[official] Linux port via Blade (#7343)

## Motivation

I ❤️ Zed! It's lightning fast and has great UX. I want it to run as
well on all major platforms. I'm currently using Linux most actively.
[Blade](https://github.com/kvark/blade) is a good candidate for
providing GPU access: it supports Vulkan, Metal, and GLES/WebGL. Its
abstraction is extremely thin, while having one of the nicest GPU APIs.
Codebase is also tiny. Checkout [the meetup
recording](https://www.youtube.com/watch?v=63dnzjw4azI&t=623s) from a
year ago.
I believe these projects make a good match 🚀 !

### Why this is a bad idea

If Zed team wants to use off-the-shelf components from Rust ecosystem,
then Blade is certainly at disadvantage here, since it's not widely
used. It would rely on Zed team adding necessary features in a branch,
then maybe upstreaming some of them. That is to say, it's unclear if
this can be avoided with more popular alternatives - being flexible with
any local changes is a good ability.

### Why it's not too bad

Blade uses [WGSL](https://www.w3.org/TR/WGSL) shaders, similar to `wgpu`
and `arcana`, but without the binding decorations. So this aspect of the
product is nicely portable.

## Progress

- [ ] Platforms
  - [x] X11 (via xcb)
    - [ ] input handling
    - [ ] get proper content size
  - [ ] Windows
  - [ ] Replace the existing Metal backend
- [ ] Text System
  - [ ] shaping
  - [ ] glyph rasterization
- [x] Texture atlas
- [ ] Rendering
  - [x] basic primitives
  - [x] path rendering
  - [x] sprite rendering
- [ ] media surfaces
- [ ] CI

## Current status
Zed starts up but crashes on text-system related checks.

![zed-linux-1](https://github.com/zed-industries/zed/assets/107301/ba536218-4d2c-43c9-ae6c-bef69b54bd0c)

Cargo.toml

@@ -277,6 +277,11 @@ wasmtime = { git = "https://github.com/bytecodealliance/wasmtime", rev = "v16.0.
 split-debuginfo = "unpacked"
 debug = "limited"
 
+# todo!(linux) - Remove this
+[profile.dev.package.blade-graphics]
+split-debuginfo = "off"
+debug = "full"
+
 [profile.dev.package.taffy]
 opt-level = 3
 

crates/fs/src/fs.rs

@@ -287,12 +287,17 @@ impl Fs for RealFs {
     ) -> Pin<Box<dyn Send + Stream<Item = Vec<Event>>>> {
         let (tx, rx) = smol::channel::unbounded();
 
+        if !path.exists() {
+            log::error!("watch path does not exist: {}", path.display());
+            return Box::pin(rx);
+        }
+
         let mut watcher = notify::recommended_watcher(move |res| match res {
             Ok(event) => {
                 let _ = tx.try_send(vec![event]);
             }
             Err(err) => {
-                eprintln!("watch error: {:?}", err);
+                log::error!("watch error: {}", err);
             }
         })
         .unwrap();

crates/gpui/Cargo.toml

@@ -33,6 +33,7 @@ dhat = { version = "0.3", optional = true }
 env_logger = { version = "0.9", optional = true }
 etagere = "0.2"
 futures.workspace = true
+font-kit = { git = "https://github.com/zed-industries/font-kit", rev = "d97147f" }
 gpui_macros.workspace = true
 image = "0.23"
 itertools = "0.10"
@@ -46,7 +47,8 @@ parking_lot.workspace = true
 pathfinder_geometry = "0.5"
 postage.workspace = true
 rand.workspace = true
-raw-window-handle = "0.6.0"
+raw-window-handle = "0.6"
+blade-rwh = { package = "raw-window-handle", version = "0.5" }
 refineable.workspace = true
 resvg = "0.14"
 schemars.workspace = true
@@ -86,9 +88,17 @@ cocoa = "0.25"
 core-foundation = { version = "0.9.3", features = ["with-uuid"] }
 core-graphics = "0.22.3"
 core-text = "19.2"
-font-kit = { git = "https://github.com/zed-industries/font-kit", rev = "d97147f" }
 foreign-types = "0.3"
 log.workspace = true
 media.workspace = true
 metal = "0.21.0"
 objc = "0.2"
+
+[target.'cfg(target_os = "linux")'.dependencies]
+flume = "0.11"
+xcb = { version = "1.3", features = ["as-raw-xcb-connection"] }
+as-raw-xcb-connection = "1"
+#TODO: use these on all platforms
+blade-graphics = { git = "https://github.com/kvark/blade", rev = "f35bc605154e210ab6190291235889b6ddad73f1" }
+blade-macros = { git = "https://github.com/kvark/blade", rev = "f35bc605154e210ab6190291235889b6ddad73f1" }
+bytemuck = "1"

