initial commit

.gitignore

@@ -0,0 +1,2 @@
+*.out
+*.o

README.md

@@ -0,0 +1,3 @@
+# C learning workplace
+
+here we learn C.

images/images.c

@@ -0,0 +1,140 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include "images.h"
+
+// write an int to a byte array
+void write_int(char* bytes, int num) {
+    for (int i = 0; i < 4; i++) {
+        bytes[i] = num >> (i * 8);
+    }
+}
+
+void write_byte(char* bytes, int num) {
+    bytes[0] = (char) num;
+}
+
+void write_16bit(char* bytes, int num) {
+    for (int i = 0; i < 2; i++) {
+        bytes[i] = num >> (i * 8);
+    }
+}
+
+int align_to_four_bytes(int size) {
+    int os = size % 4;
+    return os == 0 ? size : size + (4 - os);
+}
+
+int image_new(int width, int height, Image* img) {
+    //Image* img = malloc(sizeof(Image));
+
+    if (img == NULL) return 0;
+
+    img->height = height;
+    img->width = width;
+
+    // initialize bitmap...
+    img->bitmap = malloc(height * sizeof(int*));
+    for (int i = 0; i < height; i++) {
+        img->bitmap[i] = malloc(width * sizeof(int*));
+        for (int j = 0; j < width; j++) {
+            img->bitmap[i][j] = malloc(3 * sizeof(int));
+        }
+    }
+
+    //*image = *img;
+    return 1;
+}
+
+int image_byte_size(Image *image) {
+    // calculate size:
+    // bitmap file header = 14
+    // BITMAPCOREHEADER = 12 bytes
+    int size = 14 + 12;
+    // width must be padded to align to 4 bytes
+    int width_bytes = align_to_four_bytes(image->width * 3); // 3 bytes per pixel
+    // add width_bytes * height to total size
+    size += width_bytes * image->height;
+
+    return size;
+}
+
+// header format: 
+// BMP header (14 bytes)
+// 0x42 0x4D            "BM"
+// 0xAA 0xBB 0xCC 0xDD  bmp file size (int)
+// 0x00 0x00 0x00 0x00  nulls
+// 0x1A 0x00 0x00 0x00  pixel array offset (int) (= 14 + 12);
+// DIB  Header (BITMAPCOREHEADER) (12 bytes)
+// 0x0C 0x00 0x00 0x00  header size (int) (= 12)
+// 0xAA 0xBB            width (unsigned 16 bit int)
+// 0xCC 0xDD            height (unsigned 16 bit int)
+// 0x01 0x00            number of color planes (must be 1)
+// 0x18 0x00            number of bits per pixel (3 * 8 = 24)
+
+int image_save(Image* image, char* path) {
+    int size = image_byte_size(image);
+    char* bytes = calloc(sizeof(char), size);
+    // magic bytes, signature "BM"
+    bytes[0] = 0x42;
+    bytes[1] = 0x4d;
+    // write size to header
+    write_int(bytes + 2, size);
+    // the next 4 byte are zeros
+    // piyel array offset
+    write_int(bytes + 10, 14 + 12);
+    write_int(bytes + 14, 12);
+    write_16bit(bytes + 18, image->width);  // width
+    write_16bit(bytes + 20, image->height); // height
+    write_16bit(bytes + 22, 1);             // color planes
+    write_16bit(bytes + 24, 3 * 8);         // bits per pixel
+
+    int byte_offset = 26;
+    int byte_pos = 0;
+    int line;
+    for (line = 0; line < image->height; line++) {
+        byte_pos = 0;
+        for (int px = 0; px < image->width; px++) {
+            bytes[byte_offset + byte_pos++] = image->bitmap[line][px][2];
+            bytes[byte_offset + byte_pos++] = image->bitmap[line][px][1];
+            bytes[byte_offset + byte_pos++] = image->bitmap[line][px][0];
+        }
+        byte_offset += align_to_four_bytes(byte_pos);
+    }
+
+    printf("generated %i bytes out of %i calculated ones\n", byte_offset, size);
+
+    FILE *fp = fopen(path, "w");
+    int written = fwrite(bytes, sizeof(char), size, fp);
+    printf("wrote %i bytes...\n", written);
+    fclose(fp);
+    free(bytes);
+    return 1;
+}
+
+int image_set_px(Image* image, int x, int y, int r, int g, int b) {
+    if (!image_check_coords(image, x, y)) return 0;
+
+    image->bitmap[y][x][0] = (char) r;
+    image->bitmap[y][x][1] = (char) g;
+    image->bitmap[y][x][2] = (char) b;
+
+    return 1;
+}
+
+int image_check_coords(Image* image, int x, int y) {
+    return x >= 0 && x < image->width && 
+           y >= 0 && y < image->height;
+}
+
+int image_destroy(Image* image) {
+    for (int i = 0; i < image->height; i++) {
+        for (int j = 0; j < image->width; j++) {
+            free(image->bitmap[i][j]);
+        }
+        free(image->bitmap[i]);
+    }
+    free(image->bitmap);
+
+    return 1;
+}
+

images/images.h

@@ -0,0 +1,24 @@
+#ifndef IMAGES_H
+#define IMAGES_H
+
+typedef struct _image {
+    char*** bitmap;
+    int width;
+    int height;
+} Image;
+
+int image_new(int width, int height, Image* image);
+
+int image_save(Image* image, char* path);
+
+int image_set_px(Image* image, int x, int y, int r, int g, int b);
+
+int image_check_coords(Image* image, int x, int y);
+
+int image_destroy(Image* image);
+
+int image_byte_size(Image *image);
+
+#include "images.c"
+
+#endif

main.c

@@ -0,0 +1,33 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include "images/images.h"
+
+int main(int argc, char* argv[]) {
+
+    Image img;
+    image_new(255,255, &img);
+
+    int r,g,b;
+
+    for (int i = 0; i < 255; i++) {
+        for (int j = 0; j < 255; j++) {
+            double factor = (i*i + j*j) / (100*100);
+            r = i;
+            g = 255 -j;
+            b = i -255;
+
+
+            image_set_px(&img, i, j, factor * r, factor * g, factor * b);
+
+        }
+    }
+
+    printf("Writing file to /home/anton/projects/mona/chaos/test.bmp\n");
+
+    if (!image_save(&img, "/home/anton/projects/mona/chaos/test.bmp")) {
+        printf("Error writing file!\n");
+    } else {
+        printf("Wrote file successfully\n");
+    }
+    image_destroy(&img);
+}