Function calculateDrawingTransformForAxis

calculateDrawingTransform always derives translateY assuming the caller will map model Y to paper Y with a sign flip (adjustedY = -y, matching a plan view drawn with north/Y+ up on paper) — it centers using drawingBounds.maxY for exactly that reason (see the "Flip Y" comment above).

Plan ('down') sections do NOT flip Y (see Drawing2DCanvas.tsx's flipY = sectionAxis !== 'down'): they map adjustedY = y directly, so north stays up without a sign flip. Reusing the flipped translateY unmodified in that case still centers the WIDTH but shifts the centered Y off by (minY + maxY) * scaleFactor — the drawing lands off-center on the sheet, worse the further the section's bounds sit from being symmetric about Y=0. This offset was found diverging between the sheet PREVIEW (Drawing2DCanvas.tsx, which already carried this correction) and the sheet PRINT/EXPORT path (useDrawingExport.ts's generateSheetSVG, which did not) — issue #2940.

Call this instead of calculateDrawingTransform directly wherever the axis's flip behavior is known, so every sheet consumer (screen preview, print, SVG/PDF export) derives the flip correction from one place rather than each re-deriving it. Note this function is the geometry only: it takes no view state, so two callers still agree only insofar as they pass the same flipY/flipX AND resolve any cached/pinned placement the same way. The viewer routes both sheet consumers through one resolver (apps/viewer/src/lib/drawing/sheet-transform.ts) for exactly that reason.

translateX needs the mirror-image correction, but gated the OPPOSITE way from translateY: calculateDrawingTransform's translateX bakes in the assumption that the caller maps model X to paper X with NO sign flip (adjustedX = x) — unlike translateY, which bakes in a flip. So translateX is only wrong when flipX is actually true (adjustedX = -x, used for 'side' sections to view from the conventional direction, see Drawing2DCanvas.tsx / useDrawingExport.ts's flipX = sectionAxis === 'side'): flipping negates and reverses the drawing's X extent to [-maxX, -minX], so the base translate (keyed off -minX) shifts the centered box by (minX + maxX) * scaleFactor — the drawing lands off the left/right edge of the sheet, worse the further the section's bounds sit from being symmetric about X=0. Confirmed unfixed prior to this change (issue #2940's X-axis half): a 'side' section with bounds minX=2, maxX=12 on a 190mm-wide viewport landed 140mm off-center.