Download Progress

The progress-download example demonstrates how to download a file while indicating download progress through Bubble Tea.

Preview

Code

pkgs/artisanal/example/tui/examples/progress-download/main.dart

/// Download progress example ported from Bubble Tea.
library;

import 'package:artisanal/bubbles.dart'
    as tui
    hide
        CodeBlockCommentDelimiters,
        CodeLanguageProfile,
        Column,
        CommonKeyBindings,
        EditBuffer,
        EditHistoryCoalescePredicate,
        EditHistoryController,
        EditHistoryMarkerBuilder,
        EditHistoryStateEquals,
        EditorCoreConfig,
        EditorState,
        GraphemePredicate,
        GraphemeReader,
        Help,
        KeyBinding,
        KeyMap,
        PasteMsg,
        Row,
        Spinner,
        SpinnerModel,
        SpinnerTickMsg,
        Spinners,
        Text,
        TextCommandResult,
        TextCursorCommandResult,
        TextDecorationLayerKey,
        TextDecorationRange,
        TextDiagnosticRange,
        TextDiagnosticSeverity,
        TextDocument,
        TextDocumentChange,
        TextDocumentEditResult,
        TextEditResult,
        TextExtmark,
        TextExtmarkOptions,
        TextExtmarkPositionRange,
        TextExtmarksController,
        TextHighlightRange,
        TextHitResult,
        TextLineCommandResult,
        TextLineDecoration,
        TextLineStateCommandExtensions,
        TextLineStateSnapshot,
        TextOffsetStateCommandExtensions,
        TextOffsetStateDocumentEditingExtensions,
        TextOffsetStateSnapshot,
        TextPasteChunk,
        TextPasteChunkStep,
        TextPasteController,
        TextPasteMode,
        TextPastePlan,
        TextPasteReference,
        TextPasteReferenceStore,
        TextPasteSession,
        TextPatternDiagnosticRule,
        TextPosition,
        TextPositionDiagnosticRange,
        TextSelection,
        TextSyntaxBuildResult,
        TextSyntaxChangeWindow,
        TextSyntaxDecorationPatch,
        TextSyntaxLineWindow,
        TextSyntaxProvider,
        TextSyntaxSession,
        TextSyntaxSnapshot,
        TextView,
        TextViewLine,
        TextViewport,
        TextVisualCursorPosition,
        UndoCommandDecoder,
        UndoCommandJournalEntry,
        UndoManager,
        UndoableCommand;

import 'dart:math';

import 'package:artisanal/artisanal.dart' show Style, AnsiColor;
import 'package:artisanal/tui.dart' as tui;

class DownloadProgressMsg extends tui.Msg {
  const DownloadProgressMsg(this.bytes, this.total);
  final int bytes;
  final int total;
}

class DownloadModel implements tui.Model {
  DownloadModel({
    required this.totalBytes,
    this.downloaded = 0,
    tui.ProgressModel? progress,
    Random? rand,
  }) : progress =
           progress ??
           tui.ProgressModel(
             width: 60,
             useGradient: true,
             gradientColorA: '#5A56E0',
             gradientColorB: '#EE6FF8',
           ),
       _rand = rand ?? Random();

  final int totalBytes;
  final int downloaded;
  final tui.ProgressModel progress;
  final Random _rand;

  @override
  tui.Cmd? init() => _startDownload();

  @override
  (tui.Model, tui.Cmd?) update(tui.Msg msg) {
    switch (msg) {
      case tui.KeyMsg():
        return (this, tui.Cmd.quit());

      case DownloadProgressMsg(:final bytes, :final total):
        final pct = bytes / total;
        final (newProgress, animCmd) = progress.setPercent(pct);
        final cmds = <tui.Cmd?>[animCmd];
        if (bytes < total) {
          cmds.add(_nextChunk(bytes));
        } else {
          cmds.add(tui.Cmd.quit());
        }
        return (
          copyWith(downloaded: bytes, progress: newProgress),
          tui.Cmd.batch(cmds.whereType<tui.Cmd>().toList()),
        );

      case tui.ProgressFrameMsg():
        final (newProgress, cmd) = progress.update(msg);
        return (copyWith(progress: newProgress), cmd);

      default:
        return (this, null);
    }
  }

  DownloadModel copyWith({
    int? downloaded,
    tui.ProgressModel? progress,
    Random? rand,
  }) {
    return DownloadModel(
      totalBytes: totalBytes,
      downloaded: downloaded ?? this.downloaded,
      progress: progress ?? this.progress,
      rand: rand ?? _rand,
    );
  }

  tui.Cmd _startDownload() => _nextChunk(downloaded);

  tui.Cmd _nextChunk(int current) {
    return tui.Cmd.tick(const Duration(milliseconds: 120), (_) {
      final remaining = totalBytes - current;
      final step = _rand.nextInt((totalBytes / 40).ceil()).clamp(0, remaining);
      final next = (current + step).clamp(0, totalBytes);
      return DownloadProgressMsg(next, totalBytes);
    });
  }

  @override
  String view() {
    final pct = (downloaded / totalBytes * 100)
        .clamp(0, 100)
        .toStringAsFixed(0);
    final kb = (totalBytes / 1024).toStringAsFixed(0);
    final info = Style()
        .foreground(const AnsiColor(98))
        .render('Downloading... $pct% of $kb KB (press any key to quit)');
    return '\n${progress.view()}\n\n$info\n';
  }
}

Future<void> main() async {
  await tui.runProgram(
    DownloadModel(totalBytes: 500_000),
    options: const tui.ProgramOptions(altScreen: false, hideCursor: false),
  );
}

Run it

dart run pkgs/artisanal/example/tui/examples/progress-download/main.dart