libpaint/painter.c

#include "painter.h"

#include "stdio.h"

lp_pixel lp_rgb(uint8_t r, uint8_t g, uint8_t b) {
    return (lp_pixel){r, g, b};
}

lp_painter *lp_painter_create(size_t width, size_t height) {
    lp_painter *painter = malloc(sizeof(lp_painter));
    lp_pixel *buf = malloc(width * height * sizeof(lp_pixel));

    painter->buf = buf;
    painter->buf_length = width * height;
    painter->width = width;
    painter->height = height;

    return painter;
}

void lp_painter_free(lp_painter *painter) {
    if (painter) {
        if (painter->buf) {
            free(painter->buf);
        }
        free(painter);
    }
}

static inline void lp_painter_put_pixel(lp_painter *painter, lp_pixel color, size_t x, size_t y) {
    size_t index = y * painter->width + x;
    painter->buf[index] = color;
}

void lp_painter_fill_rect(lp_painter *painter, lp_pixel fill_color, size_t pos_x, size_t pos_y, size_t width, size_t height) {
    for (size_t y = pos_y; y < pos_y + height; y++) {
        for (size_t x = pos_x; x < pos_x + width; x++) {
            lp_painter_put_pixel(painter, fill_color, pos_x, pos_y);
        }
    }
}

void _lp_painter_line_low(lp_painter *p, lp_pixel color, int32_t x0, int32_t y0, int32_t x1, int32_t y1) {
    int32_t dx = x1 - x0;
    int32_t dy = y1 - y0;
    int32_t y_inc = 1;
    if (dy < 0) {
        y_inc = -1;
        dy = -dy;
    }
    int32_t d = dy * 2 - dx;
    int32_t y = y0;
    
    for (int32_t x = x0; x < x1; x++) {
        lp_painter_put_pixel(p, color, x, y);
        if (d > 0) {
            y += y_inc;
            d += 2 * (dy - dx);
        } else {
            d += 2 * dy;
        }
    }
}


void _lp_painter_line_high(lp_painter *p, lp_pixel color, int32_t x0, int32_t y0, int32_t x1, int32_t y1) {
    int32_t dx = x1 - x0;
    int32_t dy = y1 - y0;
    int32_t x_inc = 1;
    if (dx < 0) {
        x_inc = -1;
        dx = -dx;
    }
    int32_t d = dx * 2 - dy;
    int32_t x = x0;
    
    for (int32_t y = y0; y < y1; y++) {
        lp_painter_put_pixel(p, color, x, y);
        if (d > 0) {
            x += x_inc;
            d += 2 * (dx - dy);
        } else {
            d += 2 * dx;
        }
    }
}
void lp_painter_line(lp_painter *p, lp_pixel color, int32_t x0, int32_t y0, int32_t x1, int32_t y1) {
    if (abs(y1 - y0) < abs(x1 -x0)) {
        if (x0 > x1) {
            _lp_painter_line_low(p, color, x1, y1, x0, y0);
        } else {
            _lp_painter_line_low(p, color, x0, y0, x1, y1);
        }
    } else {
        if (y0 > y1) {
            _lp_painter_line_high(p, color, x1, y1, x0, y0);
        } else {
            _lp_painter_line_high(p, color, x0, y0, x1, y1);
        }
    }
}

void lp_painter_save_ppm(lp_painter *painter, const char *filename) {
    FILE *fp = fopen(filename, "w");
    if (fp == NULL) {
        fprintf(stderr, "Failed to open file");
        return;
    }
    fprintf(fp, "P6\n%zu %zu 255\n", painter->width, painter->height);
    for (size_t i = 0; i < painter->width * painter->height; i++) {
        fwrite(&painter->buf[i].r, sizeof(uint8_t), 1, fp);
        fwrite(&painter->buf[i].g, sizeof(uint8_t), 1, fp);
        fwrite(&painter->buf[i].b, sizeof(uint8_t), 1, fp);
    }
    fwrite(painter->buf, sizeof(lp_pixel), painter->width * painter->height, fp);
    fclose(fp);
}