/*====================================================================*
- Copyright (C) 2001 Leptonica. All rights reserved.
- This software is distributed in the hope that it will be
- useful, but with NO WARRANTY OF ANY KIND.
- No author or distributor accepts responsibility to anyone for the
- consequences of using this software, or for whether it serves any
- particular purpose or works at all, unless he or she says so in
- writing. Everyone is granted permission to copy, modify and
- redistribute this source code, for commercial or non-commercial
- purposes, with the following restrictions: (1) the origin of this
- source code must not be misrepresented; (2) modified versions must
- be plainly marked as such; and (3) this notice may not be removed
- or altered from any source or modified source distribution.
*====================================================================*/
/*
* shear.c
*
* About arbitrary lines
* PIX *pixHShear()
* PIX *pixVShear()
*
* About special 'points': UL corner and center
* PIX *pixHShearCorner()
* PIX *pixVShearCorner()
* PIX *pixHShearCenter()
* PIX *pixVShearCenter()
*
* In place about arbitrary lines
* l_int32 pixHShearIP()
* l_int32 pixVShearIP()
*
* Static helper
* static l_float32 normalizeAngleForShear()
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "allheaders.h"
/* Shear angle must not get too close to -pi/2 or pi/2 */
static const l_float32 MIN_DIFF_FROM_HALF_PI = 0.04;
static l_float32 normalizeAngleForShear(l_float32 radang, l_float32 mindist);
#ifndef NO_CONSOLE_IO
#define DEBUG 0
#endif /* ~NO_CONSOLE_IO */
/*-------------------------------------------------------------*
* About arbitrary lines *
*-------------------------------------------------------------*/
/*!
* pixHShear()
*
* Input: pixd (<optional>, this can be null, equal to pixs,
* or different from pixs)
* pixs (no restrictions on depth)
* liney (location of horizontal line, measured from origin)
* angle (in radians)
* incolor (L_BRING_IN_WHITE, L_BRING_IN_BLACK);
* Return: pixd, always
*
* Notes:
* (1) There are 3 cases:
* (a) pixd == null (make a new pixd)
* (b) pixd == pixs (in-place)
* (c) pixd != pixs
* (2) For these three cases, use these patterns, respectively:
* pixd = pixHShear(NULL, pixs, ...);
* pixHShear(pixs, pixs, ...);
* pixHShear(pixd, pixs, ...);
* (3) This shear leaves the horizontal line of pixels at y = liney
* invariant. For a positive shear angle, pixels above this
* line are shoved to the right, and pixels below this line
* move to the left.
* (4) With positive shear angle, this can be used, along with
* pixVShear(), to perform a cw rotation, either with 2 shears
* (for small angles) or in the general case with 3 shears.
* (5) Changing the value of liney is equivalent to translating
* the result horizontally.
* (6) This brings in 'incolor' pixels from outside the image.
* (7) For in-place operation, pixs cannot be colormapped,
* because the in-place operation only blits in 0 or 1 bits,
* not an arbitrary colormap index.
* (8) The angle is brought into the range [-pi, -pi]. It is
* not permitted to be within MIN_DIFF_FROM_HALF_PI radians
* from either -pi/2 or pi/2.
