Newline wrapping

[Caleb Gingles]

Any plans to add text wrapping (on newline)? Specifically, in the text iteration functions used by NanoVG.

I've started to look into it, and got the simple (left-align) case working, but it gets complicated with right/center alignment. I'm not yet familiar enough with fons__decutf8() to scan for newlines without it crashing. I'd like to get your thoughts/plans before pursuing it further.

[Mikko Mononen]

I think the simplest way to do that for now is to first break the text into lines and then draw each line at a time. Something like this:

char* start = text;
char* end = text;
while (*end) {
    if (*end == ‘\r’ || *end == ‘\n’) {
        fonsDrawText(fs, x,y, start, end, NULL);
        y += lineHeight;
        end++;
        // handle cr-lf, and lf-cr too.
        if (*end == ‘\r’ || *end == ‘\n’) str++;
        start = end;
    } else {
        str++;
    }
}
if (start != end)
    fonsDrawText(fs, x,y, start, end, NULL);

The above should work with UTF-8 too as well as the iterator.

[Caleb Gingles]

While that looks great, my instinct is to wrap it in a function, so I can call a single function to render text as before. Maybe fonsDrawTextMulti()? Or are you wanting to keep this sort of thing out of the library?

[Caleb Gingles]

Though, the bigger issue in my mind is implementing it in such a way that NanoVG can use it. Since NanoVG uses the fons iterator functions, not fonsDrawText, it would either require a change in both, or this wrapper function might need to exist within NanoVG instead. Since NanoVG uses the iterators, I don't know if there is a clean separation as far as where multi-line text support should be added.

[Mikko Mononen]

I think it might be better to have the multi line draw functionality be build on top of fontstash, that is, in nanovg. Please add an issue there so that it won't get overlooked.

For the time being, you should be able to build similar wrapper on top of nanovg. Proper vertical align for all cases can be a little tricky to implement.

[Caleb Gingles]

Good point, I didn't even think of vertical alignment and multiple lines. I've opened the NanoVG issue, and your wrapper idea should work fine for now. Thanks!