rework SymbolFactory

- rename & move to Pilz.UI..Telerik.Symbols.RadSymbolFactory
- make default implementaiton available at Pilz.UI.Symbols.SymbolFactory
- add interfaces

Pilz.UI/Symbols/SymbolFactory.cs

@@ -0,0 +1,53 @@
+using System.Reflection;
+
+namespace Pilz.UI.Symbols;
+
+public abstract class SymbolFactory<TSymbols> : ISymbolFactory<TSymbols>
+{
+    public abstract string GetImageRessourcePath(TSymbols svgImage);
+    public abstract Assembly GetImageResourceAssembly();
+
+    protected virtual Size ResolveCommonSize(SymbolSize size)
+    {
+        return size switch
+        {
+            SymbolSize.Small => new Size(16, 16),
+            SymbolSize.Medium => new Size(20, 20),
+            SymbolSize.Large => new Size(32, 32),
+            _ => Size.Empty,
+        };
+    }
+
+    public virtual Stream? GetImageRessourceStream(TSymbols svgImage)
+    {
+        var asm = GetImageResourceAssembly();
+        var path = GetImageRessourcePath(svgImage);
+        return asm.GetManifestResourceStream(path);
+    }
+
+    public virtual Image? GetImage(TSymbols svgImage, SymbolSize size)
+    {
+        return GetImage(svgImage, ResolveCommonSize(size));
+    }
+
+    public virtual Image? GetImage(TSymbols svgImage, Size size)
+    {
+        using var stream = GetImageRessourceStream(svgImage);
+
+        if (stream is null)
+            return null;
+
+        var img = Image.FromStream(stream);
+
+        if (!size.IsEmpty)
+        {
+            var img2 = new Bitmap(size.Width, size.Height);
+            using var g = Graphics.FromImage(img2);
+            g.DrawImage(img2, 0, 0, size.Width, size.Height);
+            img.Dispose();
+            img = img2;
+        }
+
+        return img;
+    }
+}