UtinniPlugins/docs/patterns.html at master · kennethlong/UtinniPlugins · GitHub

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<!DOCTYPE html>
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<meta charset="utf-8" />
<title>Patterns — UtinniPlugins</title>
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<link rel="stylesheet" href="style.css" />
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<body>
<header class="site">
  <h1><span class="accent">UtinniPlugins</span> — Idiomatic Utinni plugin design</h1>
  <div class="sub">Cross-cutting conventions distilled from The Jawa Toolbox.</div>
</header>
<nav class="top">
  <a href="index.html">Overview</a>
  <a href="jawa-toolbox.html">The Jawa Toolbox</a>
  <a href="patterns.html" class="active">Patterns</a>
  <a href="sytners.html">Sytner's plugin</a>
  <a href="../../Utinni/docs/index.html">↗ Utinni framework docs</a>
</nav>
<main>

<h1>Plugin patterns</h1>

<p>
Conventions distilled from <a href="jawa-toolbox.html">The Jawa Toolbox</a>. Adopting
them gives you a clean, idiomatic Utinni plugin.
</p>

<h2>1. Composition over inheritance</h2>

<p>
JT has zero deep class hierarchies. Every feature area is a top-level
<code>&lt;Feature&gt;Impl</code> class plus one or more <code>SubPanel</code>s. The plugin class
(<code>TheJawaToolboxPlugin</code>) is <strong>a composition root</strong> — it instantiates each
<code>Impl</code>, hands them the shared settings/hotkey manager, and exposes them to
<code>FormMain</code> via <code>GetSubPanels()</code> / <code>GetForms()</code> / <code>GetStandalonePanels()</code>.
</p>

<pre><code>public class MyPlugin : IEditorPlugin
{
    private readonly FeatureAImpl a;
    private readonly FeatureBImpl b;
    private readonly FeatureCImpl c;

    public MyPlugin()
    {
        // shared state
        var ini = new UtINI("settings.ini");
        var hk  = new HotkeyManager(false);

        // wire features
        a = new FeatureAImpl(ini, hk);
        b = new FeatureBImpl(ini, hk, a);   // B uses A
        c = new FeatureCImpl(ini, hk);

        hk.CreateSettings();
        ini.Load();
    }

    // ...
}
</code></pre>

<p>
Why this matters: features are independently testable, easy to remove, and
their dependencies are explicit (you see exactly which features touch
which).
</p>

<h2>2. One <code>*Impl</code> per feature; panels are thin</h2>

<p>
A <code>SubPanel</code> should be presentation only — controls and event handlers that
forward to <code>Impl</code> methods. All callback registration, hotkey setup, undo
emission, and settings I/O happens in <code>Impl</code>.
</p>

<pre><code>// SnapshotPanel.cs (thin)
public class SnapshotPanel : SubPanel
{
    private readonly WorldSnapshotImpl impl;
    public SnapshotPanel(WorldSnapshotImpl impl) : base("Snapshot", true)
    {
        this.impl = impl;
        // ... build controls
        btnSave.Click  += (s,e) =&gt; impl.Save();
        btnAdd.Click   += (s,e) =&gt; impl.AddNode(txtFile.Text);
        gizmoTranslate.Click += (s,e) =&gt; impl.SetOperationModeToTranslate();
    }
}
</code></pre>

<p>
This means <strong>swapping the UI</strong> (e.g. adding a second SubPanel that exposes
the same features differently) doesn't touch the business logic at all.
</p>

<h2>3. Marshal everything</h2>

<p>
The single most common bug in new plugins is calling a game API on the UI
thread, or touching WinForms from a callback. The rule is:
</p>

<table>
  <thead>
    <tr><th>You're on the…</th><th>You want to call a…</th><th>Do this</th></tr>
  </thead>
  <tbody>
    <tr><td>UI thread (button, hotkey)</td><td>game API</td><td><code>GameCallbacks.AddMainLoopCall(() =&gt; Game.Foo())</code> or <code>GroundSceneCallbacks.AddUpdateLoopCall(...)</code></td></tr>
    <tr><td>game thread (callback)</td><td>WinForms control</td><td><code>myControl.BeginInvoke((MethodInvoker)(() =&gt; myControl.Text = ...))</code></td></tr>
    <tr><td>Background <code>Task</code></td><td>game API</td><td>enqueue a callback, await it via <code>TaskCompletionSource</code></td></tr>
    <tr><td>Background <code>Task</code></td><td>WinForms control</td><td><code>Invoke</code> to UI</td></tr>
  </tbody>
</table>

