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1/* SPDX-License-Identifier: GPL-3.0
2 * VisHash - An easy way to visualise hashes
3 *
4 * image.cpp
5 *
6 * COPYRIGHT NOTICE
7 * Copyright (C) 2025 0x4248 and contributors
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the license is not changed.
10 *
11 * This software is free and open source. Licensed under the GNU general
12 * public license version 3.0 as published by the Free Software Foundation.
13*/
14
15#include <vector>
16#include <openssl/sha.h>
17#include <cstring>
18#include <cmath>
19
20#include "const.h"
21
22std::vector<std::vector<int>> heatmap(const std::vector<uint8_t> &digest) {
23    std::vector<std::vector<int>> grid(H, std::vector<int>(W, 0));
24
25    uint8_t buf[SHA256_DIGEST_LENGTH];
26    memcpy(buf, digest.data(), digest.size());
27
28    int samples = H * W * 3;
29    for (int i = 0; i < samples; i++) {
30        uint8_t tmp[SHA256_DIGEST_LENGTH];
31        SHA256(buf, SHA256_DIGEST_LENGTH, tmp);
32        memcpy(buf, tmp, SHA256_DIGEST_LENGTH);
33
34
35        int y = buf[0] % H;
36        int x = buf[1] % W;
37
38        grid[y][x]++;
39    }
40
41    return grid;
42}
43
44std::vector<std::vector<int>> blur(const std::vector<std::vector<int>>& grid) {
45    std::vector<std::vector<int>> out = grid;
46
47    static int kernel[3][3] = {
48        {1, 2, 1},
49        {2, 4, 2},
50        {1, 2, 1}
51    };
52
53    int H = grid.size();
54    int W = grid[0].size();
55
56    for (int y = 0; y < H; y++) {
57        for (int x = 0; x < W; x++) {
58
59            int sum = 0, weight = 0;
60            for (int dy = -1; dy <= 1; dy++) {
61                for (int dx = -1; dx <= 1; dx++) {
62                    int ny = y + dy;
63                    int nx = x + dx;
64                    if (ny >= 0 && ny < H && nx >= 0 && nx < W) {
65                        int w = kernel[dy+1][dx+1];
66                        sum += grid[ny][nx] * w;
67                        weight += w;
68                    }
69                }
70            }
71
72            out[y][x] = sum / weight;
73        }
74    }
75
76    return out;
77}
78
79int apply_contrast(int v, int maxv, double gamma = 1.8) {
80    if (maxv == 0) return 0;
81    double norm = (double)v / maxv;
82    norm = pow(norm, gamma);
83    return (int)(norm * maxv);
84}
85
86char level_to_char(int level, int maxLevel)
87{
88    if (maxLevel == 0) return ' ';
89
90    int adjusted = apply_contrast(level, maxLevel, 1.8);
91
92    int idx = (adjusted * (RAMP.size() - 1)) / maxLevel;
93    return RAMP[idx];
94}
95
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