Added alphaChannel to Magick++.

Magick++/lib/Image.cpp

@@ -417,6 +417,13 @@ void Magick::Image::affineTransform ( const DrawableAffine &affine_ )
   (void) DestroyExceptionInfo( &exceptionInfo );
 }
 
+void Magick::Image::alphaChannel ( AlphaChannelType alphaType_ )
+{
+  modifyImage();
+  SetImageAlphaChannel( image(), alphaType_ );
+  throwImageException();
+}
+
 // Annotate using specified text, and placement location
 void Magick::Image::annotate ( const std::string &text_,
                                const Geometry &location_ )

Magick++/lib/Magick++/Image.h

@@ -145,6 +145,9 @@ namespace Magick
     // Transform image by specified affine (or free transform) matrix.
     void            affineTransform ( const DrawableAffine &affine );
 
+    // Activates, deactivates, resets, or sets the alpha channel.
+    void            alphaChannel ( AlphaChannelType alphaType_ );
+
     //
     // Annotate image (draw text on image)
     //

Magick++/lib/Magick++/Include.h

@@ -231,6 +231,21 @@ namespace Magick
   using MagickCore::MagickFalse;
   using MagickCore::MagickTrue;
 
+  // Alpha channel types
+  using MagickCore::AlphaChannelType;
+  using MagickCore::UndefinedAlphaChannel;
+  using MagickCore::ActivateAlphaChannel;
+  using MagickCore::BackgroundAlphaChannel;
+  using MagickCore::CopyAlphaChannel;
+  using MagickCore::DeactivateAlphaChannel;
+  using MagickCore::ExtractAlphaChannel;
+  using MagickCore::OpaqueAlphaChannel;
+  using MagickCore::SetAlphaChannel;
+  using MagickCore::ShapeAlphaChannel;
+  using MagickCore::TransparentAlphaChannel;
+  using MagickCore::FlattenAlphaChannel;
+  using MagickCore::RemoveAlphaChannel;
+
   // Image class types
   using MagickCore::ClassType;
   using MagickCore::UndefinedClass;