fixed a bug of Screenshot on win7

src/Shared/HandyControl_Shared/Data/Enum/ImageCodecFlags.cs

@@ -0,0 +1,18 @@
+using System;
+
+namespace HandyControl.Data
+{
+    [Flags]
+    internal enum ImageCodecFlags
+    {
+        Encoder = 0x00000001,
+        Decoder = 0x00000002,
+        SupportBitmap = 0x00000004,
+        SupportVector = 0x00000008,
+        SeekableEncode = 0x00000010,
+        BlockingDecode = 0x00000020,
+        Builtin = 0x00010000,
+        System = 0x00020000,
+        User = 0x00040000
+    }
+}

src/Shared/HandyControl_Shared/Data/Gif/GPStream.cs

@@ -3,12 +3,12 @@ using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Runtime.InteropServices;
 using System.Security.Permissions;
-using HandyControl.Tools;
+using HandyControl.Tools.Interop;
 
 namespace HandyControl.Data
 {
     // ReSharper disable once InconsistentNaming
-    internal class GPStream : ExternDllHelper.IStream
+    internal class GPStream : InteropValues.IStream
     {
         protected Stream DataStream;
 
@@ -55,7 +55,7 @@ namespace HandyControl.Data
             _virtualPosition = -1;
         }
 
-        public virtual ExternDllHelper.IStream Clone()
+        public virtual InteropValues.IStream Clone()
         {
             NotImplemented();
             return null;
@@ -72,7 +72,7 @@ namespace HandyControl.Data
             UIPermission(SecurityAction.Demand, Window = UIPermissionWindow.AllWindows),
             SecurityPermission(SecurityAction.Assert, Flags = SecurityPermissionFlag.UnmanagedCode)
         ]
-        public virtual long CopyTo(ExternDllHelper.IStream pstm, long cb, long[] pcbRead)
+        public virtual long CopyTo(InteropValues.IStream pstm, long cb, long[] pcbRead)
         {
 
             const int bufsize = 4096;
@@ -117,7 +117,7 @@ namespace HandyControl.Data
 
         protected static ExternalException EFail(string msg)
         {
-            throw new ExternalException(msg, ExternDllHelper.E_FAIL);
+            throw new ExternalException(msg, InteropMethods.E_FAIL);
         }
 
         protected static void NotImplemented()
@@ -154,7 +154,7 @@ namespace HandyControl.Data
             var len = DataStream.Length;
             switch (origin)
             {
-                case ExternDllHelper.StreamConsts.STREAM_SEEK_SET:
+                case InteropValues.StreamConsts.STREAM_SEEK_SET:
                     if (offset <= len)
                     {
                         DataStream.Position = offset;
@@ -165,7 +165,7 @@ namespace HandyControl.Data
                         _virtualPosition = offset;
                     }
                     break;
-                case ExternDllHelper.StreamConsts.STREAM_SEEK_END:
+                case InteropValues.StreamConsts.STREAM_SEEK_END:
                     if (offset <= 0)
                     {
                         DataStream.Position = len + offset;
@@ -176,7 +176,7 @@ namespace HandyControl.Data
                         _virtualPosition = len + offset;
                     }
                     break;
-                case ExternDllHelper.StreamConsts.STREAM_SEEK_CUR:
+                case InteropValues.StreamConsts.STREAM_SEEK_CUR:
                     if (offset + pos <= len)
                     {
                         DataStream.Position = pos + offset;

src/Shared/HandyControl_Shared/Data/Gif/GifPropertyItemInternal.cs

@@ -1,6 +1,6 @@
 using System;
 using System.Runtime.InteropServices;
-using HandyControl.Tools;
+using HandyControl.Tools.Interop;
 
 namespace HandyControl.Data
 {
@@ -85,7 +85,7 @@ namespace HandyControl.Data
                 GifPropertyItemInternal propcopy = null;
                 try
                 {
-                    propcopy = (GifPropertyItemInternal) ExternDllHelper.PtrToStructure(propdata,
+                    propcopy = (GifPropertyItemInternal) InteropMethods.PtrToStructure(propdata,
                         typeof(GifPropertyItemInternal));
 
