Add Typewriter effect SE5 plugin (Avalonia)

.github/workflows/typewriter.yml

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+name: Build TypewriterEffect (SE5)
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'se5/TypewriterEffect/**'
+      - '.github/workflows/typewriter.yml'
+  pull_request:
+    paths:
+      - 'se5/TypewriterEffect/**'
+      - '.github/workflows/typewriter.yml'
+  workflow_dispatch:
+    inputs:
+      tag:
+        description: 'Release tag to publish the zips under (e.g. se5-typewriter-v1.0). Leave empty to build artifacts only.'
+        required: false
+        type: string
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - rid: win-x64
+            os: windows
+            exe: TypewriterEffect.exe
+          - rid: win-arm64
+            os: windows
+            exe: TypewriterEffect.exe
+          - rid: linux-x64
+            os: linux
+            exe: TypewriterEffect
+          - rid: linux-arm64
+            os: linux
+            exe: TypewriterEffect
+          - rid: osx-x64
+            os: macos
+            exe: TypewriterEffect
+          - rid: osx-arm64
+            os: macos
+            exe: TypewriterEffect
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup .NET 8
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: '8.0.x'
+
+      - name: Publish self-contained (${{ matrix.rid }})
+        working-directory: se5/TypewriterEffect
+        run: |
+          dotnet publish TypewriterEffect.csproj \
+            -c Release \
+            -r ${{ matrix.rid }} \
+            --self-contained true \
+            -p:PublishSingleFile=true \
+            -p:IncludeNativeLibrariesForSelfExtract=true \
+            -o staging/TypewriterEffect
+
+      - name: Rewrite plugin.json for ${{ matrix.os }}
+        working-directory: se5/TypewriterEffect
+        run: |
+          jq '
+            del(.runtime, .entry) |
+            .executables = { "${{ matrix.os }}": "${{ matrix.exe }}" }
+          ' plugin.json > staging/TypewriterEffect/plugin.json
+
+      - name: Package zip
+        working-directory: se5/TypewriterEffect/staging
+        run: zip -r "$GITHUB_WORKSPACE/TypewriterEffect-${{ matrix.rid }}.zip" TypewriterEffect
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: TypewriterEffect-${{ matrix.rid }}
+          path: TypewriterEffect-${{ matrix.rid }}.zip
+
+  release:
+    name: Publish GitHub Release
+    needs: build
+    if: github.event_name == 'workflow_dispatch' && github.event.inputs.tag != ''
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - name: Download all zips
+        uses: actions/download-artifact@v4
+        with:
+          path: dist
+          pattern: TypewriterEffect-*
+          merge-multiple: true
+
+      - name: Create release and upload zips
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          gh release create "${{ github.event.inputs.tag }}" dist/TypewriterEffect-*.zip \
+            --repo "${{ github.repository }}" \
+            --target "${{ github.sha }}" \
+            --title "TypewriterEffect ${{ github.event.inputs.tag }}" \
+            --notes "Self-contained TypewriterEffect plugin builds for win/linux/osx (x64 + arm64)."

se5-plugins.json

@@ -1,5 +1,22 @@
 {
   "plugins": [
+    {
+      "name": "Typewriter effect",
+      "description": "Splits each subtitle line into short timed parts that progressively reveal the text, character by character.",
+      "version": "1.0.0",
+      "author": "Subtitle Edit",
+      "url": "https://github.com/SubtitleEdit/plugins/tree/main/se5/TypewriterEffect",
+      "date": "2026-05-17",
+      "minSeVersion": "5.0.0",
+      "downloads": {
+        "win-x64":     "https://github.com/SubtitleEdit/plugins/releases/download/se5-typewriter-v1.0/TypewriterEffect-win-x64.zip",
+        "win-arm64":   "https://github.com/SubtitleEdit/plugins/releases/download/se5-typewriter-v1.0/TypewriterEffect-win-arm64.zip",
+        "linux-x64":   "https://github.com/SubtitleEdit/plugins/releases/download/se5-typewriter-v1.0/TypewriterEffect-linux-x64.zip",
+        "linux-arm64": "https://github.com/SubtitleEdit/plugins/releases/download/se5-typewriter-v1.0/TypewriterEffect-linux-arm64.zip",
+        "osx-x64":     "https://github.com/SubtitleEdit/plugins/releases/download/se5-typewriter-v1.0/TypewriterEffect-osx-x64.zip",
+        "osx-arm64":   "https://github.com/SubtitleEdit/plugins/releases/download/se5-typewriter-v1.0/TypewriterEffect-osx-arm64.zip"
+      }
+    },
     {
       "name": "Haxor",
       "description": "Translates the text of the selected lines (or all lines) to haxor.",

