Update test plugin to properly release the resources when being stopped

src/DesktopMagicPlugin.Test/PluginScript.cs

@@ -6,14 +6,13 @@ using System.Collections.Generic;
 using System.Drawing;
 using System.Drawing.Imaging;
 using System.IO;
+using System.Threading;
 using System.Threading.Tasks;
 
 namespace DesktopMagic.PluginTest;
 
 public class GifPlugin : Plugin
 {
-    private const string SaveFilePath = "gifPath.txt";
-
     [Setting("gif-path", "Gif path:")]
     private readonly TextBox input = new TextBox("");
 
@@ -22,22 +21,33 @@ public class GifPlugin : Plugin
 
     private readonly List<Bitmap> bitmaps = [];
 
+    private readonly CancellationTokenSource cancellationTokenSource;
     private int frameCount = -1;
 
-    public override void Start()
+    public GifPlugin()
+    {
+        cancellationTokenSource = new CancellationTokenSource();
+    }
+
+    public override async void Start()
     {
         input.OnValueChanged += Input_OnValueChanged;
-        if (File.Exists(SaveFilePath))
-        {
-            input.Value = File.ReadAllText(SaveFilePath);
-        }
+
+        await LoadGif();
+    }
+
+    public override void Stop()
+    {
+        cancellationTokenSource.Cancel();
+
+        bitmaps.Clear();
     }
 
     public override Bitmap Main()
     {
         if (bitmaps.Count == 0)
         {
-            return new Bitmap(1, 1);
+            return null;
         }
 
         frameCount++;
@@ -50,9 +60,14 @@ public class GifPlugin : Plugin
         return bitmaps[frameCount];
     }
 
-    private void Input_OnValueChanged()
+    private async void Input_OnValueChanged()
     {
-        _ = Task.Run(() =>
+        await LoadGif();
+    }
+
+    private Task LoadGif()
+    {
+        return Task.Run(() =>
         {
             try
             {
@@ -63,15 +78,19 @@ public class GifPlugin : Plugin
 
                     PropertyItem item = gif.GetPropertyItem(0x5100); // FrameDelay in libgdiplus
 
-                    UpdateInterval = (item.Value[0] + item.Value[1] * 256) * 10; //FrameDelay in ms
+                    UpdateInterval = (item.Value[0] + (item.Value[1] * 256)) * 10; //FrameDelay in ms
                     bitmaps.Clear();
                     for (int i = 0; i < gif.GetFrameCount(FrameDimension.Time); i++)
                     {
+                        cancellationTokenSource.Token.ThrowIfCancellationRequested();
+
                         _ = gif.SelectActiveFrame(FrameDimension.Time, i);
 
                         bitmaps.Add(new Bitmap(gif));
+
+                        info.Value = $"Loading frame {i + 1} of {gif.GetFrameCount(FrameDimension.Time)}";
                     }
-                    File.WriteAllText(SaveFilePath, input.Value);
+
                     info.Value = string.Empty;
                 }
                 else
@@ -83,6 +102,6 @@ public class GifPlugin : Plugin
             {
                 info.Value = $"Error: {ex.Message}";
             }
-        });
+        }, cancellationTokenSource.Token);
     }
 }