                     props[i] = new GifPropertyItem

src/Shared/HandyControl_Shared/Data/ImageCodecInfo.cs

@@ -0,0 +1,158 @@
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.InteropServices;
+using HandyControl.Tools.Interop;
+
+namespace HandyControl.Data
+{
+    internal sealed class ImageCodecInfo
+    {
+        private string _dllName;
+
+        public Guid Clsid { get; set; }
+
+        public Guid FormatID { get; set; }
+
+        public string CodecName { get; set; }
+
+        public string DllName
+        {
+            [SuppressMessage("Microsoft.Security", "CA2103:ReviewImperativeSecurity")]
+            get
+            {
+                if (_dllName != null)
+                {
+                    new System.Security.Permissions.FileIOPermission(System.Security.Permissions.FileIOPermissionAccess.PathDiscovery, _dllName).Demand();
+                }
+                return _dllName;
+            }
+            [SuppressMessage("Microsoft.Security", "CA2103:ReviewImperativeSecurity")]
+            set
+            {
+                if (value != null)
+                {
+                    new System.Security.Permissions.FileIOPermission(System.Security.Permissions.FileIOPermissionAccess.PathDiscovery, value).Demand();
+                }
+                _dllName = value;
+            }
+        }
+
+        public string FormatDescription { get; set; }
+
+        public string FilenameExtension { get; set; }
+
+        public string MimeType { get; set; }
+
+        public ImageCodecFlags Flags { get; set; }
+
+        public int Version { get; set; }
+
+        public byte[][] SignaturePatterns { get; set; }
+
+        public byte[][] SignatureMasks { get; set; }
+
+        public static ImageCodecInfo[] GetImageDecoders()
+        {
+            ImageCodecInfo[] imageCodecs;
+
+            var status = InteropMethods.Gdip.GdipGetImageDecodersSize(out var numDecoders, out var size);
+
+            if (status != InteropMethods.Gdip.Ok)
+            {
+                throw InteropMethods.Gdip.StatusException(status);
+            }
+
+            var memory = Marshal.AllocHGlobal(size);
+
+            try
+            {
+                status = InteropMethods.Gdip.GdipGetImageDecoders(numDecoders, size, memory);
+
+                if (status != InteropMethods.Gdip.Ok)
+                {
+                    throw InteropMethods.Gdip.StatusException(status);
+                }
+
+                imageCodecs = ConvertFromMemory(memory, numDecoders);
+            }
+            finally
+            {
+                Marshal.FreeHGlobal(memory);
+            }
+
+            return imageCodecs;
+        }
+
+        public static ImageCodecInfo[] GetImageEncoders()
+        {
+            ImageCodecInfo[] imageCodecs;
+
+            var status = InteropMethods.Gdip.GdipGetImageEncodersSize(out var numEncoders, out var size);
+
+            if (status != InteropMethods.Gdip.Ok)
+            {
+                throw InteropMethods.Gdip.StatusException(status);
+            }
+
+            var memory = Marshal.AllocHGlobal(size);
+
+            try
+            {
+                status = InteropMethods.Gdip.GdipGetImageEncoders(numEncoders, size, memory);
+
+                if (status != InteropMethods.Gdip.Ok)
+                {
+                    throw InteropMethods.Gdip.StatusException(status);
+                }
+
+                imageCodecs = ConvertFromMemory(memory, numEncoders);
+            }
+            finally
+            {
+                Marshal.FreeHGlobal(memory);
+            }
+
+            return imageCodecs;
+        }
+
+        public static ImageCodecInfo[] ConvertFromMemory(IntPtr memoryStart, int numCodecs)
+        {
+            var codecs = new ImageCodecInfo[numCodecs];
+
+            int index;
+
+            for (index = 0; index < numCodecs; index++)
+            {
+                var curcodec = (IntPtr)((long)memoryStart + Marshal.SizeOf(typeof(InteropValues.ImageCodecInfoPrivate)) * index);
+                var codecp = new InteropValues.ImageCodecInfoPrivate();
+                InteropMethods.PtrToStructure(curcodec, codecp);
+
+                codecs[index] = new ImageCodecInfo
+                {
+                    Clsid = codecp.Clsid,
+                    FormatID = codecp.FormatID,
+                    CodecName = Marshal.PtrToStringUni(codecp.CodecName),
+                    DllName = Marshal.PtrToStringUni(codecp.DllName),
+                    FormatDescription = Marshal.PtrToStringUni(codecp.FormatDescription),
+                    FilenameExtension = Marshal.PtrToStringUni(codecp.FilenameExtension),
+                    MimeType = Marshal.PtrToStringUni(codecp.MimeType),
+                    Flags = (ImageCodecFlags) codecp.Flags,
+                    Version = codecp.Version,
+                    SignaturePatterns = new byte[codecp.SigCount][],
+                    SignatureMasks = new byte[codecp.SigCount][]
+                };
+
+                for (var j = 0; j < codecp.SigCount; j++)
+                {
+                    codecs[index].SignaturePatterns[j] = new byte[codecp.SigSize];
+                    codecs[index].SignatureMasks[j] = new byte[codecp.SigSize];
+
+                    Marshal.Copy((IntPtr)((long)codecp.SigMask + j * codecp.SigSize), codecs[index].SignatureMasks[j], 0, codecp.SigSize);
+                    Marshal.Copy((IntPtr)((long)codecp.SigPattern + j * codecp.SigSize), codecs[index].SignaturePatterns[j], 0, codecp.SigSize);
+                }
+            }
+
+            return codecs;
+        }
+    }
+}