1 files changed, 132 insertions, 0 deletions
diff --git a/src/picture.c b/src/picture.c
new file mode 100644
index 0000000..52deb0e
--- /dev/null
+++ b/src/picture.c
@@ -0,0 +1,132 @@
+#include "picture.h"
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+Picture new_picture(int width, int height) {
+    Picture ret;
+    ret.width = width;
+    ret.height = height;
+    ret.buffer = malloc(sizeof(float) * width * height * 3);
+    return ret;
+}
+
+void delete_picture(Picture pic) {
+    free(pic.buffer);
+}
+
+void set_pixel(Picture pic, Vec2i pos, Color c) {
+    int idx = pos.y * pic.width * 3 + pos.x * 3;
+    pic.buffer[idx] = c.b;
+    pic.buffer[idx+1] = c.g;
+    pic.buffer[idx+2] = c.r;
+}
+
+void normalize_picture(Picture pic) {
+    float maxval = 0;
+    for (size_t i = 0; i < pic.width * pic.height * 3; i++) {
+        float val = pic.buffer[i];
+        if (val < 0) val = 0;
+        if (val > maxval) maxval = val;
+    }
+    if (maxval < 1.0) return;
+    for (size_t i = 0; i < pic.width * pic.height * 3; i++) {
+        pic.buffer[i] = pic.buffer[i] / maxval;
+    }
+}
+
+
+static bool fwrite_word16le(FILE* fp, uint16_t x) {
+    uint8_t buf[2];
+    buf[0] = x & 0xff;
+    buf[1] = (x >> 8) & 0xff;
+    int r = fwrite(buf, 1, 2, fp);
+    if (r != 2) return false;
+    return true;
+}
+
+static bool fwrite_word32le(FILE* fp, uint32_t x) {
+    bool ret = false;
+    uint16_t buf[2];
+
+    buf[0] = x & 0xffff;
+    buf[1] = (x >> 16) & 0xffff;
+    ret = fwrite_word16le(fp, buf[0]);
+    if (!ret) return ret;
+    ret = fwrite_word16le(fp, buf[1]);
+    if (!ret) return ret;
+    return true;
+}
+
+
+bool writeBMP(const char* filename, Picture pic) {
+    bool ret = false;
+    FILE *fp = NULL;
+    uint8_t *databuf = NULL;
+
+    fp = fopen(filename, "wb");
+    if (!fp) goto end;
+
+    int row_data_len = 3 * pic.width;
+    int padding = (4 - row_data_len % 4) % 4;
+    int row_len = row_data_len + padding;
+    int img_len = row_len * pic.height;
+    int file_len = 53 + img_len;
+
+    ret = fwrite_word16le(fp, 0x4d42);
+    if (!ret) goto end;
+    ret = fwrite_word32le(fp, file_len);
+    if (!ret) goto end;
+    ret = fwrite_word32le(fp, 0);
+    if (!ret) goto end;
+    ret = fwrite_word32le(fp, 54);
+    if (!ret) goto end;
+
+    ret = fwrite_word32le(fp, 40);
+    if (!ret) goto end;
+    ret = fwrite_word32le(fp, pic.width);
+    if (!ret) goto end;
+    ret = fwrite_word32le(fp, -pic.height);
+    if (!ret) goto end;
+    ret = fwrite_word16le(fp, 1);
+    if (!ret) goto end;
+    ret = fwrite_word16le(fp, 24);
+    if (!ret) goto end;
+    ret = fwrite_word32le(fp, 0); // BI_RGB
+    if (!ret) goto end;
+    ret = fwrite_word32le(fp, img_len);
+    if (!ret) goto end;
+    ret = fwrite_word32le(fp, 0);
+    if (!ret) goto end;
+    ret = fwrite_word32le(fp, 0);
+    if (!ret) goto end;
+    ret = fwrite_word32le(fp, 0);
+    if (!ret) goto end;
+    ret = fwrite_word32le(fp, 0);
+    if (!ret) goto end;
+    databuf = malloc(img_len);
+    memset(databuf, 0, img_len);
+    for (int i = 0; i < pic.height; i++) {
+        for (int j = 0; j < pic.width * 3; j++) {
+            int fromidx = i * pic.width * 3 + j;
+            int toidx = i * row_len + j;
+            float value = pic.buffer[fromidx];
+            if (value < 0) databuf[toidx] = 0;
+            else if (value > 1.0) {
+                databuf[toidx] = 255;
+            } else databuf[toidx] = 255 * value;
+        }
+    }
+    if (fwrite(databuf, 1, img_len, fp) != img_len) {
+        ret = false;
+        goto end;
+    }
+    ret = true;
+
+end:
+    if (databuf != NULL) free(databuf);
+    if (fp != NULL) fclose(fp);
+    return ret;
+}