sixel: fix crash when splitting up an image across the scrollback
If an image was split up across the scrollback, and the first image
chunk was resized due to it being blended with an already existing
sixel, we crashed.
The reason being the second chunk, emitted *after* the scrollback,
tried to memcpy() image data from a now-free:d image buffer.
The fix is pretty simple: create copies for *all* chunks when an image
has to be split up across the scrollback. Previously, the first chunk
re-used the source image buffer.
Closes #608
↧