How to resize gif which is stored in bitmap?

An animated GIF contains multiple image frames for the animation. To resize it correctly, you will need to resize each of these frames and store them correctly to maintain the animation.

One way to do this is through the LEADTOOLS imaging toolkit(https://www.leadtools.com/downloads?category=main), which has classes for animating GIF images. The code will look like this:

Stream imageStream = File.OpenRead("InputGIFImage.gif");
int targetWidth = 955;
var codec = new RasterCodecs();
codec.Options.Load.AllPages = true;
codec.ThrowExceptionsOnInvalidImages = true;
RasterImage image = codec.Load(imageStream);
var scale = 1.0 * targetWidth / image.Width;
int resizeHeight = (int)Math.Round(scale * image.Height);
int counter = 0;
RasterImage newGif = null;
RasterImage targetImage = new RasterImage(RasterMemoryFlags.Conventional,
image.AnimationGlobalSize.Width,
image.AnimationGlobalSize.Height,
image.BitsPerPixel,
image.Order,
image.ViewPerspective,
null,
IntPtr.Zero,
0);
RasterImageAnimator animator = new RasterImageAnimator(targetImage, image);
RasterImageAnimatorState state;
do
{
state = animator.Process();
switch (state)
{
case RasterImageAnimatorState.WaitDelay:
case RasterImageAnimatorState.WaitInputDelay:
case RasterImageAnimatorState.Render:
// Continue processing
break;
case RasterImageAnimatorState.WaitInput:
// In case the animated image has the "wait for user input" flags,
// cancel the waiting
animator.CancelWait();
break;
case RasterImageAnimatorState.PostClear:
case RasterImageAnimatorState.PostRender:
RasterImage resizedPage = RasterImage.Create(targetWidth, resizeHeight, 8, image.XResolution, RasterColor.White);
ResizeCommand resize = new ResizeCommand(resizedPage, RasterSizeFlags.Resample);
targetImage.CopyPaletteTo(resizedPage);
resize.Run(targetImage);
if (counter == 0)
counter = 0; //skip, do nothing
else if (counter == 1)
newGif = resizedPage.Clone();
else
newGif.AddPage(resizedPage);
counter++;
Console.Write(".. " + counter.ToString());
break;
default:
break;
}
}
while (state != RasterImageAnimatorState.End);
var fileName = Path.Combine("OutputGIFImage.gif");
codec.Save(newGif, fileName, RasterImageFormat.Gif, 8);
Console.WriteLine("output file was written " + fileName);
Console.ReadKey();
animator.Dispose();
targetImage.Dispose();

4 Replies

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Hussam Barouqa8y ago
An animated GIF contains multiple image frames for the animation. To resize it correctly, you will need to resize each of these frames and store them correctly to maintain the animation.

One way to do this is through the LEADTOOLS imaging toolkit(https://www.leadtools.com/downloads?category=main), which has classes for animating GIF images. The code will look like this:
Stream imageStream = File.OpenRead("InputGIFImage.gif");

int targetWidth = 955;



var codec = new RasterCodecs();

codec.Options.Load.AllPages = true;

codec.ThrowExceptionsOnInvalidImages = true;

RasterImage image = codec.Load(imageStream);

var scale = 1.0 * targetWidth / image.Width;

int resizeHeight = (int)Math.Round(scale * image.Height);

int counter = 0;

RasterImage newGif = null;

RasterImage targetImage = new RasterImage(RasterMemoryFlags.Conventional,

                     image.AnimationGlobalSize.Width,

                     image.AnimationGlobalSize.Height,

                     image.BitsPerPixel,

                     image.Order,

                     image.ViewPerspective,

                     null,

                     IntPtr.Zero,

                     0);

RasterImageAnimator animator = new RasterImageAnimator(targetImage, image);

RasterImageAnimatorState state;

do

{

   state = animator.Process();

   switch (state)

   {

      case RasterImageAnimatorState.WaitDelay:

      case RasterImageAnimatorState.WaitInputDelay:

      case RasterImageAnimatorState.Render:

         // Continue processing

         break;

      case RasterImageAnimatorState.WaitInput:

         // In case the animated image has the "wait for user input" flags,

         // cancel the waiting

         animator.CancelWait();

         break;

      case RasterImageAnimatorState.PostClear:

      case RasterImageAnimatorState.PostRender:

         RasterImage resizedPage = RasterImage.Create(targetWidth, resizeHeight, 8, image.XResolution, RasterColor.White);

         ResizeCommand resize = new ResizeCommand(resizedPage, RasterSizeFlags.Resample);

         targetImage.CopyPaletteTo(resizedPage);

         resize.Run(targetImage);

         if (counter == 0)

            counter = 0; //skip, do nothing

         else if (counter == 1)

            newGif = resizedPage.Clone();

         else

            newGif.AddPage(resizedPage);

         counter++;

         Console.Write(".. " + counter.ToString());

         break;

      default:

         break;

   }

}

while (state != RasterImageAnimatorState.End);

var fileName = Path.Combine("OutputGIFImage.gif");

codec.Save(newGif, fileName, RasterImageFormat.Gif, 8);

Console.WriteLine("output file was written " + fileName);

Console.ReadKey();

animator.Dispose();

targetImage.Dispose();
Sanwar Ranwa8y ago
https://www.codeproject.com/Questions/1227710/How-to-resize-gif-which-is-stored-in-bitmap
Nanddeep Nachan8y ago
Here are few references on same topic:
https://www.codeproject.com/Questions/1227710/How-to-resize-gif-which-is-stored-in-bitmap
https://forums.asp.net/t/1439399.aspx?Image+Resizer+in+C+
Prashant Kumar8y ago
You should simply set the PictureBox's SizeMode to StretchImage to make the PictureBox stretch the image for you.