NGif, Animated GIF Encoder for .NET

Hi,

Your fix so nearly almost worked! The bottom-right pixel of the resulting animation appears to flicker through a selection of colours. Any ideas on how to fix this?

Edit: I've just also noticed parts of the image becoming transparent which weren't originally transparent. I'm guessing this is something to do with the colour of those parts matching the transparency colour. Does this mean having to write an algorithm to find an unused colour in all frames prior to adding them?

Nope. Still doesn't work. Anyone find a solution to this problem?

hello can you please email me updated bugs free file of this example on my email id ..its arpit@sleexs.com

Thank you in advance

I have use the code on the Net CF 1.0. and Found it does not pharse the gif file well.
When I fixed the follow code, it work well now.
I just modify the function GetPixels in the file GifDecoder
int [] GetPixels( Bitmap bitmap )
{
//int [] pixels = new int [ 3 * image.Width * image.Height ]; //Orginal
int[] pixels = new int[3 * image.Width * image.Height]; //Modified
int count = 0;
for (int th = 0; th < image.Height; th++)
{
for (int tw = 0; tw < image.Width; tw++)
{
Color color = bitmap.GetPixel(tw, th);
// pixels[count] = color.R; //Orginal
// count++; //Orginal
// pixels[count] = color.G;//Orginal
// count++;//Orginal
// pixels[count] = color.B;//Orginal
pixels[count] = color.ToArgb(); //Added
count++;
}
}
return pixels;

Would anyone please confirm it?

Good work. However this line should be
//int[] pixels = new int[3 * image.Width * image.Height]; //Modified
int[] pixels = new int[image.Width * image.Height]; // New Modified

Smile | :)

This WORKED. NICE Job! Smile | :)

I looked all over the NET. This by far is the only good enough solution I see (even in April 2007) -- full 2 years after this article was written.

The only thing I would want to change in this code would be to optimize for speed and size; nothing else!

I have been able to optimize the GifDecoder quiet a bit, but at the expense of compatability. The realy slow code which runs a lot (realy A LOT) of times is the GetPixel() and SetPixel() functions. I have rewritten the code to avoid the use of those, but this have to be done in "usafe" context. This means that you have to compile with the compiler option "unsafe", and that the executable will only run on the processor type you compiled it on (afair). You can just replace the two functions below in the GifDecoder.cs file.
Here is the code for the GetPixels function

int [] GetPixels( Bitmap bitmap )
{
	int [] pixels = new int [ 3 * image.Width * image.Height ];
	int count = 0;
    int tw, th;

    BitmapData data = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.ReadWrite, bitmap.PixelFormat);
    int scanwidth = data.Stride;
    System.IntPtr Scan = data.Scan0;
    int width = bitmap.Width;
    int height = bitmap.Height;

    unsafe
    {
        int offset; // excess pixels at each row, to counter word alignment
        if (bitmap.PixelFormat == PixelFormat.Format32bppArgb ||
            bitmap.PixelFormat == PixelFormat.Format32bppPArgb ||
            bitmap.PixelFormat == PixelFormat.Format32bppRgb)
        {
            offset = scanwidth - bitmap.Width * 4;
        }
        else // assume 24 bits per pixel
            offset = scanwidth - bitmap.Width * 3; 
        int x, y;
        byte colr, colg, colb;
        byte* p = (byte*)(void*)Scan;
        for (y = 0; y < height; y++)
        {
            for (x = 0; x < width; x++)
            {
                pixels[count++] = (int)*(p++);
                pixels[count++] = (int)*(p++);
                pixels[count++] = (int)*(p++);
            }
            p += offset;
        }
    } // End of unsafe
    bitmap.UnlockBits(data);
	return pixels;
}

Here is the code for the SetPixels function

void SetPixels( int [] pixels )
{
	int count = 0;

    BitmapData data = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height),
        ImageLockMode.ReadWrite, bitmap.PixelFormat);
    int scanwidth = data.Stride;
    System.IntPtr Scan = data.Scan0;
    int width = image.Width;
    int height = image.Height;
    unsafe
    {
        bool fourBytePerPixel = false;
        int offset; // excess pixels at each row, to counter word alignment
        if (bitmap.PixelFormat == PixelFormat.Format32bppArgb ||
            bitmap.PixelFormat == PixelFormat.Format32bppPArgb ||
            bitmap.PixelFormat == PixelFormat.Format32bppRgb)
        {
            offset = scanwidth - bitmap.Width * 4;
            fourBytePerPixel = true;
        }
        else // assume 24 bits per pixel
            offset = scanwidth - bitmap.Width * 3;
        int x, y;
        byte* p = (byte*)(void*)Scan;
        Int32 pixeldata;
        for (y = 0; y < height; y++)
        {
            for (x = 0; x < width; x++)
            {
                pixeldata = pixels[count++];

