Add image copy functions to QImage.

Quik/Media/QImage.cs

@@ -1,5 +1,4 @@
 using System;
-
 namespace Quik.Media
 {
     public abstract class QImage : IDisposable
@@ -62,5 +61,60 @@ namespace Quik.Media
             Depth = depth;
             ImagePtr = ptr;
         }
+
+        public unsafe void CopyTo(QImageLock destination, int x, int y)
+        {
+            if (
+                Width + x > destination.Width ||
+                Height + y > destination.Height)
+            {
+                throw new Exception("Image falls outside the bounds of the destination.");
+            }
+            else if (Format != destination.Format)
+            {
+                throw new Exception("Image formats must be the same.");
+            }
+
+            int bpp = Format.BytesPerPixel();
+            for (int i = 0; i < Height; i++)
+            {
+                IntPtr srcPtr = (IntPtr)((long)ImagePtr + i * bpp);
+
+                long dstPos = x + i * destination.Width;
+                IntPtr dstPtr = (IntPtr)((long)destination.ImagePtr + dstPos * bpp);
+
+                Buffer.MemoryCopy((void*)srcPtr, (void*)dstPtr, Width * bpp, Width * bpp);
+            }
+        }
+
+        public unsafe void ExtractFrom(QImageLock destination, int x, int y, int width, int height)
+        {
+            if (
+                width != destination.Width ||
+                height != destination.Height)
+            {
+                throw new Exception("Destination is not the same size as the subregion.");
+            }
+            else if (x + width > Width || y + height > Height)
+            {
+                throw new Exception("The subregion is larger than this image.");
+            }
+            else if (Format != destination.Format)
+            {
+                throw new Exception("Image formats must be the same.");
+            }
+
+            int bpp = Format.BytesPerPixel();
+            for (int i = 0; i < height; i++)
+            {
+                long srcPos = x + y * i;
+                IntPtr srcPtr = (IntPtr)((long)ImagePtr + srcPos * bpp);
+
+                long dstPos = i * destination.Width;
+                IntPtr dstPtr = (IntPtr)((long)destination.ImagePtr + dstPos * bpp);
+
+                Buffer.MemoryCopy((void*)srcPtr, (void*)dstPtr, width * bpp, width * bpp);
+            }
+        }
     }
 }