bitmaps which span the viewing area. Need test with a short one.