enhance(frontend): テーマをドラッグ&ドロップできるように

packages/frontend/src/drag-and-drop.ts

@@ -23,6 +23,15 @@ export function setDragData<T extends keyof DragDataMap>(
 	event.dataTransfer.setData(`misskey/${type}`.toLowerCase(), JSON.stringify(data));
 }
 
+export function setPlainDragData(
+	event: DragEvent,
+	data: string,
+) {
+	if (event.dataTransfer == null) return;
+
+	event.dataTransfer.setData('text/plain', data);
+}
+
 export function getDragData<T extends keyof DragDataMap>(
 	event: DragEvent,
 	type: T,
@@ -35,6 +44,17 @@ export function getDragData<T extends keyof DragDataMap>(
 	return JSON.parse(data);
 }
 
+export function getPlainDragData(
+	event: DragEvent,
+): string | null {
+	if (event.dataTransfer == null) return null;
+
+	const data = event.dataTransfer.getData('text/plain');
+	if (data == null || data === '') return null;
+
+	return data;
+}
+
 export function checkDragDataType(
 	event: DragEvent,
 	types: (keyof DragDataMap)[],