                *(p++) = (byte)(pixeldata);
                *(p++) = (byte)(pixeldata >> 8);
                *(p++) = (byte)(pixeldata >> 16);
                if (fourBytePerPixel)
                    *(p++) = (byte)(pixeldata >> 24);
            }
            p += offset;
        }
    } // End of unsafe
    bitmap.UnlockBits(data);
}

You must have me excused if the code is a bit cluttered, but it should be usefull anyway. Actually I have not gone into details to see whether it is necessary to test for 24 or 32 bit images, as the code might use purly 32 bit images.

- Lothver

Has anyone been able to optimize this code for the encoder?

I have 15 frames which amount to 82kb, however if I use a animated gif application its only 38kb, something isn't right?

modified 19-Aug-21 21:01pm.

Do you mean size optimization such that the resulting GIF file is smaller?

- Lothver

Yeah

I've managed to do it now Smile | :)

modified 19-Aug-21 21:01pm.

Any possibility of sharing your optimisations?

Thanks

Do you know how I can play a gif in a Form?

_____________________________

...and justice for all

APe

http://blog.csdn.net/yefanqiu[^] This is What you want .

Just FYI

This will violate LZW Patent No. 4,558,302 by Unisys.

Compuserve hold copyright on the GIF89a but the compression used for the images internaly is LZW.

Schneider

Schneider

I am no lawyer, but I think the patent expired few years ago...

It did a few YEARS ago Laugh | :laugh:

So png freaks put a cap on it Smile | :)

Feature request number 1 on my pet project, www.foodcandy.com after its launch six months ago was that there're no animated gifs supported on the site. I now have it working! It should go live next week. So many thanks for this code. If someone maintains an open source version I'll be glad to contribute pieces.

dB. - dblock.org

Default loop count should be -1 (don't loop), 1 means loop once (animate twice).

dB. - dblock.org

I think that forcing the GIF to crop is not very nice Smile | :)

Here's a change to resize the GIF frames to whatever the target (or first frame) size is.

<br />
        private static Image GetResizedImage(Image imgPhoto, Size ts)<br />
        {<br />
            // http://www.codeproject.com/csharp/imageresize.asp<br />
<br />
            int sourceWidth = imgPhoto.Width;<br />
            int sourceHeight = imgPhoto.Height;<br />
            int sourceX = 0;<br />
            int sourceY = 0;<br />
            int destX = 0;<br />
            int destY = 0;<br />
<br />
            float nPercent = 0;<br />
            float nPercentW = 0;<br />
            float nPercentH = 0;<br />
<br />
            bool sourceVertical = sourceWidth < sourceHeight;<br />
            bool targetVeritcal = ts.Width < ts.Height;<br />
<br />
            if (sourceVertical != targetVeritcal)<br />
            {<br />
                int t = ts.Width;<br />
                ts.Width = ts.Height;<br />
                ts.Height = t;<br />
            }<br />
<br />
            nPercentW = ((float)ts.Width / (float)sourceWidth);<br />
            nPercentH = ((float)ts.Height / (float)sourceHeight);<br />
            if (nPercentH < nPercentW)<br />
            {<br />
                nPercent = nPercentH;<br />
                destX = System.Convert.ToInt16((ts.Width -<br />
                              (sourceWidth * nPercent)) / 2);<br />
            }<br />
            else<br />
            {<br />
                nPercent = nPercentW;<br />
                destY = System.Convert.ToInt16((ts.Height -<br />
                              (sourceHeight * nPercent)) / 2);<br />
            }<br />
<br />
            int destWidth = (int)(sourceWidth * nPercent);<br />
            int destHeight = (int)(sourceHeight * nPercent);<br />
<br />
            Bitmap bmPhoto = new Bitmap(ts.Width, ts.Height,<br />
                              PixelFormat.Format24bppRgb);<br />
            bmPhoto.SetResolution(imgPhoto.HorizontalResolution,<br />
                             imgPhoto.VerticalResolution);<br />
<br />
            Graphics grPhoto = Graphics.FromImage(bmPhoto);<br />
            grPhoto.Clear(Color.White);<br />
            grPhoto.InterpolationMode =<br />
                    InterpolationMode.HighQualityBicubic;<br />
<br />
            grPhoto.DrawImage(imgPhoto,<br />
                new Rectangle(destX, destY, destWidth, destHeight),<br />
                new Rectangle(sourceX, sourceY, sourceWidth, sourceHeight),<br />
                GraphicsUnit.Pixel);<br />
<br />
            grPhoto.Dispose();<br />
            return bmPhoto;<br />
        }<br />

