Module ffi.koptcontext

Leptonica cheatsheet:

-- Data structures:
PIX -- basic data structure - stores image
BOX -- stores rectangle (x, y, w, h)
BOXA -- array of BOX
NUMA -- array of numbers

-- Functions:
-- note that all of them take/return pointers, or null/nil on failure

pixDestroy(pix) -- free memory from PIX
boxDestroy(box) -- free memory from BOX
selDestroy(sel) -- free memory from SEL
boxaDestroy(boxa) -- free memory from BOXA
numaGetIValue(nai, counter_w, counter_l) -- returns int value from NUMA
pixGetWidth(pix) -- return pix width
pixGetHeight(pix) -- return pix height
pixConvertTo32(pix) -- converts pix to 32bpp
boxaCombineOverlaps(boxa) -- return intersection of all box in a boxa
boxCreate(x, y, w, h) -- create box with given dimensions
boxaGetCount(boxa) -- get number of elements in boxa array

-- get element from BOXA flag can be C.L_COPY (creates new copy) or
-- C.L_CLONE (returns ref-counted handle)
boxaGetBox(boxa, index, flag)

-- add box to boxa array, flag can be C.L_INSERT, or C.L_COPY
boxaAddBox(boxa, box, flag)

-- adjust box's size by given deltas and write it to boxd
boxAdjustSides(boxd, boxs, d_left, d_right, d_top, d_bottom)

-- returns boxa where each element intersects with box,
-- or is removed if it doesn't intersect
boxaClipToBox(boxa, box)

-- returns intersection of both box, or null if they don't intersect
boxOverlapRegion(box, box)

-- returns new black-white PIX,
-- if the source pixel is < threshold,
-- resulting pixel is 1 (black),
-- otherwise 0 (white)
pixThresholdToBinary(pix, threshold)

-- returns 0 on success and 1 on failure, output_* are PIX

-- draw boxa elements in random color with given width
pixDrawBoxaRandom(pix, boxa, width)

-- creates png from pix, useful for debugging
pixWritePng(path, pix, gamma)

-- multiplies box part of pixs by color and writes it to pixd
pixMultiplyByColor(pixd, pixs, box, color)

-- converts float_array to NUMA, flag is either C.L_INSERT or C.L_COPY
numaCreateFromFArray(float_array, size, flag)

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