*/
PIX *
pixHShear(PIX *pixd,
PIX *pixs,
l_int32 liney,
l_float32 radang,
l_int32 incolor)
{
l_int32 sign, w, h;
l_int32 y, yincr, inityincr, hshift;
l_float32 tanangle, invangle;
PROCNAME("pixHShear");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, pixd);
if (incolor != L_BRING_IN_WHITE && incolor != L_BRING_IN_BLACK)
return (PIX *)ERROR_PTR("invalid incolor value", procName, pixd);
if (pixd == pixs) { /* in place */
if (pixGetColormap(pixs) != NULL)
return (PIX *)ERROR_PTR("pixs is colormapped", procName, pixd);
pixHShearIP(pixd, liney, radang, incolor);
return pixd;
}
/* Make sure pixd exists and is same size as pixs */
if (!pixd) {
if ((pixd = pixCreateTemplate(pixs)) == NULL)
return (PIX *)ERROR_PTR("pixd not made", procName, NULL);
}
else /* pixd != pixs */
pixResizeImageData(pixd, pixs);
/* Normalize angle. If no rotation, return a copy */
radang = normalizeAngleForShear(radang, MIN_DIFF_FROM_HALF_PI);
if (radang == 0.0 || tan(radang) == 0.0)
return pixCopy(pixd, pixs);
/* Initialize to value of incoming pixels */
pixSetBlackOrWhite(pixd, incolor);
pixGetDimensions(pixs, &w, &h, NULL);
sign = L_SIGN(radang);
tanangle = tan(radang);
invangle = L_ABS(1. / tanangle);
inityincr = (l_int32)(invangle / 2.);
yincr = (l_int32)invangle;
pixRasterop(pixd, 0, liney - inityincr, w, 2 * inityincr, PIX_SRC,
pixs, 0, liney - inityincr);
for (hshift = 1, y = liney + inityincr; y < h; hshift++) {
yincr = (l_int32)(invangle * (hshift + 0.5) + 0.5) - (y - liney);
if (h - y < yincr) /* reduce for last one if req'd */
yincr = h - y;
pixRasterop(pixd, -sign*hshift, y, w, yincr, PIX_SRC, pixs, 0, y);
#if DEBUG
fprintf(stderr, "y = %d, hshift = %d, yincr = %d\n", y, hshift, yincr);
#endif /* DEBUG */
y += yincr;
}
for (hshift = -1, y = liney - inityincr; y > 0; hshift--) {
yincr = (y - liney) - (l_int32)(invangle * (hshift - 0.5) + 0.5);
if (y < yincr) /* reduce for last one if req'd */
yincr = y;
pixRasterop(pixd, -sign*hshift, y - yincr, w, yincr, PIX_SRC,
pixs, 0, y - yincr);
#if DEBUG
fprintf(stderr, "y = %d, hshift = %d, yincr = %d\n",
y - yincr, hshift, yincr);
#endif /* DEBUG */
y -= yincr;
}
return pixd;
}
/*!
* pixVShear()
*
* Input: pixd (<optional>, this can be null, equal to pixs,
* or different from pixs)
* pixs (no restrictions on depth)
* linex (location of vertical line, measured from origin)
* angle (in radians; not too close to +-(pi / 2))
* incolor (L_BRING_IN_WHITE, L_BRING_IN_BLACK);
* Return: pixd, or null on error
*
* Notes:
* (1) There are 3 cases:
* (a) pixd == null (make a new pixd)
* (b) pixd == pixs (in-place)
* (c) pixd != pixs
* (2) For these three cases, use these patterns, respectively:
* pixd = pixVShear(NULL, pixs, ...);
* pixVShear(pixs, pixs, ...);
* pixVShear(pixd, pixs, ...);
* (3) This shear leaves the vertical line of pixels at x = linex
* invariant. For a positive shear angle, pixels to the right
* of this line are shoved downward, and pixels to the left
* of the line move upward.
* (4) With positive shear angle, this can be used, along with
* pixHShear(), to perform a cw rotation, either with 2 shears
* (for small angles) or in the general case with 3 shears.
* (5) Changing the value of linex is equivalent to translating
* the result vertically.
* (6) This brings in 'incolor' pixels from outside the image.
* (7) For in-place operation, pixs cannot be colormapped,
* because the in-place operation only blits in 0 or 1 bits,
* not an arbitrary colormap index.
* (8) The angle is brought into the range [-pi, -pi]. It is
* not permitted to be within MIN_DIFF_FROM_HALF_PI radians
* from either -pi/2 or pi/2.
