added GTK like spinner for flutter

babylonia_terminal_launcher/lib/widgets/gtk_spinner_widget.dart

@@ -0,0 +1,112 @@
+import 'dart:math';
+
+import 'package:flutter/material.dart';
+
+class GtkSpinner extends StatefulWidget {
+  const GtkSpinner({
+    super.key,
+    this.size = 15.0,
+    this.strokeSize = 5.0,
+    this.color = Colors.grey,
+  });
+  final double size;
+  final double strokeSize;
+  final Color color;
+
+  @override
+  State<GtkSpinner> createState() => _GtkSpinnerState();
+}
+
+class _GtkSpinnerState extends State<GtkSpinner>
+    with SingleTickerProviderStateMixin {
+  late AnimationController _controller;
+
+  @override
+  void initState() {
+    super.initState();
+    _controller = AnimationController(
+      vsync: this,
+      duration: const Duration(seconds: 1, milliseconds: 500),
+    )..repeat();
+  }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Padding(
+      padding: const EdgeInsets.all(8.0),
+      child: AnimatedBuilder(
+        animation: _controller,
+        builder: (context, child) {
+          return CustomPaint(
+            painter: _GtkSpinnerPainter(
+              _controller.value * 2 * pi,
+              widget.strokeSize,
+              widget.color,
+            ),
+            size: Size(widget.size, widget.size),
+          );
+        },
+      ),
+    );
+  }
+}
+
+class _GtkSpinnerPainter extends CustomPainter {
+  _GtkSpinnerPainter(this.angle, this.strokeSize, this.color);
+
+  final double angle;
+  final double strokeSize;
+  final Color color;
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final double radius = size.width / 2;
+    final Rect rect =
+        Rect.fromCircle(center: Offset(radius, radius), radius: radius);
+
+    // Define the gradient for the arc
+    final Paint gradientPaint = Paint()
+      ..shader = SweepGradient(
+        startAngle: 0.0,
+        endAngle: 2 * pi,
+        colors: [
+          color,
+          color.withOpacity(0.0),
+        ],
+        stops: const [0.0, 0.90],
+        transform: GradientRotation(angle),
+      ).createShader(rect)
+      ..style = PaintingStyle.stroke
+      ..strokeCap = StrokeCap.round
+      ..strokeWidth = strokeSize;
+
+    // Draw the gradient arc
+    canvas.drawArc(
+      rect,
+      angle,
+      7 * pi / 4, // Draw an arc of 300 degrees
+      false,
+      gradientPaint,
+    );
+
+    // Add two circles at the start and end to create the rounded caps effect
+    final Paint capPaint = Paint()
+      ..color = color
+      ..style = PaintingStyle.fill;
+
+    canvas.drawCircle(
+      Offset(radius + radius * cos(angle), radius + radius * sin(angle)),
+      strokeSize / 2,
+      capPaint,
+    );
+  }
+
+  @override
+  bool shouldRepaint(CustomPainter oldDelegate) => true;
+}

babylonia_terminal_launcher/lib/widgets/steps/dxvk_steps_widget.dart

@@ -5,6 +5,7 @@ import 'package:yaru/widgets.dart';
 import './../../models/github.dart';
 import './../../models/dxvk.dart';
 import './../../widgets/simple_button.dart';
+import './../../widgets/gtk_spinner_widget.dart';
 import './../../providers/providers.dart';
 
 class DXVKSteps extends StatefulWidget {
@@ -36,7 +37,7 @@ class _DXVKStepsState extends State<DXVKSteps> {
                   children: [
                     Padding(
                       padding: EdgeInsets.all(8.0),
-                      child: CircularProgressIndicator(),
+                      child: GtkSpinner(),
                     ),
                     Text('Installing...'),
                   ],
@@ -89,7 +90,7 @@ class _InstallDXVKState extends State<InstallDXVK> {
             children: [
               Padding(
                 padding: EdgeInsets.all(8.0),
-                child: CircularProgressIndicator(),
+                child: GtkSpinner(),
               ),
               Text('Fetching versions...'),
             ],

babylonia_terminal_launcher/lib/widgets/steps/proton_steps_widget.dart

@@ -5,6 +5,7 @@ import 'package:yaru/widgets.dart';
 import './../../models/github.dart';
 import './../../models/proton.dart';
 import './../../widgets/simple_button.dart';
+import './../../widgets/gtk_spinner_widget.dart';
 import './../../providers/providers.dart';
 
 class ProtonSteps extends StatefulWidget {
@@ -36,7 +37,7 @@ class _ProtonStepsState extends State<ProtonSteps> {
                   children: [
                     Padding(
                       padding: EdgeInsets.all(8.0),
-                      child: CircularProgressIndicator(),
+                      child: GtkSpinner(),
                     ),
                     Text('decompressing...'),
                   ],
@@ -89,7 +90,7 @@ class _InstallProtonState extends State<InstallProton> {
             children: [
               Padding(
                 padding: EdgeInsets.all(8.0),
-                child: CircularProgressIndicator(),
+                child: GtkSpinner(),
               ),
               Text('Fetching versions...'),
             ],