#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.Globalization;
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 shading dictionary.
  /// </summary>
  public sealed class PdfShading : PdfDictionary
  {
    /// <summary>
    /// Initializes a new instance of the <see cref="PdfShading"/> class.
    /// </summary>
    public PdfShading(PdfDocument document)
      : base(document)
    { }

    /// <summary>
    /// Setups the shading from the specified brush.
    /// </summary>
    public void SetupFromBrush(XLinearGradientBrush brush)
    {
      if (brush == null)
        throw new ArgumentNullException("brush");

      PdfColorMode colorMode = this.document.Options.ColorMode;
      XColor color1 = ColorSpaceHelper.EnsureColorMode(colorMode, brush.color1);
      XColor color2 = ColorSpaceHelper.EnsureColorMode(colorMode, brush.color2);

      PdfDictionary function = new PdfDictionary();

      Elements[Keys.ShadingType] = new PdfInteger(2);
      if (colorMode != PdfColorMode.Cmyk)
        Elements[Keys.ColorSpace] = new PdfName("/DeviceRGB");
      else
        Elements[Keys.ColorSpace] = new PdfName("/DeviceCMYK");

      double x1 = 0, y1 = 0, x2 = 0, y2 = 0;
      if (brush.useRect)
      {
        switch (brush.linearGradientMode)
        {
          case XLinearGradientMode.Horizontal:
            x1 = brush.rect.x;
            y1 = brush.rect.y;
            x2 = brush.rect.x + brush.rect.width;
            y2 = brush.rect.y;
            break;

          case XLinearGradientMode.Vertical:
            x1 = brush.rect.x;
            y1 = brush.rect.y;
            x2 = brush.rect.x;
            y2 = brush.rect.y + brush.rect.height;
            break;

          case XLinearGradientMode.ForwardDiagonal:
            x1 = brush.rect.x;
            y1 = brush.rect.y;
            x2 = brush.rect.x + brush.rect.width;
            y2 = brush.rect.y + brush.rect.height;
            break;

          case XLinearGradientMode.BackwardDiagonal:
            x1 = brush.rect.x + brush.rect.width;
            y1 = brush.rect.y;
            x2 = brush.rect.x;
            y2 = brush.rect.y + brush.rect.height;
            break;
        }
      }
      else
      {
        x1 = brush.point1.x;
        y1 = brush.point1.y;
        x2 = brush.point2.x;
        y2 = brush.point2.y;
      }
      Elements[Keys.Coords] = new PdfLiteral("[{0:0.###} {1:0.###} {2:0.###} {3:0.###}]", x1, y1, x2, y2);

      //Elements[Keys.Background] = new PdfRawItem("[0 1 1]");
      //Elements[Keys.Domain] = 
      Elements[Keys.Function] = function;
      //Elements[Keys.Extend] = new PdfRawItem("[true true]");

      string clr1 = "[" + PdfEncoders.ToString(color1, colorMode) + "]";
      string clr2 = "[" + PdfEncoders.ToString(color2, colorMode) + "]";

      function.Elements["/FunctionType"] = new PdfInteger(2);
      function.Elements["/C0"] = new PdfLiteral(clr1);
      function.Elements["/C1"] = new PdfLiteral(clr2);
      function.Elements["/Domain"] = new PdfLiteral("[0 1]");
      function.Elements["/N"] = new PdfInteger(1);
    }

    /// <summary>
    /// Common keys for all streams.
    /// </summary>
    internal sealed class Keys : KeysBase
    {
      /// <summary>
      /// (Required) The shading type:
      /// 1 Function-based shading
      /// 2 Axial shading
      /// 3 Radial shading
      /// 4 Free-form Gouraud-shaded triangle mesh
      /// 5 Lattice-form Gouraud-shaded triangle mesh
      /// 6 Coons patch mesh
      /// 7 Tensor-product patch mesh
      /// </summary>
      [KeyInfo(KeyType.Integer | KeyType.Required)]
      public const string ShadingType = "/ShadingType";

