[flutter] Atas loading POC including async image load.

spine-flutter/example/lib/main.dart

@@ -1,7 +1,6 @@
 import 'package:flutter/material.dart';
-import 'dart:async';
-
 import 'package:spine_flutter/spine_flutter.dart' as spine_flutter;
+import 'package:flutter/services.dart' show rootBundle;
 
 void main() {
   runApp(const MyApp());
@@ -21,8 +20,9 @@ class _MyAppState extends State<MyApp> {
   @override
   void initState() {
     super.initState();
-    majorVersion = spine_flutter.spine_major_version();
+    majorVersion = spine_flutter.majorVersion();
-    minorVersion = spine_flutter.spine_minor_version();
+    minorVersion = spine_flutter.minorVersion();
+    spine_flutter.loadAtlas(rootBundle, "assets/spineboy.atlas");
   }
 
   @override
@@ -31,20 +31,12 @@ class _MyAppState extends State<MyApp> {
     const spacerSmall = SizedBox(height: 10);
     return MaterialApp(
       home: Scaffold(
-        appBar: AppBar(
-          title: const Text('Native Packages'),
-        ),
         body: SingleChildScrollView(
           child: Container(
             padding: const EdgeInsets.all(10),
             child: Column(
               children: [
-                const Text(
+                const Image(image: AssetImage("assets/spineboy.png")),
-                  'This calls a native function through FFI that is shipped as source in the package. '
-                  'The native code is built as part of the Flutter Runner build.',
-                  style: textStyle,
-                  textAlign: TextAlign.center,
-                ),
                 spacerSmall,
                 Text(
                   'Spine version: $majorVersion.$minorVersion',

spine-flutter/example/pubspec.lock

@@ -57,6 +57,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.3.0"
+  ffi:
+    dependency: transitive
+    description:
+      name: ffi
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.1"
   flutter:
     dependency: "direct main"
     description: flutter

spine-flutter/lib/spine_flutter.dart

@@ -1,17 +1,41 @@
 
-import 'dart:async';
 import 'dart:ffi';
 import 'dart:io';
-import 'dart:isolate';
+import 'package:ffi/ffi.dart';
 
+import 'package:flutter/services.dart';
+import 'package:flutter/widgets.dart';
 import 'spine_flutter_bindings_generated.dart';
+import 'package:path/path.dart' as Path;
 
-int spine_major_version() => _bindings.spine_major_version();
+int majorVersion() => _bindings.spine_major_version();
-int spine_minor_version() => _bindings.spine_minor_version();
+int minorVersion() => _bindings.spine_minor_version();
+
+void loadAtlas(AssetBundle assetBundle, String atlasFileName) async {
+  final atlasData = await assetBundle.loadString(atlasFileName);
+  final atlasDataNative = atlasData.toNativeUtf8();
+  final atlas = _bindings.spine_atlas_load(atlasDataNative.cast());
+  calloc.free(atlasDataNative);
+  if (atlas.ref.error.address != nullptr.address) {
+    final Pointer<Utf8> error = atlas.ref.error.cast();
+    final message = error.toDartString();
+    _bindings.spine_atlas_dispose(atlas);
+    throw Exception("Couldn't load atlas: " + message);
+  }
+
+  final atlasDir = Path.dirname(atlasFileName);
+  List<Image> atlasPages = [];
+  for (int i = 0; i < atlas.ref.numImagePaths; i++) {
+    final Pointer<Utf8> atlasPageFile = atlas.ref.imagePaths[i].cast();
+    final imagePath = Path.join(atlasDir, atlasPageFile.toDartString());
+    atlasPages.add(await Image(image: AssetImage(imagePath)));
+  }
+
+  _bindings.spine_atlas_dispose(atlas);
+}
 
 const String _libName = 'spine_flutter';
 
-/// The dynamic library in which the symbols for [SpineFlutterBindings] can be found.
 final DynamicLibrary _dylib = () {
   if (Platform.isMacOS || Platform.isIOS) {
     return DynamicLibrary.open('$_libName.framework/$_libName');
@@ -25,5 +49,4 @@ final DynamicLibrary _dylib = () {
   throw UnsupportedError('Unknown platform: ${Platform.operatingSystem}');
 }();
 
