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//========================================================================
//
// SplashScreen.cc
//
//========================================================================
//========================================================================
//
// Modified under the Poppler project - http://poppler.freedesktop.org
//
// All changes made under the Poppler project to this file are licensed
// under GPL version 2 or later
//
// Copyright (C) 2009, 2016, 2018, 2020, 2021 Albert Astals Cid <aacid@kde.org>
// Copyright (C) 2012 Fabio D'Urso <fabiodurso@hotmail.it>
//
// To see a description of the changes please see the Changelog file that
// came with your tarball or type make ChangeLog if you are building from git
//
//========================================================================
#include <config.h>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include "goo/gmem.h"
#include "goo/grandom.h"
#include "goo/GooLikely.h"
#include "SplashMath.h"
#include "SplashScreen.h"
static const SplashScreenParams defaultParams = {
splashScreenDispersed, // type
2, // size
2, // dotRadius
1.0, // gamma
0.0, // blackThreshold
1.0 // whiteThreshold
};
//------------------------------------------------------------------------
struct SplashScreenPoint
{
int x, y;
int dist;
};
struct cmpDistancesFunctor
{
bool operator()(const SplashScreenPoint p0, const SplashScreenPoint p1) { return p0.dist < p1.dist; }
};
//------------------------------------------------------------------------
// SplashScreen
//------------------------------------------------------------------------
// If <clustered> is true, this generates a 45 degree screen using a
// circular dot spot function. DPI = resolution / ((size / 2) *
// sqrt(2)). If <clustered> is false, this generates an optimal
// threshold matrix using recursive tesselation. Gamma correction
// (gamma = 1 / 1.33) is also computed here.
SplashScreen::SplashScreen(const SplashScreenParams *params)
{
if (!params) {
params = &defaultParams;
}
screenParams = params;
mat = nullptr;
size = 0;
maxVal = 0;
minVal = 0;
}
void SplashScreen::createMatrix()
{
unsigned char u;
int black, white, i;
const SplashScreenParams *params = screenParams;
// size must be a power of 2, and at least 2
for (size = 2, log2Size = 1; size < params->size; size <<= 1, ++log2Size) {
;
}
switch (params->type) {
case splashScreenDispersed:
mat = (unsigned char *)gmallocn(size * size, sizeof(unsigned char));
buildDispersedMatrix(size / 2, size / 2, 1, size / 2, 1);
break;
case splashScreenClustered:
mat = (unsigned char *)gmallocn(size * size, sizeof(unsigned char));
buildClusteredMatrix();
break;
case splashScreenStochasticClustered:
// size must be at least 2*r
while (size < (params->dotRadius << 1)) {
size <<= 1;
++log2Size;
}
mat = (unsigned char *)gmallocn(size * size, sizeof(unsigned char));
buildSCDMatrix(params->dotRadius);
break;
}
sizeM1 = size - 1;
// do gamma correction and compute minVal/maxVal
minVal = 255;
maxVal = 0;
black = splashRound((SplashCoord)255.0 * params->blackThreshold);
if (black < 1) {
black = 1;
}
