NAME
Image::Leptonica::Func::boxfunc1
VERSION
version 0.04
boxfunc1.c
boxfunc1.c
Box geometry
l_int32 boxContains()
l_int32 boxIntersects()
BOXA *boxaContainedInBox()
BOXA *boxaIntersectsBox()
BOXA *boxaClipToBox()
BOXA *boxaCombineOverlaps()
BOX *boxOverlapRegion()
BOX *boxBoundingRegion()
l_int32 boxOverlapFraction()
l_int32 boxOverlapArea()
BOXA *boxaHandleOverlaps()
l_int32 boxSeparationDistance()
l_int32 boxContainsPt()
BOX *boxaGetNearestToPt()
l_int32 boxIntersectByLine()
l_int32 boxGetCenter()
BOX *boxClipToRectangle()
l_int32 boxClipToRectangleParams()
BOX *boxRelocateOneSide()
BOX *boxAdjustSides()
BOXA *boxaSetSide()
BOXA *boxaAdjustWidthToTarget()
BOXA *boxaAdjustHeightToTarget()
l_int32 boxEqual()
l_int32 boxaEqual()
l_int32 boxSimilar()
l_int32 boxaSimilar()
Boxa combine and split
l_int32 boxaJoin()
l_int32 boxaaJoin()
l_int32 boxaSplitEvenOdd()
BOXA *boxaMergeEvenOdd()FUNCTIONS
boxAdjustSides
BOX * boxAdjustSides ( BOX *boxd, BOX *boxs, l_int32 delleft, l_int32 delright, l_int32 deltop, l_int32 delbot )
boxAdjustSides()
Input: boxd (<optional>; this can be null, equal to boxs,
or different from boxs)
boxs (starting box; to have sides adjusted)
delleft, delright, deltop, delbot (changes in location of
each side)
Return: boxd, or null on error or if the computed boxd has
width or height <= 0.
Notes:
(1) Set boxd == NULL to get new box; boxd == boxs for in-place;
or otherwise to resize existing boxd.
(2) For usage, suggest one of these:
boxd = boxAdjustSides(NULL, boxs, ...); // new
boxAdjustSides(boxs, boxs, ...); // in-place
boxAdjustSides(boxd, boxs, ...); // other
(1) New box dimensions are cropped at left and top to x >= 0 and y >= 0.
(2) For example, to expand in-place by 20 pixels on each side, use
boxAdjustSides(box, box, -20, 20, -20, 20);boxBoundingRegion
BOX * boxBoundingRegion ( BOX *box1, BOX *box2 )
boxBoundingRegion()
Input: box1, box2 (two boxes)
Return: box (of bounding region containing the input boxes),
or null on errorboxClipToRectangle
BOX * boxClipToRectangle ( BOX *box, l_int32 wi, l_int32 hi )
boxClipToRectangle()
Input: box
wi, hi (rectangle representing image)
Return: part of box within given rectangle, or NULL on error
or if box is entirely outside the rectangle
Notes:
(1) This can be used to clip a rectangle to an image.
The clipping rectangle is assumed to have a UL corner at (0, 0),
and a LR corner at (wi - 1, hi - 1).boxClipToRectangleParams
l_int32 boxClipToRectangleParams ( BOX *box, l_int32 w, l_int32 h, l_int32 *pxstart, l_int32 *pystart, l_int32 *pxend, l_int32 *pyend, l_int32 *pbw, l_int32 *pbh )
boxClipToRectangleParams()
Input: box (<optional> requested box; can be null)
w, h (clipping box size; typ. the size of an image)
&xstart (<return>)
&ystart (<return>)
&xend (<return> one pixel beyond clipping box)
¥d (<return> one pixel beyond clipping box)
&bw (<optional return> clipped width)
&bh (<optional return> clipped height)
Return: 0 if OK; 1 on error
Notes:
(1) The return value should be checked. If it is 1, the
returned parameter values are bogus.
