#region PDFsharp - A .NET library for processing PDF
//
// Authors:
//   Stefan Lange (mailto:Stefan.Lange@pdfsharp.com)
//
// Copyright (c) 2005-2008 empira Software GmbH, Cologne (Germany)
//
// http://www.pdfsharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using System.Collections;
using System.Text;
using System.IO;
#if GDI
using System.Drawing;
using System.Drawing.Imaging;
#endif
#if WPF
using System.Windows.Media;
#endif
using PdfSharp.Drawing;
using PdfSharp.Fonts.TrueType;
using PdfSharp.Internal;
using PdfSharp.Pdf.Internal;

namespace PdfSharp.Pdf.Advanced
{
  /// <summary>
  /// Represents a PDF transparency group XObject.
  /// </summary>
  public sealed class PdfTransparencyGroupAttributes : PdfGroupAttributes
  {
    internal PdfTransparencyGroupAttributes(PdfDocument thisDocument)
      : base(thisDocument)
    {
      Elements.SetName(Keys.S, "/Transparency");
    }

    /// <summary>
    /// Predefined keys of this dictionary.
    /// </summary>
    public sealed new class Keys : PdfGroupAttributes.Keys
    {
      /// <summary>
      /// (Sometimes required, as discussed below)
      /// The group color space, which is used for the following purposes:
      /// • As the color space into which colors are converted when painted into the group
      /// • As the blending color space in which objects are composited within the group
      /// • As the color space of the group as a whole when it in turn is painted as an object onto its backdrop
      /// The group color space may be any device or CIE-based color space that
      /// treats its components as independent additive or subtractive values in the
      /// range 0.0 to 1.0, subject to the restrictions described in Section 7.2.3, “Blending Color Space.”
      /// These restrictions exclude Lab and lightness-chromaticity ICCBased color spaces,
      /// as well as the special color spaces Pattern, Indexed, Separation, and DeviceN.
      /// Device color spaces are subject to remapping according to the DefaultGray,
      /// DefaultRGB, and DefaultCMYK entries in the ColorSpace subdictionary of the
      /// current resource dictionary.
      /// Ordinarily, the CS entry is allowed only for isolated transparency groups
      /// (those for which I, below, is true), and even then it is optional. However,
      /// this entry is required in the group attributes dictionary for any transparency
      /// group XObject that has no parent group or page from which to inherit — in
      /// particular, one that is the value of the G entry in a soft-mask dictionary of
      /// subtype Luminosity.
      /// In addition, it is always permissible to specify CS in the group attributes
      /// dictionary associated with a page object, even if I is false or absent. In the
      /// normal case in which the page is imposed directly on the output medium,
      /// the page group is effectively isolated regardless of the I value, and the 
      /// specified CS value is therefore honored. But if the page is in turn used as an
      /// element of some other page and if the group is non-isolated, CS is ignored
      /// and the color space is inherited from the actual backdrop with which the
      /// page is composited.
      /// Default value: the color space of the parent group or page into which this
      /// transparency group is painted. (The parent’s color space in turn can be
      /// either explicitly specified or inherited.)
      /// </summary>
      [KeyInfo(KeyType.NameOrArray | KeyType.Optional)]
      public const string CS = "/CS";

      /// <summary>
      /// (Optional) A flag specifying whether the transparency group is isolated.
      /// If this flag is true, objects within the group are composited against a fully
      /// transparent initial backdrop; if false, they are composited against the
      /// group’s backdrop.
      /// Default value: false.
      /// In the group attributes dictionary for a page, the interpretation of this
      /// entry is slightly altered. In the normal case in which the page is imposed
      /// directly on the output medium, the page group is effectively isolated and
      /// the specified I value is ignored. But if the page is in turn used as an
      /// element of some other page, it is treated as if it were a transparency
      /// group XObject; the I value is interpreted in the normal way to determine
      /// whether the page group is isolated.
      /// </summary>
      [KeyInfo(KeyType.Boolean | KeyType.Optional)]
      public const string I = "/I";

      /// <summary>
      /// (Optional) A flag specifying whether the transparency group is a knockout
      /// group. If this flag is false, later objects within the group are composited
      /// with earlier ones with which they overlap; if true, they are composited with
      /// the group’s initial backdrop and overwrite (“knock out”) any earlier
      /// overlapping objects.
      /// Default value: false.
      /// </summary>
      [KeyInfo(KeyType.Boolean | KeyType.Optional)]
      public const string K = "/K";

      /// <summary>
      /// Gets the KeysMeta for these keys.
      /// </summary>
      internal static new DictionaryMeta Meta
      {
        get
        {
          if (Keys.meta == null)
            Keys.meta = CreateMeta(typeof(Keys));
          return Keys.meta;
        }
      }
      static DictionaryMeta meta;
    }

    /// <summary>
    /// Gets the KeysMeta of this dictionary type.
    /// </summary>
    internal override DictionaryMeta Meta
    {
      get { return Keys.Meta; }
    }
  }
}