      /// <summary>
      /// (Required) The color space in which color values are expressed. This may be any device, 
      /// CIE-based, or special color space except a Pattern space.
      /// </summary>
      [KeyInfo(KeyType.NameOrArray | KeyType.Required)]
      public const string ColorSpace = "/ColorSpace";

      /// <summary>
      /// (Optional) An array of color components appropriate to the color space, specifying
      /// a single background color value. If present, this color is used, before any painting 
      /// operation involving the shading, to fill those portions of the area to be painted 
      /// that lie outside the bounds of the shading object. In the opaque imaging model, 
      /// the effect is as if the painting operation were performed twice: first with the 
      /// background color and then with the shading.
      /// </summary>
      [KeyInfo(KeyType.Array | KeyType.Optional)]
      public const string Background = "/Background";

      /// <summary>
      /// (Optional) An array of four numbers giving the left, bottom, right, and top coordinates, 
      /// respectively, of the shading’s bounding box. The coordinates are interpreted in the 
      /// shading’s target coordinate space. If present, this bounding box is applied as a temporary 
      /// clipping boundary when the shading is painted, in addition to the current clipping path
      /// and any other clipping boundaries in effect at that time.
      /// </summary>
      [KeyInfo(KeyType.Rectangle | KeyType.Optional)]
      public const string BBox = "/BBox";

      /// <summary>
      /// (Optional) A flag indicating whether to filter the shading function to prevent aliasing 
      /// artifacts. The shading operators sample shading functions at a rate determined by the 
      /// resolution of the output device. Aliasing can occur if the function is not smooth—that
      /// is, if it has a high spatial frequency relative to the sampling rate. Anti-aliasing can
      /// be computationally expensive and is usually unnecessary, since most shading functions
      /// are smooth enough or are sampled at a high enough frequency to avoid aliasing effects.
      /// Anti-aliasing may not be implemented on some output devices, in which case this flag
      /// is ignored.
      /// Default value: false.
      /// </summary>
      [KeyInfo(KeyType.Boolean | KeyType.Optional)]
      public const string AntiAlias = "/AntiAlias";


      // ---- Type 2 ----------------------------------------------------------

      /// <summary>
      /// (Required) An array of four numbers [x0 y0 x1 y1] specifying the starting and
      /// ending coordinates of the axis, expressed in the shading’s target coordinate space.
      /// </summary>
      [KeyInfo(KeyType.Array | KeyType.Required)]
      public const string Coords = "/Coords";

      /// <summary>
      /// (Optional) An array of two numbers [t0 t1] specifying the limiting values of a
      /// parametric variable t. The variable is considered to vary linearly between these
      /// two values as the color gradient varies between the starting and ending points of
      /// the axis. The variable t becomes the input argument to the color function(s).
      /// Default value: [0.0 1.0].
      /// </summary>
      [KeyInfo(KeyType.Array | KeyType.Optional)]
      public const string Domain = "/Domain";

      /// <summary>
      /// (Required) A 1-in, n-out function or an array of n 1-in, 1-out functions (where n
      /// is the number of color components in the shading dictionary’s color space). The
      /// function(s) are called with values of the parametric variable t in the domain defined
      /// by the Domain entry. Each function’s domain must be a superset of that of the shading
      /// dictionary. If the value returned by the function for a given color component is out
      /// of range, it is adjusted to the nearest valid value.
      /// </summary>
      [KeyInfo(KeyType.Function | KeyType.Required)]
      public const string Function = "/Function";

      /// <summary>
      /// (Optional) An array of two boolean values specifying whether to extend the shading
      /// beyond the starting and ending points of the axis, respectively.
      /// Default value: [false false].
      /// </summary>
      [KeyInfo(KeyType.Array | KeyType.Optional)]
      public const string Extend = "/Extend";

      /// <summary>
      /// Gets the KeysMeta for these keys.
      /// </summary>
      internal static 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; }
    }
  }
}
