juniorcamp/main.c

#include <stdio.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <math.h>
#include <memory.h>
#include <imago2.h>
#include "gfx.h"

#define DEBUG_BUILD 0

typedef struct {
    uint32_t    width;
    uint32_t    height;
    uint32_t    new_width;
    uint32_t    new_height;
    uint32_t*   buffer;
    uint32_t*   dist_buffer;
} image_T;

uint32_t pixel_distance(uint32_t pixel_a, uint32_t pixel_b) {
    uint8_t r_a = (pixel_a)       & 0xFF;
    uint8_t g_a = (pixel_a >> 8)  & 0xFF;
    uint8_t b_a = (pixel_a >> 16) & 0xFF;

    uint8_t r_b = (pixel_b)       & 0xFF;
    uint8_t g_b = (pixel_b >> 8)  & 0xFF;
    uint8_t b_b = (pixel_b >> 16) & 0xFF;

    uint32_t dist = (uint32_t)sqrt(pow(r_a - r_b, 2) +
                                      pow(g_a - g_b, 2) +
                                      pow(b_a - b_b, 2));

    #if DEBUG_BUILD
        printf("    %x %x %x  --> %x %x %x  =  %d\n", r_a, g_a, b_a, r_b, g_b, b_b, dist);
    #endif

    return dist;
}

image_T* image_load(const char* filename) {
    printf("loading '%s'...\n", filename);

    image_T* image     = malloc(sizeof(image_T));
    image->buffer      = img_load_pixels(filename, (int*)&image->width, (int*)&image->height, IMG_FMT_RGBA32);
    image->dist_buffer = calloc(image->width * image->height, sizeof(uint32_t));
    image->new_width   = image->width;
    image->new_height  = image->height;
}

void image_destruct(image_T* image) {
    printf("destructing resources\n");

    img_free_pixels(image->buffer);
    free(image->dist_buffer);
    free(image);
}

void image_calculate_dist_buffer(image_T* image) {
    memset(image->dist_buffer, 0, image->height * image->width * sizeof(uint32_t));

    uint32_t* last_row       = image->buffer;
    uint32_t* pixel_row      = &last_row[image->width];
    uint32_t* dist_last_row  = image->dist_buffer;
    uint32_t* dist_pixel_row = &dist_last_row[image->width];

    for (int y = 1; y < image->new_height; y++) {
        #if DEBUG_BUILD
                printf("  Y\n");
        #endif
        for (int x = 0; x < image->new_width; x++) {
            uint32_t pixel = pixel_row[x];

            #if DEBUG_BUILD
                printf("  X\n");
            #endif

            int32_t shortest_dist = -1;
            for (int i = (x > 0 ? -1 : 0); i < (x < image->new_width-1 ? 2 : 1); i++) {
                uint32_t dist = pixel_distance(pixel, last_row[x + i]) + dist_last_row[x + i];

                if (shortest_dist == -1 || shortest_dist > dist) {
                    shortest_dist = (int32_t)dist;
                }

                #if DEBUG_BUILD
                    printf("    0x%x  -  %d\n", dist, x+i);
                #endif
            }
            #if DEBUG_BUILD
                printf("        0x%x\n", shortest_dist);
            #endif

            dist_pixel_row[x] = shortest_dist;
        }

        last_row       = pixel_row;
        pixel_row      = &pixel_row[image->width];
        dist_last_row  = dist_pixel_row;
        dist_pixel_row = &dist_pixel_row[image->width];
    }
}

uint32_t image_find_best_line(image_T* image) {
    uint32_t* row           = &image->dist_buffer[(image->new_height-1) * image->width];
    uint32_t  line_id       = 0;
    int32_t   shortest_dist = -1;

    for (uint32_t x = 0; x < image->new_width; x++) {
        if (shortest_dist == -1 || shortest_dist > row[x]) {
            shortest_dist = (int32_t)row[x];
            line_id       = x;
            printf("id: %d  dist: %d\n", x, row[x]);
        }
    }

    return line_id;
}

void image_cut_line(image_T* image, uint32_t line_id) {
    uint32_t x = line_id;

    for (uint32_t y = image->height-1; y > 0; y--) {
        int32_t shortest_dist = -1;
        int8_t  offset;
        for (int i = (x > 0 ? -1 : 0); i < (x < image->new_width-1 ? 2 : 1); i++) {
            uint32_t dist = image->dist_buffer[(image->width * y) + x + i];

            if (shortest_dist == -1 || shortest_dist > dist) {
                shortest_dist = (int32_t)dist;
                offset = i;
            }
        }
        x += offset;
        memcpy(&image->buffer[(image->width * y) + x], &image->buffer[(image->width * y) + x + 1], (image->new_width - x) * sizeof(uint32_t));
        gfx_color(0, 0xFF, 0);
        gfx_point(x, y);
        gfx_flush();
    }
    image->new_width -= 1;
}

void image_dump(image_T* image) {
    #if DEBUG_BUILD
        printf("Pixels:\n");
    #endif
    for (int y = 0; y < image->new_height; y++) {
        uint32_t* pixel_row = &image->buffer[y * image->width];

        #if DEBUG_BUILD
            printf("  ");
        #endif
        for (int x = 0; x < image->new_width; x++) {
            #if DEBUG_BUILD
                printf("%x ", pixel_row[x]);
            #endif
            gfx_color((uint8_t)(pixel_row[x] & 0xFF),
                      (uint8_t)((pixel_row[x] >> 8) & 0xFF),
                      (uint8_t)((pixel_row[x] >> 16) & 0xFF));
            gfx_point(x, y);
        }

        #if DEBUG_BUILD
            printf("\n");
        #endif
    }

    gfx_color(0, 0, 0);
    for (int y = 0; y < image->new_height; y++) {
        gfx_point(image->new_width, y);
    }

    gfx_flush();

    #if DEBUG_BUILD
        printf("Distances:\n");
    #endif
    for (int y = 0; y < image->height; y++) {
        uint32_t* dist_row = &image->dist_buffer[y * image->width];

        #if DEBUG_BUILD
            printf("  ");
        #endif
        for (int x = 0; x < image->width; x++) {
            #if DEBUG_BUILD
                printf("%x ", dist_row[x]);
            #endif
        }

        #if DEBUG_BUILD
            printf("\n");
        #endif
    }
}

int main() {
    printf("Line Cutter - Juniorcamp Informatik\n");

    image_T* image = image_load("../paris.png");

    gfx_open(800, 600, "Juniorcamp Informatik - Line Cutter");

    bool running = true;
    while(running) {
        image_dump(image);
        char c = gfx_wait();
        switch (c) {
            case 's': {
                image_calculate_dist_buffer(image);
                image_cut_line(image, image_find_best_line(image));
                break;
            }
            case 'q': {
                running = false;
                break;
            }
        }
    }

    image_destruct(image);

    return 0;
}