Code:
/ FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / fx / src / CommonUI / System / Drawing / ImageConverter.cs / 1 / ImageConverter.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //----------------------------------------------------------------------------- /* */ namespace System.Drawing { using System.Runtime.Serialization.Formatters; using System.Runtime.InteropServices; using System.IO; using System.Diagnostics; using System.Diagnostics.CodeAnalysis; using Microsoft.Win32; using System.Collections; using System.ComponentModel; using System.Globalization; using System.Reflection; using System.Drawing.Imaging; using System.ComponentModel.Design.Serialization; ////// /// ImageConverter is a class that can be used to convert /// Image from one data type to another. Access this /// class through the TypeDescriptor. /// public class ImageConverter : TypeConverter { Type iconType = typeof(Icon); ////// /// public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType) { if (sourceType == iconType) { return true; } if (sourceType == typeof(byte[])) { return true; } if(sourceType == typeof(InstanceDescriptor)){ return false; } return base.CanConvertFrom(context, sourceType); } ///Gets a value indicating whether this converter can /// convert an object in the given source type to the native type of the converter /// using the context. ////// /// public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType) { if (destinationType == typeof(byte[])) { return true; } return base.CanConvertTo(context, destinationType); } ///Gets a value indicating whether this converter can /// convert an object to the given destination type using the context. ////// /// [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance", "CA1800:DoNotCastUnnecessarily")] public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value) { if (value is Icon) { Icon icon = (Icon) value; return icon.ToBitmap(); } byte[] bytes = value as byte[]; 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); } // hopefully GDI+ knows what to do with this! // return Image.FromStream(memStream); } return base.ConvertFrom(context, culture, value); } ///Converts the given object to the converter's native type. ////// /// Converts the given object to another type. The most common types to convert /// are to and from a string object. The default implementation will make a call /// to ToString on the object if the object is valid and if the destination /// type is string. If this cannot convert to the desitnation type, this will /// throw a NotSupportedException. /// [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance", "CA1800:DoNotCastUnnecessarily")] [SuppressMessage("Microsoft.Reliability", "CA2000:DisposeObjectsBeforeLosingScope")] public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType) { if (destinationType == null) { throw new ArgumentNullException("destinationType"); } if (destinationType == typeof(string)) { if (value != null) { // should do something besides ToString() the image...go get the filename Image image = (Image)value; return image.ToString(); } else { return SR.GetString(SR.toStringNone); } } else if (destinationType == typeof(byte[])) { if (value != null) { bool createdNewImage = false; MemoryStream ms = null; Image image = null; try { ms = new MemoryStream(); image = (Image) value; //We don't want to serialize an icon - since we're not really working with //icons, these are "Images". So, we'll force a new and valid bitmap to be //created around our icon with the ideal size. if (image.RawFormat.Equals(ImageFormat.Icon)) { createdNewImage = true; image = new Bitmap(image, image.Width, image.Height); } image.Save(ms); } finally { if (ms != null) { ms.Close(); } if (createdNewImage && image != null) { image.Dispose(); } } if (ms != null) { return ms.ToArray(); } else { return null; } } else { return new byte[0]; } } 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. /// [SuppressMessage("Microsoft.Performance", "CA1808:AvoidCallsThatBoxValueTypes")] private unsafe Stream GetBitmapStream(byte[] rawData) { Debug.Assert( rawData != null, "rawData is null." ); try { 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, but I found a KB: // // http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q175261 // SafeNativeMethods.OBJECTHEADER pHeader = (SafeNativeMethods.OBJECTHEADER)Marshal.PtrToStructure(addr, typeof(SafeNativeMethods.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; } // okay, 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); } } } } catch (OutOfMemoryException) // this exception may be caused by creating a new MemoryStream { } catch (ArgumentException) // may be caused by Marshal.PtrToStructure { } // nevermind... return null; } ////// /// Retrieves the set of properties for this type. By default, a type has /// does not return any properties. An easy implementation of this method /// can just call TypeDescriptor.GetProperties for the correct data type. /// public override PropertyDescriptorCollection GetProperties(ITypeDescriptorContext context, object value, Attribute[] attributes) { return TypeDescriptor.GetProperties(typeof(Image), attributes); } ////// /// Determines if this object supports properties. By default, this /// is false. /// public override bool GetPropertiesSupported(ITypeDescriptorContext context) { return true; } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
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