Add `JavaScriptBridge` buffer methods

doc/classes/JavaScriptBridge.xml

@@ -60,6 +60,20 @@
 				Returns an interface to a JavaScript object that can be used by scripts. The [param interface] must be a valid property of the JavaScript [code]window[/code]. The callback must accept a single [Array] argument, which will contain the JavaScript [code]arguments[/code]. See [JavaScriptObject] for usage.
 			</description>
 		</method>
+		<method name="is_js_buffer">
+			<return type="bool" />
+			<param index="0" name="javascript_object" type="JavaScriptObject" />
+			<description>
+				Returns [code]true[/code] if the given [param javascript_object] is of type [url=https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer][code]ArrayBuffer[/code][/url], [url=https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView][code]DataView[/code][/url], or one of the many [url=https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray]typed array objects[/url].
+			</description>
+		</method>
+		<method name="js_buffer_to_packed_byte_array">
+			<return type="PackedByteArray" />
+			<param index="0" name="javascript_buffer" type="JavaScriptObject" />
+			<description>
+				Returns a copy of [param javascript_buffer]'s contents as a [PackedByteArray]. See also [method is_js_buffer].
+			</description>
+		</method>
 		<method name="pwa_needs_update" qualifiers="const">
 			<return type="bool" />
 			<description>

platform/web/api/api.cpp

@@ -66,6 +66,8 @@ void JavaScriptBridge::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("eval", "code", "use_global_execution_context"), &JavaScriptBridge::eval, DEFVAL(false));
 	ClassDB::bind_method(D_METHOD("get_interface", "interface"), &JavaScriptBridge::get_interface);
 	ClassDB::bind_method(D_METHOD("create_callback", "callable"), &JavaScriptBridge::create_callback);
+	ClassDB::bind_method(D_METHOD("is_js_buffer", "javascript_object"), &JavaScriptBridge::is_js_buffer);
+	ClassDB::bind_method(D_METHOD("js_buffer_to_packed_byte_array", "javascript_buffer"), &JavaScriptBridge::js_buffer_to_packed_byte_array);
 	{
 		MethodInfo mi;
 		mi.name = "create_object";
@@ -93,6 +95,14 @@ Ref<JavaScriptObject> JavaScriptBridge::create_callback(const Callable &p_callab
 	return Ref<JavaScriptObject>();
 }
 
+bool JavaScriptBridge::is_js_buffer(Ref<JavaScriptObject> p_js_obj) {
+	return false;
+}
+
+PackedByteArray JavaScriptBridge::js_buffer_to_packed_byte_array(Ref<JavaScriptObject> p_js_obj) {
+	return PackedByteArray();
+}
+
 Variant JavaScriptBridge::_create_object_bind(const Variant **p_args, int p_argcount, Callable::CallError &r_error) {
 	if (p_argcount < 1) {
 		r_error.error = Callable::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;

platform/web/api/javascript_bridge_singleton.h

@@ -57,6 +57,8 @@ public:
 	Variant eval(const String &p_code, bool p_use_global_exec_context = false);
 	Ref<JavaScriptObject> get_interface(const String &p_interface);
 	Ref<JavaScriptObject> create_callback(const Callable &p_callable);
+	bool is_js_buffer(Ref<JavaScriptObject> p_js_obj);
+	PackedByteArray js_buffer_to_packed_byte_array(Ref<JavaScriptObject> p_js_obj);
 	Variant _create_object_bind(const Variant **p_args, int p_argcount, Callable::CallError &r_error);
 	void download_buffer(Vector<uint8_t> p_arr, const String &p_name, const String &p_mime = "application/octet-stream");
 	bool pwa_needs_update() const;