(2) This simplifies the selection of pixel locations within
a given rectangle:
for (i = ystart; i < yend; i++ {
...
for (j = xstart; j < xend; j++ {
....boxContains
l_int32 boxContains ( BOX *box1, BOX *box2, l_int32 *presult )
boxContains()
Input: box1, box2
&result (<return> 1 if box2 is entirely contained within
box1, and 0 otherwise)
Return: 0 if OK, 1 on errorboxContainsPt
l_int32 boxContainsPt ( BOX *box, l_float32 x, l_float32 y, l_int32 *pcontains )
boxContainsPt()
Input: box
x, y (a point)
&contains (<return> 1 if box contains point; 0 otherwise)
Return: 0 if OK, 1 on error.boxEqual
l_int32 boxEqual ( BOX *box1, BOX *box2, l_int32 *psame )
boxEqual()
Input: box1
box2
&same (<return> 1 if equal; 0 otherwise)
Return 0 if OK, 1 on errorboxGetCenter
l_int32 boxGetCenter ( BOX *box, l_float32 *pcx, l_float32 *pcy )
boxGetCenter()
Input: box
&cx, &cy (<return> location of center of box)
Return 0 if OK, 1 on errorboxIntersectByLine
l_int32 boxIntersectByLine ( BOX *box, l_int32 x, l_int32 y, l_float32 slope, l_int32 *px1, l_int32 *py1, l_int32 *px2, l_int32 *py2, l_int32 *pn )
boxIntersectByLine()
Input: box
x, y (point that line goes through)
slope (of line)
(&x1, &y1) (<return> 1st point of intersection with box)
(&x2, &y2) (<return> 2nd point of intersection with box)
&n (<return> number of points of intersection)
Return: 0 if OK, 1 on error
Notes:
(1) If the intersection is at only one point (a corner), the
coordinates are returned in (x1, y1).
(2) Represent a vertical line by one with a large but finite slope.boxIntersects
l_int32 boxIntersects ( BOX *box1, BOX *box2, l_int32 *presult )
boxIntersects()
Input: box1, box2
&result (<return> 1 if any part of box2 is contained
in box1, and 0 otherwise)
Return: 0 if OK, 1 on errorboxOverlapArea
l_int32 boxOverlapArea ( BOX *box1, BOX *box2, l_int32 *parea )
boxOverlapArea()
Input: box1, box2 (two boxes)
&area (<return> the number of pixels in the overlap)
Return: 0 if OK, 1 on error.boxOverlapFraction
l_int32 boxOverlapFraction ( BOX *box1, BOX *box2, l_float32 *pfract )
boxOverlapFraction()
Input: box1, box2 (two boxes)
&fract (<return> the fraction of box2 overlapped by box1)
Return: 0 if OK, 1 on error.
Notes:
(1) The result depends on the order of the input boxes,
because the overlap is taken as a fraction of box2.boxOverlapRegion
BOX * boxOverlapRegion ( BOX *box1, BOX *box2 )
boxOverlapRegion()
Input: box1, box2 (two boxes)
Return: box (of overlap region between input boxes),
or null if no overlap or on errorboxRelocateOneSide
BOX * boxRelocateOneSide ( BOX *boxd, BOX *boxs, l_int32 loc, l_int32 sideflag )
boxRelocateOneSide()
Input: boxd (<optional>; this can be null, equal to boxs,
or different from boxs);
boxs (starting box; to have one side relocated)
loc (new location of the side that is changing)
sideflag (L_FROM_LEFT, etc., indicating the side that moves)
Return: boxd, or null on error or if the computed boxd has
width or height <= 0.
Notes:
(1) Set boxd == NULL to get new box; boxd == boxs for in-place;
or otherwise to resize existing boxd.
