Refactor denoLoadLibrary and add documentation (#39)

* Refactored getLibraryPaths

* Update Readme.me

.gitignore

@@ -1,3 +1,4 @@
+.lib/
 bin/
 ext/SDL/include/
 tmp/

Readme.md

@@ -67,6 +67,27 @@ Located in the directory [examples/getting-started](examples/getting-started/) a
 a project up and running. Copy these files onto your computer and start the project with `deno task start`. You should
 see a window with `SDL_ts` as the title.
 
+### Loading shared libraries
+
+Unless `libraryPath` is specified in the `Init` functions, `SDL_ts` will attempt to "find" the SDL shared libraries by
+determining the prefix and file extension appropriate for the operating system and looking in a set of different places
+also based on the operating system. The places where the shared libraries are searched for can be influenced by the
+environment variable [`SDL_TS_LIBRARY_PATH`](#sdl-ts-library-path).
+
+#### libraryPath
+
+The `Init` functions (i.e. `SDL_Init`) have in their `options` object a `libraryPath` property. This property should be
+a path to the shared library and `SDL_ts` will make no attempt to guess where the library should be loaded from. This
+means it's up to the caller of the `Init` function to account for changes in the name of the library between the
+different platforms. For example the shared library on Linux is called `libSDL2.so` and Windows it is called `SDL2.dll`.
+There is a `lib` prefix on Linux and on Windows the file extension is `.dll` instead of `.so`.
+
+#### SDL_TS_LIBRARY_PATH
+
+The environmnet variable `SDL_TS_LIBRARY_PATH` can be used to instruct SDL_ts where the SDL shared libraries should be
+loaded from. See [deno.json](deno.json). All example projects will load the SDL shared libraries from the `.lib`
+directory if it exists.
+
 ### Loading only required functions
 
 Per default `SDL.Init` (or `IMG.Init` or `TTF.Init`) will load all known functions from the SDL assemblies. This can be

deno.json

@@ -29,14 +29,13 @@
     "check": "deno check",
     "codegen": "cd ./tools && deno run --unstable-ffi --allow-run -R -W $DENO_FLAGS ./codegen.ts",
     "codegen-scraper": "cd ./tools && deno run -R -W --allow-run ./codegen-scraper.ts",
-    "run:init": "deno run --allow-net -R=. -W=. ./init.ts ./tmp/init",
-    "run:doom-fire": "cd ./examples/doom-fire && deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
-    "run:hello-world": "cd ./examples/hello-world && deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
-    "run:hello-world-async": "cd ./examples/hello-world-async && deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
-    "run:play-wav": "cd ./examples/play-wav && deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
-    "run:renderer": "cd ./examples/renderer && deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
-    "run:same-game": "cd ./examples/same-game && deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
-    "run:version": "cd ./examples/version && deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
+    "run:doom-fire": "cd ./examples/doom-fire && SDL_TS_LIBRARY_PATH=$INIT_CWD/.lib deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
+    "run:hello-world": "cd ./examples/hello-world && SDL_TS_LIBRARY_PATH=$INIT_CWD/.lib deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
+    "run:hello-world-async": "cd ./examples/hello-world-async && SDL_TS_LIBRARY_PATH=$INIT_CWD/.lib deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
+    "run:play-wav": "cd ./examples/play-wav && SDL_TS_LIBRARY_PATH=$INIT_CWD/.lib deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
+    "run:renderer": "cd ./examples/renderer && SDL_TS_LIBRARY_PATH=$INIT_CWD/.lib deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
+    "run:same-game": "cd ./examples/same-game && SDL_TS_LIBRARY_PATH=$INIT_CWD/.lib deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
+    "run:version": "cd ./examples/version && SDL_TS_LIBRARY_PATH=$INIT_CWD/.lib deno run --unstable-ffi -E --allow-ffi -R=../.. $DENO_FLAGS ./main.ts",
     "test": "deno test --unstable-ffi --allow-ffi"
   }
 }

