phylum/client/lib/ui/explorer/folder_grid_view.dart

import 'package:flutter/material.dart';
import 'package:phylum/ui/app/shortcuts.dart';
import 'package:phylum/libphylum/db/db.dart';
import 'package:phylum/ui/explorer/folder_grid_item.dart';
import 'package:phylum/ui/explorer/resource_drop_and_drop.dart';
import 'package:phylum/ui/explorer/resource_item_gesture_handler.dart';
import 'package:provider/provider.dart';

import 'explorer_controller.dart';

const _rowSpacing = 12.0;

class FolderGridView extends StatefulWidget {
  const FolderGridView({super.key});

  @override
  State<FolderGridView> createState() => _FolderGridViewState();
}

class _FolderGridViewState extends State<FolderGridView> {
  double _rowHeight = 0.0;
  double _viewportHeight = 0.0;
  int _crossAxisCount = 1;
  final _scrollController = ScrollController(debugLabel: "ResourceItemGrid");

  @override
  void initState() {
    super.initState();
  }

  @override
  void dispose() {
    _scrollController.dispose();
    super.dispose();
  }

  void ensureVisible(int index) {
    final currentOffset = _scrollController.offset;
    final itemStart = (index ~/ _crossAxisCount) * (_rowHeight + _rowSpacing);
    if (itemStart < currentOffset) {
      _scrollController.jumpTo(itemStart);
    } else if (currentOffset <= itemStart + _rowHeight + -_viewportHeight) {
      _scrollController.jumpTo(itemStart - _viewportHeight + _rowHeight);
    }
  }

  @override
  Widget build(BuildContext context) {
    final resources = context.select<ExplorerState, List<Resource>>((state) => state.resources);
    return LayoutBuilder(builder: (context, constraints) {
      _viewportHeight = constraints.maxHeight;
      final idealCount = constraints.maxWidth / 240;
      _crossAxisCount = idealCount.toInt();
      if (idealCount - _crossAxisCount > 0.75) {
        _crossAxisCount++;
      }
      _rowHeight = constraints.maxWidth / _crossAxisCount;
      return Actions(
        actions: {
          FocusUpIntent: CallbackAction<FocusUpIntent>(onInvoke: (i) {
            final index = context
                .read<ExplorerController>()
                .updateSelection((i) => i < _crossAxisCount ? i : i - _crossAxisCount, i.mode, true);
            ensureVisible(index);
            return null;
          }),
          FocusDownIntent: CallbackAction<FocusDownIntent>(onInvoke: (i) {
            final index = context.read<ExplorerController>().updateSelection(
                (i) => i < 0
                    ? 0
                    : i + _crossAxisCount >= resources.length
                        ? i
                        : i + _crossAxisCount,
                i.mode,
                true);
            ensureVisible(index);
            return null;
          }),
          FocusLeftIntent: CallbackAction<FocusLeftIntent>(onInvoke: (i) {
            final index = context.read<ExplorerController>().updateSelection((i) => i - 1, i.mode, true);
            ensureVisible(index);
            return null;
          }),
          FocusRightIntent: CallbackAction<FocusRightIntent>(onInvoke: (i) {
            final index = context.read<ExplorerController>().updateSelection((i) => i + 1, i.mode, true);
            ensureVisible(index);
            return null;
          }),
          FocusFirstIntent: CallbackAction<FocusFirstIntent>(onInvoke: (i) {
            final index = context.read<ExplorerController>().updateSelection((i) => 0, i.mode, true);
            ensureVisible(index);
            return null;
          }),
          FocusLastIntent: CallbackAction<FocusLastIntent>(onInvoke: (i) {
            final index = context.read<ExplorerController>().updateSelection((i) => 1 << 31, i.mode, true);
            ensureVisible(index);
            return null;
          }),
        },
        child: Focus(
          autofocus: true,
          descendantsAreFocusable: false,
          child: GridView.builder(
              itemCount: resources.length,
              controller: _scrollController,
              gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
                crossAxisCount: _crossAxisCount,
                crossAxisSpacing: 12,
                mainAxisSpacing: _rowSpacing,
                mainAxisExtent: _rowHeight,
              ),
              itemBuilder: (context, index) {
                final resource = resources[index];
                return (resource.dir)
                    ? ResourceDragTarget(
                        resourceId: resource.id,
                        buildItem: (context, dropTargetActive) => ResourceItemGestureHandler(
                          index: index,
                          resource: resource,
                          buildItem: () => FolderGridItem(
                            resource: resource,
                            dropTargetActive: dropTargetActive,
                          ),
                        ),
                      )
                    : ResourceItemGestureHandler(
                        index: index,
                        resource: resource,
                        buildItem: () => FolderGridItem(
                          resource: resource,
                          dropTargetActive: false,
                        ),
                      );
              }),
        ),
      );
    });
  }
}