<p>
JT does this consistently — every <code>Impl</code> method that touches the game wraps
the call in a callback enqueue. Adopt the same style and a whole category of
bugs disappears.
</p>

<h2>4. Hotkeys with scope flags + dynamic enable</h2>

<p>
Define hotkeys once in the <code>Impl</code> constructor with <code>Name = "MyPlugin.X"</code>
prefixes. Use the scope flags:
</p>

<ul>
  <li><code>OnGameFocusOnly</code> — most editor shortcuts should set this true (otherwise
    they fire while the user is typing in a textbox in the side panel).</li>
  <li><code>OverrideGameInput</code> — set true for hotkeys that should not also feed
    through to SWG's input map (e.g. saving with <code>Ctrl+S</code> should not send <code>S</code>
    to the chat window). It's not frame-perfect — for hard guarantees, call
    <code>Client.SuspendInput()</code> / <code>ResumeInput()</code> directly in your handler.</li>
</ul>

<p>For context-sensitive shortcuts, toggle <code>Enabled</code> from a state callback:</p>

<pre><code>private void OnGizmoEnabled()  =&gt;
    hotkeys.Hotkeys["MyPlugin.GizmoTranslate"].Enabled = true;
private void OnGizmoDisabled() =&gt;
    hotkeys.Hotkeys["MyPlugin.GizmoTranslate"].Enabled = false;
</code></pre>

<h2>5. Undo via events, never via the stack</h2>

<p>
Never touch <code>UndoRedoManager</code> directly from a plugin. Always raise
<code>IEditorPlugin.AddUndoCommand</code>:
</p>

<pre><code>owner.AddUndoCommand?.Invoke(owner,
    new AddUndoCommandEventArgs(new MyCommand(before, after)));
</code></pre>

<p>
For continuous edits (gizmo drag, slider drag) capture <code>before</code> on the
edit-start callback (<code>OnGizmoEnabled</code>, <code>Slider.MouseDown</code>), capture <code>after</code>
on the edit-end callback (<code>OnGizmoDisabled</code>, <code>Slider.MouseUp</code>), and push
<strong>once</strong> with the pair.
</p>

<p>
For multi-object batched edits, write one <code>IUndoCommand</code> that holds a list
of (object, before, after) tuples — see the <code>Commands/WorldSnapshotCommands</code>
built-ins as the contract.
</p>

<h2>6. Settings as composition root</h2>

<p>
One <code>UtINI</code> per plugin, passed to every feature. Each feature owns its own
INI section name and seeds its defaults in <code>CreateSettings()</code>:
</p>

<pre><code>public class FeatureAImpl
{
    public FeatureAImpl(UtINI ini, HotkeyManager hk)
    {
        ini.AddSetting("FeatureA", "defaultThing", "naboo",  VtString);
        ini.AddSetting("FeatureA", "autoStart",    "false",  VtBool);
        // ...
    }
}
</code></pre>

<p>
<code>AddSetting</code> is idempotent — re-adding doesn't clobber an existing value.
So features can call it from every constructor and the user's edits in
<code>settings.ini</code> are preserved.
</p>

<h2>7. Async polling for live UI</h2>

<p>
When you want a label to update every frame (player position, time-of-day,
free-cam speed), don't poll from a WinForms timer — you'll either poll too
slow or too fast. Instead:
</p>

<pre><code>public FeatureImpl()
{
    Task.Run(UpdateView);
}

private async Task UpdateView()
{
    while (!ShouldStop)
    {
        await Task.Delay(50);   // 20 Hz

        var tcs = new TaskCompletionSource&lt;float&gt;();
        GroundSceneCallbacks.AddUpdateLoopCall(() =&gt;
            tcs.SetResult(Terrain.Get().GetTimeOfDay()));
        var tod = await tcs.Task;

        OnTodUpdated?.Invoke(tod);   // panel subscribes, marshals to UI
    }
}
</code></pre>

<p>Or simpler — re-enqueue an update-loop call each frame:</p>

<pre><code>void OnUpdate()
{
    var t = Terrain.Get().GetTimeOfDay();
    panel.BeginInvoke((MethodInvoker)(() =&gt; panel.UpdateTod(t)));
    GroundSceneCallbacks.AddUpdateLoopCall(OnUpdate);
}
GroundSceneCallbacks.AddUpdateLoopCall(OnUpdate);
</code></pre>

<p>
Pick whichever feels cleaner; the JT mostly uses the <code>Task.Delay</code> pattern
for 10–20 Hz UI refresh.
</p>

