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Fixes for loading document from stream #10

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Fixes for loading document from stream #10

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694c02c
Cleaned up parameters for creating a PdfDocument from a stream
avonwyss Jul 28, 2025
a835705
Added optimization in FPDF_FILEREAD to direcly copy data from buffer …
avonwyss Jul 28, 2025
670a3ac
Keep reference to FileReadBlockHandler delegate to prevent it from be…
avonwyss Jul 29, 2025
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5 changes: 2 additions & 3 deletions PDFiumSharp/PDFium.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -122,14 +122,13 @@ public static FPDF_DOCUMENT FPDF_LoadDocument(byte[] data, int index = 0, int co
/// <summary>
/// Loads a PDF document from '<paramref name="count" />' bytes read from a stream.
/// </summary>
/// <param name="fileRead"></param>
/// <param name="count">
/// The number of bytes to read from the <paramref name="stream" />.
/// If the value is equal to or smaller than 0, the stream is read to the end.
/// </param>
/// <param name="stream"></param>
/// <param name="fileRead">The FILEREAD structure ready for reading.</param>
/// <param name="password">Pdf password</param>
public static FPDF_DOCUMENT FPDF_LoadDocument(Stream stream, FPDF_FILEREAD fileRead, int count = 0, string password = null)
public static FPDF_DOCUMENT FPDF_LoadDocument(FPDF_FILEREAD fileRead, string password = null)
=> FPDF_LoadCustomDocument(fileRead, password);

//public static string FPDF_VIEWERREF_GetName(FPDF_DOCUMENT document, string key)
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22 changes: 17 additions & 5 deletions PDFiumSharp/PdfDocument.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,8 @@ public sealed class PdfDocument : NativeWrapper<FPDF_DOCUMENT>
private FPDF_FORMFILLINFO formCallbacks;

private GCHandle formCallbacksHandle;

private FPDF_FILEREAD fileRead;

private FPDF_FORMHANDLE form;

Expand Down Expand Up @@ -138,15 +140,23 @@ public PdfDocument(byte[] data, int index = 0, int count = -1, string password =
/// Loads a <see cref="PdfDocument"/> from '<paramref name="count"/>' bytes read from a <paramref name="stream"/>.
/// <see cref="Close"/> must be called in order to free unmanaged resources.
/// </summary>
/// <param name="stream"></param>
/// <param name="fileRead"></param>
/// <param name="data">Stream containing the bytes of the PDF document to load. Must remain open and accessible as long as the document is being used.</param>
/// <param name="count">
/// The number of bytes to read from the <paramref name="stream"/>.
/// If the value is equal to or smaller than 0, the stream is read to the end.
/// </param>
/// <param name="password"></param>
public PdfDocument(Stream stream, FPDF_FILEREAD fileRead, int count = 0, string password = null)
: this(PDFium.FPDF_LoadDocument(stream, fileRead, count, password)) { }
/// <param name="password">Password.</param>
public PdfDocument(Stream stream, int count = 0, string password = null)
: this(FPDF_FILEREAD.FromStream(stream, count), password) { }

/// <summary>
/// Private overload which keeps the FILEREAD reference so that the delegate and its callback stub remain valid for the lifetime of the document.
/// </summary>
private PdfDocument(FPDF_FILEREAD fileRead, string password)
: this(PDFium.FPDF_LoadDocument(fileRead, password))
{
this.fileRead = fileRead;
}

/// <summary>
/// Closes the <see cref="PdfDocument"/> and frees unmanaged resources.
Expand Down Expand Up @@ -209,6 +219,8 @@ protected override void Dispose(FPDF_DOCUMENT handle)

((IDisposable)this.Pages).Dispose();
PDFium.FPDF_CloseDocument(handle);

this.fileRead = null;
}
}
}
51 changes: 37 additions & 14 deletions PDFiumSharp/Types/FPDF_FILEACCESS.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,9 +12,9 @@
namespace PDFiumSharp.Types
{
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate bool FileReadBlockHandler(IntPtr ignore, int position, IntPtr buffer, int size);
public delegate bool FileReadBlockHandler(IntPtr param, int position, IntPtr buffer, int size);
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate bool FileWriteBlockHandler(IntPtr ignore, IntPtr data, int size);
public delegate bool FileWriteBlockHandler(IntPtr self, IntPtr data, int size);

[StructLayout(LayoutKind.Sequential)]
public class FPDF_FILEREAD
Expand All @@ -26,29 +26,52 @@ public class FPDF_FILEREAD

readonly IntPtr _param;

public FPDF_FILEREAD(int fileLength, FileReadBlockHandler readBlock)
public FPDF_FILEREAD(int fileLength, FileReadBlockHandler readBlock, IntPtr param = default)
{
_fileLength = fileLength;
_readBlock = readBlock;
_param = IntPtr.Zero;
_param = param;
}

public static FPDF_FILEREAD FromStream(Stream stream, int count = 0)
{
if (count <= 0)
count = (int)(stream.Length - stream.Position);
var start = stream.Position;

var memoryStream = stream as MemoryStream;
if (memoryStream != null) {
try {
memoryStream.GetBuffer();
} catch (UnauthorizedAccessException) {
// Buffer is not public, and thus not directly usable
memoryStream = null;
}
}

byte[] data = null;
FPDF_FILEREAD fileRead = new FPDF_FILEREAD(count, (ignore, position, buffer, size) =>
{
stream.Position = start + position;
if (data == null || data.Length < size)
data = new byte[size];
if (stream.Read(data, 0, size) != size)
return false;
Marshal.Copy(data, 0, buffer, size);
return true;
});
FPDF_FILEREAD fileRead = memoryStream != null
? new FPDF_FILEREAD(count, (_, position, buffer, size) =>
{
if (position < 0 || size <= 0 || start+position+size > memoryStream.Length)
return false;
var streamBuffer = memoryStream.GetBuffer();
Marshal.Copy(streamBuffer, (int)start+position, buffer, size);
return true;
})
: new FPDF_FILEREAD(count, (_, position, buffer, size) =>
{
if (position < 0 || size <= 0)
return false;
stream.Seek(start + position, SeekOrigin.Begin);
if (data == null || data.Length < size)
data = new byte[size];
if (stream.Read(data, 0, size) != size)
return false;

Marshal.Copy(data, 0, buffer, size);
return true;
});
return fileRead;
}
}
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