--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/leptonica/src/dewarp.h	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,191 @@
+/*====================================================================*
+ -  Copyright (C) 2001 Leptonica.  All rights reserved.
+ -
+ -  Redistribution and use in source and binary forms, with or without
+ -  modification, are permitted provided that the following conditions
+ -  are met:
+ -  1. Redistributions of source code must retain the above copyright
+ -     notice, this list of conditions and the following disclaimer.
+ -  2. Redistributions in binary form must reproduce the above
+ -     copyright notice, this list of conditions and the following
+ -     disclaimer in the documentation and/or other materials
+ -     provided with the distribution.
+ -
+ -  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ -  ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ -  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ -  A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL ANY
+ -  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ -  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ -  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ -  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ -  OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ -  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ -  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *====================================================================*/
+
+#ifndef  LEPTONICA_DEWARP_H
+#define  LEPTONICA_DEWARP_H
+
+/*!
+ * \file dewarp.h
+ *
+ * <pre>
+ *     Data structure to hold arrays and results for generating
+ *     horizontal and vertical disparity arrays based on textlines.
+ *     Each disparity array is two-dimensional.  The vertical disparity
+ *     array gives a vertical displacement, relative to the lowest point
+ *     in the textlines.  The horizontal disparty array gives a horizontal
+ *     displacement, relative to the minimum values (for even pages)
+ *     or maximum values (for odd pages) of the left and right ends of
+ *     full textlines.  Horizontal alignment always involves translations
+ *     away from the book gutter.
+ *
+ *     We have intentionally separated the process of building models
+ *     from the rendering process that uses the models.  For any page,
+ *     the building operation either creates an actual model (that is,
+ *     a model with at least the vertical disparity being computed, and
+ *     for which the 'success' flag is set) or fails to create a model.
+ *     However, at rendering time, a page can have one of two different
+ *     types of models.
+ *     (1) A valid model is an actual model that meets the rendering
+ *         constraints, which are limits on model curvature parameters.
+ *         See dewarpaTestForValidModel() for details.
+ *         Valid models are identified by dewarpaInsertRefModels(),
+ *         which sets the 'vvalid' and 'hvalid' fields.  Only valid
+ *         models are used for rendering.
+ *     (2) A reference model is used by a page that doesn't have
+ *         a valid model, but has a nearby valid model of the same
+ *         parity (even/odd page) that it can use.  The range in pages
+ *         to search for a valid model is given by the 'maxdist' field.
+ *
+ *     At the rendering stage, vertical and horizontal disparities are
+ *     treated differently.  It is somewhat more robust to generate
+ *     vertical disparity models (VDM) than horizontal disparity
+ *     models (HDM). A valid VDM is required for any correction to
+ *     be made; if a valid VDM is not available, just use the input
+ *     image.  Otherwise, assuming it is available, the use of the
+ *     HDM is controlled by two fields: 'useboth' and 'check_columns'.
+ *       (a) With useboth == 0, we use only the VDM.
+ *       (b) With useboth == 1, we require using the VDM and, if a valid
+ *           horizontal disparity model (HDM) is available, we also use it.
+ *       (c) With check_columns == 1, check for multiple columns and if
+ *           true, only use the VDM, even if a valid HDM is available.
+ *           Note that 'check_columns' takes precedence over 'useboth'
+ *           when there is more than 1 column of text.  By default,
+ *           check_columns == 0.
+ *
+ *     The 'maxdist' parameter is input when the dewarpa is created.
+ *     The other rendering parameters have default values given in dewarp1.c.
+ *     All parameters used by rendering can be set (or reset) using accessors.
+ *
+ *     After dewarping, use of the VDM will cause all points on each
+ *     altered curve to have a y-value equal to the minimum.  Use of
+ *     the HDA will cause the left and right edges of the textlines
+ *     to be vertically aligned if they had been typeset flush-left
+ *     and flush-right, respectively.
+ *
+ *     The sampled disparity arrays are expanded to full resolution,
+ *     using linear interpolation, and this is further expanded
+ *     by slope continuation to the right and below if the image
+ *     is larger than the full resolution disparity arrays.  Then
+ *     the disparity correction can be applied to the input image.
+ *     If the input pix are 2x reduced, the expansion from sampled
+ *     to full res uses the product of (sampling) * (redfactor).
+ *
+ *     The most accurate results are produced at full resolution, and
+ *     this is generally recommended.
+ * </pre>
+ */
+
+    /*! Dewarp version for serialization
+     * <pre>
+     * Note on versioning of the serialization of this data structure:
+     * The dewarping utility and the stored data can be expected to change.
+     * In most situations, the serialized version is ephemeral -- it is
+     * not needed after being used.  No functions will be provided to
+     * convert between different versions.
