Enum PageOrientationHandling 

pub enum PageOrientationHandling {
    SelfCorrecting,
    RecognisesRotatedText,
    RequiresUpright,
}

How a backend copes with a page raster whose text is not upright.

Rotated-page handling is a backend capability, not a universal guarantee. An A/B run this session against /Rotate 270 scanned pages showed the three handled cases genuinely differ: Tesseract reconstructs correct reading order on a sideways raster outright; PaddleOCR recognises the rotated text correctly (it warps each detected quad upright before running recognition) but leaves its block list in raw raster (y, x) order, so the caller must reorder; sceptre produces character garbage on the same sideways raster and only reads correctly once the page is rendered upright first. A caller that skips an upright-render step for a backend that actually needs one gets silent garbage, not an error.

Only one variant is discriminated (#657)

Read this before “simplifying” the type. There is exactly one decision point in the codebase that inspects this value: upright_raster_for_backend (crate::extractors::pdf::ocr), which tests orientation_handling != RequiresUpright and otherwise does nothing. Every other mention forwards the value to that test. So, to that codepath, SelfCorrecting and RecognisesRotatedText are behaviourally identical — the enum is a boolean at the point of use, and the three variants describe measured backend behaviour rather than three dispatch paths.

RecognisesRotatedText’s actual remedy is not this enum. The block-order fix is the backend_options["page_rotation_degrees"] hint injected by ocr_config_with_page_rotation_hint (crate::extractors::pdf::ocr) unconditionally, for every backend, which PaddleOcrBackend::process_image reads back (page_rotation_degrees_from_backend_options -> residual_rotation_for_reorder -> reorder_blocks_for_page_rotation, crate::paddle_ocr::backend) and applies internally. Declaring RecognisesRotatedText therefore changes nothing on its own; a backend in that class must also read the hint. Conversely, gating that hint on this enum would remove a field from Tesseract’s OcrConfig and hence from the OCR cache key (hash(image + language + config)), invalidating every cached page — do not do it without its own A/B.

PDF-route-only

Only the PDF OCR routes call OcrBackend::page_orientation_handling (the --force-ocr route via extract_with_ocr and the scanned-pages route via extract_mixed_ocr_native). The raw-image route (crate::extractors::image) never calls it: there is no /Rotate to consult, and orientation there is handled by the PP-LCNet document-orientation classifier (crate::doc_orientation) gated on OcrConfig::auto_rotate.

Cost of the default

The trait default is RequiresUpright (deliberately the least capable option, see OcrBackend::page_orientation_handling). A backend that does not declare therefore pays, on every page with /Rotate != 0, a re-encode plus rotation of the raster in upright_raster_for_backend and a bounding-box round-trip back through undo_upright_raster_correction. That is the safe direction to be wrong in, but it is not free, and for a backend that never got measured it is not known to be necessary either.

Variants

SelfCorrecting

Reconstructs reading order regardless of page rotation — safe to hand a raster in any orientation.

RecognisesRotatedText

Recognises rotated text correctly but emits blocks in raw raster order, so the caller must reorder.

RequiresUpright

Requires an upright raster; rotated text produces garbage.

Trait Implementations

impl Clone for PageOrientationHandling

fn clone(&self) -> PageOrientationHandling

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for PageOrientationHandling

impl Debug for PageOrientationHandling

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for PageOrientationHandling

fn default() -> PageOrientationHandling

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for PageOrientationHandling

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for PageOrientationHandling

impl PartialEq for PageOrientationHandling

fn eq(&self, other: &PageOrientationHandling) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for PageOrientationHandling

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for PageOrientationHandling