(2) For usage, suggest one of these:
boxd = boxRelocateOneSide(NULL, boxs, ...); // new
boxRelocateOneSide(boxs, boxs, ...); // in-place
boxRelocateOneSide(boxd, boxs, ...); // otherboxSeparationDistance
l_int32 boxSeparationDistance ( BOX *box1, BOX *box2, l_int32 *ph_sep, l_int32 *pv_sep )
boxSeparationDistance()
Input: box1, box2 (two boxes, in any order)
&h_sep (<optional return> horizontal separation)
&v_sep (<optional return> vertical separation)
Return: 0 if OK, 1 on error
Notes:
(1) This measures horizontal and vertical separation of the
two boxes. If the boxes are touching but have no pixels
in common, the separation is 0. If the boxes overlap by
a distance d, the returned separation is -d.boxSimilar
l_int32 boxSimilar ( BOX *box1, BOX *box2, l_int32 leftdiff, l_int32 rightdiff, l_int32 topdiff, l_int32 botdiff, l_int32 *psimilar )
boxSimilar()
Input: box1
box2
leftdiff, rightdiff, topdiff, botdiff
&similar (<return> 1 if similar; 0 otherwise)
Return 0 if OK, 1 on error
Notes:
(1) The values of leftdiff (etc) are the maximum allowed deviations
between the locations of the left (etc) sides. If any side
pairs differ by more than this amount, the boxes are not similar.boxaAdjustHeightToTarget
BOXA * boxaAdjustHeightToTarget ( BOXA *boxad, BOXA *boxas, l_int32 sides, l_int32 target, l_int32 thresh )
boxaAdjustHeightToTarget()
Input: boxad (use null to get a new one)
boxas
sides (L_ADJUST_TOP, L_ADJUST_BOT, L_ADJUST_TOP_AND_BOT)
target (target height if differs by more than thresh)
thresh (min abs difference in height to cause adjustment)
Return: boxad, or null on error
Notes:
(1) Conditionally adjusts the height of each box, by moving
the indicated edges (top and/or bot) if the height differs
by @thresh or more from @target.
(2) Use boxad == NULL for a new boxa, and boxad == boxas for in-place.
Use one of these:
boxad = boxaAdjustHeightToTarget(NULL, boxas, ...); // new
boxaAdjustHeightToTarget(boxas, boxas, ...); // in-placeboxaAdjustWidthToTarget
BOXA * boxaAdjustWidthToTarget ( BOXA *boxad, BOXA *boxas, l_int32 sides, l_int32 target, l_int32 thresh )
boxaAdjustWidthToTarget()
Input: boxad (use null to get a new one; same as boxas for in-place)
boxas
sides (L_ADJUST_LEFT, L_ADJUST_RIGHT, L_ADJUST_LEFTL_AND_RIGHT)
target (target width if differs by more than thresh)
thresh (min abs difference in width to cause adjustment)
Return: boxad, or null on error
Notes:
(1) Conditionally adjusts the width of each box, by moving
the indicated edges (left and/or right) if the width differs
by @thresh or more from @target.
(2) Use boxad == NULL for a new boxa, and boxad == boxas for in-place.
Use one of these:
boxad = boxaAdjustWidthToTarget(NULL, boxas, ...); // new
boxaAdjustWidthToTarget(boxas, boxas, ...); // in-placeboxaClipToBox
BOXA * boxaClipToBox ( BOXA *boxas, BOX *box )
boxaClipToBox()
Input: boxas
box (for clipping)
Return boxad (boxa with boxes in boxas clipped to box),
or null on error
Notes:
(1) All boxes in boxa not intersecting with box are removed, and
the remaining boxes are clipped to box.boxaCombineOverlaps
BOXA * boxaCombineOverlaps ( BOXA *boxas )
boxaCombineOverlaps()
Input: boxas
Return: boxad (where each set of boxes in boxas that overlap are
combined into a single bounding box in boxad), or
null on error.
Notes:
(1) If there are no overlapping boxes, it simply returns a copy
of @boxas.
(2) The alternative method of painting each rectanle and finding
the 4-connected components gives the wrong result, because
two non-overlapping rectangles, when rendered, can still
be 4-connected, and hence they will be joined.
