[WIP] Basic text shaping and rendering using HarfBuzz

[anirudhb]

Doesn't render properly yet, though.
I'd like it if someone could figure out why it's not rendering the proper glyphs!

edit for using:
Compile Alacritty with the feature hb-ft. This will enable FreeType on all platforms, and use HarfBuzz.

Closes #50 (I think)

[anirudhb]

How would I make the raw glyphs go through the glyph cache? Right now it's being re-rasterized each time, so it's really, really slow.

[z2oh]

Thanks so much for working on this! This is the last feature I'm waiting for before I switch to alacritty as my daily driver!

I wanted to test out your PR and see if there was any way I could help; I ran into some build issues but was able to fix them.

I'm on OSx, and the font crate's manifest has not yet been updated to bring in servo-fontconfig and freetype-rs dependencies on non linux platforms. I'm sure this was already on your radar, but I thought I would mention it in case others try to test this PR.

Once I did add the freetype-rs and servo-fontconfig dependencies to the font crate, I had to rm all Cargo.lock files to get anything building. At this point, I ran into a weird build error for harfbuzz about a missing file during the build. Following the suggestion here, I added the harfbuzz-sys dependency and was able to get it running!

Here's my font/Cargo.toml

[package]
name = "font"
version = "0.1.0"
authors = ["Joe Wilm <joe@jwilm.com>"]
description = "Font rendering using the best available solution per platform"
license = "Apache-2.0"

[dependencies]
euclid = "0.19.2"
libc = "0.2"
foreign-types = "0.3"
log = "0.4"

harfbuzz-sys = { version = "=0.3.0", optional = true }
harfbuzz = { version = "0.3.0", optional = true }
servo-fontconfig = { version = "0.4.0", optional = true }
freetype-rs = { version = "0.19", optional = true }

[target.'cfg(not(any(target_os = "macos", windows)))'.dependencies]
servo-fontconfig = "0.4.0"
freetype-rs = "0.19"

[target.'cfg(target_os = "macos")'.dependencies]
core-foundation = "0.6"
core-text = "13"
core-graphics = "0.17"
core-foundation-sys = "0.6"

[target.'cfg(windows)'.dependencies]
font-loader = "0.6.0"
rusttype = "0.4.1"

[features]
default = []
hb-ft = ["harfbuzz-sys", "harfbuzz", "servo-fontconfig", "freetype-rs"]

I plan to continue poking around your PR to see if I can help. If you have any pointers on what I might be able to do to maximize usefulness please let me know!!

[anirudhb]

@z2oh Thanks! Actually, I've been planning to create a common, font-rasterizer-independent shaper that works directly on the font file, but I've not had the time to do it 😅

[anirudhb]

Additionally, this is also the thing stopping me from switching too!

[BYK]

I can help testing (and potentially fixing) on Windows once this gets to a more mature state.

[chrisduerr]

Looks like there was some additional work done for this in #2677. Since this PR hasn't been updated in a while, I'll close this one in favor of #2677.

If you have any contributions you wish to make on top of #2677 you can send a PR to the author, if he is unresponsive we can just re-open a new PR. This way we don't run into trouble with multiple people working on the same thing.