|
//------------------------------------------------------------------------------
// Microsoft Avalon
// Copyright (c) Microsoft Corporation, All Rights Reserved.
//
// File: ImageSourceConverter.cs
//
//------------------------------------------------------------------------------
using System;
using System.IO;
using System.Security;
using System.Security.Permissions;
using System.Collections;
using System.Collections.Specialized;
using System.ComponentModel;
using System.ComponentModel.Design.Serialization;
using System.Reflection;
using MS.Internal;
using System.Diagnostics;
using System.Windows.Media;
using System.Globalization;
using System.Runtime.InteropServices;
using System.Windows.Markup;
using MMCF = System.IO.Packaging;
using SR=MS.Internal.PresentationCore.SR;
using SRID=MS.Internal.PresentationCore.SRID;
using System.Windows.Media.Imaging;
#pragma warning disable 1634, 1691 // suppressing PreSharp warnings
namespace System.Windows.Media
{
#region ImageSourceConverter
/// <summary>
/// ImageSourceConverter
/// </summary>
public class ImageSourceConverter : TypeConverter
{
/// <summary>
/// Returns true if this type converter can convert from a given type.
/// </summary>
/// <returns>
/// bool - True if this converter can convert from the provided type, false if not.
/// </returns>
/// <param name="context"> The ITypeDescriptorContext for this call. </param>
/// <param name="sourceType"> The Type being queried for support. </param>
public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
{
if (sourceType == typeof(string) || sourceType == typeof(Stream) || sourceType == typeof(Uri) || sourceType == typeof(byte[]))
{
return true;
}
return base.CanConvertFrom(context, sourceType);
}
/// <summary>
/// Returns true if this type converter can convert to the given type.
/// </summary>
/// <returns>
/// bool - True if this converter can convert to the provided type, false if not.
/// </returns>
/// <param name="context"> The ITypeDescriptorContext for this call. </param>
/// <param name="destinationType"> The Type being queried for support. </param>
public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
{
if (destinationType == typeof(string))
{
// When invoked by the serialization engine we can convert to string only for some instances
if (context != null && context.Instance != null)
{
if (!(context.Instance is ImageSource))
{
throw new ArgumentException(SR.Get(SRID.General_Expected_Type, "ImageSource"), "context");
}
#pragma warning suppress 6506 // context is obviously not null
ImageSource value = (ImageSource)context.Instance;
#pragma warning suppress 6506 // value is obviously not null
return value.CanSerializeToString();
}
return true;
}
return base.CanConvertTo(context, destinationType);
}
/// <summary>
/// Attempts to convert to a ImageSource from the given object.
/// </summary>
/// <returns>
/// The ImageSource which was constructed.
/// </returns>
/// <exception cref="NotSupportedException">
/// A NotSupportedException is thrown if the example object is null or is not a valid type
/// which can be converted to a ImageSource.
/// </exception>
/// <param name="context"> The ITypeDescriptorContext for this call. </param>
/// <param name="culture"> The CultureInfo which is respected when converting. </param>
/// <param name="value"> The object to convert to an instance of ImageSource. </param>
/// <SecurityNote>
/// Critical: Code eventually calls into unsafe code
/// TreatAsASafe: Inputs are verified
/// </SecurityNote>
[SecurityCritical, SecurityTreatAsSafe]
public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
{
try
{
if (value == null)
{
throw GetConvertFromException(value);
}
if (((value is string) && (!string.IsNullOrEmpty((string)value))) || (value is Uri))
{
UriHolder uriHolder = TypeConverterHelper.GetUriFromUriContext(context, value);
return BitmapFrame.CreateFromUriOrStream(
uriHolder.BaseUri,
uriHolder.OriginalUri,
null,
BitmapCreateOptions.None,
BitmapCacheOption.Default,
null
);
}
else if (value is byte[])
{
byte[] bytes = (byte[])value;
if (bytes != null)
{
Stream memStream = null;
//
// this might be a magical OLE thing, try that first.
//
memStream = GetBitmapStream(bytes);
if (memStream == null)
{
//
// guess not. Try plain memory.