(3) A bad case is to have n boxes, none of which overlap.
Then you have one iteration with O(n^2) compares. This
is still faster than painting each rectangle and finding
the connected components, even for thousands of rectangles.boxaContainedInBox
BOXA * boxaContainedInBox ( BOXA *boxas, BOX *box )
boxaContainedInBox()
Input: boxas
box (for containment)
Return: boxad (boxa with all boxes in boxas that are
entirely contained in box), or null on error
Notes:
(1) All boxes in boxa that are entirely outside box are removed.boxaEqual
l_int32 boxaEqual ( BOXA *boxa1, BOXA *boxa2, l_int32 maxdist, NUMA **pnaindex, l_int32 *psame )
boxaEqual()
Input: boxa1
boxa2
maxdist
&naindex (<optional return> index array of correspondences
&same (<return> 1 if equal; 0 otherwise)
Return 0 if OK, 1 on error
Notes:
(1) The two boxa are the "same" if they contain the same
boxes and each box is within @maxdist of its counterpart
in their positions within the boxa. This allows for
small rearrangements. Use 0 for maxdist if the boxa
must be identical.
(2) This applies only to geometry and ordering; refcounts
are not considered.
(3) @maxdist allows some latitude in the ordering of the boxes.
For the boxa to be the "same", corresponding boxes must
be within @maxdist of each other. Note that for large
@maxdist, we should use a hash function for efficiency.
(4) naindex[i] gives the position of the box in boxa2 that
corresponds to box i in boxa1. It is only returned if the
boxa are equal.boxaGetNearestToPt
BOX * boxaGetNearestToPt ( BOXA *boxa, l_int32 x, l_int32 y )
boxaGetNearestToPt()
Input: boxa
x, y (point)
Return box (box with centroid closest to the given point [x,y]),
or NULL if no boxes in boxa)
Notes:
(1) Uses euclidean distance between centroid and point.boxaHandleOverlaps
BOXA * boxaHandleOverlaps ( BOXA *boxas, l_int32 op, l_int32 range, l_float32 min_overlap, l_float32 max_ratio, NUMA **pnamap )
boxaHandleOverlaps()
Input: boxas
op (L_COMBINE, L_REMOVE_SMALL)
range (> 0, forward distance over which overlaps are checked)
min_overlap (minimum fraction of smaller box required for
overlap to count; 0.0 to ignore)
max_ratio (maximum fraction of small/large areas for
overlap to count; 1.0 to ignore)
&namap (<optional return> combining map)
Return: boxad, or null on error.
Notes:
(1) For all n(n-1)/2 box pairings, if two boxes overlap, either:
(a) op == L_COMBINE: get the bounding region for the two,
replace the larger with the bounding region, and remove
the smaller of the two, or
(b) op == L_REMOVE_SMALL: just remove the smaller.
(2) If boxas is 2D sorted, range can be small, but if it is
not spatially sorted, range should be large to allow all
pairwise comparisons to be made.
(3) The @min_overlap parameter allows ignoring small overlaps.
If @min_overlap == 1.0, only boxes fully contained in larger
boxes can be considered for removal; if @min_overlap == 0.0,
this constraint is ignored.
