first commit

lib/modules/preview/opacity_dialog.dart

@@ -0,0 +1,49 @@
+import 'package:flutter/material.dart';
+
+class OpacityDialog extends StatefulWidget {
+  final double initial;
+  const OpacityDialog({super.key, required this.initial});
+  @override
+  _OpacityDialogState createState() => _OpacityDialogState();
+}
+
+class _OpacityDialogState extends State<OpacityDialog> {
+  late double val;
+  @override
+  void initState() {
+    super.initState();
+    val = widget.initial;
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return AlertDialog(
+      title: Text('Opacity Watermark'),
+      content: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          Slider(
+            value: val,
+            min: 0.1,
+            max: 1.0,
+            divisions: 9,
+            label: '${(val * 100).toStringAsFixed(0)}%',
+            onChanged: (v) => setState(() => val = v),
+          ),
+          SizedBox(height: 8),
+          Text('Preview: ${(val * 100).toStringAsFixed(0)}%'),
+        ],
+      ),
+      actions: [
+        TextButton(
+          onPressed: () => Navigator.pop(context),
+          child: Text('Batal'),
+        ),
+        TextButton(
+          onPressed: () => Navigator.pop(context, val),
+          child: Text('OK'),
+        ),
+      ],
+    );
+  }
+}