save_image.cpp

#include <tuple>
#include <iostream>

#include <FreeImage.h>
#include "window.hpp"
#include "save_image.hpp"

std::tuple<int, int, int> get_rgb_piecewise_linear(int n, int iter_max) {
	int N = 256;
	int N3 = N * N * N;

	double t = (double)n / (double)iter_max;
	n = (int)(t * (double)N3);

	int b = n / (N * N);
	int nn = n - b * N * N;
	int r  = nn / N;
	int g = nn - r * N;
	return std::tuple<int, int, int>(r, g, b);
}

std::tuple<int, int, int> get_rgb_smooth(int n, int iter_max) {
	double t = (double)n / (double)iter_max;

	int r = (int)(9 * (1 - t) * t * t * t * 255);
	int g = (int)(15 * (1 - t) * (1 - t) * t * t * 255);
	int b = (int)(8.5 * (1 - t) * (1 - t) * (1 - t) * t * 255);

	return std::tuple<int, int, int>(r, g, b);
}

void plot(window<int> & scr, std::vector<int> & colors, int iter_max, const char * fname, bool smooth_color) {
	#ifdef FREEIMAGE_LIB
		FreeImage_Initialise();
	#endif

	unsigned int width = scr.width(), height = scr.height();
	FIBITMAP * bitmap = FreeImage_Allocate(width, height, 32);
	int k = 0;
	std::tuple<int, int, int> rgb;
	for (int i = scr.y_min(); i < scr.y_max(); ++i) {
		for (int j = scr.x_min(); j < scr.x_max(); ++j) {
			int n = colors[k];

			if (!smooth_color)
				rgb = get_rgb_piecewise_linear(n, iter_max);
			else
				rgb = get_rgb_smooth(n, iter_max);

			RGBQUAD col;
			col.rgbRed = std::get<0>(rgb);
			col.rgbGreen = std::get<1>(rgb);
			col.rgbBlue = std::get<2>(rgb);
			col.rgbReserved = 255;

			FreeImage_SetPixelColor(bitmap, j, i, &col);
			++k;
		}
	}

	FreeImage_Save(FIF_PNG, bitmap, fname, PNG_DEFAULT);
	FreeImage_Unload(bitmap);

	#ifdef FREEIMAGE_LIB
		FreeImage_DeInitialise();
	#endif
}