aasaas

#pragma warning(disable : 4996)
#include <cstdio>
#include <cmath>
#include <iostream>

int type, h, w, max;
unsigned char *pixels;

//useful functions
template <class T>
void swap(T& a, T& b)
{
    T tmp = a;
    a = b;
    b = tmp;
}

float CharTofloat(char *strnum)
{
    float num = 0;
    int i, j;
    for (i = 0; strnum[i] != '\0' && strnum[i] != '.'; i++)
        num = num * 10 + strnum[i] - '0';
    if (strnum[i] == '\0')
        return num;

    for (j = 0; strnum[j + i + 1] != '\0'; j++)
        num = num * 10 + strnum[j + i + 1] - '0';
    for (int k = 0; k < j; k++)
        num /= 10;

    return num;
}

template <class T>
T sign(T num) { return num < 0 ? -1 : num > 0 ? 1 : 0; }

bool OnPic(int coord_x, int coord_y) { return coord_x > 0 && coord_x < w && coord_y > 0 && coord_y < h; }

int Rounding(float num) { return (int)(sign(num) * (fabs(num) + 0.5)); }

//file check
int ReadFile(char* filename)
{
    FILE *f;

    // file checking (closing file)
    if ((f = fopen(filename, "rb")) == NULL)
    {
        printf("Put another filename!\n");
        fclose(f);
        return 0;
    }

    if (fscanf(f, "P%i%i%i%i\n", &type, &w, &h, &max) == NULL)
    {
        printf("Can't read this file\n");
        fclose(f);
        return 0;
    }

    // data checking (closing file)
    if (h < 1 || w < 1)
    {
        printf("Wrong heigh or width\n");
        fclose(f);
        return 0;
    }

    if (type != 5 && type != 6)
    {
        printf("Wrong filetype\n");
        fclose(f);
        return 0;
    }

    if (max != 255)
    {
        printf("Wrong value of max color\n");
        fclose(f);
        return 0;
    }
    unsigned char check;
    pixels = new unsigned char[w * h];

    //memory checking (closing file and deleting array)
    if (pixels == nullptr)
    {
        printf("Not enoudh memory!\n");
        delete[]pixels;
        fclose(f);
        return 0;
    }

    //data checking (closing file and deleting array)
    if (fread(pixels, 1, w * h, f) < w * h)
    {
        printf("Not enougth pixels\n");
        delete[]pixels;
        fclose(f);
        return 0;
    }

    if (fread(&check, 1, 1, f) == 1)
    {
        printf("Too much pixels\n");
        delete[]pixels;
        fclose(f);
        return 0;
    }

    fclose(f);
    return 1;
}

int WriteFile(char* filename)
{
    FILE* f;

    if ((f = fopen(filename, "wb")) == NULL)
    {
        printf("Can't open output file\n");
        delete[] pixels;
        return 0;
    }

    fprintf(f, "P%i\n%i %i\n%i\n", type, w, h, max);
    fwrite(pixels, 1, w * h, f);

    fclose(f);
    return 1;
}

//graphic fucntions
float Correction(float color, float g) { return (g != 0) ? pow(color / max, 1 / g) * max : (color / max <= 0.0031308) ? 12.92 * color : (pow(1.055 * color / max, 1 / 2.4) - 0.055) * max; }

float ToNormal(float color, float g) { return (g != 0) ? pow(color / max, g) * max : (color / max <= 12.92 * 0.0031308) ? color / 12.92 : pow((color / max + 0.055), 2.4) / 1.055 * max; }

float TrueColor(float color) { return color < 0 ? 0 : color > max ? max : color; }

void PutPoint(float x, float y, float color, float g, float intensity)
{
    if (OnPic(x, y))
        pixels[Rounding(y * w + x)] = (int)TrueColor(Correction(ToNormal(pixels[Rounding(y * w + x)], g) * (1 - intensity) + color * intensity, g));
}

