Extract the FemtoVG renderer into a separate crate

This will be needed for a future experiment. Unlike the Skia renderer,
which operates on raw window handles, the FemtoVG renderer exposes a
different interface where it assumes that the caller takes care of the
OpenGL context state. This means more boilerplate remains in the winit
backend, including the glutin dependency. The upside is that it will
allow using the FemtoVG renderer in environments without glutin.

In order to work in an environment without fontconfig or memmap, the
crate has two features:

  - fontconfig (set when we anticipate fontconfig to be available at
    run-time and libloading being available at compile time).
  - diskfonts (set when we want to be able to load fonts from disk)

The winit crate enables fontconfig on "Linux" and diskfonts on !wasm.

Cargo.toml

@@ -32,6 +32,7 @@ members = [
     'internal/backends/selector',
     'internal/backends/testing',
     'internal/renderers/skia',
+    'internal/renderers/femtovg',
     'internal/common',
     'internal/compiler',
     'internal/compiler/parser-test-macro',

internal/backends/winit/Cargo.toml

@@ -21,7 +21,7 @@ path = "lib.rs"
 [features]
 wayland = ["winit/wayland", "glutin/wayland", "copypasta/wayland", "i-slint-renderer-skia?/wayland"]
 x11 = ["winit/x11", "glutin/x11", "glutin/glx", "copypasta/x11", "i-slint-renderer-skia?/x11"]
-renderer-winit-femtovg = ["femtovg", "fontdb", "libc", "yeslogic-fontconfig-sys", "winapi", "dwrote", "imgref", "unicode-script", "ttf-parser", "rgb", "i-slint-core/box-shadow-cache"]
+renderer-winit-femtovg = ["i-slint-renderer-femtovg"]
 renderer-winit-skia = ["i-slint-renderer-skia"]
 renderer-winit-skia-opengl = ["renderer-winit-skia", "i-slint-renderer-skia/opengl"]
 renderer-winit-software = ["softbuffer", "imgref", "rgb", "i-slint-core/systemfonts"]
@@ -49,43 +49,32 @@ raw-window-handle = { version = "0.5", features = ["alloc"] }
 scopeguard =  { version = "1.1.0", default-features = false }
 
 # For the FemtoVG renderer
-femtovg = { version = "0.6.0", optional = true }
-fontdb = { version = "0.12.0", optional = true, default-features = false }
-ttf-parser = { version = "0.18.0", optional = true } # Use the same version was femtovg's rustybuzz, to avoid duplicate crates
-unicode-script = { version = "0.5.4", optional = true } # Use the same version was femtovg's rustybuzz, to avoid duplicate crates
-imgref = { version = "1.6.1", optional = true }
-rgb = { version = "0.8.27", optional = true }
+i-slint-renderer-femtovg = { version = "=1.0.0", path = "../../renderers/femtovg", optional = true }
 
 # For the Skia renderer
 i-slint-renderer-skia = { version = "=1.0.0", path = "../../renderers/skia", optional = true }
 
 # For the software renderer
 softbuffer = { version = "0.2.0", optional = true }
+imgref = { version = "1.6.1", optional = true }
+rgb = { version = "0.8.27", optional = true }
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
-web-sys = { version = "0.3", features=["console", "WebGlContextAttributes", "CanvasRenderingContext2d", "HtmlInputElement", "HtmlCanvasElement", "Window", "Document", "CssStyleDeclaration", "Event", "KeyboardEvent", "InputEvent", "CompositionEvent"] }
+web-sys = { version = "0.3", features=["HtmlInputElement", "HtmlCanvasElement", "Window", "Document", "Event", "KeyboardEvent", "InputEvent", "CompositionEvent"] }
 wasm-bindgen = { version = "0.2" }
 send_wrapper = "0.6.0"
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
-fontdb = { version = "0.12", optional = true, features = ["memmap", "fontconfig"] }
 glutin = { version = "0.30", optional = true, default-features = false, features = ["egl", "wgl"] }
-
-# For the FemtoVG renderer
-[target.'cfg(target_family = "windows")'.dependencies]
-dwrote = { version = "0.11.0", optional = true }
-winapi = { version = "0.3", optional = true, features = ["dwrite"] }
+i-slint-renderer-femtovg = { version = "=1.0.0", path = "../../renderers/femtovg", optional = true, features = ["diskfonts"] }
 
 [target.'cfg(not(any(target_family = "windows", target_os = "macos", target_os = "ios", target_arch = "wasm32")))'.dependencies]
-libc = { version = "0.2", optional = true }
-yeslogic-fontconfig-sys = { version = "3.2", optional = true }
+i-slint-renderer-femtovg = { version = "=1.0.0", path = "../../renderers/femtovg", optional = true, features = ["fontconfig"] }
 dark-light = "1.0"
 
 [target.'cfg(target_os = "macos")'.dependencies]
 # For GL rendering
 cocoa = { version = "0.24.0" }
-core-foundation = { version = "0.9.1" }
-core-text = { version = "19.1.0" }
 
 [build-dependencies]
 cfg_aliases = "0.1.0"

internal/backends/winit/lib.rs

@@ -58,7 +58,7 @@ pub(crate) mod wasm_input_helper;
 
 #[cfg(target_arch = "wasm32")]
 pub fn create_gl_window_with_canvas_id(canvas_id: String) -> Rc<dyn WindowAdapter> {
-    GLWindow::<crate::renderer::femtovg::FemtoVGRenderer>::new(canvas_id)
+    GLWindow::<crate::renderer::femtovg::GlutinFemtoVGRenderer>::new(canvas_id)
 }
 
 fn window_factory_fn<R: WinitCompatibleRenderer + 'static>() -> Rc<dyn WindowAdapter> {
@@ -70,7 +70,7 @@ fn window_factory_fn<R: WinitCompatibleRenderer + 'static>() -> Rc<dyn WindowAda
 
 cfg_if::cfg_if! {
     if #[cfg(feature = "renderer-winit-femtovg")] {
-        type DefaultRenderer = renderer::femtovg::FemtoVGRenderer;
+        type DefaultRenderer = renderer::femtovg::GlutinFemtoVGRenderer;
     } else if #[cfg(enable_skia_renderer)] {
         type DefaultRenderer = renderer::skia::SkiaRenderer;
     } else if #[cfg(feature = "renderer-winit-software")] {
@@ -98,7 +98,9 @@ impl Backend {
     pub fn new(renderer_name: Option<&str>) -> Self {
         let window_factory_fn = match renderer_name {
             #[cfg(feature = "renderer-winit-femtovg")]
-            Some("gl") | Some("femtovg") => window_factory_fn::<renderer::femtovg::FemtoVGRenderer>,
+            Some("gl") | Some("femtovg") => {
+                window_factory_fn::<renderer::femtovg::GlutinFemtoVGRenderer>
+            }
             #[cfg(enable_skia_renderer)]
             Some("skia") => window_factory_fn::<renderer::skia::SkiaRenderer>,
             #[cfg(feature = "renderer-winit-software")]