*/
PIX *
pixVShear(PIX *pixd,
PIX *pixs,
l_int32 linex,
l_float32 radang,
l_int32 incolor)
{
l_int32 sign, w, h;
l_int32 x, xincr, initxincr, vshift;
l_float32 tanangle, invangle;
PROCNAME("pixVShear");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (incolor != L_BRING_IN_WHITE && incolor != L_BRING_IN_BLACK)
return (PIX *)ERROR_PTR("invalid incolor value", procName, NULL);
if (pixd == pixs) { /* in place */
if (pixGetColormap(pixs) != NULL)
return (PIX *)ERROR_PTR("pixs is colormapped", procName, pixd);
pixVShearIP(pixd, linex, radang, incolor);
return pixd;
}
/* Make sure pixd exists and is same size as pixs */
if (!pixd) {
if ((pixd = pixCreateTemplate(pixs)) == NULL)
return (PIX *)ERROR_PTR("pixd not made", procName, NULL);
}
else /* pixd != pixs */
pixResizeImageData(pixd, pixs);
/* Normalize angle. If no rotation, return a copy */
radang = normalizeAngleForShear(radang, MIN_DIFF_FROM_HALF_PI);
if (radang == 0.0 || tan(radang) == 0.0)
return pixCopy(pixd, pixs);
/* Initialize to value of incoming pixels */
pixSetBlackOrWhite(pixd, incolor);
pixGetDimensions(pixs, &w, &h, NULL);
sign = L_SIGN(radang);
tanangle = tan(radang);
invangle = L_ABS(1. / tanangle);
initxincr = (l_int32)(invangle / 2.);
xincr = (l_int32)invangle;
pixRasterop(pixd, linex - initxincr, 0, 2 * initxincr, h, PIX_SRC,
pixs, linex - initxincr, 0);
for (vshift = 1, x = linex + initxincr; x < w; vshift++) {
xincr = (l_int32)(invangle * (vshift + 0.5) + 0.5) - (x - linex);
if (w - x < xincr) /* reduce for last one if req'd */
xincr = w - x;
pixRasterop(pixd, x, sign*vshift, xincr, h, PIX_SRC, pixs, x, 0);
#if DEBUG
fprintf(stderr, "x = %d, vshift = %d, xincr = %d\n", x, vshift, xincr);
#endif /* DEBUG */
x += xincr;
}
for (vshift = -1, x = linex - initxincr; x > 0; vshift--) {
xincr = (x - linex) - (l_int32)(invangle * (vshift - 0.5) + 0.5);
if (x < xincr) /* reduce for last one if req'd */
xincr = x;
pixRasterop(pixd, x - xincr, sign*vshift, xincr, h, PIX_SRC,
pixs, x - xincr, 0);
#if DEBUG
fprintf(stderr, "x = %d, vshift = %d, xincr = %d\n",
x - xincr, vshift, xincr);
#endif /* DEBUG */
x -= xincr;
}
return pixd;
}
/*-------------------------------------------------------------*
* Shears about UL corner and center *
*-------------------------------------------------------------*/
/*!
* pixHShearCorner()
*
* Input: pixd (<optional>, if not null, must be equal to pixs)
* pixs
* angle (in radians)
* incolor (L_BRING_IN_WHITE, L_BRING_IN_BLACK);
* Return: pixd, or null on error.
*
* Notes:
* (1) See pixHShear() for usage.
* (2) This does a horizontal shear about the UL corner, with (+) shear
* pushing increasingly leftward (-x) with increasing y.
*/
PIX *
pixHShearCorner(PIX *pixd,
PIX *pixs,
l_float32 radang,
l_int32 incolor)
{
PROCNAME("pixHShearCorner");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, pixd);
return pixHShear(pixd, pixs, 0, radang, incolor);
}
/*!
* pixVShearCorner()
*
* Input: pixd (<optional>, if not null, must be equal to pixs)
* pixs
* angle (in radians)
* incolor (L_BRING_IN_WHITE, L_BRING_IN_BLACK);
* Return: pixd, or null on error.
*
* Notes:
* (1) See pixVShear() for usage.
* (2) This does a vertical shear about the UL corner, with (+) shear
* pushing increasingly downward (+y) with increasing x.
*/
PIX *
pixVShearCorner(PIX *pixd,
PIX *pixs,
l_float32 radang,
l_int32 incolor)
{
PROCNAME("pixVShearCorner");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, pixd);
return pixVShear(pixd, pixs, 0, radang, incolor);
}
/*!