//easy line
void VerticalLine(float x1, float y1, float x2, float y2, int color, float g, float thickness)
{
    if ((int)thickness % 2 != 0 && (int)thickness == 0)
        for (int j = y1; j != y2; j += sign(y2 - y1))
            for (int i = -thickness / 2; i <= thickness / 2; i++)
                PutPoint(x1 + i, j, color, g, (1.0 - fabs(i) / thickness * 2.0 / 3.0));
    else
        for (int j = y1; j != y2; j += sign(y2 - y1))
            for (int i = -thickness / 2; i < thickness / 2; i++)
                PutPoint(x1 + i, j, color, g, (1.0 - fabs(i) / thickness * 2.0 / 3.0));
}

void HorizontalLine(float x1, float y1, float x2, float y2, int color, float g, float thickness)
{
    if ((int)thickness % 2 != 0 && (int)thickness == 0)
        for (int j = x1; j != x2; j += sign(x2 - x1))
            for (int i = -thickness / 2; i <= thickness / 2; i++)
                PutPoint(j, y1 + i, color, g, (1.0 - fabs(i) / thickness * 2.0 / 3.0));
    else
        for (int j = x1; j != x2; j += sign(x2 - x1))
            for (int i = -thickness / 2; i < thickness / 2; i++)
                PutPoint(j, y1 + i, color, g, (1.0 - fabs(i) / thickness * 2.0 / 3.0));
}

void EasyLine(float x1, float y1, float x2, float y2, int color, float g, float thickness)
{
    float intensity = 0;
    if (thickness < 1)
        color *= thickness;

    thickness = Rounding(thickness);
    if (y1 == y2)
        HorizontalLine(x1, y1, x2, y2, color, g, thickness);
    else
        VerticalLine(x1, y1, x2, y2, color, g, thickness);
}

//wu line

void WuLine(float x1, float y1, float x2, float y2, int color, float g, float thickness)
{
    bool is_swaped = false;

    if (abs(x1 - x2) < abs(y1 - y2))
    {
        is_swaped = true;
        swap(x1, y1);
        swap(x2, y2);
    }

    if (x1 > x2)
    {
        swap(x1, x2);
        swap(y1, y2);
    }

    float k = (y2 - y1) / (x2 - x1);
//  float thick_x = thickness * cos, thick_y;
    float cur_y = y1 + k * (Rounding(x1) - x1);

    for (float i = x1; i <= x2; i += 1)
    {
        for (float j = y1 - thickness; j <= y1 + thickness; j++)
        {
            if (!is_swaped)
            {
                PutPoint(i, (int)cur_y, color, g, TrueColor((thickness + 1.0) / 2.0 - fabs(cur_y - j) * cos(atan(k)) * max));
                PutPoint(i, (int)cur_y + 1, color, g, cur_y - (int)cur_y);
            }
            else
            {
                PutPoint((int)cur_y, i, color, g, 1 - (cur_y - (int)cur_y));
                PutPoint((int)cur_y + 1, i, color, g, cur_y - (int)cur_y);
            }
            cur_y += k;
        }
    }
}

//main functions
void MakeLine(float x1, float y1, float x2, float y2, float g, int color, float thickness)
{
    if ((Rounding(x1 - x2) == 0) || (Rounding(y1 - y2) == 0))
        EasyLine(x1, y1, x2, y2, color, g, thickness);
    else
        WuLine(x1, y1, x2, y2, color, g, thickness);
}

int main(int argc, char **argv)
{
    if (argc < 9)
    {
        printf("Not enough data!\n");
        return 0;
    }

    if (!ReadFile(argv[1]))
        return 0;

    int color = (int)CharTofloat(argv[3]);
    float thickness = CharTofloat(argv[4]);
    float x1 = CharTofloat(argv[5]), y1 = CharTofloat(argv[6]), x2 = CharTofloat(argv[7]), y2 = CharTofloat(argv[8]);
    float g = argc < 10 ? 0 : CharTofloat(argv[9]);

    MakeLine(x1, y1, x2, y2, g, color, thickness);

    if (!WriteFile(argv[2]))
        return 0;

    delete[] pixels;
    system("pause");
    return 0;
}