se5/TypewriterEffect/App.axaml

@@ -0,0 +1,8 @@
+<Application xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             x:Class="SubtitleEdit.Plugins.TypewriterEffect.App"
+             RequestedThemeVariant="Default">
+    <Application.Styles>
+        <FluentTheme />
+    </Application.Styles>
+</Application>

se5/TypewriterEffect/App.axaml.cs

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+using Avalonia;
+using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Markup.Xaml;
+using Avalonia.Styling;
+
+namespace SubtitleEdit.Plugins.TypewriterEffect;
+
+public partial class App : Application
+{
+    /// <summary>Set by Program.Main before Avalonia starts.</summary>
+    public static PluginRequest? PendingRequest;
+
+    /// <summary>Filled in by MainWindow when the user clicks OK or Cancel.</summary>
+    public static PluginResponse? Response;
+
+    public override void Initialize() => AvaloniaXamlLoader.Load(this);
+
+    public override void OnFrameworkInitializationCompleted()
+    {
+        if (PendingRequest is not null)
+        {
+            RequestedThemeVariant = string.Equals(PendingRequest.Theme, "Dark", System.StringComparison.OrdinalIgnoreCase)
+                ? ThemeVariant.Dark
+                : ThemeVariant.Light;
+
+            if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+            {
+                desktop.MainWindow = new MainWindow(PendingRequest);
+            }
+        }
+
+        base.OnFrameworkInitializationCompleted();
+    }
+}

se5/TypewriterEffect/MainWindow.axaml

@@ -0,0 +1,54 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        mc:Ignorable="d"
+        x:Class="SubtitleEdit.Plugins.TypewriterEffect.MainWindow"
+        Title="Typewriter effect"
+        Width="520" Height="360"
+        WindowStartupLocation="CenterScreen"
+        CanResize="False">
+    <DockPanel Margin="20">
+        <StackPanel DockPanel.Dock="Bottom"
+                    Orientation="Horizontal"
+                    HorizontalAlignment="Right"
+                    Spacing="10"
+                    Margin="0,16,0,0">
+            <Button Content="Cancel"
+                    Click="OnCancel"
+                    MinWidth="100" />
+            <Button x:Name="OkButton"
+                    Content="OK"
+                    Click="OnOk"
+                    MinWidth="100"
+                    Classes="accent"
+                    IsDefault="True" />
+        </StackPanel>
+
+        <StackPanel Orientation="Vertical" Spacing="14">
+            <TextBlock FontSize="18"
+                       FontWeight="SemiBold"
+                       Text="Typewriter effect" />
+
+            <TextBlock x:Name="InfoLabel"
+                       Opacity="0.8"
+                       TextWrapping="Wrap" />
+
+            <StackPanel Orientation="Vertical" Spacing="6">
+                <TextBlock Text="End delay (seconds)" />
+                <NumericUpDown x:Name="EndDelayInput"
+                               Minimum="0"
+                               Maximum="10"
+                               Increment="0.5"
+                               FormatString="0.0##"
+                               Value="0.5"
+                               Width="160"
+                               HorizontalAlignment="Left" />
+                <TextBlock Opacity="0.65"
+                           FontSize="11"
+                           TextWrapping="Wrap"
+                           Text="After the last character appears, the full line stays on screen for this long before the original end time." />
+            </StackPanel>
+        </StackPanel>
+    </DockPanel>
+</Window>

