Lab 14

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <math.h>
#include <errno.h>
#include <stdlib.h>
#include "graphics.h"

double f(double x); //Подпрограмма, вычисляющая значение функции x^2*exp(-x)
void draw_chart(double a, double b, int x_steps, int y_steps); //Подпрограмма, рисующая график функции x^2*exp(-x)
void draw_histogram(double a, double b, int x_steps, int y_steps); //Подпрограмма, рисующая гистограмму функции x^2*exp(-x)
void save_chart(); //Подпрограмма, рисующая и сохраняющая гистограмму функции x^2*exp(-x)

int main()
{
    int res;
    double a = -1, b = 2;

    int gdriver = DETECT, gmode;
    initgraph(&gdriver, &gmode, ""); //Инициализация графического режима
    res = graphresult();
    if (res != grOk)
    {
        printf("An error has occured while initializing graphicsl output.");
        return -1;
    }

    draw_chart(a, b, 78, 25);
    draw_histogram(a, b, 60, 80);
    save_chart();
    closegraph(); //Выход из графического режима
    return 0;
}

double f(double x) //Подпрограмма, вычисляющая значение функции x^2*exp(-x)
{
    double result;
    result = x * x;
    return (result / exp(x));
}

void draw_chart(double a, double b, int x_steps, int y_steps) //Подпрограмма, рисующая график функции x^2*exp(-x)
{
    int i, max_x, max_y, zero_x, zero_y;
    double x, y;
    int poly[6];
    char str[10];
    double top_y, x_inc, del_x, del_y;
    double len = b - a; //Длина отрезка
    double offset_percent; //Процент от максимальных координат, который отступается от осей

    max_x = getmaxx();
    max_y = getmaxy();

    //Сделать фон белым, а цвет рисования чёрным.
    setfillstyle(1, WHITE);
    bar(0, 0, max_x, max_y);
    setcolor(BLACK);
    setlinestyle(0, 0, 1);
    setbkcolor(WHITE);

    offset_percent = 0.1;

    //Вычисляем положение нуля на оси x
    zero_x = 0;
    if (a < 0 && b >0)
    {
        zero_x += (fabs(a)/len) * x_steps;
    }
    if (a < 0 && b < 0)
    {
        zero_x = x_steps - 1;
    }

    zero_y = y_steps - 1;

    line(max_x * offset_percent, max_y * (1 - offset_percent), max_x * (1 - offset_percent), max_y * (1 - offset_percent)); //Ось x
    del_x = (max_x * (1 - 2 * offset_percent)) / x_steps; //Цена деления по оси x в пикселя
    for (i = 0; i < x_steps; i++)
    {
        line(max_x * offset_percent + i * del_x, max_y * (1 - offset_percent) + 1, max_x * offset_percent + i * del_x, max_y * (1 - offset_percent) - 1);
        /*if (i % 10 == 0)
        {
            sprintf(str, "%3.2f", del_x * i); //TODO: переделать
            outtextxy(max_x * offset_percent + i * del_x - 10, zero_y + 10, str);
        }*/
    }
    poly[0] = max_x * (1 - offset_percent) - 5;
    poly[1] = max_y * (1 - offset_percent) + 3;
    poly[2] = max_x * (1 - offset_percent);
    poly[3] = max_y * (1 - offset_percent);
    poly[4] = max_x * (1 - offset_percent) - 5;
    poly[5] = max_y * (1 - offset_percent) - 3;
    drawpoly(3, poly);
    outtextxy(max_x * (1 - offset_percent), max_y * (1 - offset_percent) + 5, "x");

    line(max_x * offset_percent + zero_x * del_x, max_y * (1 - offset_percent), max_x * offset_percent + zero_x * del_x, max_y * offset_percent); //Ось y
    del_y = (max_y * (1 - 2 * offset_percent)) / y_steps; //Цена деления по оси y в пикселях
    for (i = 0; i < y_steps; i++)
    {
        line(max_x * offset_percent + zero_x * del_x - 1, max_y * (1 - offset_percent) - i * del_y, max_x * offset_percent + zero_x * del_x + 1, max_y * (1 - offset_percent) - i * del_y);
    }
    poly[0] = max_x * offset_percent + zero_x * del_x + 3;
    poly[1] = max_y * offset_percent + 5;
    poly[2] = max_x * offset_percent + zero_x * del_x;
    poly[3] = max_y * offset_percent;
    poly[4] = max_x * offset_percent + zero_x * del_x - 3;
    poly[5] = max_y * offset_percent + 5;
    drawpoly(3, poly);
    outtextxy(max_x * offset_percent + zero_x * del_x - 15, max_y * offset_percent - 10, "y");
    //TODO: добавить подписи

    top_y = (f(a) > f(b)) ?  f(a) : f (b); //Наибольшее значение по y. TODO: исправить
    del_y = (max_y * (1 - 2 *offset_percent)) / top_y; //Цена деления по оси y;

    x_inc = len / x_steps;
    double prev_x, prev_y, cur_x, cur_y;
    x = a;
    for (i = 0; i < x_steps; i++, x += x_inc)
    {
        cur_x = max_x * offset_percent + i * del_x;
        cur_y = max_y * (1 - offset_percent) - f(x) * del_y;
        setfillstyle(1, BLACK);
        circle(cur_x, cur_y, 2);
        floodfill(cur_x, cur_y, BLACK);
        prev_x = cur_x;
        prev_y = cur_y;
    }
    system("pause");
}

void draw_histogram(double a, double b, int x_steps, int y_steps)
{
    int i, max_x, max_y, zero_x, zero_y, y;
    double x, tmp;
    int poly[6];
    char str[10];
    double top_y, x_inc, del_x, del_y;
    double len = b - a; //Длина отрезка
    double offset_percent; //Процент от максимальных координат, который отступается от осей.

