feat: Introduce terrain SVG export functionality via FFI to a Windows DLL, providing an Arma 3 exportSVG command.

arma/server/extension/src/terrain.rs

@@ -4,29 +4,31 @@
 //! rendering options (location names, grid, contour lines, etc.).
 
 use arma_rs::Group;
-use std::ffi::CString;
-use std::os::raw::{c_char, c_void};
 
 #[cfg(target_os = "windows")]
-#[link(name = "kernel32")]
+mod windows_ffi {
-unsafe extern "stdcall" {
+    use std::os::raw::{c_char, c_void};
-    fn GetModuleHandleA(lpModuleName: *const u8) -> *mut c_void;
+
-    fn LoadLibraryA(lpLibFileName: *const u8) -> *mut c_void;
+    #[link(name = "kernel32")]
-    fn GetProcAddress(hModule: *mut c_void, lpProcName: *const u8) -> *mut c_void;
+    unsafe extern "system" {
+        pub(super) fn GetModuleHandleA(lpModuleName: *const u8) -> *mut c_void;
+        pub(super) fn LoadLibraryA(lpLibFileName: *const u8) -> *mut c_void;
+        pub(super) fn GetProcAddress(hModule: *mut c_void, lpProcName: *const u8) -> *mut c_void;
+    }
+
+    /// Mangled C++ name for the ExportSVG function.
+    /// Format: `?ExportSVG@@YAXPEBD_N11111@Z` matches signature:
+    /// `void ExportSVG(const char*, bool, bool, bool, bool, bool, bool)`
+    pub(super) const EXPORT_SVG_PROC_NAME: &[u8] = b"?ExportSVG@@YAXPEBD_N11111@Z\0";
+
+    /// Name of the DLL containing the ExportSVG function.
+    /// Update this to match your actual DLL name.
+    pub(super) const TERRAIN_DLL_NAME: &[u8] = b"TerrainExport.dll\0";
+
+    pub(super) type FnExportSVG =
+        extern "system" fn(*const c_char, bool, bool, bool, bool, bool, bool) -> *const c_void;
 }
 
-/// Mangled C++ name for the ExportSVG function.
-/// Format: `?ExportSVG@@YAXPEBD_N11111@Z` matches signature:
-/// `void ExportSVG(const char*, bool, bool, bool, bool, bool, bool)`
-const EXPORT_SVG_PROC_NAME: &[u8] = b"?ExportSVG@@YAXPEBD_N11111@Z\0";
-
-/// Name of the DLL containing the ExportSVG function.
-/// Update this to match your actual DLL name.
-const TERRAIN_DLL_NAME: &[u8] = b"TerrainExport.dll\0";
-
-type FnExportSVG =
-    extern "stdcall" fn(*const c_char, bool, bool, bool, bool, bool, bool) -> *const c_void;
-
 /// Creates the Arma 3 command group for the terrain module.
 ///
 /// Registers the `exportSVG` command with the Arma 3 extension.
@@ -59,6 +61,8 @@ pub fn export_terrain_svg(
     simple_roads: bool,
 ) -> Result<(), String> {
     unsafe {
+        use windows_ffi::*;
+
         // Try to get already loaded module, or load the DLL
         let module = GetModuleHandleA(TERRAIN_DLL_NAME.as_ptr());
         let module = if module.is_null() {
@@ -85,7 +89,7 @@ pub fn export_terrain_svg(
 
         // Convert file path to C string
         let file_path_cstr =
-            CString::new(file_path).map_err(|e| format!("Invalid file path: {}", e))?;
+            std::ffi::CString::new(file_path).map_err(|e| format!("Invalid file path: {}", e))?;
 
         // Call the export function
         export_svg(
@@ -137,15 +141,27 @@ struct ExportSvgOptions {
 ///
 /// # SQF Usage
 /// ```sqf
-/// ["forge", ["terrain", "exportSVG", "{
+/// // Register callback handler (optional, for async result)
-///     ""filePath"": ""C:\\path\\to\\output.svg"",
+/// ["terrain:exportSVG", {
-///     ""drawLocationNames"": true,
+///     params ["_response"];
-///     ""drawGrid"": true,
+///     systemChat format ["Export %1: %2",
-///     ""drawContourlines"": true,
+///         _response get "status",
-///     ""drawTreeObjects"": false,
+///         _response get "message"
-///     ""drawMountainHeightpoints"": true,
+///     ];
-///     ""simpleRoads"": false
+/// }] call forge_x_extension_fnc_setHandler;
-/// }"]] call forge_fnc_callExtension;
+///
+/// // Create options and call extension
+/// private _options = createHashMapFromArray [
+///     ["filePath", "C:\terrain.svg"],
+///     ["drawLocationNames", true],
+///     ["drawGrid", true],
+///     ["drawContourlines", true],
+///     ["drawTreeObjects", false],
+///     ["drawMountainHeightpoints", true],
+///     ["simpleRoads", false]
+/// ];
+///
+/// ["terrain:exportSVG", [toJSON _options]] call forge_x_extension_fnc_extCall;
 /// ```
 fn export_svg(options_json: String) -> String {
     // Parse options from JSON