-/// The bindings to the native functions in [_dylib].
 final SpineFlutterBindings _bindings = SpineFlutterBindings(_dylib);

spine-flutter/lib/spine_flutter_bindings_generated.dart

@@ -43,4 +43,44 @@ class SpineFlutterBindings {
       _lookup<ffi.NativeFunction<ffi.Int32 Function()>>('spine_minor_version');
   late final _spine_minor_version =
       _spine_minor_versionPtr.asFunction<int Function()>();
+
+  ffi.Pointer<spine_atlas> spine_atlas_load(
+    ffi.Pointer<ffi.Int8> atlasData,
+  ) {
+    return _spine_atlas_load(
+      atlasData,
+    );
+  }
+
+  late final _spine_atlas_loadPtr = _lookup<
+      ffi.NativeFunction<
+          ffi.Pointer<spine_atlas> Function(
+              ffi.Pointer<ffi.Int8>)>>('spine_atlas_load');
+  late final _spine_atlas_load = _spine_atlas_loadPtr
+      .asFunction<ffi.Pointer<spine_atlas> Function(ffi.Pointer<ffi.Int8>)>();
+
+  void spine_atlas_dispose(
+    ffi.Pointer<spine_atlas> atlas,
+  ) {
+    return _spine_atlas_dispose(
+      atlas,
+    );
+  }
+
+  late final _spine_atlas_disposePtr =
+      _lookup<ffi.NativeFunction<ffi.Void Function(ffi.Pointer<spine_atlas>)>>(
+          'spine_atlas_dispose');
+  late final _spine_atlas_dispose = _spine_atlas_disposePtr
+      .asFunction<void Function(ffi.Pointer<spine_atlas>)>();
+}
+
+class spine_atlas extends ffi.Struct {
+  external ffi.Pointer<ffi.Void> atlas;
+
+  external ffi.Pointer<ffi.Pointer<ffi.Int8>> imagePaths;
+
+  @ffi.Int32()
+  external int numImagePaths;
+
+  external ffi.Pointer<ffi.Int8> error;
 }

spine-flutter/pubspec.yaml

@@ -11,13 +11,14 @@ dependencies:
   flutter:
     sdk: flutter
   plugin_platform_interface: ^2.0.2
+  ffi: ^1.1.2
 
 dev_dependencies:
-  ffi: ^1.1.2
   ffigen: ^4.1.2
   flutter_test:
     sdk: flutter
   flutter_lints: ^2.0.0
+  ffi: ^1.1.2
 
 # For information on the generic Dart part of this file, see the
 # following page: https://dart.dev/tools/pub/pubspec

spine-flutter/src/spine_flutter.cpp

@@ -2,14 +2,39 @@
 #include <spine/spine.h>
 #include <spine/Version.h>
 
-int32_t spine_major_version() {
+using namespace spine;
+
+FFI_PLUGIN_EXPORT int32_t spine_major_version() {
     return SPINE_MAJOR_VERSION;
 }
 
-int32_t spine_minor_version() {
+FFI_PLUGIN_EXPORT int32_t spine_minor_version() {
     return SPINE_MINOR_VERSION;
 }
 
+FFI_PLUGIN_EXPORT spine_atlas* spine_atlas_load(const char *atlasData) {
+    int length = strlen(atlasData);
+    auto atlas = new Atlas(atlasData, length, "", (TextureLoader*)nullptr, false);
+    spine_atlas *result = SpineExtension::calloc<spine_atlas>(1, __FILE__, __LINE__);
+    result->atlas = atlas;
+    result->numImagePaths = atlas->getPages().size();
+    result->imagePaths = SpineExtension::calloc<char *>(result->numImagePaths, __FILE__, __LINE__);
+    for (int i = 0; i < result->numImagePaths; i++) {
+        result->imagePaths[i] = strdup(atlas->getPages()[i]->texturePath.buffer());
+    }
+    return result;
+}
+
+FFI_PLUGIN_EXPORT void spine_atlas_dispose(spine_atlas *atlas) {
+    if (!atlas) return;
+    if (atlas->atlas) delete (Atlas*)atlas->atlas;
+    if (atlas->error) free(atlas->error);
+    for (int i = 0; i < atlas->numImagePaths; i++) {
+        free(atlas->imagePaths[i]);
+    }
+    SpineExtension::free(atlas, __FILE__, __LINE__);
+}
+
 spine::SpineExtension *spine::getDefaultExtension() {
    return new spine::DefaultSpineExtension();
 }

spine-flutter/src/spine_flutter.h

@@ -9,13 +9,30 @@
 #include <unistd.h>
 #endif
 
+#ifdef __cplusplus
 #if _WIN32
 #define FFI_PLUGIN_EXPORT extern "C" __declspec(dllexport)
 #else
 #define FFI_PLUGIN_EXPORT extern "C"
 #endif
+#else
+#if _WIN32
+#define FFI_PLUGIN_EXPORT __declspec(dllexport)
+#else
+#define FFI_PLUGIN_EXPORT
+#endif
+#endif
 
 FFI_PLUGIN_EXPORT int32_t spine_major_version();
 FFI_PLUGIN_EXPORT int32_t spine_minor_version();
 
+typedef struct spine_atlas {
+    void *atlas;
+    char **imagePaths;
+    int32_t numImagePaths;
+    char *error;
+} spine_atlas;
+
+FFI_PLUGIN_EXPORT spine_atlas* spine_atlas_load(const char *atlasData);
+FFI_PLUGIN_EXPORT void spine_atlas_dispose(spine_atlas *atlas);