    max_x = getmaxx();
    max_y = getmaxy();

    //Сделать фон белым, а цвет рисования чёрным.
    setfillstyle(1, 15);
    bar(0, 0, max_x, max_y);
    setcolor(0);
    setlinestyle(0, 0, 1);

    offset_percent = 0.1;

    //Вычисляем положение нуля по вертикали (на оси y)
    zero_x = 0;
    if (a < 0 && b >0)
    {
        zero_x += (fabs(a) / len) * x_steps;
    }
    if (a < 0 && b < 0)
    {
        zero_x = x_steps - 1;
    }

    zero_y = 0;

    del_y = (max_x * (1 - 2 * offset_percent)) / y_steps;
    del_x = max_y * (1 - 2 * offset_percent) / x_steps;
    line(max_x * offset_percent, max_y * offset_percent + zero_x * del_y, max_x * (1 - offset_percent), max_y * offset_percent + zero_x * del_y); //Ось y (горизонтальная)
    for (i = 0; i < y_steps; i++)
    {
        line(max_x * offset_percent + i * del_y, max_y * offset_percent + zero_x * del_y + 1, max_x * offset_percent + i * del_y, max_y * offset_percent + zero_x * del_y - 1);
    }
    poly[0] = max_x * (1 - offset_percent) - 5;
    poly[1] = max_y * offset_percent + zero_x * del_y - 3;
    poly[2] = max_x * (1 - offset_percent);
    poly[3] = max_y * offset_percent + zero_x * del_y;
    poly[4] = max_x * (1 - offset_percent)- 5;
    poly[5] = max_y * offset_percent + zero_x * del_y + 3;
    drawpoly(3, poly);
    outtextxy(max_x * (1 - offset_percent), max_y * offset_percent + zero_x * del_y + 5, "y");

    line(max_x * offset_percent , max_y * offset_percent, max_x * offset_percent , max_y *  (1 - offset_percent)); //Ось x (вертикальная)
    del_x = (max_y * (1 - 2 * offset_percent)) / x_steps;
    for (i = 0; i < x_steps; i++)
    {
        line(max_x *offset_percent - 1, max_y * offset_percent + del_x * i, max_x *offset_percent + 1, max_y * offset_percent + del_x * i);
    }
    poly[0] = max_x * offset_percent + 3;
    poly[1] = max_y * (1 - offset_percent) - 5;
    poly[2] = max_x * offset_percent;
    poly[3] = max_y * (1 - offset_percent);
    poly[4] = max_x * offset_percent - 3;
    poly[5] = max_y * (1 - offset_percent) - 5;
    drawpoly(3, poly);
    outtextxy(max_x *offset_percent - 15, max_y * (1 - offset_percent) , "x");

    tmp = del_y;
    top_y = (f(a) > f(b)) ? f(a) : f(b); //Наибольшее значение по y. TODO: исправить
    del_y = (max_x * (1 - 2 * offset_percent)) / top_y; //Цена делания по оси y (горизонтальная)

    x_inc = len / x_steps;

    double prev_x, prev_y, cur_x, cur_y;
    settextstyle(SMALL_FONT, HORIZ_DIR, 3);
    setfillstyle(1, CYAN);

    /*for (i = 1; i < y_steps - 1; i++)
    {
        if (i % 10 == 0)
        {
            sprintf(str, "%3.2f", f(a + x_inc * i));
            outtextxy(max_x * offset_percent + i * tmp, max_y * offset_percent + zero_x * tmp + 10, str);
        }
    }*/

    for (x = a, i = 0; i < x_steps; i++, x += x_inc)
    {
        tmp = f(x);
        cur_y = max_x * offset_percent + tmp * del_y;
        cur_x = max_y * offset_percent + i * del_x;

        if (cur_y - max_x * offset_percent < 2)
        {
            circle(cur_y, cur_x, 2);
        }
        else
        {
            y = max_x * offset_percent+2;
            while (y <= cur_y)
            {
                circle(y, cur_x, 2);
                y += 4;
            }
        }
        sprintf(str, "%f", tmp);
        outtextxy(cur_y + 1, cur_x - 3, str);
        prev_x = cur_x;
        prev_y = cur_y;
    }

}


void save_chart()
{
    writeimagefile(NULL, 0, 0, getmaxx() - 1, getmaxy() - 1, 1, NULL);
}