* pixHShearCenter()
*
* Input: pixd (<optional>, if not null, must be equal to pixs)
* pixs
* angle (in radians)
* incolor (L_BRING_IN_WHITE, L_BRING_IN_BLACK);
* Return: pixd, or null on error.
*
* Notes:
* (1) See pixHShear() for usage.
* (2) This does a horizontal shear about the center, with (+) shear
* pushing increasingly leftward (-x) with increasing y.
*/
PIX *
pixHShearCenter(PIX *pixd,
PIX *pixs,
l_float32 radang,
l_int32 incolor)
{
PROCNAME("pixHShearCenter");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, pixd);
return pixHShear(pixd, pixs, pixGetHeight(pixs) / 2, radang, incolor);
}
/*!
* pixVShearCenter()
*
* Input: pixd (<optional>, if not null, must be equal to pixs)
* pixs
* angle (in radians)
* incolor (L_BRING_IN_WHITE, L_BRING_IN_BLACK);
* Return: pixd, or null on error.
*
* Notes:
* (1) See pixVShear() for usage.
* (2) This does a vertical shear about the center, with (+) shear
* pushing increasingly downward (+y) with increasing x.
*/
PIX *
pixVShearCenter(PIX *pixd,
PIX *pixs,
l_float32 radang,
l_int32 incolor)
{
PROCNAME("pixVShearCenter");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, pixd);
return pixVShear(pixd, pixs, pixGetWidth(pixs) / 2, radang, incolor);
}
/*--------------------------------------------------------------------------*
* In place about arbitrary lines *
*--------------------------------------------------------------------------*/
/*!
* pixHShearIP()
*
* Input: pixs
* liney (location of horizontal line, measured from origin)
* angle (in radians)
* incolor (L_BRING_IN_WHITE, L_BRING_IN_BLACK);
* Return: 0 if OK; 1 on error
*
* Notes:
* (1) This is an in-place version of pixHShear(); see comments there.
* (2) This brings in 'incolor' pixels from outside the image.
* (3) pixs cannot be colormapped, because the in-place operation
* only blits in 0 or 1 bits, not an arbitrary colormap index.
* (4) Does a horizontal full-band shear about the line with (+) shear
* pushing increasingly leftward (-x) with increasing y.
*/
l_int32
pixHShearIP(PIX *pixs,
l_int32 liney,
l_float32 radang,
l_int32 incolor)
{
l_int32 sign, w, h;
l_int32 y, yincr, inityincr, hshift;
l_float32 tanangle, invangle;
PROCNAME("pixHShearIP");
if (!pixs)
return ERROR_INT("pixs not defined", procName, 1);
if (incolor != L_BRING_IN_WHITE && incolor != L_BRING_IN_BLACK)
return ERROR_INT("invalid incolor value", procName, 1);
if (pixGetColormap(pixs) != NULL)
return ERROR_INT("pixs is colormapped", procName, 1);
/* Normalize angle */
radang = normalizeAngleForShear(radang, MIN_DIFF_FROM_HALF_PI);
if (radang == 0.0 || tan(radang) == 0.0)
return 0;
sign = L_SIGN(radang);
pixGetDimensions(pixs, &w, &h, NULL);
tanangle = tan(radang);
invangle = L_ABS(1. / tanangle);
inityincr = (l_int32)(invangle / 2.);
yincr = (l_int32)invangle;
pixRasteropHip(pixs, liney - inityincr, 2 * inityincr, 0, incolor);
for (hshift = 1, y = liney + inityincr; y < h; hshift++) {
yincr = (l_int32)(invangle * (hshift + 0.5) + 0.5) - (y - liney);
if (h - y < yincr) /* reduce for last one if req'd */
yincr = h - y;
pixRasteropHip(pixs, y, yincr, -sign*hshift, incolor);
y += yincr;
}
for (hshift = -1, y = liney - inityincr; y > 0; hshift--) {
yincr = (y - liney) - (l_int32)(invangle * (hshift - 0.5) + 0.5);
if (y < yincr) /* reduce for last one if req'd */
yincr = y;
pixRasteropHip(pixs, y - yincr, yincr, -sign*hshift, incolor);
y -= yincr;
}
return 0;
}
/*!