se5/TypewriterEffect/MainWindow.axaml.cs

@@ -0,0 +1,90 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Avalonia.Markup.Xaml;
+using System;
+using System.Text.Json;
+
+namespace SubtitleEdit.Plugins.TypewriterEffect;
+
+public partial class MainWindow : Window
+{
+    private readonly PluginRequest _request;
+
+    // Parameterless constructor only exists for the XAML designer.
+    public MainWindow() : this(new PluginRequest()) { }
+
+    public MainWindow(PluginRequest request)
+    {
+        InitializeComponent();
+        _request = request;
+
+        var selectedCount = request.SelectedIndices.Count;
+        InfoLabel.Text = selectedCount > 0
+            ? $"Each of the {selectedCount} selected line(s) will be split into several short lines that progressively reveal the text."
+            : "Every line will be split into several short lines that progressively reveal the text.";
+
+        EndDelayInput.Value = (decimal)LoadEndDelaySetting(request.Settings, defaultValue: 0.5);
+    }
+
+    private void InitializeComponent() => AvaloniaXamlLoader.Load(this);
+
+    private void OnCancel(object? sender, RoutedEventArgs e)
+    {
+        App.Response = new PluginResponse { Status = "cancelled" };
+        Close();
+    }
+
+    private void OnOk(object? sender, RoutedEventArgs e)
+    {
+        var endDelaySec = (double)(EndDelayInput.Value ?? 0m);
+
+        try
+        {
+            var blocks = SubRipParser.Parse(_request.Subtitle.SubRip);
+            var selected = new HashSet<int>(_request.SelectedIndices);
+            var (resultBlocks, changed) = TypewriterEngine.Apply(blocks, selected, endDelaySec);
+
+            App.Response = new PluginResponse
+            {
+                Status = "ok",
+                Message = changed == 0
+                    ? "No lines changed."
+                    : $"Typewriter applied to {changed} line(s).",
+                UndoDescription = "Typewriter effect",
+                Subtitle = new PluginSubtitle
+                {
+                    Format = "SubRip",
+                    Native = SubRipParser.Serialize(resultBlocks),
+                },
+                Settings = BuildSettings(endDelaySec),
+            };
+        }
+        catch (Exception ex)
+        {
+            App.Response = new PluginResponse { Status = "error", Message = ex.Message };
+        }
+
+        Close();
+    }
+
+    private static double LoadEndDelaySetting(JsonElement? settings, double defaultValue)
+    {
+        if (settings is null || settings.Value.ValueKind != JsonValueKind.Object)
+        {
+            return defaultValue;
+        }
+        if (settings.Value.TryGetProperty("endDelay", out var value) &&
+            value.ValueKind == JsonValueKind.Number &&
+            value.TryGetDouble(out var parsed))
+        {
+            return parsed;
+        }
+        return defaultValue;
+    }
+
+    private static JsonElement BuildSettings(double endDelay)
+    {
+        using var doc = JsonDocument.Parse($"{{\"endDelay\":{endDelay.ToString("0.###", System.Globalization.CultureInfo.InvariantCulture)}}}");
+        return doc.RootElement.Clone();
+    }
+}

se5/TypewriterEffect/PluginContract.cs

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+using System.Text.Json;
+
+namespace SubtitleEdit.Plugins.TypewriterEffect;
+
+// Mirrors the Subtitle Edit 5 plugin JSON contract.
+// See https://github.com/SubtitleEdit/subtitleedit/blob/main/docs/plugin.md
+
+public sealed class PluginRequest
+{
+    public int ApiVersion { get; set; } = 1;
+    public string RequestType { get; set; } = "run";
+    public string ResponseFilePath { get; set; } = string.Empty;
+    public string TempDirectory { get; set; } = string.Empty;
+    public PluginSubtitle Subtitle { get; set; } = new();
+    public List<int> SelectedIndices { get; set; } = new();
+    public string VideoFileName { get; set; } = string.Empty;
+    public double FrameRate { get; set; }
+    public string UiLanguage { get; set; } = string.Empty;
+    public string Theme { get; set; } = string.Empty;
+    public string SeVersion { get; set; } = string.Empty;
+    public JsonElement? Settings { get; set; }
+}
+
+public sealed class PluginSubtitle
+{
+    public string Format { get; set; } = string.Empty;
+    public string FileName { get; set; } = string.Empty;
+    public string Native { get; set; } = string.Empty;
+    public string SubRip { get; set; } = string.Empty;
+}
+
+public sealed class PluginResponse
+{
+    public int ApiVersion { get; set; } = 1;
+    public string Status { get; set; } = "cancelled";
+    public string? Message { get; set; }
+    public PluginSubtitle? Subtitle { get; set; }
+    public JsonElement? Settings { get; set; }
+    public string? UndoDescription { get; set; }
+}