svgfe-backdrop-ext-scroll-offset.yaml

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# Tests that an SVGFE *backdrop* filter subregion is NOT normalized by the

# external scroll offset. A backdrop filter's picture is anchored to the

# backdrop root, not to the scrolling spatial node, so the backdrop root does

# not re-apply the external scroll offset at frame time and the subregion must

# be left as authored. Here the green flood subregion is positioned so that,

# un-normalized, it exactly covers the visible viewport over the red backdrop.

# If the subregion were (incorrectly) offset by the 50px external scroll

# offset, the flood would shift and red would show through. See bug 2046779.

root:

  items:

    - type: scroll-frame

      bounds: [0, 0, 100, 100]

      content-size: [100, 1000]

      scroll-offset: [0, 0]

      external-scroll-offset: [0, 50]

      items:

        - type: rect

          color: red

          bounds: [0, 50, 100, 100]

        - type: backdrop-filter

          bounds: [0, 50, 100, 100]

          filters:

            - svgfe: SourceGraphic

            - svgfe: flood

              linear: false

              color: green

              subregion: [0, 100, 100, 100]

            - svgfe: compositeover

              linear: false

              subregion: [0, 0, 100, 1000]

              in: 1

              in2: 0