Flutter web, custom cursor (#7545)

* Flutter web, custom cursor Signed-off-by: fufesou <shuanglongchen@yeah.net> * trivial changes Signed-off-by: fufesou <shuanglongchen@yeah.net> * Flutter web, custom cursor, use date after 'updateGetKey()' Signed-off-by: fufesou <shuanglongchen@yeah.net> * trivial changes Signed-off-by: fufesou <shuanglongchen@yeah.net> --------- Signed-off-by: fufesou <shuanglongchen@yeah.net>
2025-12-13 19:47:17 +00:00 · 2024-03-29 10:52:32 +08:00
parent 4b0e88ce46
commit 3ef9824d8e
5 changed files with 192 additions and 39 deletions
--- a/flutter/lib/web/custom_cursor.dart
+++ b/flutter/lib/web/custom_cursor.dart
@@ -0,0 +1,121 @@
+import 'dart:convert';
+import 'dart:js' as js;
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
+
+import 'package:flutter_hbb/models/model.dart' as model;
+
+class CursorData {
+  final String key;
+  final String url;
+  final double hotX;
+  final double hotY;
+  final int width;
+  final int height;
+
+  CursorData({
+    required this.key,
+    required this.url,
+    required this.hotX,
+    required this.hotY,
+    required this.width,
+    required this.height,
+  });
+}
+
+/// The cursor manager
+class CursorManager {
+  final Map<String, CursorData> _cursors = <String, CursorData>{};
+  String latestKey = '';
+
+  CursorManager._();
+  static CursorManager instance = CursorManager._();
+
+  Future<void> registerCursor(CursorData data) async {
+    _cursors[data.key] = data;
+  }
+
+  Future<void> deleteCursor(String key) async {
+    _cursors.remove(key);
+  }
+
+  Future<void> setSystemCursor(String key) async {
+    if (latestKey == key) {
+      return;
+    }
+    latestKey = key;
+
+    final CursorData? cursorData = _cursors[key];
+    if (cursorData != null) {
+      js.context.callMethod('setByName', [
+        'cursor',
+        jsonEncode({
+          'url': cursorData.url,
+          'hotx': cursorData.hotX.toInt(),
+          'hoty': cursorData.hotY.toInt(),
+        })
+      ]);
+    }
+  }
+}
+
+class FlutterCustomMemoryImageCursor extends MouseCursor {
+  final String key;
+  const FlutterCustomMemoryImageCursor({required this.key});
+
+  @override
+  MouseCursorSession createSession(int device) =>
+      _FlutterCustomMemoryImageCursorSession(this, device);
+
+  @override
+  String get debugDescription =>
+      objectRuntimeType(this, 'FlutterCustomMemoryImageCursor');
+}
+
+class _FlutterCustomMemoryImageCursorSession extends MouseCursorSession {
+  _FlutterCustomMemoryImageCursorSession(
+      FlutterCustomMemoryImageCursor cursor, int device)
+      : super(cursor, device);
+
+  @override
+  FlutterCustomMemoryImageCursor get cursor =>
+      super.cursor as FlutterCustomMemoryImageCursor;
+
+  @override
+  Future<void> activate() async {
+    await CursorManager.instance.setSystemCursor(cursor.key);
+  }
+
+  @override
+  void dispose() {}
+}
+
+deleteCustomCursor(String key) => CursorManager.instance.deleteCursor(key);
+
+MouseCursor buildCursorOfCache(
+    model.CursorModel cursor, double scale, model.CursorData? cache) {
+  if (cache == null) {
+    return MouseCursor.defer;
+  } else {
+    final key = cache.updateGetKey(scale);
+    if (!cursor.cachedKeys.contains(key)) {
+      // data should be checked here, because it may be changed after `updateGetKey()`
+      final data = cache.data;
+      if (data == null) {
+        return MouseCursor.defer;
+      }
+      debugPrint(
+          "Register custom cursor with key $key (${cache.hotx},${cache.hoty})");
+      CursorManager.instance.registerCursor(CursorData(
+          key: key,
+          url: 'data:image/rgba;base64,${base64Encode(data)}',
+          width: (cache.width * cache.scale).toInt(),
+          height: (cache.height * cache.scale).toInt(),
+          hotX: cache.hotx,
+          hotY: cache.hoty));
+      cursor.addKey(key);
+    }
+    return FlutterCustomMemoryImageCursor(key: key);
+  }
+}