finish bmp writer

3 files changed, 147 insertions, 53 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..41cd10b
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+*.bmp
+a.out
diff --git a/Main.hs b/Main.hs
deleted file mode 100644
index e433b09..0000000
--- a/Main.hs
+++ /dev/null
@@ -1,53 +0,0 @@
-import Data.Array.MArray
-import Data.Array.IO
-import System.IO
-import qualified Data.ByteString.Builder as B
-
-data Picture = Picture
-    { picWidth :: Int
-    , picHeight :: Int
-    , picArray :: IOUArray Int Float}
-
-newPicture :: Int -> Int -> IO Picture
-newPicture w h = do {
-    arr <- newArray (0, w * h * 3) 0.0;
-    return $ Picture w h arr;
-}
-
-setPixel :: (Int, Int) -> (Float, Float, Float) -> Picture -> IO ()
-setPixel (x, y) (r, g, b) pic = let {
-    idx = (y * picWidth pic + x) * 3;
-} in do {
-    writeArray (picArray pic) idx r;
-    writeArray (picArray pic) (idx+1) g;
-    writeArray (picArray pic) (idx+2) b;
-}
-
-outputPicture :: String -> Picture -> IO ()
-outputPicture fileName pic = withBinaryFile fileName WriteMode $ \h -> let {
-    fileLength = undefined;
-    width = undefined;
-    height = undefined;
-    imageSize = undefined;
-} in do {
-    B.hPutBuilder h $ mconcat 
-        [ -- header
-          B.word16LE 0x4d42
-        , B.word32LE fileLength
-        , B.word32LE 0
-        , B.word32LE 54
-          -- info
-        , B.word32LE 40
-        , B.int32LE width
-        , B.int32LE height
-        , B.word16LE 1
-        , B.word16LE 24
-        , B.word32LE 0 -- BI_RGB
-        , B.word32LE imageSize
-        , B.word32LE 0
-        , B.word32LE 0
-        , B.word32LE 0
-        , B.word32LE 0
-        ];
-}
-
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..d5a4773
--- /dev/null
+++ b/main.c
@@ -0,0 +1,145 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+
+typedef enum {
+    kRetSucc,
+    kRetFail,
+} Ret;
+
+typedef struct {
+    int width;
+    int height;
+    float *buffer;
+} Picture;
+
+
+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, int x, int y, float r, float g, float b) {
+    int idx = y * pic.width * 3 + x * 3;
+    pic.buffer[idx] = b;
+    pic.buffer[idx+1] = g;
+    pic.buffer[idx+2] = r;
+}
+
+Ret 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 kRetFail;
+    return kRetSucc;
+}
+
+Ret fwrite_word32le(FILE* fp, uint32_t x) {
+    Ret ret;
+    uint16_t buf[2];
+
+    buf[0] = x & 0xffff;
+    buf[1] = (x >> 16) & 0xffff;
+    ret = fwrite_word16le(fp, buf[0]);
+    if (ret != kRetSucc) return ret;
+    ret = fwrite_word16le(fp, buf[1]);
+    if (ret != kRetSucc) return ret;
+    return kRetSucc;
+}
+
+
+Ret writeBMP(const char* filename, Picture pic) {
+    Ret ret = kRetFail;
+    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 != kRetSucc) goto end;
+    ret = fwrite_word32le(fp, file_len);
+    if (ret != kRetSucc) goto end;
+    ret = fwrite_word32le(fp, 0);
+    if (ret != kRetSucc) goto end;
+    ret = fwrite_word32le(fp, 54);
+    if (ret != kRetSucc) goto end;
+
+    ret = fwrite_word32le(fp, 40);
+    if (ret != kRetSucc) goto end;
+    ret = fwrite_word32le(fp, pic.width);
+    if (ret != kRetSucc) goto end;
+    ret = fwrite_word32le(fp, -pic.height);
+    if (ret != kRetSucc) goto end;
+    ret = fwrite_word16le(fp, 1);
+    if (ret != kRetSucc) goto end;
+    ret = fwrite_word16le(fp, 24);
+    if (ret != kRetSucc) goto end;
+    ret = fwrite_word32le(fp, 0); // BI_RGB
+    if (ret != kRetSucc) goto end;
+    ret = fwrite_word32le(fp, img_len);
+    if (ret != kRetSucc) goto end;
+    ret = fwrite_word32le(fp, 0);
+    if (ret != kRetSucc) goto end;
+    ret = fwrite_word32le(fp, 0);
+    if (ret != kRetSucc) goto end;
+    ret = fwrite_word32le(fp, 0);
+    if (ret != kRetSucc) goto end;
+    ret = fwrite_word32le(fp, 0);
+    if (ret != kRetSucc) 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 = kRetFail;
+        goto end;
+    }
+    ret = kRetSucc;
+
+end:
+    if (databuf != NULL) free(databuf);
+    if (fp != NULL) fclose(fp);
+    return ret;
+}
+
+int main() {
+    Picture pic = new_picture(1600, 900);
+    for (int i = 0; i < 900; i++) {
+        for (int j = 0; j < 1600; j++) {
+            float r = (i + j) % 177 / 177.0;
+            float g = (i + j) % 71 / 71.0;
+            float b = (i + j) % 337 / 337.0;
+            set_pixel(pic, j, i, r, g, b);
+        }
+    }
+    writeBMP("test.bmp", pic);
+    delete_picture(pic);
+    return 0;
+}
+