Set/Get loop count of animated webp on ImageMagick6

[diego-choi]

Hi, I found that it couldn't set/get loop count of animated webp on ImageMagick6. but I found this issue (ImageMagick/ImageMagick#2863) about this problem on ImageMagick7.

I also found some commits for resolving this problem in IM7. so I think it is possible on IM7 now.

• get loop count: ImageMagick/ImageMagick@0e421ed
• set loop count: ImageMagick/ImageMagick@af1b1b6

Could you apply these improvements to IM6 too? or please let me know if I can be of any help for it. Thank you.

[dlemstra]

The code used in ImageMagick 6 is a lot different now because we added some extra features inside ImageMagick 7. Not sure when we will apply these changes to ImageMagick 6 or if we even can do that easily. We are open to pull requests for this.