Unable to render flattened version of PlatformViewRepresentableAdaptor<VariablurView>

[shindgew]

Summary

Using Variablur in SwiftUI hierarchies that are flattened or snapshotted can log:

Unable to render flattened version of PlatformViewRepresentableAdaptor<VariablurView>.

This was observed when applying Variablur to a SwiftUI card that also participates in a context menu preview shape.

Reproduction

Image(uiImage: uiImage)
    .resizable()
     .aspectRatio(contentMode: .fill)
    .blur(32, variation: .bottom())

A similar warning can occur when the Variablur-backed view is placed inside other SwiftUI flattening paths, such as ImageRenderer, drawingGroup(), or snapshot/export surfaces.

Expected Behavior

Variablur should either avoid this warning where possible or clearly document that the live UIKit-backed blur cannot be used in SwiftUI flattening/snapshot paths.

Actual Behavior

SwiftUI attempts to flatten a hierarchy containing VariablurView and logs:

Unable to render flattened version of PlatformViewRepresentableAdaptor<VariablurView>.

Likely Cause

VariablurView is a UIViewRepresentable backed by UIVisualEffectView and the runtime CAFilter("variableBlur") path. SwiftUI cannot flatten platform views into an offscreen render target for context menu previews, ImageRenderer, drawingGroup(), and similar APIs.

Workaround

For snapshot-sensitive card backgrounds, use a pure SwiftUI/image-renderable fallback: duplicate the image, apply native .blur(radius:), and mask the blurred copy with a LinearGradient or another snapshot-safe mask.

Acceptance Criteria

• Document that Variablur is not compatible with SwiftUI flattening/snapshot paths.
• Mention known triggers: context menu previews, ImageRenderer, drawingGroup(), and similar effects that flatten input.
• Add README or DocC guidance with a snapshot-safe fallback example.
• Consider whether the public API should expose a static/image-renderable fallback for common card backgrounds.