Fix getDimFromCell trailing space for XSSF in-cell picture anchors

[arimu1]

Summary

• Fix ImageUtils.getDimFromCell when hssfUnits == 0 (XSSF/OOXML anchors): use endD for trailing space instead of dim - endD, matching the semantics of the HSSF branch above it.
• Add regression test for a single-cell XSSF anchor where zero offsets previously produced 0-sized dimensions and broke picture.resize().

Fixes #1201

Test plan

• ./gradlew :poi-ooxml:test --tests org.apache.poi.xssf.usermodel.TestXSSFPicture.testGetDimensionFromAnchorSingleCell
• ./gradlew :poi:test --tests org.apache.poi.ss.util.TestImageUtils

Made with Cursor

[arimu1]

Thanks for the review — you're right that the global trailSpace = endD change was incorrect.

What was wrong: For XSSF, endD is the EMU offset from the left of the end cell, so trailing space must stay dim - endD (same fraction semantics as HSSF). Setting trailSpace = endD globally would:

• add a full extra cell for multi-cell anchors with dx2/dy2 == 0
• under-report normal in-cell anchors where startD < endD (dim - startD - endD instead of endD - startD)

Actual fix (#1201): The bug is only the degenerate same-cell case (col1==col2, dx1==dy1==dx2==dy2==0) where endD - startD == 0, causing picture.resize() to fail. The updated commit reverts the global flip and handles only that case: when startCell == endCell and computed span <= 0, use full cell size if both offsets are 0, otherwise remaining cell space (dim - leadSpace).

Tests added:

1. Degenerate in-cell (0,0,0,0) → full cell width/height (issue repro + resize)
2. Normal in-cell startD < endD → size == endD - startD
3. Multi-cell dx2==0 → width == first column only (no extra cell)

Tip: 05307f004acc5427f5c1164a37b6e1c299413757

[pjfanning]

use XSSFITestDataProvider

[arimu1]

Thanks @pjfanning — switched testGetDimensionFromAnchorDegenerateInCell to XSSFITestDataProvider.instance.getTestDataFileContent and dropped the unused HSSF import. TestXSSFPicture (13 tests) and TestImageUtils pass locally (JDK 17). Tip: 2b9a8ab760c07e2b19edeedbe5bf4effe9a5868a.