| 1 | // |
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| 2 | // HtmlUtils.h |
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| 3 | // |
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| 4 | // Created on: Jun 8, 2011 |
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| 5 | // Author: Joshua Richardson <jric@chegg.com> |
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| 6 | // Copyright 2011 |
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| 7 | // |
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| 8 | // All changes made under the Poppler project to this file are licensed |
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| 9 | // under GPL version 2 or later |
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| 10 | // |
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| 11 | // Copyright (C) 2011 Joshua Richardson <jric@chegg.com> |
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| 12 | // |
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| 13 | // To see a description of the changes please see the Changelog file that |
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| 14 | // came with your tarball or type make ChangeLog if you are building from git |
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| 15 | // |
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| 16 | //======================================================================== |
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| 17 | |
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| 18 | #ifndef HTMLUTILS_H_ |
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| 19 | #define HTMLUTILS_H_ |
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| 20 | |
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| 21 | #include <cmath> // fabs |
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| 22 | |
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| 23 | // Returns true iff the difference between a and b is less than the threshold |
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| 24 | // We always use fuzzy math when comparing decimal numbers due to imprecision |
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| 25 | inline bool is_within(double a, double thresh, double b) |
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| 26 | { |
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| 27 | return fabs(x: a - b) < thresh; |
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| 28 | } |
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| 29 | |
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| 30 | inline bool rot_matrices_equal(const double *const mat0, const double *const mat1) |
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| 31 | { |
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| 32 | return is_within(a: mat0[0], thresh: .1, b: mat1[0]) && is_within(a: mat0[1], thresh: .1, b: mat1[1]) && is_within(a: mat0[2], thresh: .1, b: mat1[2]) && is_within(a: mat0[3], thresh: .1, b: mat1[3]); |
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| 33 | } |
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| 34 | |
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| 35 | // rotation is (cos q, sin q, -sin q, cos q, 0, 0) |
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| 36 | // sin q is zero iff there is no rotation, or 180 deg. rotation; |
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| 37 | // for 180 rotation, cos q will be negative |
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| 38 | inline bool isMatRotOrSkew(const double *const mat) |
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| 39 | { |
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| 40 | return mat[0] < 0 || !is_within(a: mat[1], thresh: .1, b: 0); |
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| 41 | } |
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| 42 | |
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| 43 | // Alters the matrix so that it does not scale a vector's x component; |
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| 44 | // If the matrix does not skew, then that will also normalize the y |
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| 45 | // component, keeping any rotation, but removing scaling. |
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| 46 | inline void normalizeRotMat(double *mat) |
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| 47 | { |
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| 48 | double scale = fabs(x: mat[0] + mat[1]); |
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| 49 | if (!scale) { |
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| 50 | return; |
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| 51 | } |
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| 52 | for (int i = 0; i < 4; i++) { |
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| 53 | mat[i] /= scale; |
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| 54 | } |
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| 55 | } |
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| 56 | |
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| 57 | #endif /* HTMLUTILS_H_ */ |
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| 58 | |
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