mcs/class/System.Drawing/System.Drawing.Imaging/EncoderParameters.cs

   1 //
   2 // System.Drawing.Imaging.EncoderParameters.cs
   3 //
   4 // Author:
   5 //      Ravindra (rkumar@novell.com)
   6 //  Vladimir Vukicevic (vladimir@pobox.com)
   7 //
   8 // (C) 2004 Novell, Inc.  http://www.novell.com
   9 //
  10
  11 //
  12 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  13 //
  14 // Permission is hereby granted, free of charge, to any person obtaining
  15 // a copy of this software and associated documentation files (the
  16 // "Software"), to deal in the Software without restriction, including
  17 // without limitation the rights to use, copy, modify, merge, publish,
  18 // distribute, sublicense, and/or sell copies of the Software, and to
  19 // permit persons to whom the Software is furnished to do so, subject to
  20 // the following conditions:
  21 //
  22 // The above copyright notice and this permission notice shall be
  23 // included in all copies or substantial portions of the Software.
  24 //
  25 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  26 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  27 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  28 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  29 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  30 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  31 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  32 //
  33
  34 using System;
  35 using System.Runtime.InteropServices;
  36
  37 namespace System.Drawing.Imaging
  38 {
  39         public sealed class EncoderParameters : IDisposable
  40         {
  41                 private EncoderParameter[] parameters;
  42
  43                 public EncoderParameters () {
  44                         parameters = new EncoderParameter[1];
  45                 }
  46
  47                 public EncoderParameters (int count) {
  48                         parameters = new EncoderParameter[count];
  49                 }
  50
  51                 public EncoderParameter[] Param {
  52                         get {
  53                                 return parameters;
  54                         }
  55
  56                         set {
  57                                 parameters = value;
  58                         }
  59                 }
  60
  61                 public void Dispose () {
  62                         // Nothing
  63                 }
  64
  65                 internal IntPtr ToNativePtr () {
  66                         IntPtr result;
  67                         IntPtr ptr;
  68
  69                         // 4 is the initial int32 "count" value
  70                         result = Marshal.AllocHGlobal (4 + parameters.Length * EncoderParameter.NativeSize());
  71
  72                         ptr = result;
  73                         Marshal.WriteInt32 (ptr, parameters.Length);
  74
  75                         ptr = (IntPtr) ((int) ptr + 4);
  76                         for (int i = 0; i < parameters.Length; i++) {
  77                                 parameters[i].ToNativePtr (ptr);
  78                                 ptr = (IntPtr) ((int) ptr + EncoderParameter.NativeSize());
  79                         }
  80
  81                         return result;
  82                 }
  83
  84                 /* The IntPtr passed in here is a blob returned from
  85                  * GdipImageGetEncoderParameterList.  Its internal pointers
  86                  * (i.e. the Value pointers in the EncoderParameter entries)
  87                  * point to areas within this block of memeory; this means
  88                  * that we need to free it as a whole, and also means that
  89                  * we can't Marshal.PtrToStruct our way to victory.
  90                  */
  91                 internal static EncoderParameters FromNativePtr (IntPtr epPtr) {
  92                         if (epPtr == IntPtr.Zero)
  93                                 return null;
  94
  95                         IntPtr ptr = epPtr;
  96
  97                         int count = Marshal.ReadInt32 (ptr);
  98                         ptr = (IntPtr) ((int) ptr + 4);
  99
 100                         if (count == 0)
 101                                 return null;
 102
 103                         EncoderParameters result = new EncoderParameters (count);
 104
 105                         for (int i = 0; i < count; i++) {
 106                                 result.parameters[i] = EncoderParameter.FromNativePtr (ptr);
 107                                 ptr = (IntPtr) ((int) ptr + EncoderParameter.NativeSize());
 108                         }
 109
 110                         return result;
 111                 }
 112         }
 113 }