(4) The @max_ratio parameter allows ignoring overlaps between
boxes that are not too different in size. If @max_ratio == 0.0,
no boxes can be removed; if @max_ratio == 1.0, this constraint
is ignored.boxaIntersectsBox
BOXA * boxaIntersectsBox ( BOXA *boxas, BOX *box )
boxaIntersectsBox()
Input: boxas
box (for intersecting)
Return boxad (boxa with all boxes in boxas that intersect box),
or null on error
Notes:
(1) All boxes in boxa that intersect with box (i.e., are completely
or partially contained in box) are retained.boxaJoin
l_int32 boxaJoin ( BOXA *boxad, BOXA *boxas, l_int32 istart, l_int32 iend )
boxaJoin()
Input: boxad (dest boxa; add to this one)
boxas (source boxa; add from this one)
istart (starting index in boxas)
iend (ending index in boxas; use -1 to cat all)
Return: 0 if OK, 1 on error
Notes:
(1) This appends a clone of each indicated box in boxas to boxad
(2) istart < 0 is taken to mean 'read from the start' (istart = 0)
(3) iend < 0 means 'read to the end'
(4) if boxas == NULL or has no boxes, this is a no-op.boxaMergeEvenOdd
BOXA * boxaMergeEvenOdd ( BOXA *boxae, BOXA *boxao, l_int32 fillflag )
boxaMergeEvenOdd()
Input: boxae (boxes to go in even positions in merged boxa)
boxao (boxes to go in odd positions in merged boxa)
fillflag (1 if there are invalid boxes in placeholders)
Return: boxad (merged), or null on error
Notes:
(1) This is essentially the inverse of boxaSplitEvenOdd().
Typically, boxae and boxao were generated by boxaSplitEvenOdd(),
and the value of @fillflag needs to be the same in both calls.
(2) If @fillflag == 1, both boxae and boxao are of the same size;
otherwise boxae may have one more box than boxao.boxaSetSide
BOXA * boxaSetSide ( BOXA *boxad, BOXA *boxas, l_int32 side, l_int32 val, l_int32 thresh )
boxaSetSide()
Input: boxad (use null to get a new one; same as boxas for in-place)
boxas
side (L_SET_LEFT, L_SET_RIGHT, L_SET_TOP, L_SET_BOT)
val (location to set for given side, for each box)
thresh (min abs difference to cause resetting to @val)
Return: boxad, or null on error
Notes:
(1) Sets the given side of each box. Use boxad == NULL for a new
boxa, and boxad == boxas for in-place.
(2) Use one of these:
boxad = boxaSetSide(NULL, boxas, ...); // new
boxaSetSide(boxas, boxas, ...); // in-placeboxaSimilar
l_int32 boxaSimilar ( BOXA *boxa1, BOXA *boxa2, l_int32 leftdiff, l_int32 rightdiff, l_int32 topdiff, l_int32 botdiff, l_int32 debugflag, l_int32 *psimilar )
boxaSimilar()
Input: boxa1
boxa2
leftdiff, rightdiff, topdiff, botdiff
debugflag (output details of non-similar boxes)
&similar (<return> 1 if similar; 0 otherwise)
Return 0 if OK, 1 on error
Notes:
(1) See boxSimilar() for parameter usage.
(2) Corresponding boxes are taken in order in the two boxa.
(3) With debugflag == 1, boxes continue to be tested after failure.boxaSplitEvenOdd
l_int32 boxaSplitEvenOdd ( BOXA *boxa, l_int32 fillflag, BOXA **pboxae, BOXA **pboxao )
boxaSplitEvenOdd()
Input: boxa
fillflag (1 to put invalid boxes in place; 0 to omit)
&boxae, &boxao (<return> save even and odd boxes in their
separate boxa, setting the other type to invalid boxes.)
Return: 0 if OK, 1 on error
Notes:
(1) If @fillflag == 1, boxae has copies of the even boxes
in their original location, and nvalid boxes are placed
in the odd array locations. And v.v.
(2) If @fillflag == 0, boxae has only copies of the even boxes.boxaaJoin
l_int32 boxaaJoin ( BOXAA *baad, BOXAA *baas, l_int32 istart, l_int32 iend )
boxaaJoin()
Input: baad (dest boxaa; add to this one)
baas (source boxaa; add from this one)
istart (starting index in baas)
iend (ending index in baas; use -1 to cat all)
Return: 0 if OK, 1 on error
Notes:
(1) This appends a clone of each indicated boxa in baas to baad
(2) istart < 0 is taken to mean 'read from the start' (istart = 0)
(3) iend < 0 means 'read to the end'
(4) if baas == NULL, this is a no-op.AUTHOR
Zakariyya Mughal <zmughal@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2014 by Zakariyya Mughal.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.