点击放大后锁定罗盘

lib/components/grid_clip_paint.dart

@@ -1,9 +1,76 @@
+import 'dart:async';
 import 'dart:ui' as ui;
 
 import 'package:flutter/material.dart';
 
-class GridClipPaint extends StatelessWidget {
-  const GridClipPaint({Key key}) : super(key: key);
+// class GridClipPaint extends StatelessWidget {
+//   const GridClipPaint(
+//     this.left,
+//     this.top,
+//     this.right,
+//     this.bottom, {
+//     Key key,
+//   }) : super(key: key);
+//
+//   // ui.Image image;
+//   final double left;
+//   final double top;
+//   final double right;
+//   final double bottom;
+//
+//   @override
+//   Widget build(BuildContext context) {
+//     ui.Image image;
+//     return Container(
+//       color: Colors.transparent,
+//       alignment: Alignment.center,
+//       child: CustomPaint(
+//         // 使用CustomPaint 背景画板
+//         painter: ClipPainter(image),
+//       ),
+//     );
+//   }
+// }
+
+class GridClipPaint extends StatefulWidget {
+  const GridClipPaint(this.image, this.left, this.top, this.right, this.bottom,
+      {Key key})
+      : super(key: key);
+  final ui.Image image;
+  final double left;
+  final double top;
+  final double right;
+  final double bottom;
+
+  @override
+  State<GridClipPaint> createState() => _GridClipPaintState();
+}
+
+class _GridClipPaintState extends State<GridClipPaint> {
+  ui.Image image;
+
+  @override
+  void initState() async {
+    // TODO: implement initState
+    // final appDataDirectory = await getApplicationDocumentsDirectory();
+    // File file = File(join(appDataDirectory.path, 'rotate_image'));
+    super.initState();
+  }
+
+  Future<ui.Image> imageLoader() {
+    ImageStream imageStream = const AssetImage("assets/images/arrow.png")
+        .resolve(ImageConfiguration(size: Size(700, 700)));
+    Completer<ui.Image> imageCompleter = Completer<ui.Image>();
+
+    void imageListener(ImageInfo info, bool synchronousCall) {
+      ui.Image image = info.image;
+      imageCompleter.complete(image);
+      imageStream.removeListener(ImageStreamListener(imageListener));
+    }
+
+    imageStream.addListener(ImageStreamListener(imageListener));
+    return imageCompleter.future;
+  }
 
   @override
   Widget build(BuildContext context) {
@@ -12,32 +79,37 @@ class GridClipPaint extends StatelessWidget {
       alignment: Alignment.center,
       child: CustomPaint(
         // 使用CustomPaint 背景画板
-        painter: ClipPainter(),
+        painter: ClipPainter(image),
       ),
     );
   }
 }
 
 class ClipPainter extends CustomPainter {
-  ui.Image image;
+  final ui.Image image;
+  final double left;
+  final double top;
+  final double right;
+  final double bottom;
+
+  ClipPainter(this.image,
+      {this.left = 0.3, this.top = 0.3, this.right = 0.6, this.bottom = 0.6});
 
   @override
   void paint(Canvas canvas, Size size) {
-    // 创建画笔
-    final Paint paint = Paint();
+    // TODO: implement paint
+    Paint paint = Paint();
     canvas.drawImageRect(
         image,
-        // Image(image: AssetImage("assets/images/arrow.png")),
-        Rect.fromLTRB(0, 0, 700 / 3, 700 / 3),
-        Rect.fromLTWH(0, 0, 700 / 3, 700 / 3),
+        Rect.fromLTRB(image.width * left, image.height * top,
+            image.width * right, image.height * bottom),
+        Rect.fromLTWH(0, 0, size.width, size.height),
         paint);
-    //   ..color = Colors.white
-    //   ..strokeWidth = 2;
-    // 绘制线
-    // canvas.drawLine(const Offset(-400, 0), const Offset(400, 0), paintLine);
-    // canvas.drawLine(const Offset(0, 500), const Offset(0, -440), paintLine);
   }
 
   @override
-  bool shouldRepaint(CustomPainter oldDelegate) => false;
+  bool shouldRepaint(CustomPainter oldDelegate) {
+    // TODO: implement shouldRepaint
+    return false;
+  }
 }