- Remove unnecessary code

- Execute `OnValueChanged` event in task

src/DesktopMagicPlugin.Test/PluginScript.cs

@@ -1,28 +1,60 @@
 using DesktopMagicPluginAPI;
 using DesktopMagicPluginAPI.Inputs;
 using System.Drawing;
-using System.Diagnostics;
+using System.Drawing.Imaging;
+using System.Drawing.Drawing2D;
+using System.IO;
+using System.Collections.Generic;
 
 namespace DesktopMagicPlugin.Test
 {
     public class GifPlugin : Plugin
     {
         [Element("Gif path:")]
-        public TextBox input = new TextBox("");
+        private TextBox input = new TextBox("");
 
-        public override int UpdateInterval { get; set; } = 100;
+        private List<Bitmap> bitmaps = new List<Bitmap>();
 
-        public override void OnMouseWheel(Point position, int delta)
+        private int frameCount = -1;
+
+        public override void Start()
         {
-            Debug.WriteLine(position + " | " + delta);
+            input.OnValueChanged += Input_OnValueChanged;
+        }
+
+        private void Input_OnValueChanged()
+        {
+            try
+            {
+                if (File.Exists(input.Value))
+                {
+                    Image gif = Image.FromFile(input.Value);
+                    PropertyItem item = gif.GetPropertyItem(0x5100); // FrameDelay in libgdiplus
+
+                    UpdateInterval = (item.Value[0] + item.Value[1] * 256) * 10; //FrameDelay in ms
+                    bitmaps.Clear();
+                    for (int i = 0; i < gif.GetFrameCount(FrameDimension.Time); i++)
+                    {
+                        gif.SelectActiveFrame(FrameDimension.Time, i);
+
+                        bitmaps.Add(new Bitmap(gif));
+                    }
+                }
+            }
+            catch { }
         }
 
         public override Bitmap Main()
         {
-            Bitmap bmp = new Bitmap(100, 100);
-            using Graphics graphics = Graphics.FromImage(bmp);
-            graphics.Clear(Application.Color);
-            return bmp;
+            if (bitmaps.Count == 0)
+                return new Bitmap(1, 1);
+
+            frameCount++;
+
+            if (frameCount >= bitmaps.Count)
+                frameCount = 0;
+
+            return bitmaps[frameCount];
         }
     }
 }