Export

‍Verified against 42eca0e8fe on 2026-09-29.

How an export request's size is resolved, and where that decision must happen.

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The export size is resolved once, by whoever dispatches the export

Found 6a99540222, 2026-09-26.

libs/export.c offers five ways to size an export – a pixel box, a print size in cm or inch at a dpi, a scale factor, the original resolution – and each keeps settings of its own: width / height, print_width / print_height (always stored in cm, shown in the unit selected) with print_dpi, resizing_factor; dimensions_type picks one. Switching modes changes nothing but dimensions_type, so no mode can erase or rewrite another's size, and what a mode shows is what it exports.

_resolve_export_size() turns the selected mode into one size when the export is dispatched, and that size travels by value: dt_control_export() -> the job -> store() -> dt_imageio_export() -> dt_imageio_export_with_flags(), as max_width x max_height or a scale_factor (> 0 reduces by it, capped at 1; otherwise the image fits the box, 0 x 0 meaning full size). Nothing below the export module reads its configuration: a job runs on a worker thread, possibly long after it was queued, so a size read there would be whatever the settings say by then, not what the user exported with. For the same reason every other caller – ansel-cli, the gallery's thumbnails, the HDR merge, print, the mipmap and drawlayer exports – states its own size and passes 0.0.

The two print_* keys are deliberately not in the confgen: dt_conf_key_exists() is true for any confgen key, and their absence is what lets _ensure_print_size_conf() derive them once from the pixel box of an older configuration.

The preset blob holds a pixel box only: get_params() stores the size the selected mode resolves to, or the pixel box in scale mode, which a blob cannot express.