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ImageLineHelper?.cs in methods ToARGB8(int, int, bool) and ToARGB8(byte, int, 
bool): The expressions with and without the alpha channel seems to be 
exchanged, so it doesn't return the alpha channel for alpha channel images and 
give IndexOutOfRangeException? for non-alpha images when you try to get the 
last pixel of the line.

Reported in comments
https://code.google.com/p/pngcs/wiki/Comments

What steps will reproduce the problem?

On the image attached, the transparency is not detected in an Unity 3.5 
application (compiled with Mono-Develop Unity on MacOSX 10.7.5 or with Visual 
Studio on Windows 7).
The transparency is not detected either when building and running the 
MainProgram.cs provided with the revision pngcs-25ae2a736db5 on Windows7, the 
output images don't have transparency.

What is the expected output? What do you see instead?
expected : Images with transparency
what I get : the correct images without transparency (alpha channel replaced 
with white color)

What version of the product are you using? On what operating system?
pngcs-25ae2a736db5, MacOS 10.7.5 & Windows7

see attached images (original and outputs)

Would it be possible to replace the SharpZipLib source with source from 
DotNetZipLib so that this software can be licensed under the MIT or Apache 
license? GPL for a library makes it pretty much useless in the .NET world... 

I'd love to use this library, but I need LGPL or better to make it work, since 
I release under the MIT license.

Would it be possible to access directly the bytes part of one or multiple 
chunks such as IDAT? I can't find any example about obtaining PNG DATA without 
inflating process applied.

I find your library very useful, but I need some example and/or guidance about 
this topic. A workaround would also suffice in this case.

Thank you in advance for your suggestions.

Best regards.

Tez.

A new build should be done for WinRT.

Hello,

I've tried to build Pngcs with MonoDevelop on Linux.

Got a bunch of errors like: "Type of conditional expression cannot be 
determined as 'byte' and 'int' convert implicitly to each other".

It is the same problem as discussed at 
http://stackoverflow.com/questions/5524968/type-of-conditional-expression-cannot
-be-determined-as

There are just a few lines to be fixed, I've attached the patch.

---
WBR,
Andrey

Migrate javadocs ( http://goo.gl/KqHs2 ), write wikis, and samples

This is not a defect but an enhancement request.

While using the library I realized that a function to set 16bpp grayscale 
pixels is not available and the existing SetPixel() functions in 
ImageLineHelper.cs are based on an RGB model. So it doesn't work to use these 
with the same values for r,g, and b.

So I wrote my own and would kindly ask to add this to the code stack after a 
review by the gurus of this library.

My code is:

public static void SetPixel16bppGray(ImageLine line, int col, int gray)
{
    int offset = col * line.channels;
    if (line.IsInt())
    {
        line.Scanline[offset] = gray;
    }
    else
    {
        line.ScanlineB[offset++] = (byte)gray;
        line.ScanlineB[offset] = (byte)(gray >> 8);
    }
}

I hope this contribution is valuable.
Keep up the good work!

kr
Michael

What steps will reproduce the problem?
1. add Pngcs45.dll to project
2. add reference to pngcs45.dll
3. implement library in code and start the program

What is the expected output? What do you see instead?
You will always get an exception, like:
"System.IO.FileNotFoundException?: The file or Assembly "Pngcs, 
Version=1.1.4.1, Culture=neutral, PublicKeyToken?=null" has not been found."

What version of the product are you using? On what operating system?
.NET 4.5 application, Visual Studio 2013

Please provide any additional information below.
The (simple) solution is to rename the library-file to pngcs.dll, after that 
you may have to re-add the reference (or do so before adding) and the 
application is running as expected and the library can be used.

Please change this in a future release and rename the file in the provided 
archive.
Otherwise, very well done!

Thanks

【problem 1】
PngChunkTEXT.ParseFromRaw(ChunkRaw c) throws a exception, because the length of 
String[] k is 1,
where k[0] is "Software\\0Adobe....".

I modified the code, and it works well:

// Updated by Jerin@2012-11-28
//String[] k = 
Hjg.Pngcs.PngHelperInternal.charsetLatin1.GetString(c.Data).Split(new char[] { 
'\0' });
String[] k = Hjg.Pngcs.PngHelperInternal.charsetLatin1.GetString( c.Data 
).Split( new string[] { @"\0" }, StringSplitOptions.None );


【problem 2】
My scenario is to add/read a custom metadata of png.

I browsed samples of the project but found no way to read chunks only -- 
SampleCustomChunk/Program.cs/testRead(String file) gives an advice: call 
pngr.GetRow(pngr.ImgInfo.Rows - 1) first.

so i add a public method in PngReader class:

public void ReadChunksOnly() {
  if ( FirstChunksNotYetRead() )
    ReadFirstChunks();
  ReadLastChunks();
}




Thanks for your work very much!

By view point of parallelism, sometimes we access .png files by multiple 
threads simultaneously. Current pngcs implementation prevents things from 
working properly because OpenFileForReading method in FileHelper performs 
Read/Write (calling FileStream(String, FileMode) constructor without passing 
third argument; FileAccess, result in R/W access) and perform locks on files.

So, I propose applying the following patch on FileHelper.cs

-            isx = new FileStream(file, FileMode.Open);
+            isx = new FileStream(file, FileMode.Open, FileAccess.Read);