WebAssembly FFI shells (#322)

* Allow imgui-rs to generate wasm-ffi bindings

* Missing wasm_bindings.rs file

* Update wasm bindings

* Take wasm import name from environment variable

* Remove debug message

* Formatting

Cargo.toml

@@ -22,6 +22,9 @@ imgui-sys = { version = "0.4.0-pre", path = "imgui-sys" }
 lazy_static = "1.1"
 parking_lot = "0.10"
 
+[features]
+wasm = ["imgui-sys/wasm"]
+
 [dev-dependencies]
 memoffset = "0.5"
 

imgui-sys-bindgen/Cargo.toml

@@ -13,4 +13,4 @@ bindgen = "0.53"
 failure = "0.1"
 serde = "1.0"
 serde_derive = "1.0"
-serde_json = "1.0"
+serde_json = "1.0"

imgui-sys-bindgen/src/lib.rs

@@ -77,7 +77,10 @@ fn parse_whitelist<R: Read>(
     })
 }
 
-pub fn generate_bindings<P: AsRef<Path>>(cimgui_path: &P) -> Result<Bindings, Error> {
+pub fn generate_bindings<P: AsRef<Path>>(
+    cimgui_path: &P,
+    wasm_import_name: Option<String>,
+) -> Result<Bindings, Error> {
     let cimgui_output_path = cimgui_path.as_ref().join("generator").join("output");
     let structs_and_enums = File::open(cimgui_output_path.join("structs_and_enums.json"))?;
     let definitions = File::open(cimgui_output_path.join("definitions.json"))?;
@@ -105,6 +108,11 @@ pub fn generate_bindings<P: AsRef<Path>>(cimgui_path: &P) -> Result<Bindings, Er
         .impl_debug(true)
         .rustfmt_bindings(true)
         .clang_arg("-DCIMGUI_DEFINE_ENUMS_AND_STRUCTS=1");
+
+    if let Some(name) = wasm_import_name {
+        builder = builder.wasm_import_module_name(name);
+    }
+
     for e in whitelist.structs {
         builder = builder.whitelist_type(format!("^{}", e));
     }

imgui-sys-bindgen/src/main.rs

@@ -10,11 +10,25 @@ fn main() {
         .join("imgui-sys")
         .canonicalize()
         .expect("Failed to find imgui-sys directory");
-    let bindings = generate_bindings(&sys_path.join("third-party").join("cimgui"))
+
+    let bindings = generate_bindings(&sys_path.join("third-party").join("cimgui"), None)
         .expect("Failed to generate bindings");
     let output_path = sys_path.join("src").join("bindings.rs");
     bindings
         .write_to_file(&output_path)
         .expect("Failed to write bindings");
-    println!("Wrote bindings to {}", output_path.to_string_lossy());
+
+    let wasm_ffi_import_name = option_env!("IMGUI_RS_WASM_IMPORT_NAME")
+        .map(|s| s.to_string())
+        .or(Some("imgui-sys".to_string()));
+
+    let wasm_bindings = generate_bindings(
+        &sys_path.join("third-party").join("cimgui"),
+        wasm_ffi_import_name,
+    )
+    .expect("Failed to generate bindings");
+    let output_path = sys_path.join("src").join("wasm_bindings.rs");
+    wasm_bindings
+        .write_to_file(&output_path)
+        .expect("Failed to write wasm bindings");
 }

imgui-sys/Cargo.toml

@@ -12,3 +12,7 @@ build = "build.rs"
 
 [build-dependencies]
 cc = "1.0"
+
+[features]
+default = []
+wasm = []

imgui-sys/build.rs

@@ -1,3 +1,5 @@
+#![allow(dead_code)]
+
 use std::fs;
 use std::io;
 
