Added methods to generate the native Win32 structures for each toolba…

…r item.

src/BetterControls/BetterToolbar/Items/BetterToolbarItem.NativeStructures.cs

@@ -0,0 +1,60 @@
+using System;
+using System.ComponentModel;
+using System.Runtime.InteropServices;
+
+namespace BetterControls
+{
+    /// <summary>
+    /// Extend this class to create a toolbar item.
+    /// </summary>
+    partial class BetterToolbarItem
+    {
+        /// <summary>
+        /// Computes the native structure as an instance of <see cref="NativeMethods.TBBUTTON"/>.
+        /// </summary>
+        /// <returns>An instance of <see cref="NativeMethods.TBBUTTON"/>.</returns>
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        internal virtual NativeMethods.TBBUTTON ComputeTbButton()
+        {
+            NativeMethods.TBBUTTON structure = new NativeMethods.TBBUTTON();
+
+            if (!Visible)
+                structure.fsState |= NativeMethods.TBSTATE_HIDDEN;
+
+            structure.idCommand = UniqueIdentifier;
+            structure.dwData = (IntPtr)0;
+            structure.iBitmap = NativeMethods.I_IMAGENONE;
+            structure.iString = (IntPtr)(-1);
+
+            return structure;
+        }
+
+        /// <summary>
+        /// Computes the native structure as an instance of <see cref="NativeMethods.TBBUTTONINFO"/>.
+        /// </summary>
+        /// <returns>An instance of <see cref="NativeMethods.TBBUTTONINFO"/>.</returns>
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        internal virtual NativeMethods.TBBUTTONINFO ComputeTbButtonInfo()
+        {
+            NativeMethods.TBBUTTONINFO structure = new NativeMethods.TBBUTTONINFO();
+
+            structure.cbSize = Marshal.SizeOf(typeof(NativeMethods.TBBUTTONINFO));
+
+            if (!Visible)
+                structure.fsState |= NativeMethods.TBSTATE_HIDDEN;
+
+            structure.idCommand = UniqueIdentifier;
+
+            // Always update the width. Lots of other changes can cause issues
+            // with the width, so updating to be sure.
+            structure.dwMask = NativeMethods.TBIF_SIZE;
+            structure.fsState = 0;
+            structure.cx = (short)ComputedWidth;
+
+            // Set the default image. This may be overridden by a child class.
+            structure.iImage = NativeMethods.I_IMAGENONE;
+
+            return structure;
+        }
+    }
+}