Help reading blp file on c#

[Trigger.edge]

Hello guys.

I'm looking for a library (dll) or command-line tool to convert blp images into tga/png/jpg and vice versa.

What do you recommend me?

 

[GhostWolf]

I don't believe any command-line tools exist, but you can ask DSG to make one - Imperial BLP.

Note that if what you are really looking for is batch conversion, BLP Lab supports it.

If you want to actually use BLP textures, parsing them is fairly simple!

 

[Dr Super Good]

Currently there are no C++ (can be integrated into C#) libraries which correctly parse blp0/1. I do plan on making one eventually but unfortunately I have too many projects at the moment to consider.

I could create a simple Java (jar) program that could be run from the command line to convert BLP0/1 files into tga or png files. I would not advise conversion directly to jpg due to the losy nature of jpg, at least in its most common form.

 

[Trigger.edge]

Thanks guys, I'm using PitzerMike's blpaletter, although it makes me a bit complicated since I have to adapt some of its functions.

 

[TriggerHappy]

I can probably make something for you when I have time.

You can try porting my PHP-BLP library to C# yourself if you like.

 

[Trigger.edge]

Well, since blpaletter does not support read images with alpha channels, I will try to use your library.

Although it would be helpful if you convert it to c#

 

[Dr Super Good]

Thanks guys, I'm using PitzerMike's blpaletter, although it makes me a bit complicated since I have to adapt some of its functions.

That library seems wrong. For example it is not correctly parsing the alphaBits and hasMipmaps fields.

Here is an implementation for Java ImageIO framework which can also be used as a reference.

 

[PurgeandFire]

@Shadow Daemon gave me a command-line version of BLPLab a few years ago. Here it is, help is in blplabcl.txt:

 

[Dr Super Good]

Worth noting that BLP Lab's BLP library is incorrect. It will work for most common textures, but it is not complaint with Warcraft III.

 

[Trigger.edge]

@Shadow Daemon gave me a command-line version of BLPLab a few years ago. Here it is, help is in blplabcl.txt:

My antivirus will not let me use blplabcl.exe

That library seems wrong. For example it is not correctly parsing the alphaBits and hasMipmaps fields.

Here is an implementation for Java ImageIO framework which can also be used as a reference.

With this code I am able to read the Blp header, however I do not know how to read the image data :/

public BlpFile(Stream stream)
        {
            str = stream;
            byte[] buffer = new byte[4];

            str.Read(buffer, 0, 4);


            //Prints BLP type
            DebugMsg(Encoding.ASCII.GetString(buffer, 0, 4));


            // Reading compression
            str.Read(buffer, 0, 4);
            uint compression = BitConverter.ToUInt32(buffer, 0);

            DebugMsg(compression.ToString());
           
            // Reading encoding, alphaBitDepth, alphaEncoding and hasMipmaps
            str.Read(buffer, 0, 4);

            encoding = buffer[0];
            alphaDepth = buffer[1];
            alphaEncoding = buffer[2];
            hasMipmaps = buffer[3];

            // Reading width
            str.Read(buffer, 0, 4);
            width = BitConverter.ToInt32(buffer, 0);

            DebugMsg(width.ToString());

            // Reading height
            str.Read(buffer, 0, 4);
            height = BitConverter.ToInt32(buffer, 0);

            DebugMsg(height.ToString());
           
            // Reading MipmapOffset Array
            for (int i = 0; i < 16; i++)
            {
                str.Read(buffer, 0, 4);
                mipmapOffsets[i] = BitConverter.ToUInt32(buffer, 0);
            }

            // Reading MipmapSize Array
            for (int i = 0; i < 16; i++)
            {
                str.Read(buffer, 0, 4);
                mippmapSize[i] = BitConverter.ToUInt32(buffer, 0);
            }

            // When encoding is 1, there is no image compression and we have to read a color palette
            if (encoding == 1)
            {
                // Reading palette
                for (int i = 0; i < 256; i++)
                {
                    byte[] color = new byte[4];
                    str.Read(color, 0, 4);
                    paletteBGRA[i].blue = color[0];
                    paletteBGRA[i].green = color[1];
                    paletteBGRA[i].red = color[2];
                    paletteBGRA[i].alpha = color[3];
                }
            }
        }

 

[Dr Super Good]

With this code I am able to read the Blp header, however I do not know how to read the image data :/

That seems to be the header for BLP2 (World of Warcraft) and not BLP1 (Warcraft III).

There are a ton of C++ implementations for reading BLP2. However my Java, and possibly GhostWolf's JavaScrpt are the only BLP1 libraries to correctly read the format. TriggerHappy's PHP mostly reads BLP1, but appears to be lacking decoding logic for index content with 1 and 4 bit alpha packing.