src/deno/_library.ts

@@ -1,4 +1,4 @@
-import { join } from "@std/path";
+import { join, SEPARATOR } from "@std/path";
 import { SDLError } from "../error.ts";
 import { DynamicLibrary, DynamicLibraryInterface } from "../_library.ts";
 import { ENV_LIBRARY_PATH } from "../_constants.ts";
@@ -11,7 +11,7 @@ const WINDOWS_LIBRARY_PATHS: string[] = [];
 const UNIX_LIBRARY_PATHS: string[] = [
   "/usr/local/lib",
   "/usr/lib64",
-  "/home/linuxbrew/.linuxbrew/lib"
+  "/home/linuxbrew/.linuxbrew/lib",
 ];
 
 const MACOS_LIBRARY_PATHS: string[] = [
@@ -31,35 +31,34 @@ function getLibrarySuffix(): string {
   return ".so";
 }
 
-function getLibraryPaths(libraryName: string, libraryPath?: string): string[] {
+function getLibraryPaths(libraryName: string): string[] {
   const libraryPrefix = !IS_WINDOWS ? "lib" : "";
   const librarySuffix = getLibrarySuffix();
   const fullLibraryName = libraryPrefix + libraryName + librarySuffix;
 
   const libraryPaths: string[] = [];
 
-  const os = Deno.build.os;
-  const arch = "x64"; // TODO: Detect this somehow.
+  // Try and load it from the same directory.
+  // NOTE: Using `join` here doesn't seem to work as it was just returning the file without the ./
+  libraryPaths.push(`.${SEPARATOR}${fullLibraryName}`);
 
-  if (libraryPath) {
-    libraryPaths.push(join(libraryPath, os, arch, fullLibraryName));
+  // Then look and see if SDL_TS_LIBRARY_PATH was specified.
+  const envLibraryPath = Deno.env.get(ENV_LIBRARY_PATH);
+  if (envLibraryPath) {
+    libraryPaths.push(join(envLibraryPath, fullLibraryName));
   }
 
-  libraryPaths.push(join(".", fullLibraryName));
+  // Next try and load it globally
+  libraryPaths.push(fullLibraryName);
 
   if (!IS_WINDOWS && !IS_MAC) {
-    // On Debain libSDL2_image and libSDL2_ttf only have symbolic links with this format.
+    // On Debain libSDL2_image and libSDL2_ttf only have symbolic links with this format so
+    // search for those globally as well.
     libraryPaths.push(
       libraryPrefix + libraryName + "-2.0" + librarySuffix + ".0"
     );
   }
 
-  libraryPath = Deno.env.get(ENV_LIBRARY_PATH);
-
-  if (libraryPath) {
-    libraryPaths.push(join(libraryPath, os, arch, fullLibraryName));
-  }
-
   if (!IS_WINDOWS) {
     const ldLibraryPath = Deno.env.get("LD_LIBRARY_PATH");
 
@@ -100,14 +99,21 @@ export function denoLoadLibrary<T extends DynamicLibraryInterface>(
   symbols: T,
   libraryPath?: string
 ): DynamicLibrary<T> {
-  const libraryPaths = getLibraryPaths(libraryName, libraryPath);
+  const libraryPaths = libraryPath
+    ? [libraryPath]
+    : getLibraryPaths(libraryName);
   const errors: Record<string, Error> = {};
 
   for (const libraryPath of libraryPaths) {
     try {
-      // Cast the symbols as any in order to prevent a type checking bug.
-      // deno-lint-ignore no-explicit-any
-      return Deno.dlopen(libraryPath, symbols as any) as DynamicLibrary<T>;
+      const result = Deno.dlopen(
+        libraryPath,
+        // Cast the symbols as any in order to prevent a type checking bug.
+        // deno-lint-ignore no-explicit-any
+        symbols as any
+      ) as DynamicLibrary<T>;
+      console.debug(`SDL_ts: Loaded ${libraryName} from "${libraryPath}"`);
+      return result;
     } catch (error) {
       errors[libraryPath] = error;
     }