platform/web/javascript_bridge_singleton.cpp

@@ -59,6 +59,8 @@ extern void godot_js_wrapper_object_unref(int p_id);
 extern int godot_js_wrapper_create_cb(void *p_ref, void (*p_callback)(void *p_ref, int p_arg_id, int p_argc));
 extern void godot_js_wrapper_object_set_cb_ret(int p_type, godot_js_wrapper_ex *p_val);
 extern int godot_js_wrapper_create_object(const char *p_method, void **p_args, int p_argc, GodotJSWrapperVariant2JSCallback p_variant2js_callback, godot_js_wrapper_ex *p_cb_rval, void **p_lock, GodotJSWrapperFreeLockCallback p_lock_callback);
+extern int godot_js_wrapper_object_is_buffer(int p_id);
+extern int godot_js_wrapper_object_transfer_buffer(int p_id, void *p_byte_arr, void *p_byte_arr_write, void *(*p_callback)(void *p_ptr, void *p_ptr2, int p_len));
 };
 
 class JavaScriptObjectImpl : public JavaScriptObject {
@@ -366,6 +368,27 @@ Variant JavaScriptBridge::eval(const String &p_code, bool p_use_global_exec_cont
 	}
 }
 
+bool JavaScriptBridge::is_js_buffer(Ref<JavaScriptObject> p_js_obj) {
+	Ref<JavaScriptObjectImpl> obj = p_js_obj;
+	if (obj.is_null()) {
+		return false;
+	}
+	return godot_js_wrapper_object_is_buffer(obj->_js_id);
+}
+
+PackedByteArray JavaScriptBridge::js_buffer_to_packed_byte_array(Ref<JavaScriptObject> p_js_obj) {
+	ERR_FAIL_COND_V_MSG(!is_js_buffer(p_js_obj), PackedByteArray(), "The JavaScript object is not a buffer.");
+	Ref<JavaScriptObjectImpl> obj = p_js_obj;
+
+	PackedByteArray arr;
+	VectorWriteProxy<uint8_t> arr_write;
+
+	godot_js_wrapper_object_transfer_buffer(obj->_js_id, &arr, &arr_write, resize_PackedByteArray_and_open_write);
+
+	arr_write = VectorWriteProxy<uint8_t>();
+	return arr;
+}
+
 #endif // JAVASCRIPT_EVAL_ENABLED
 
 void JavaScriptBridge::download_buffer(Vector<uint8_t> p_arr, const String &p_name, const String &p_mime) {

platform/web/js/libs/library_godot_javascript_singleton.js

@@ -127,6 +127,10 @@ const GodotJSWrapper = {
 			GodotRuntime.setHeapValue(p_exchange, id, 'i64');
 			return 24; // OBJECT
 		},
+
+		isBuffer: function (obj) {
+			return obj instanceof ArrayBuffer || ArrayBuffer.isView(obj);
+		},
 	},
 
 	godot_js_wrapper_interface_get__proxy: 'sync',
@@ -303,6 +307,34 @@ const GodotJSWrapper = {
 			return -1;
 		}
 	},
+
+	godot_js_wrapper_object_is_buffer__proxy: 'sync',
+	godot_js_wrapper_object_is_buffer__sig: 'ii',
+	godot_js_wrapper_object_is_buffer: function (p_id) {
+		const obj = GodotJSWrapper.get_proxied_value(p_id);
+		return GodotJSWrapper.isBuffer(obj)
+			? 1
+			: 0;
+	},
+
+	godot_js_wrapper_object_transfer_buffer__proxy: 'sync',
+	godot_js_wrapper_object_transfer_buffer__sig: 'viiii',
+	godot_js_wrapper_object_transfer_buffer: function (p_id, p_byte_arr, p_byte_arr_write, p_callback) {
+		let obj = GodotJSWrapper.get_proxied_value(p_id);
+		if (!GodotJSWrapper.isBuffer(obj)) {
+			return;
+		}
+
+		if (ArrayBuffer.isView(obj) && !(obj instanceof Uint8Array)) {
+			obj = new Uint8Array(obj.buffer);
+		} else if (obj instanceof ArrayBuffer) {
+			obj = new Uint8Array(obj);
+		}
+
+		const resizePackedByteArrayAndOpenWrite = GodotRuntime.get_func(p_callback);
+		const bytesPtr = resizePackedByteArrayAndOpenWrite(p_byte_arr, p_byte_arr_write, obj.length);
+		HEAPU8.set(obj, bytesPtr);
+	},
 };
 
 autoAddDeps(GodotJSWrapper, '$GodotJSWrapper');