<h2>8. Drag-drop as asset placement</h2>

<p>
The Object Browser's drag-drop pattern is general-purpose. Adapt it for any
"drag from a listbox / treeview, drop into the live game world":
</p>

<div class="mermaid">
sequenceDiagram
  participant U as User
  participant L as ListBox
  participant DD as GameDragDropEventHandlers
  participant W as Game world
  participant S as Snapshot impl

  U->>L: mousedown on item
  L->>L: capture filename
  U->>L: mousemove (with LMB)
  L->>L: DoDragDrop(filename)

  U->>W: drag over PanelGame
  W->>DD: OnDragEnter fires
  DD->>W: create temporary preview Object, addObjectNotifications
  U->>W: drag-move
  DD->>W: collide cursor → world point; reposition preview
  U->>W: drop
  DD->>S: snapshotImpl.AddNodeAt(previewPosition, filename)
  DD->>W: destroy preview object
</div>

<p>
The trick is <strong>showing live feedback</strong> during drag (the preview object
follows the cursor) so the user knows what they're placing and where.
</p>

<h2>9. C++ shim only when necessary</h2>

<p>Don't write a C++ half unless you need one of:</p>

<ul>
  <li><strong>Chat slash commands</strong> (<code>/foo</code>) — must register at <code>CuiChatWindow::ctor</code>
    time, which is before the CLR is ready.</li>
  <li><strong>A new detour</strong> that UtinniCore doesn't already wrap — you're adding a
    <code>swg/&lt;subsystem&gt;/</code> entry.</li>
  <li><strong>Per-frame work that's prohibitively expensive in managed code</strong> — rare;
    the bridge is fast.</li>
</ul>

<p>
In every other case, write a <code>IPlugin</code> / <code>IEditorPlugin</code> in C# and use the
existing callbacks. If you do need C++, keep it to plugin scaffolding +
forwarding to managed events (e.g. via <code>EventHandler&lt;T&gt;</code> raised on a shared
static instance).
</p>

<h2>10. Disable controls until a scene is loaded</h2>

<p>
Most editor controls only make sense inside a scene. Wire enable/disable on
<code>GameCallbacks</code>:
</p>

<pre><code>public MySubPanel()
{
    GameCallbacks.AddSetupSceneCall(() =&gt;
        this.BeginInvoke((MethodInvoker)(() =&gt; SetEnabled(true))));
    GameCallbacks.AddCleanupSceneCall(() =&gt;
        this.BeginInvoke((MethodInvoker)(() =&gt; SetEnabled(false))));
    SetEnabled(false);   // default
}

private void SetEnabled(bool enabled)
{
    foreach (Control c in Controls)
        if (c is UtinniButton or UtinniNumericUpDown or UtinniTextbox)
            c.Enabled = enabled;
}
</code></pre>

<p>Better UX, fewer null-deref bugs in your handlers.</p>

<h2>11. Name things with plugin prefixes</h2>

<p>
For hotkeys, INI sections, and anything else that might collide with other
plugins, prefix:
</p>

<ul>
  <li>Hotkey <code>Name</code> → <code>MyPlugin.SaveScene</code> not <code>SaveScene</code>.</li>
  <li>Logger callouts → <code>[MyPlugin] ...</code> (use <code>Log.Info("[MyPlugin] " + msg)</code> or
    rely on the <code>writeClassName</code> config flag).</li>
</ul>

<p>
This is also why <code>[Plugins] plugin_N</code> in <code>ut.ini</code> is keyed by <em>directory
name</em> — that directory name is your plugin's namespace.
</p>

<h2>12. Build outputs into <code>Plugins/&lt;Name&gt;/</code></h2>

<p>
The Directory.Build.props the VSIX wizard writes does this for you. If
you're hand-rolling a project:
</p>

<pre><code>&lt;PropertyGroup&gt;
  &lt;OutputPath&gt;$(SolutionDir)bin\$(Configuration)\Plugins\$(MSBuildProjectName)\&lt;/OutputPath&gt;
&lt;/PropertyGroup&gt;
</code></pre>

<p>
And reference <code>UtinniCoreDotNet.dll</code> with <code>Private=False</code> so you don't
shadow the install's copy.
</p>

<h2>See also</h2>

<ul>
  <li><a href="jawa-toolbox.html">The Jawa Toolbox</a> — the worked example these patterns
    come from.</li>
  <li><a href="../../Utinni/docs/index.html">Utinni docs</a> — the framework these
    patterns sit on top of.</li>
</ul>

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