|
//------------------------------------------------------------------------------
// <copyright file="GPStream.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Drawing.Internal {
using System;
using System.IO;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Diagnostics.CodeAnalysis;
using System.Security.Permissions;
internal class GPStream : UnsafeNativeMethods.IStream {
protected Stream dataStream;
// to support seeking ahead of the stream length...
long virtualPosition = -1;
internal GPStream(Stream stream) {
if (!stream.CanSeek) {
const int ReadBlock = 256;
byte[] bytes = new byte[ReadBlock];
int readLen;
int current = 0;
do {
if (bytes.Length < current + ReadBlock) {
byte[] newData = new byte[bytes.Length * 2];
Array.Copy(bytes, newData, bytes.Length);
bytes = newData;
}
readLen = stream.Read(bytes, current, ReadBlock);
current += readLen;
} while (readLen != 0);
dataStream = new MemoryStream(bytes);
}
else {
dataStream = stream;
}
}
private void ActualizeVirtualPosition() {
if (virtualPosition == -1) return;
if (virtualPosition > dataStream.Length)
dataStream.SetLength(virtualPosition);
dataStream.Position = virtualPosition;
virtualPosition = -1;
}
public virtual UnsafeNativeMethods.IStream Clone() {
NotImplemented();
return null;
}
public virtual void Commit(int grfCommitFlags) {
dataStream.Flush();
// Extend the length of the file if needed.
ActualizeVirtualPosition();
}
[
UIPermission(SecurityAction.Demand, Window=UIPermissionWindow.AllWindows),
SecurityPermission(SecurityAction.Assert, Flags=SecurityPermissionFlag.UnmanagedCode)
]
public virtual long CopyTo(UnsafeNativeMethods.IStream pstm, long cb, long[] pcbRead) {
int bufsize = 4096; // one page
IntPtr buffer = Marshal.AllocHGlobal(bufsize);
if (buffer == IntPtr.Zero) throw new OutOfMemoryException();
long written = 0;
try {
while (written < cb) {
int toRead = bufsize;
if (written + toRead > cb) toRead = (int) (cb - written);
int read = Read(buffer, toRead);
if (read == 0) break;
if (pstm.Write(buffer, read) != read) {
throw EFail("Wrote an incorrect number of bytes");
}
written += read;
}
}
finally {
Marshal.FreeHGlobal(buffer);
}
if (pcbRead != null && pcbRead.Length > 0) {
pcbRead[0] = written;
}
return written;
}
public virtual Stream GetDataStream() {
return dataStream;
}
public virtual void LockRegion(long libOffset, long cb, int dwLockType) {
}
protected static ExternalException EFail(string msg) {
throw new ExternalException(msg, SafeNativeMethods.E_FAIL);
}
protected static void NotImplemented() {
throw new ExternalException(SR.GetString(SR.NotImplemented), SafeNativeMethods.E_NOTIMPL);
}
public virtual int Read(IntPtr buf, /* cpr: int offset,*/ int length) {
// System.Text.Out.WriteLine("IStream::Read(" + length + ")");
byte[] buffer = new byte[length];
int count = Read(buffer, length);
Marshal.Copy(buffer, 0, buf, length);
return count;
}
public virtual int Read(byte[] buffer, /* cpr: int offset,*/ int length) {
ActualizeVirtualPosition();
return dataStream.Read(buffer, 0, length);
}
public virtual void Revert() {
NotImplemented();
}
public virtual long Seek(long offset, int origin) {
// Console.WriteLine("IStream::Seek("+ offset + ", " + origin + ")");
long pos = virtualPosition;
if (virtualPosition == -1) {
pos = dataStream.Position;
}
long len = dataStream.Length;
switch (origin) {
case SafeNativeMethods.StreamConsts.STREAM_SEEK_SET:
if (offset <= len) {
dataStream.Position = offset;
virtualPosition = -1;
}
else {
virtualPosition = offset;
}
break;
case SafeNativeMethods.StreamConsts.STREAM_SEEK_END:
if (offset <= 0) {
dataStream.Position = len + offset;
virtualPosition = -1;
}
else {
virtualPosition = len + offset;
}
break;
case SafeNativeMethods.StreamConsts.STREAM_SEEK_CUR:
if (offset+pos <= len) {
dataStream.Position = pos + offset;
virtualPosition = -1;
}
else {
virtualPosition = offset + pos;
}
break;
}
if (virtualPosition != -1) {
return virtualPosition;
}
else {
return dataStream.Position;
}
}
public virtual void SetSize(long value) {
dataStream.SetLength(value);
}
public void Stat(IntPtr pstatstg, int grfStatFlag) {
STATSTG stats = new STATSTG();
stats.cbSize = dataStream.Length;
Marshal.StructureToPtr(stats, pstatstg, true);
}
public virtual void UnlockRegion(long libOffset, long cb, int dwLockType) {
}
public virtual int Write(IntPtr buf, /* cpr: int offset,*/ int length) {
byte[] buffer = new byte[length];
Marshal.Copy(buf, buffer, 0, length);
return Write(buffer, length);
}
public virtual int Write(byte[] buffer, /* cpr: int offset,*/ int length) {
ActualizeVirtualPosition();
dataStream.Write(buffer, 0, length);
return length;
}
[StructLayout(LayoutKind.Sequential)]
public class STATSTG {
[SuppressMessage("Microsoft.Reliability", "CA2006:UseSafeHandleToEncapsulateNativeResources")]
public IntPtr pwcsName = IntPtr.Zero;
public int type;
[MarshalAs(UnmanagedType.I8)]
public long cbSize;
[MarshalAs(UnmanagedType.I8)]
public long mtime;
[MarshalAs(UnmanagedType.I8)]
public long ctime;
[MarshalAs(UnmanagedType.I8)]
public long atime;
[MarshalAs(UnmanagedType.I4)]
public int grfMode;
[MarshalAs(UnmanagedType.I4)]
public int grfLocksSupported;
public int clsid_data1;
[MarshalAs(UnmanagedType.I2)]
public short clsid_data2;
[MarshalAs(UnmanagedType.I2)]
public short clsid_data3;
[MarshalAs(UnmanagedType.U1)]
public byte clsid_b0;
[MarshalAs(UnmanagedType.U1)]
public byte clsid_b1;
[MarshalAs(UnmanagedType.U1)]
public byte clsid_b2;
[MarshalAs(UnmanagedType.U1)]
public byte clsid_b3;
[MarshalAs(UnmanagedType.U1)]
public byte clsid_b4;
[MarshalAs(UnmanagedType.U1)]
public byte clsid_b5;
[MarshalAs(UnmanagedType.U1)]
public byte clsid_b6;
[MarshalAs(UnmanagedType.U1)]
public byte clsid_b7;
[MarshalAs(UnmanagedType.I4)]
public int grfStateBits;
[MarshalAs(UnmanagedType.I4)]
public int reserved;
}
}
}
|