Handle unicode characters.

[rygwdn]

Fixes #10

• Neovim sends the bytes for each individual column separately, so use that data to determine the width of the characters.
• Also fix grouping of chars for 'put' to make painting more efficient.

[coolwanglu]

How about the maxWidth parameter for fillText, I think it should also be change this way.

[rygwdn]

@coolwanglu @kopischke I just pushed a new version that lets neovim determine how many columns there are. It should also speed up painting of characters

[coolwanglu]

@rygwdn This looks interesting, why the old version was not working? Maybe some Unicode characters are mis-interpreted by the browser? How about special Unicode characters and double-width characters?

[rygwdn]

The main issue was in handle_redraw, which was never actually handling put specially. It looks like the values inside the event are not actually strings, so e[0] == 'put' is never true. The next issue was in joining all the characters, since that would require re-calculating the number of columns (since "some string".length in JS is the number of bytes, not the number of columns). Then I needed to add in the loop to draw the characters individually because the spacing used for the grid apparently doesn't exactly line up with how the canvas draws it.

I determined that put provides the columns individually by looking at some of the other neovim UI implementations (specifically the python GTK one and the C++ Qt one) where they just handle each put individually and increase the column by 1. I'm not sure how it will handle weird cases, but at the moment this should handle them the same way

[coolwanglu]

OK I see. Thanks!