Nutrient Web SDK
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    Type Alias AnnotationRenderingOrderComparator

    AnnotationRenderingOrderComparator: (
        a: AnnotationsUnion,
        b: AnnotationsUnion,
    ) => -1 | 1

    A comparator function that defines a strict total order for annotation rendering.

    Return -1 if a should render below (behind) b, or 1 if a should render above (in front of) b. A strict total order is required — every pair of distinct annotations must have a deterministic ordering.

    When set via NutrientViewer.Instance#setAnnotationRenderingOrderComparator, this comparator replaces the SDK's default type-based rendering order for non-interactive annotations (e.g. text markups, ink, images, shapes, stamps).

    Interactive annotations — widget annotations (form fields), link annotations, and signature annotations — are always rendered above all other annotations regardless of the comparator. This is required to preserve keyboard tab order and accessibility. Use NutrientViewer.Instance#setPageTabOrder to customize the tab order of interactive annotations.

    Limitations:

    • This only affects the visual stacking order of non-interactive annotations.
    • Widget, link, and signature annotations always render on top, independent of this comparator, to preserve keyboard accessibility.
    • It does not change the keyboard tab order. Use NutrientViewer.Instance#setPageTabOrder to customize that separately.
    • Hit testing (click/tap) follows the DOM stacking context, which matches the visual rendering order set by this comparator — the topmost (last-rendered) annotation receives pointer events first.
    • It does not affect annotation order in exported PDFs or backend storage. The ordering is purely a local, view-layer concern.

    Type Declaration

    // Render image annotations behind everything else, tiebreak by creation time then id.
    instance.setAnnotationRenderingOrderComparator((a, b) => {
      const isImageA = a instanceof NutrientViewer.Annotations.ImageAnnotation;
      const isImageB = b instanceof NutrientViewer.Annotations.ImageAnnotation;
      if (isImageA !== isImageB) return isImageA ? -1 : 1;
      if (a.createdAt < b.createdAt) return -1;
      if (a.createdAt > b.createdAt) return 1;
      return a.id < b.id ? -1 : 1;
    });

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