crates/gpui/build.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(not(target_os = "macos"), allow(unused))]
+
 use std::{
     env,
     path::{Path, PathBuf},
@@ -6,10 +8,14 @@ use std::{
 use cbindgen::Config;
 
 fn main() {
+    #[cfg(target_os = "macos")]
     generate_dispatch_bindings();
+    #[cfg(target_os = "macos")]
     let header_path = generate_shader_bindings();
+    #[cfg(target_os = "macos")]
     #[cfg(feature = "runtime_shaders")]
     emit_stitched_shaders(&header_path);
+    #[cfg(target_os = "macos")]
     #[cfg(not(feature = "runtime_shaders"))]
     compile_metal_shaders(&header_path);
 }

crates/gpui/examples/hello_world.rs

@@ -9,9 +9,12 @@ impl Render for HelloWorld {
         div()
             .flex()
             .bg(rgb(0x2e7d32))
-            .size_full()
+            .size(Length::Definite(Pixels(300.0).into()))
             .justify_center()
             .items_center()
+            .shadow_lg()
+            .border()
+            .border_color(rgb(0x0000ff))
             .text_xl()
             .text_color(rgb(0xffffff))
             .child(format!("Hello, {}!", &self.text))

crates/gpui/src/elements/img.rs

@@ -7,6 +7,7 @@ use crate::{
     StyleRefinement, Styled, UriOrPath,
 };
 use futures::FutureExt;
+#[cfg(target_os = "macos")]
 use media::core_video::CVImageBuffer;
 use util::ResultExt;
 
@@ -21,6 +22,7 @@ pub enum ImageSource {
     Data(Arc<ImageData>),
     // TODO: move surface definitions into mac platform module
     /// A CoreVideo image buffer
+    #[cfg(target_os = "macos")]
     Surface(CVImageBuffer),
 }
 
@@ -54,6 +56,7 @@ impl From<Arc<ImageData>> for ImageSource {
     }
 }
 
+#[cfg(target_os = "macos")]
 impl From<CVImageBuffer> for ImageSource {
     fn from(value: CVImageBuffer) -> Self {
         Self::Surface(value)
@@ -144,6 +147,7 @@ impl Element for Img {
                                 .log_err();
                         }
 
+                        #[cfg(target_os = "macos")]
                         ImageSource::Surface(surface) => {
                             let size = size(surface.width().into(), surface.height().into());
                             let new_bounds = preserve_aspect_ratio(bounds, size);

crates/gpui/src/gpui.rs

@@ -6,8 +6,7 @@
 //! ## Getting Started
 //!
 //! GPUI is still in active development as we work on the Zed code editor and isn't yet on crates.io.
-//! You'll also need to use the latest version of stable rust and be on macOS. Add the following to your
-//! Cargo.toml:
+//! You'll also need to use the latest version of stable rust. Add the following to your Cargo.toml:
 //!
 //! ```
 //! gpui = { git = "https://github.com/zed-industries/zed" }

crates/gpui/src/platform.rs

@@ -1,5 +1,7 @@
 mod app_menu;
 mod keystroke;
+#[cfg(target_os = "linux")]
+mod linux;
 #[cfg(target_os = "macos")]
 mod mac;
 #[cfg(any(test, feature = "test-support"))]
@@ -33,6 +35,8 @@ use uuid::Uuid;
 
 pub use app_menu::*;
 pub use keystroke::*;
+#[cfg(target_os = "linux")]
+pub(crate) use linux::*;
 #[cfg(target_os = "macos")]
 pub(crate) use mac::*;
 #[cfg(any(test, feature = "test-support"))]
@@ -44,6 +48,10 @@ pub use util::SemanticVersion;
 pub(crate) fn current_platform() -> Rc<dyn Platform> {
     Rc::new(MacPlatform::new())
 }
+#[cfg(target_os = "linux")]
+pub(crate) fn current_platform() -> Rc<dyn Platform> {
+    Rc::new(LinuxPlatform::new())
+}
 
 pub(crate) trait Platform: 'static {
     fn background_executor(&self) -> BackgroundExecutor;
@@ -298,6 +306,7 @@ pub(crate) trait PlatformAtlas: Send + Sync {
 pub(crate) struct AtlasTile {
     pub(crate) texture_id: AtlasTextureId,
     pub(crate) tile_id: TileId,
+    pub(crate) padding: u32,
     pub(crate) bounds: Bounds<DevicePixels>,
 }
 

crates/gpui/src/platform/linux.rs

@@ -0,0 +1,18 @@
+mod blade_atlas;
+mod blade_belt;
+mod blade_renderer;
+mod dispatcher;
+mod display;
+mod platform;
+mod text_system;
+mod window;
+
+pub(crate) use blade_atlas::*;
+pub(crate) use dispatcher::*;
+pub(crate) use display::*;
+pub(crate) use platform::*;
+pub(crate) use text_system::*;
+pub(crate) use window::*;
+
+use blade_belt::*;
+use blade_renderer::*;