int whiteAux = splashRound((SplashCoord)255.0 * params->whiteThreshold);
if (whiteAux > 255) {
white = 255;
} else {
white = whiteAux;
}
for (i = 0; i < size * size; ++i) {
u = splashRound((SplashCoord)255.0 * splashPow((SplashCoord)mat[i] / 255.0, params->gamma));
if (u < black) {
u = (unsigned char)black;
} else if (u >= white) {
u = (unsigned char)white;
}
mat[i] = u;
if (u < minVal) {
minVal = u;
} else if (u > maxVal) {
maxVal = u;
}
}
}
void SplashScreen::buildDispersedMatrix(int i, int j, int val, int delta, int offset)
{
if (delta == 0) {
// map values in [1, size^2] --> [1, 255]
mat[(i << log2Size) + j] = 1 + (254 * (val - 1)) / (size * size - 1);
} else {
buildDispersedMatrix(i, j, val, delta / 2, 4 * offset);
buildDispersedMatrix((i + delta) % size, (j + delta) % size, val + offset, delta / 2, 4 * offset);
buildDispersedMatrix((i + delta) % size, j, val + 2 * offset, delta / 2, 4 * offset);
buildDispersedMatrix((i + 2 * delta) % size, (j + delta) % size, val + 3 * offset, delta / 2, 4 * offset);
}
}
void SplashScreen::buildClusteredMatrix()
{
SplashCoord *dist;
SplashCoord u, v, d;
unsigned char val;
int size2, x, y, x1, y1, i;
size2 = size >> 1;
// initialize the threshold matrix
for (y = 0; y < size; ++y) {
for (x = 0; x < size; ++x) {
mat[(y << log2Size) + x] = 0;
}
}
// build the distance matrix
dist = (SplashCoord *)gmallocn(size * size2, sizeof(SplashCoord));
for (y = 0; y < size2; ++y) {
for (x = 0; x < size2; ++x) {
if (x + y < size2 - 1) {
u = (SplashCoord)x + 0.5 - 0;
v = (SplashCoord)y + 0.5 - 0;
} else {
u = (SplashCoord)x + 0.5 - (SplashCoord)size2;
v = (SplashCoord)y + 0.5 - (SplashCoord)size2;
}
dist[y * size2 + x] = u * u + v * v;
}
}
for (y = 0; y < size2; ++y) {
for (x = 0; x < size2; ++x) {
if (x < y) {
u = (SplashCoord)x + 0.5 - 0;
v = (SplashCoord)y + 0.5 - (SplashCoord)size2;
} else {
u = (SplashCoord)x + 0.5 - (SplashCoord)size2;
v = (SplashCoord)y + 0.5 - 0;
}
dist[(size2 + y) * size2 + x] = u * u + v * v;
}
}
// build the threshold matrix
x1 = y1 = 0; // make gcc happy
for (i = 0; i < size * size2; ++i) {
d = -1;
for (y = 0; y < size; ++y) {
for (x = 0; x < size2; ++x) {
if (mat[(y << log2Size) + x] == 0 && dist[y * size2 + x] > d) {
x1 = x;
y1 = y;
d = dist[y1 * size2 + x1];
}
}
}
// map values in [0, 2*size*size2-1] --> [1, 255]
val = 1 + (254 * (2 * i)) / (2 * size * size2 - 1);
mat[(y1 << log2Size) + x1] = val;
val = 1 + (254 * (2 * i + 1)) / (2 * size * size2 - 1);
if (y1 < size2) {
mat[((y1 + size2) << log2Size) + x1 + size2] = val;
} else {
mat[((y1 - size2) << log2Size) + x1 + size2] = val;
}
}
gfree(dist);
}
// Compute the distance between two points on a toroid.
int SplashScreen::distance(int x0, int y0, int x1, int y1)
{
int dx0, dx1, dx, dy0, dy1, dy;
dx0 = abs(x0 - x1);
dx1 = size - dx0;
dx = dx0 < dx1 ? dx0 : dx1;
dy0 = abs(y0 - y1);
dy1 = size - dy0;
dy = dy0 < dy1 ? dy0 : dy1;
return dx * dx + dy * dy;
}
// Algorithm taken from:
// Victor Ostromoukhov and Roger D. Hersch, "Stochastic Clustered-Dot
// Dithering" in Color Imaging: Device-Independent Color, Color
// Hardcopy, and Graphic Arts IV, SPIE Vol. 3648, pp. 496-505, 1999.