* pixVShearIP()
*
* Input: pixs (all depths; not colormapped)
* linex (location of vertical line, measured from origin)
* angle (in radians)
* incolor (L_BRING_IN_WHITE, L_BRING_IN_BLACK);
* Return: 0 if OK; 1 on error
*
* Notes:
* (1) This is an in-place version of pixVShear(); see comments there.
* (2) This brings in 'incolor' pixels from outside the image.
* (3) pixs cannot be colormapped, because the in-place operation
* only blits in 0 or 1 bits, not an arbitrary colormap index.
* (4) Does a vertical full-band shear about the line with (+) shear
* pushing increasingly downward (+y) with increasing x.
*/
l_int32
pixVShearIP(PIX *pixs,
l_int32 linex,
l_float32 radang,
l_int32 incolor)
{
l_int32 sign, w, h;
l_int32 x, xincr, initxincr, vshift;
l_float32 tanangle, invangle;
PROCNAME("pixVShearIP");
if (!pixs)
return ERROR_INT("pixs not defined", procName, 1);
if (incolor != L_BRING_IN_WHITE && incolor != L_BRING_IN_BLACK)
return ERROR_INT("invalid incolor value", procName, 1);
if (pixGetColormap(pixs) != NULL)
return ERROR_INT("pixs is colormapped", procName, 1);
/* Normalize angle */
radang = normalizeAngleForShear(radang, MIN_DIFF_FROM_HALF_PI);
if (radang == 0.0 || tan(radang) == 0.0)
return 0;
sign = L_SIGN(radang);
pixGetDimensions(pixs, &w, &h, NULL);
tanangle = tan(radang);
invangle = L_ABS(1. / tanangle);
initxincr = (l_int32)(invangle / 2.);
xincr = (l_int32)invangle;
pixRasteropVip(pixs, linex - initxincr, 2 * initxincr, 0, incolor);
for (vshift = 1, x = linex + initxincr; x < w; vshift++) {
xincr = (l_int32)(invangle * (vshift + 0.5) + 0.5) - (x - linex);
if (w - x < xincr) /* reduce for last one if req'd */
xincr = w - x;
pixRasteropVip(pixs, x, xincr, sign*vshift, incolor);
x += xincr;
}
for (vshift = -1, x = linex - initxincr; x > 0; vshift--) {
xincr = (x - linex) - (l_int32)(invangle * (vshift - 0.5) + 0.5);
if (x < xincr) /* reduce for last one if req'd */
xincr = x;
pixRasteropVip(pixs, x - xincr, xincr, sign*vshift, incolor);
x -= xincr;
}
return 0;
}
/*-------------------------------------------------------------------------*
* Angle normalization *
*-------------------------------------------------------------------------*/
static l_float32
normalizeAngleForShear(l_float32 radang,
l_float32 mindist)
{
l_float32 pi, diff90;
PROCNAME("normalizeAngleForShear");
/* Bring angle into range from [-pi, pi] */
pi = 3.14159265;
if (radang < -pi || radang > pi)
radang = radang - (l_int32)(radang / pi) * pi;
/* If angle is too close to pi/2 or -pi/2, move away and issue warning */
diff90 = radang - pi / 2.0;
if (L_ABS(diff90) < mindist)
L_WARNING("angle close to pi/2; shifting away", procName);
if (diff90 > -mindist && diff90 < 0.0)
radang = pi / 2.0 - mindist;
else if (diff90 >= 0.0 && diff90 < mindist)
radang = pi / 2.0 + mindist;
diff90 = radang + pi / 2.0;
if (L_ABS(diff90) < mindist)
L_WARNING("angle close to -pi/2; shifting away", procName);
if (diff90 > -mindist && diff90 < 0.0)
radang = -pi / 2.0 - mindist;
else if (diff90 >= 0.0 && diff90 < mindist)
radang = -pi / 2.0 + mindist;
return radang;
}