Some animated GIFs don't render frames correctly on Linux

[jeffhandley]

Description

When using ImageAnimator.Animate to animate GIFs that use variable frame delays, max loop counts, or partial frame updates, there are issues rendering the frames on Linux.

The issues seem to be down in libgdiplus and corresponding issues were filed there. This is a tracking issue for the .NET Libraries.

• GIF PropertyTagFrameDelay PropertyItem does not retrieve all frame delays GIF PropertyTagFrameDelay PropertyItem does not retrieve all frame delays mono/libgdiplus#703
  • The first frame's delay gets used for all frames, leading to animation timing drift
• GIF PropertyTagLoopCount PropertyItem always returns 0 GIF PropertyTagLoopCount PropertyItem always returns 0 mono/libgdiplus#704
  • GIFs will loop indefinitely instead of stopping after the loop count
• Animated GIFs don't render the frame correctly when only a portion is updated Animated GIFs don't render the frame correctly when only a portion is updated mono/libgdiplus#705
  • The images are rendered as partial images and often contain noise

Configuration

• .NET 6.0 Preview 5
• Ubuntu 20.04 (via WSL2 on Windows 10)
• x64
• Linux specific; not sure if specific to Ubuntu or Ubuntu under WSL

Regression?

No. There were worse problems with ImageAnimator on Linux before #52236. These issues were discovered while adding manual tests for ImageAnimator that capture frame renderings of animations.

Other information

I recommend we close this since it's been a longstanding issue, there aren't currently app models that easily surface this scenario, and there haven't been customer reports of it. But I wanted to file it so that we could have the known issue logged.

[ghost]

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Issue Details

---

Description

When using ImageAnimator.Animate to animate GIFs that use variable frame delays, max loop counts, or partial frame updates, there are issues rendering the frames on Linux.

The issues seem to be down in libgdiplus and corresponding issues were filed there. This is a tracking issue for the .NET Libraries.

• GIF PropertyTagFrameDelay PropertyItem does not retrieve all frame delays GIF PropertyTagFrameDelay PropertyItem does not retrieve all frame delays mono/libgdiplus#703
  • The first frame's delay gets used for all frames, leading to animation timing drift
• GIF PropertyTagLoopCount PropertyItem always returns 0 GIF PropertyTagLoopCount PropertyItem always returns 0 mono/libgdiplus#704
  • GIFs will loop indefinitely instead of stopping after the loop count
• Animated GIFs don't render the frame correctly when only a portion is updated Animated GIFs don't render the frame correctly when only a portion is updated mono/libgdiplus#705
  • The images are rendered as partial images and often contain noise

Configuration

• .NET 6.0 Preview 5
• Ubuntu 20.04 (via WSL2 on Windows 10)
• x64
• Linux specific; not sure if specific to Ubuntu or Ubuntu under WSL

Regression?

No. There were worse problems with ImageAnimator on Linux before #52236. These issues were discovered while adding manual tests for ImageAnimator that capture frame renderings of animations.

Other information

I recommend we close this since it's been a longstanding issue, there aren't currently app models that easily surface this scenario, and there haven't been customer reports of it. But I wanted to file it so that we could have the known issue logged.

Author:	jeffhandley
Assignees:	-
Labels:	area-System.Drawing
Milestone:	-

[safern]

Thank you for the deep investigation, @jeffhandley. As you mentioned in the description, I also think we should close this, but it is a great write up to have here as history so that if a customer ever searches for this, they can find the libgdiplus underlying issues and move to the right place. I will go ahead and close the issue as we have tracking issues on libgdiplus.