@@ -23,19 +25,22 @@ fn assert_file_exists(path: &str) -> io::Result<()> {
 }
 
 fn main() -> io::Result<()> {
-    let mut build = cc::Build::new();
-    build.cpp(true);
-    // Disabled due to linking issues
-    build
-        .define("CIMGUI_NO_EXPORT", None)
-        .define("IMGUI_DISABLE_WIN32_FUNCTIONS", None)
-        .define("IMGUI_DISABLE_OSX_FUNCTIONS", None);
+    #[cfg(not(feature = "wasm"))]
+    {
+        let mut build = cc::Build::new();
+        build.cpp(true);
+        // Disabled due to linking issues
+        build
+            .define("CIMGUI_NO_EXPORT", None)
+            .define("IMGUI_DISABLE_WIN32_FUNCTIONS", None)
+            .define("IMGUI_DISABLE_OSX_FUNCTIONS", None);
 
-    build.flag_if_supported("-Wno-return-type-c-linkage");
-    for path in &CPP_FILES {
-        assert_file_exists(path)?;
-        build.file(path);
+        build.flag_if_supported("-Wno-return-type-c-linkage");
+        for path in &CPP_FILES {
+            assert_file_exists(path)?;
+            build.file(path);
+        }
+        build.compile("libcimgui.a");
     }
-    build.compile("libcimgui.a");
     Ok(())
 }

imgui-sys/src/lib.rs

@@ -1,5 +1,13 @@
+#[cfg(feature = "wasm")]
+mod wasm_bindings;
+
+#[cfg(feature = "wasm")]
+pub use crate::wasm_bindings::*;
+
+#[cfg(not(feature = "wasm"))]
 mod bindings;
 
+#[cfg(not(feature = "wasm"))]
 pub use crate::bindings::*;
 
 impl ImVec2 {

src/drag.rs

@@ -11,7 +11,7 @@ macro_rules! impl_display_format {
             self.display_format = display_format;
             self
         }
-    }
+    };
 }
 
 macro_rules! impl_speed {
@@ -21,7 +21,7 @@ macro_rules! impl_speed {
             self.speed = value;
             self
         }
-    }
+    };
 }
 
 macro_rules! impl_power {
@@ -31,7 +31,7 @@ macro_rules! impl_power {
             self.power = value;
             self
         }
-    }
+    };
 }
 
 macro_rules! impl_min_max {
@@ -47,7 +47,7 @@ macro_rules! impl_min_max {
             self.max = value;
             self
         }
-    }
+    };
 }
 
 #[must_use]

src/input_widget.rs

@@ -52,7 +52,8 @@ macro_rules! impl_text_flags {
 
         #[inline]
         pub fn callback_completion(mut self, value: bool) -> Self {
-            self.flags.set(ImGuiInputTextFlags::CallbackCompletion, value);
+            self.flags
+                .set(ImGuiInputTextFlags::CallbackCompletion, value);
             self
         }
 
@@ -70,7 +71,8 @@ macro_rules! impl_text_flags {
 
         #[inline]
         pub fn callback_char_filter(mut self, value: bool) -> Self {
-            self.flags.set(ImGuiInputTextFlags::CallbackCharFilter, value);
+            self.flags
+                .set(ImGuiInputTextFlags::CallbackCharFilter, value);
             self
         }
 
@@ -88,7 +90,8 @@ macro_rules! impl_text_flags {
 
         #[inline]
         pub fn no_horizontal_scroll(mut self, value: bool) -> Self {
-            self.flags.set(ImGuiInputTextFlags::NoHorizontalScroll, value);
+            self.flags
+                .set(ImGuiInputTextFlags::NoHorizontalScroll, value);
             self
         }
 
@@ -115,7 +118,7 @@ macro_rules! impl_text_flags {
             self.flags.set(ImGuiInputTextFlags::NoUndoRedo, value);
             self
         }
-    }
+    };
 }
 
 macro_rules! impl_step_params {
@@ -131,7 +134,7 @@ macro_rules! impl_step_params {
             self.step_fast = value;
             self
         }
-    }
+    };
 }
 
 extern "C" fn resize_callback(data: *mut sys::ImGuiInputTextCallbackData) -> c_int {