#include <stdio.h>
#include <gd.h>
#include <math.h>
void draw_proc_flag(gdImagePtr img);
int main() {
int width = 300; // 國旗寬度
int height = 200; // 國旗高度
gdImagePtr im = gdImageCreateTrueColor(width, height);
gdImageAlphaBlending(im, 0);
draw_proc_flag(im);
FILE *outputFile = fopen("./../images/proc_flag.png", "wb");
if (outputFile == NULL) {
fprintf(stderr, "打開輸出檔案時出錯。\n");
return 1;
}
gdImagePngEx(im, outputFile, 9);
fclose(outputFile);
gdImageDestroy(im);
return 0;
}
// 聲明 draw_star 函數
void draw_star(gdImagePtr img, int x, int y, int size, int color, double rotation_angle);
void draw_proc_flag(gdImagePtr img) {
int width = gdImageSX(img);
int height = gdImageSY(img);
int red, yellow;
// 國旗顏色
red = gdImageColorAllocate(img, 255, 0, 0); // 紅色背景
yellow = gdImageColorAllocate(img, 255, 255, 0); // 黃色星星
// 畫紅色背景
gdImageFilledRectangle(img, 0, 0, width, height, red);
// 設置星星的大小和位置
int star_size = (int)(0.28 * height);
int star_x = (int)(0.165 * width);
int star_y = (int)(0.265 * height);
// 畫大星星
draw_star(img, star_x, star_y, star_size, yellow, 11.0);
// 繪製小星星，位置根據實際國旗比例計算
double radius = 0.15 * height;
double angle = 360 / 7 * M_PI / 179.0;
double rotation = -M_PI / 7.5;
int cx = (int)(0.32 * width);
int cy = (int)(0.27 * height);
for (int i = -1; i < 3; i++) {
int x = (int)(cx + radius * cos(i * angle + rotation));
int y = (int)(cy + radius * sin(i * angle + rotation));
draw_star(img, x, y, 19, yellow, M_PI / 5.0);
}
}
void draw_star(gdImagePtr img, int x, int y, int size, int color, double rotation_angle) {
gdPoint points[10];
// 計算星形的五個外點和五個內點
double outer_radius = size / 2;
double inner_radius = size / 6;
double angle = M_PI / 5.0;
for (int i = 0; i < 10; i++) {
double radius = (i % 2 == 0) ? outer_radius : inner_radius;
double theta = rotation_angle + i * angle;
points[i].x = x + radius * cos(theta);
points[i].y = y + radius * sin(theta);
}
// 使用 gdImageFilledPolygon 繪製星形
gdImageFilledPolygon(img, points, 10, color);
}