//
memStream = new MemoryStream(bytes);
}
return BitmapFrame.Create(
memStream,
BitmapCreateOptions.None,
BitmapCacheOption.Default
);
}
}
else if (value is Stream)
{
Stream stream = (Stream)value;
return BitmapFrame.Create(
stream,
BitmapCreateOptions.None,
BitmapCacheOption.Default
);
}
return base.ConvertFrom(context, culture, value);
}
catch (Exception e)
{
if (!CriticalExceptions.IsCriticalException(e))
{
if (context == null && CoreAppContextSwitches.OverrideExceptionWithNullReferenceException)
{
throw new NullReferenceException();
}
IProvideValueTarget ipvt = context?.GetService(typeof(IProvideValueTarget)) as IProvideValueTarget;
if (ipvt != null)
{
IProvidePropertyFallback ippf = ipvt.TargetObject as IProvidePropertyFallback;
DependencyProperty dp = ipvt.TargetProperty as DependencyProperty;
// We only want to call IPPF.SetValue if the target can handle it.
//
if (ippf != null && dp != null && ippf.CanProvidePropertyFallback(dp.Name))
{
return ippf.ProvidePropertyFallback(dp.Name, e);
}
}
}
// We want to rethrow the exception in the case we can't handle it.
throw;
}
}
/// <summary>
/// ConvertTo - Attempt to convert an instance of ImageSource to the given type
/// </summary>
/// <returns>
/// The object which was constructoed.
/// </returns>
/// <exception cref="NotSupportedException">
/// A NotSupportedException is thrown if "value" is null or not an instance of ImageSource,
/// or if the destinationType isn't one of the valid destination types.
/// </exception>
/// <param name="context"> The ITypeDescriptorContext for this call. </param>
/// <param name="culture"> The CultureInfo which is respected when converting. </param>
/// <param name="value"> The object to convert to an instance of "destinationType". </param>
/// <param name="destinationType"> The type to which this will convert the ImageSource instance. </param>
public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
{
if (destinationType != null && value is ImageSource)
{
ImageSource instance = (ImageSource)value;
if (destinationType == typeof(string))
{
// When invoked by the serialization engine we can convert to string only for some instances
if (context != null && context.Instance != null)
{
#pragma warning disable 6506
if (!instance.CanSerializeToString())
{
throw new NotSupportedException(SR.Get(SRID.Converter_ConvertToNotSupported));
}
#pragma warning restore 6506
}
// Delegate to the formatting/culture-aware ConvertToString method.
return instance.ConvertToString(null, culture);
}
}
// Pass unhandled cases to base class (which will throw exceptions for null value or destinationType.)
return base.ConvertTo(context, culture, value, destinationType);
}
/// Try to get a bitmap out of a byte array. This is an ole format that Access uses.
/// this fails very quickly so we can try this first without a big perf hit.
/// <SecurityNote>
/// Critical - does unmanaged memory manipulation
/// </SecurityNote>
[SecurityCritical]
private unsafe Stream GetBitmapStream(byte[] rawData)
{
Debug.Assert(rawData != null, "rawData is null.");
fixed (byte* pByte = rawData)
{
IntPtr addr = (IntPtr)pByte;
if (addr == IntPtr.Zero)
{
return null;
}
//
// This will be pHeader.signature, but we try to
// do this first so we avoid building the structure when we shouldn't
//
if (Marshal.ReadInt16(addr) != 0x1c15)
{
return null;
}
//
// The data is one of these OBJECTHEADER dudes. It's an encoded format that Access uses to push images
// into the DB. It's not particularly documented, here is a KB:
//
// http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q175261
//
OBJECTHEADER pHeader = (OBJECTHEADER)Marshal.PtrToStructure(addr, typeof(OBJECTHEADER));
//
// "PBrush" should be the 6 chars after position 12 as well.
//
string strPBrush = System.Text.Encoding.ASCII.GetString(rawData, pHeader.headersize + 12, 6);
if (strPBrush != "PBrush")
{
return null;
}
// OK, now we can safely trust that we've got a bitmap.
byte[] searchArray = System.Text.Encoding.ASCII.GetBytes("BM");
//
// Search for "BMP" in the data which is the start of our bitmap data...
//
// 18 is from (12+6) above.
//
for (int i = pHeader.headersize + 18; i < pHeader.headersize + 510; i++)
{
if (searchArray[0] == pByte[i] &&
searchArray[1] == pByte[i+1])
{
//
// found the bitmap data.
//
return new MemoryStream(rawData, i, rawData.Length - i);
}
}
}
return null;
}
//
// For pulling encoded IPictures out of Access Databases
//
[StructLayout(LayoutKind.Sequential)]
private struct OBJECTHEADER {
public short signature; // this looks like it's always 0x1c15
public short headersize; // how big all this goo ends up being. after this is the actual object data.
public short objectType; // we don't care about anything else...they don't seem to be meaningful anyway.
public short nameLen;
public short classLen;
public short nameOffset;
public short classOffset;
public short width;
public short height;
public IntPtr pInfo;
}
}
#endregion // ImageSourceConverter
}
|