void SplashScreen::buildSCDMatrix(int r)
{
SplashScreenPoint *dots, *pts;
int dotsLen, dotsSize;
char *tmpl;
char *grid;
int *region, *dist;
int x, y, xx, yy, x0, x1, y0, y1, i, j, d, iMin, dMin, n;
// generate the random space-filling curve
pts = (SplashScreenPoint *)gmallocn(size * size, sizeof(SplashScreenPoint));
i = 0;
for (y = 0; y < size; ++y) {
for (x = 0; x < size; ++x) {
pts[i].x = x;
pts[i].y = y;
++i;
}
}
for (i = 0; i < size * size; ++i) {
j = i + (int)((double)(size * size - i) * grandom_double());
x = pts[i].x;
y = pts[i].y;
pts[i].x = pts[j].x;
pts[i].y = pts[j].y;
pts[j].x = x;
pts[j].y = y;
}
// construct the circle template
tmpl = (char *)gmallocn((r + 1) * (r + 1), sizeof(char));
for (y = 0; y <= r; ++y) {
for (x = 0; x <= r; ++x) {
tmpl[y * (r + 1) + x] = (x * y <= r * r) ? 1 : 0;
}
}
// mark all grid cells as free
grid = (char *)gmallocn(size * size, sizeof(char));
for (y = 0; y < size; ++y) {
for (x = 0; x < size; ++x) {
grid[(y << log2Size) + x] = 0;
}
}
// walk the space-filling curve, adding dots
dotsLen = 0;
dotsSize = 32;
dots = (SplashScreenPoint *)gmallocn(dotsSize, sizeof(SplashScreenPoint));
for (i = 0; i < size * size; ++i) {
x = pts[i].x;
y = pts[i].y;
if (!grid[(y << log2Size) + x]) {
if (dotsLen == dotsSize) {
dotsSize *= 2;
dots = (SplashScreenPoint *)greallocn(dots, dotsSize, sizeof(SplashScreenPoint));
}
dots[dotsLen++] = pts[i];
for (yy = 0; yy <= r; ++yy) {
y0 = (y + yy) % size;
y1 = (y - yy + size) % size;
for (xx = 0; xx <= r; ++xx) {
if (tmpl[yy * (r + 1) + xx]) {
x0 = (x + xx) % size;
x1 = (x - xx + size) % size;
grid[(y0 << log2Size) + x0] = 1;
grid[(y0 << log2Size) + x1] = 1;
grid[(y1 << log2Size) + x0] = 1;
grid[(y1 << log2Size) + x1] = 1;
}
}
}
}
}
gfree(tmpl);
gfree(grid);
// assign each cell to a dot, compute distance to center of dot
region = (int *)gmallocn(size * size, sizeof(int));
dist = (int *)gmallocn(size * size, sizeof(int));
for (y = 0; y < size; ++y) {
for (x = 0; x < size; ++x) {
iMin = 0;
dMin = distance(dots[0].x, dots[0].y, x, y);
for (i = 1; i < dotsLen; ++i) {
d = distance(dots[i].x, dots[i].y, x, y);
if (d < dMin) {
iMin = i;
dMin = d;
}
}
region[(y << log2Size) + x] = iMin;
dist[(y << log2Size) + x] = dMin;
}
}
// compute threshold values
for (i = 0; i < dotsLen; ++i) {
n = 0;
for (y = 0; y < size; ++y) {
for (x = 0; x < size; ++x) {
if (region[(y << log2Size) + x] == i) {
pts[n].x = x;
pts[n].y = y;
pts[n].dist = distance(dots[i].x, dots[i].y, x, y);
++n;
}
}
}
std::sort(pts, pts + n, cmpDistancesFunctor());
for (j = 0; j < n; ++j) {
// map values in [0 .. n-1] --> [255 .. 1]
mat[(pts[j].y << log2Size) + pts[j].x] = 255 - (254 * j) / (n - 1);
}
}
gfree(pts);
gfree(region);
gfree(dist);
gfree(dots);
}
SplashScreen::SplashScreen(const SplashScreen *screen)
{
screenParams = screen->screenParams;
size = screen->size;
sizeM1 = screen->sizeM1;
log2Size = screen->log2Size;
mat = (unsigned char *)gmallocn(size * size, sizeof(unsigned char));
if (likely(mat != nullptr)) {
memcpy(mat, screen->mat, size * size * sizeof(unsigned char));
}
minVal = screen->minVal;
maxVal = screen->maxVal;
}
SplashScreen::~SplashScreen()
{
gfree(mat);
}