Serie List Scroll Bar

2025-11-10 16:04:59 +01:00
parent d3a2618dd9
commit 74b84d1a4a
2 changed files with 206 additions and 53 deletions
@@ -0,0 +1,131 @@
+import 'package:flutter/material.dart';
+
+class AlwaysOnScrollbar extends StatefulWidget {
+  final ScrollController controller;
+  final Axis axis;
+  final double thickness;
+  final Color thumbColor;
+  final Color trackColor;
+  final EdgeInsets padding;
+  final bool interactive;
+
+  const AlwaysOnScrollbar({
+    super.key,
+    required this.controller,
+    required this.axis,
+    this.thickness = 8,
+    this.thumbColor = const Color(0x88000000),
+    this.trackColor = const Color(0x22000000),
+    this.padding = EdgeInsets.zero,
+    this.interactive = true,
+  });
+
+  @override
+  State<AlwaysOnScrollbar> createState() => _AlwaysOnScrollbarState();
+}
+
+class _AlwaysOnScrollbarState extends State<AlwaysOnScrollbar> {
+  void _onChanged() {
+    if (mounted) setState(() {});
+  }
+
+  @override
+  void initState() {
+    super.initState();
+    widget.controller.addListener(_onChanged);
+  }
+
+  @override
+  void didUpdateWidget(covariant AlwaysOnScrollbar oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (oldWidget.controller != widget.controller) {
+      oldWidget.controller.removeListener(_onChanged);
+      widget.controller.addListener(_onChanged);
+    }
+  }
+
+  @override
+  void dispose() {
+    widget.controller.removeListener(_onChanged);
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Padding(
+        padding: widget.padding,
+        child: LayoutBuilder(
+          builder: (context, constraints) {
+            final has = widget.controller.hasClients;
+            final position = has ? widget.controller.position : null;
+            final isVertical = widget.axis == Axis.vertical;
+            final mainExtent = isVertical ? constraints.maxHeight : constraints.maxWidth;
+            final crossExtent = isVertical ? constraints.maxWidth : constraints.maxHeight;
+
+            double thumbLen = mainExtent * 0.25; // default when no metrics
+            double thumbOffset = 0;
+            if (has && position!.maxScrollExtent > 0 && position.viewportDimension > 0) {
+              final total = position.maxScrollExtent + position.viewportDimension;
+              final ratio = (position.viewportDimension / total).clamp(0.05, 1.0);
+              thumbLen = mainExtent * ratio;
+              final offRatio = (position.pixels / position.maxScrollExtent).clamp(0.0, 1.0);
+              thumbOffset = (mainExtent - thumbLen) * offRatio;
+            } else if (has && position!.maxScrollExtent == 0) {
+              // Not scrollable: show full track and a centered thumb
+              thumbLen = mainExtent * 0.5;
+              thumbOffset = (mainExtent - thumbLen) / 2;
+            }
+
+            final track = Container(
+              color: widget.trackColor,
+              width: isVertical ? widget.thickness : crossExtent,
+              height: isVertical ? mainExtent : widget.thickness,
+            );
+            final thumb = Container(
+              decoration: BoxDecoration(
+                color: widget.thumbColor,
+                borderRadius: BorderRadius.circular(widget.thickness / 2),
+              ),
+              width: isVertical ? widget.thickness : thumbLen,
+              height: isVertical ? thumbLen : widget.thickness,
+            );
+
+            void jumpToLocal(Offset local) {
+              if (!widget.interactive) return;
+              if (!(widget.controller.hasClients)) return;
+              final pos = widget.controller.position;
+              if (pos.maxScrollExtent <= 0) return;
+              final trackLen = (mainExtent - thumbLen);
+              if (trackLen <= 0) return;
+              final along = isVertical ? local.dy : local.dx;
+              final desired = (along - thumbLen / 2).clamp(0.0, trackLen);
+              final ratio = (desired / trackLen).clamp(0.0, 1.0);
+              final target = pos.maxScrollExtent * ratio;
+              try {
+                widget.controller.jumpTo(target);
+              } catch (_) {}
+            }
+
+            return GestureDetector(
+              behavior: HitTestBehavior.opaque,
+              onTapDown: (d) => jumpToLocal(d.localPosition),
+              onPanDown: (d) => jumpToLocal(d.localPosition),
+              onPanUpdate: (d) => jumpToLocal(d.localPosition),
+              child: Stack(children: [
+              // Track
+              if (isVertical)
+                Positioned(right: 0, top: 0, bottom: 0, width: widget.thickness, child: track)
+              else
+                Positioned(left: 0, right: 0, bottom: 0, height: widget.thickness, child: track),
+              // Thumb
+              if (isVertical)
+                Positioned(right: 0, top: thumbOffset, width: widget.thickness, height: thumbLen, child: thumb)
+              else
+                Positioned(left: thumbOffset, bottom: 0, height: widget.thickness, width: thumbLen, child: thumb),
+            ]),
+            );
+          },
+        ),
+      );
+  }
+}