+     * </pre>
+     */
+#define  DEWARP_VERSION_NUMBER      4
+
+/*! Data structure to hold a number of Dewarp */
+struct L_Dewarpa
+{
+    l_int32            nalloc;        /*!< size of dewarp ptr array          */
+    l_int32            maxpage;       /*!< maximum page number in array      */
+    struct L_Dewarp  **dewarp;        /*!< array of ptrs to page dewarp      */
+    struct L_Dewarp  **dewarpcache;   /*!< array of ptrs to cached dewarps   */
+    struct Numa       *namodels;      /*!< list of page numbers for pages    */
+                                      /*!< with page models                  */
+    struct Numa       *napages;       /*!< list of page numbers with either  */
+                                      /*!< page models or ref page models    */
+    l_int32            redfactor;     /*!< reduction factor of input: 1 or 2 */
+    l_int32            sampling;      /*!< disparity arrays sampling factor  */
+    l_int32            minlines;      /*!< min number of long lines required */
+    l_int32            maxdist;       /*!< max distance for getting ref page */
+    l_int32            max_linecurv;  /*!< maximum abs line curvature,       */
+                                      /*!< in micro-units                    */
+    l_int32            min_diff_linecurv; /*!< minimum abs diff line         */
+                                          /*!< curvature in micro-units      */
+    l_int32            max_diff_linecurv; /*!< maximum abs diff line         */
+                                          /*!< curvature in micro-units      */
+    l_int32            max_edgeslope; /*!< maximum abs left or right edge    */
+                                      /*!< slope, in milli-units             */
+    l_int32            max_edgecurv;  /*!< maximum abs left or right edge    */
+                                      /*!< curvature, in micro-units         */
+    l_int32            max_diff_edgecurv; /*!< maximum abs diff left-right   */
+                                      /*!< edge curvature, in micro-units    */
+    l_int32            useboth;       /*!< use both disparity arrays if      */
+                                      /*!< available; only vertical otherwise */
+    l_int32            check_columns; /*!< if there are multiple columns,    */
+                                      /*!< only use the vertical disparity   */
+                                      /*!< array                             */
+    l_int32            modelsready;   /*!< invalid models have been removed  */
+                                      /*!< and refs built against valid set  */
+};
+typedef struct L_Dewarpa L_DEWARPA;
+
+
+/*! Data structure for a single dewarp */
+struct L_Dewarp
+{
+    struct L_Dewarpa  *dewa;         /*!< ptr to parent (not owned)          */
+    struct Pix        *pixs;         /*!< source pix, 1 bpp                  */
+    struct FPix       *sampvdispar;  /*!< sampled vert disparity array       */
+    struct FPix       *samphdispar;  /*!< sampled horiz disparity array      */
+    struct FPix       *sampydispar;  /*!< sampled slope h-disparity array    */
+    struct FPix       *fullvdispar;  /*!< full vert disparity array          */
+    struct FPix       *fullhdispar;  /*!< full horiz disparity array         */
+    struct FPix       *fullydispar;  /*!< full slope h-disparity array       */
+    struct Numa       *namidys;      /*!< sorted y val of midpoint each line */
+    struct Numa       *nacurves;     /*!< sorted curvature of each line      */
+    l_int32            w;            /*!< width of source image              */
+    l_int32            h;            /*!< height of source image             */
+    l_int32            pageno;       /*!< page number; important for reuse   */
+    l_int32            sampling;     /*!< sampling factor of disparity arrays */
+    l_int32            redfactor;    /*!< reduction factor of pixs: 1 or 2   */
+    l_int32            minlines;     /*!< min number of long lines required  */
+    l_int32            nlines;       /*!< number of long lines found         */
+    l_int32            mincurv;      /*!< min line curvature in micro-units  */
+    l_int32            maxcurv;      /*!< max line curvature in micro-units  */
+    l_int32            leftslope;    /*!< left edge slope in milli-units     */
+    l_int32            rightslope;   /*!< right edge slope in milli-units    */
+    l_int32            leftcurv;     /*!< left edge curvature in micro-units */
+    l_int32            rightcurv;    /*!< right edge curvature in micro-units*/
+    l_int32            nx;           /*!< number of sampling pts in x-dir    */
+    l_int32            ny;           /*!< number of sampling pts in y-dir    */
+    l_int32            hasref;       /*!< 0 if normal; 1 if has a refpage    */
+    l_int32            refpage;      /*!< page with disparity model to use   */
+    l_int32            vsuccess;     /*!< sets to 1 if vert disparity builds */
+    l_int32            hsuccess;     /*!< sets to 1 if horiz disparity builds */
+    l_int32            ysuccess;     /*!< sets to 1 if slope disparity builds */
+    l_int32            vvalid;       /*!< sets to 1 if valid vert disparity  */
+    l_int32            hvalid;       /*!< sets to 1 if valid horiz disparity */
+    l_int32            skip_horiz;   /*!< if 1, skip horiz disparity         */
+                                     /*!< correction                         */
+    l_int32            debug;        /*!< set to 1 if debug output requested */
+};
+typedef struct L_Dewarp L_DEWARP;
+
+#endif  /* LEPTONICA_DEWARP_H */