 

[Trigger.edge]

Well I have "fixed" the code based on magos blp format specification, does anyone have an idea that I am doing wrong here?

        public static void DebugMsg(string msg)
        {
            MessageBox.Show(msg, "", MessageBoxButtons.OK, MessageBoxIcon.Warning);
        }

        public string ReadString(byte[] buffer, int count)
        {
            str.Read(buffer, 0, count);
            return Encoding.ASCII.GetString(buffer, 0, 4);
        }

        public bool ReadBool(byte[] buffer, int count)
        {
            str.Read(buffer, 0, count);
            return BitConverter.ToBoolean(buffer, 0);
        }

        public uint ReadUInt32(byte[] buffer, int count)
        {
            str.Read(buffer, 0, count);
            return BitConverter.ToUInt32(buffer, 0);
        }

        public int ReadInt32(byte[] buffer, int count)
        {
            str.Read(buffer, 0, count);
            return BitConverter.ToInt32(buffer, 0);
        }

        public BlpFile(Stream stream)
        {
            str = stream;
            byte[] buffer = new byte[4];

            type = ReadString(buffer, 4);
            compression = ReadUInt32(buffer, 4);
            alphaFlags = ReadUInt32(buffer, 4);
            width = ReadUInt32(buffer, 4);
            height = ReadUInt32(buffer, 4);
            alphaEncoding = ReadUInt32(buffer, 4);
         
            //read unused flags
            hasMipmaps = ReadBool(buffer, 4);

            for (int i = 0; i < 16; i++)
                mipmapOffset[i] = ReadUInt32(buffer, 4);
            for (int i = 0; i < 16; i++)
                mipmapSize[i] = ReadUInt32(buffer, 4);

            while (mipmapOffset[mipmapCount] != 0 && mipmapSize[mipmapCount] != 0)
                mipmapCount++;

            if (0 == compression)
            {
                jpegHeaderSize = ReadUInt32(buffer, 4);

                jpegHeader = new byte[jpegHeaderSize];
                str.Read(jpegHeader, 0, Convert.ToInt32(jpegHeaderSize));

                if (type == "BLP1")
                {
                    imageData = new byte[mipmapSize[0]];
                    str.Position = mipmapOffset[0];
                    str.Read(imageData, 0, imageData.Length);


                    //My problem begins here for blp compressed:
                    int w = Convert.ToInt32(width);
                    int h = Convert.ToInt32(height);

                    bitmap = new Bitmap(w, h);
                    BitmapData bmpdata = bitmap.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb);
                    Marshal.Copy(imageData, 0, bmpdata.Scan0, imageData.Length);
                    bitmap.UnlockBits(bmpdata);
                }
            }
            else if (1 == compression)
            {
                // Reading palette

                for (int i = 0; i < 256; i++)
                {
                    Palette[i].blue = ReadInt32(buffer, 4);
                    Palette[i].green = ReadInt32(buffer, 4);
                    Palette[i].red = ReadInt32(buffer, 4);
                    Palette[i].alpha = ReadInt32(buffer, 4);
                }

                int[] indexList = new int[width * height];
                int[] alphaList = new int[width * height];

                for (int i = 0; i < width * height; i++)
                    indexList[i] = ReadInt32(buffer, 4);

                if (alphaFlags == 8)
                {
                    for (int i = 0; i < width * height; i++)
                        alphaList[i] = ReadInt32(buffer, 4);
                }

                // Whats Next?

            }

 

[TriggerHappy]

JPEG-BLP's are basically a JPEG image (technically multiple, with mipmaps) with a BLP header. For those you can just read the first mipmap and merge it with the JPEG header. The only issue is that the colorspace may be BGR (you want RGB), so you will have to figure out how to convert it from there. PHP-BLP uses a tool called imagemagick, and I think there is a windows binary you can use, but there may be a better way with a native C# library.

For palleted BLP's you need a way to dynamically create an image and fill it up with the correct colors.

You may want to use DSG's BLP spec:

BLP Specifications (WC3)

 

[Dr Super Good]

does anyone have an idea that I am doing wrong here?

Mipmap count is based on the hasMipmaps. If not 0 then a full set of mipmaps (ending at 1*1) is present, otherwise only the full scale image is present.

JPEG content BLPs are literally JPEG image files. This means they have their own height and width. One must use the mipmap height and width to resize the decoded JPEG image appropriately.

Indexed colour BLP files have a header consisting of 256 BGR colour entries, each entry being 4 bytes with 1 of these being unused (no alpha).