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/*************************************************************************
** utility.cpp **
** **
** This file is part of dvisvgm -- a fast DVI to SVG converter **
** Copyright (C) 2005-2022 Martin Gieseking <martin.gieseking@uos.de> **
** **
** This program is free software; you can redistribute it and/or **
** modify it under the terms of the GNU General Public License as **
** published by the Free Software Foundation; either version 3 of **
** the License, or (at your option) any later version. **
** **
** This program is distributed in the hope that it will be useful, but **
** WITHOUT ANY WARRANTY; without even the implied warranty of **
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the **
** GNU General Public License for more details. **
** **
** You should have received a copy of the GNU General Public License **
** along with this program; if not, see <http://www.gnu.org/licenses/>. **
*************************************************************************/
#include <algorithm>
#include <cctype>
#include <cmath>
#include <fstream>
#include <functional>
#include <iterator>
#include "utility.hpp"
using namespace std;
/** Computes the singular value decomposition of a given 2x2 matrix M
* so that M = rotate(phi)*scale(sx,sy)*rotate(theta), where
* rotate(t):={{cos t, -sin t}, {sin t, cos t}} and scale(sx, sy):={{sx, 0}, {0, sy}}.
* The corresponding math can be found in Jim Blinn: "Consider the Lowly 2x2 Matrix"
* https://ieeexplore.ieee.org/document/486688
* Also published in "Jim Blinn's Corner: Notation, Notation, Notation", pp. 69--95.
* @param[in] m matrix {{m00, m01}, {m10, m11}} where the inner pairs denote the rows
* @return vector {phi, sx, sy, theta} */
vector<double> math::svd (const double (&m)[2][2]) {
double phi=0, theta=0, sx=0, sy=0;
if (m[0][0] != 0 || m[0][1] != 0 || m[1][0] != 0 || m[1][1] != 0) {
double e = (m[0][0] + m[1][1])/2; // = cos(phi+theta)*(sx+sy)/2
double f = (m[0][0] - m[1][1])/2; // = cos(phi-theta)*(sx-sy)/2
double g = (m[1][0] + m[0][1])/2; // = sin(phi-theta)*(sx-sy)/2
double h = (m[1][0] - m[0][1])/2; // = sin(phi+theta)*(sx+sy)/2
double hyp1 = hypot(e, h); // = (sx+sy)/2
double hyp2 = hypot(f, g); // = (sx-sy)/2
sx = hyp1+hyp2;
sy = hyp1-hyp2;
if (hyp2 == 0) // uniformly scaled rotation?
theta = atan2(h, e);
else if (hyp1 == 0) // uniformly scaled reflection?
theta = -atan2(g, f);
else {
double a1 = atan2(g, f); // = phi-theta (g/f = tan(phi-theta))
double a2 = atan2(h, e); // = phi+theta (h/e = tan(phi+theta))
phi = (a2+a1)/2;
theta = (a2-a1)/2;
}
}
return vector<double>{phi, sx, sy, theta};
}
/** Normalizes an angle to the interval [-mod, mod). */
double math::normalize_angle (double angle, double mod) {
angle = fmod(angle+mod, 2.0*mod);
if (angle < 0)
angle += 2.0*mod;
return angle-mod;
}
double math::normalize_0_2pi (double rad) {
rad = fmod(rad, TWO_PI);
if (rad < 0)
rad += TWO_PI;
return rad;
}
/** Returns a given string with leading and trailing whitespace removed.
* @param[in] str the string to process
* @param[in] ws characters treated as whitespace
* @return the trimmed string */
string util::trim (const std::string &str, const char *ws) {
auto first = str.find_first_not_of(ws);
if (first == string::npos)
return "";
auto last = str.find_last_not_of(ws);
return str.substr(first, last-first+1);
}
/** Removes leading and trailing whitespace from a given string, and replaces
* all other whitespace sequences by single spaces.
* @param[in] str the string to process
* @param[in] ws characters treated as whitespace
* @return the normalized string */
string util::normalize_space (string str, const char *ws) {
str = trim(str);
auto first = str.find_first_of(ws);
while (first != string::npos) {
auto last = str.find_first_not_of(ws, first);
str.replace(first, last-first, " ");
first = str.find_first_of(ws, first+1);
}
return str;
}
/** Replaces all occurences of a substring with another string.
* @param[in] str string to search through
* @param[in] find string to look for
* @param[in] repl replacement for "find"
* @return the resulting string */
string util::replace (string str, const string &find, const string &repl) {
if (!find.empty() && !repl.empty()) {
auto first = str.find(find);
while (first != string::npos) {
str.replace(first, find.length(), repl);
first = str.find(find, first+repl.length());
}
}
return str;
}
/** Splits a string at all occurences of a given separator string and
* returns the substrings.
* @param[in] str string to split
* @param[in] sep separator to look for
* @return the substrings between the separators */
vector<string> util::split (const string &str, const string &sep) {
vector<string> parts;
if (str.empty() || sep.empty())
parts.push_back(str);
else {
string::size_type left=0;
while (left <= str.length()) {
auto right = str.find(sep, left);
if (right == string::npos) {
parts.push_back(str.substr(left));
left = string::npos;
}
else {
parts.push_back(str.substr(left, right-left));
left = right+sep.length();
}
}
}
return parts;
}
string util::tolower (const string &str) {
string ret=str;
transform(str.begin(), str.end(), ret.begin(), ::tolower);
return ret;
}
/** Converts a double to a string and strips redundant trailing digits/dots. */
string util::to_string (double val) {
string str = std::to_string(val);
if (str.find('.') != string::npos) { // double value and not an integer?
auto pos = str.find_last_not_of('0');
if (pos != string::npos) // trailing zeros
str.erase(pos+1, string::npos);
if (str.back() == '.') // trailing dot?
str.pop_back();
}
return str;
}
/** Returns the integer part of log10 of a given integer \f$n>0\f$.
* If \f$n<0\f$, the result is 0. */
int util::ilog10 (int n) {
int result = 0;
while (n >= 10) {
result++;
n /= 10;
}
return result;
}
/** Returns the contents of a file.
* @param[in] fname name/path of the file */
string util::read_file_contents (const string &fname) {
ifstream ifs(fname, ios::binary);
return string(istreambuf_iterator<char>(ifs.rdbuf()), istreambuf_iterator<char>());
}
/** Writes a sequence of bytes given as a string to a file.
* @param[in] name/path of the file to write
* @param[in] start iterator pointing to the begin of the byte sequence
* @param[in] end iterator pointing to the first byte after the byte sequence to write */
void util::write_file_contents (const string &fname, string::iterator start, string::iterator end) {
ofstream ofs(fname, ios::binary);
copy(start, end, ostream_iterator<char>(ofs));
}
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