<br />
        protected void GetImagePixels()<br />
        {<br />
            int w = image.Width;<br />
            int h = image.Height;<br />
            //		int type = image.GetType().;<br />
            if ((w != width)<br />
             || (h != height)<br />
             )<br />
            {<br />
                // create new image with right size/format<br />
                image = GetResizedImage(image, new Size(width, height));<br />
            }<br />
 ....<br />

<br />
        public bool IsTransparent()<br />
        {<br />
            return transparency;<br />
        }<br />
<br />
        public Color GetTransparency()<br />
        {<br />
            Color c = Color.Empty;<br />
            if (transparency)<br />
            {<br />
                c = Color.FromArgb(0, 0, 0, 0); 	// assume background is transparent<br />
            }<br />
            else<br />
            {<br />
                c = Color.FromArgb(lastBgColor);<br />
                //						c = new Color(lastBgColor); // use given background color<br />
            }<br />
            return c;<br />
        }<br />

and finally the whole resize, very simple

<br />
        /*<br />
         * Resize an animated GIF<br />
         */<br />
        public static void Resize(Stream inStream, Stream outStream, int width, int height)<br />
        {<br />
            GifDecoder decoder = new GifDecoder();<br />
            decoder.Read(inStream);<br />
<br />
            AnimatedGifEncoder encoder = new AnimatedGifEncoder();<br />
            encoder.SetSize(width, height);<br />
            encoder.SetFrameRate(5);<br />
            encoder.SetRepeat(decoder.GetLoopCount());<br />
            if (decoder.IsTransparent()) encoder.SetTransparent(decoder.GetTransparency());<br />
            encoder.Start(outStream);<br />
            for (int i = 0; i < decoder.GetFrameCount(); i++)<br />
            {<br />
                encoder.SetDelay(decoder.GetDelay(i));<br />
                encoder.AddFrame(decoder.GetFrame(i));<br />
            }<br />
            encoder.Finish();<br />
            outStream.Flush();<br />
        }<br />

dB. - dblock.org

Access to the path "c:\test.gif" is denied.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.UnauthorizedAccessException: Access to the path "c:\test.gif" is denied.

Line 253: String outputFilePath = "c:\\test.gif"; //Server.MapPath("NameLogoTool/test.gif");
Line 254: AnimatedGifEncoder e = new AnimatedGifEncoder();
Line 255: e.Start(outputFilePath);
Line 256: e.SetDelay(500);
Line 257: //-1:no repeat,0:always repeat

Would you be interested in releasing this as an open source project? I'd be happy to set it up on SourceForge, CodePlex, or Google Code. The code you've posted works well, but it would be nice to extend it:
- allow alternate quantization methode (Octree, etc.)
- include optimizations (unsafe code, image checksums, etc.)
- leverage System.Drawing
- convert to allow use of individual functions by shifting some of the class variables to method parameters

I've already made some of these changes. It would be great to get your go-ahead to release a next version. I saw that the original Java source allowed reuse for any reason, so if I don't hear back I may just start over from the original Java source.

Jon Galloway
http://weblogs.asp.net/jgalloway

[Message Deleted]

Oh, your code do not works.
Well, the follow may works.

private int NextPixel()
{
if (remaining == 0)
return EOF;

--remaining;

if (curPixel <= pixAry.GetUpperBound(0))
return pixAry[curPixel++];
return EOF;
}

Day Day Up

The solution for the problem with LZWEncoder making the last two pixels white is replacing "private int NextPixel()" with:

<br />
<br />
		//----------------------------------------------------------------------------<br />
		// Return the next pixel from the image<br />
		//----------------------------------------------------------------------------<br />
	<br />
		private int NextPixel() <br />
		{<br />
			if (remaining == 0)<br />
				return EOF;<br />
<br />
			--remaining;<br />
<br />
			//int temp = curPixel + 1;<br />
			//if ( temp < pixAry.GetUpperBound( 0 ))<br />
			//{<br />
				byte pix = pixAry[curPixel++];<br />
<br />
				return pix & 0xff;<br />
			//}<br />
			//   return 0xff;<br />
		}<br />
<br />

It is just the java code in the Refs Directory --> Gif.zip ->LZWEncoder.java

I tested it,and it works well~hoho~

NGif, Animated GIF Encoder for .NET

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