143 lines
4 KiB
Dart
143 lines
4 KiB
Dart
import 'package:flutter/foundation.dart';
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import 'package:flutter/material.dart';
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import 'package:flutter/services.dart';
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import 'package:photos/ui/huge_listview/draggable_scrollbar_thumbs.dart';
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class DraggableScrollbar extends StatefulWidget {
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final Widget child;
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final Color backgroundColor;
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final Color drawColor;
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final double heightScrollThumb;
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final EdgeInsetsGeometry padding;
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final int totalCount;
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final int initialScrollIndex;
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final int currentFirstIndex;
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final ValueChanged<double> onChange;
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final ScrollThumbBuilder scrollThumbBuilder;
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DraggableScrollbar({
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Key key,
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@required this.child,
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this.backgroundColor = Colors.white,
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this.drawColor = Colors.grey,
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this.heightScrollThumb = 48.0,
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this.padding,
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this.totalCount = 1,
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this.initialScrollIndex = 0,
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this.currentFirstIndex = 0,
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@required this.scrollThumbBuilder,
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this.onChange,
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}) : super(key: key);
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@override
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DraggableScrollbarState createState() => DraggableScrollbarState();
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}
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class DraggableScrollbarState extends State<DraggableScrollbar>
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with TickerProviderStateMixin {
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double thumbOffset = 0.0;
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bool isDragging = false;
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double get thumbMin => 0.0;
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double get thumbMax => context.size.height - widget.heightScrollThumb;
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@override
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void initState() {
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super.initState();
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if (widget.initialScrollIndex > 0 && widget.totalCount > 1) {
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WidgetsBinding.instance?.addPostFrameCallback((_) {
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setState(() => thumbOffset =
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(widget.initialScrollIndex / widget.totalCount) *
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(thumbMax - thumbMin));
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});
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}
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}
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@override
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Widget build(BuildContext context) => Stack(
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children: [
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RepaintBoundary(child: widget.child),
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RepaintBoundary(child: buildDetector()),
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],
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);
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Widget buildKeyboard() {
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if (defaultTargetPlatform == TargetPlatform.windows)
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return RawKeyboardListener(
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focusNode: FocusNode(),
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onKey: keyHandler,
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child: buildDetector(),
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);
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else
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return buildDetector();
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}
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Widget buildDetector() => GestureDetector(
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onVerticalDragStart: onDragStart,
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onVerticalDragUpdate: onDragUpdate,
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onVerticalDragEnd: onDragEnd,
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child: Container(
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alignment: Alignment.topRight,
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margin: EdgeInsets.only(top: thumbOffset),
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padding: widget.padding,
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child: widget.scrollThumbBuilder.call(
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widget.backgroundColor,
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widget.drawColor,
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widget.heightScrollThumb,
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widget.currentFirstIndex),
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),
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);
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void setPosition(double position) {
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setState(() {
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thumbOffset = position * (thumbMax - thumbMin);
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});
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}
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void onDragStart(DragStartDetails details) {
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setState(() => isDragging = true);
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}
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void onDragUpdate(DragUpdateDetails details) {
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setState(() {
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if (isDragging && details.delta.dy != 0) {
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thumbOffset += details.delta.dy;
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thumbOffset = thumbOffset.clamp(thumbMin, thumbMax);
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double position = thumbOffset / (thumbMax - thumbMin);
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widget.onChange?.call(position);
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}
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});
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}
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void onDragEnd(DragEndDetails details) {
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setState(() => isDragging = false);
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}
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void keyHandler(RawKeyEvent value) {
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if (value.runtimeType == RawKeyDownEvent) {
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if (value.logicalKey == LogicalKeyboardKey.arrowDown)
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onDragUpdate(DragUpdateDetails(
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globalPosition: Offset.zero,
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delta: Offset(0, 2),
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));
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else if (value.logicalKey == LogicalKeyboardKey.arrowUp)
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onDragUpdate(DragUpdateDetails(
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globalPosition: Offset.zero,
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delta: Offset(0, -2),
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));
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else if (value.logicalKey == LogicalKeyboardKey.pageDown)
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onDragUpdate(DragUpdateDetails(
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globalPosition: Offset.zero,
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delta: Offset(0, 25),
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));
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else if (value.logicalKey == LogicalKeyboardKey.pageUp)
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onDragUpdate(DragUpdateDetails(
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globalPosition: Offset.zero,
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delta: Offset(0, -25),
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));
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}
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}
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}
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