diff options
| -rw-r--r-- | cqrlogo.c | 21 |
1 files changed, 14 insertions, 7 deletions
@@ -22,8 +22,8 @@ /* a bitmap */ struct bitmap_t { - int width; - int height; + unsigned int width; + unsigned int height; uint8_t *pixel; }; @@ -32,7 +32,8 @@ int generate_png (struct bitmap_t *bitmap, const char *uri) { png_structp png_ptr = NULL; png_infop info_ptr = NULL; png_byte ** row_pointers = NULL; - int x, y, depth = 8; + unsigned int x, y; + uint8_t bit, byte; if ((png_ptr = png_create_write_struct (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL)) == NULL) return 1; @@ -43,7 +44,7 @@ int generate_png (struct bitmap_t *bitmap, const char *uri) { return 1; } - png_set_IHDR (png_ptr, info_ptr, bitmap->width, bitmap->height, depth, + png_set_IHDR (png_ptr, info_ptr, bitmap->width, bitmap->height, 1 /* depth */, PNG_COLOR_TYPE_GRAY, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT); png_set_compression_level(png_ptr, Z_BEST_COMPRESSION); @@ -74,10 +75,16 @@ int generate_png (struct bitmap_t *bitmap, const char *uri) { row_pointers = png_malloc (png_ptr, bitmap->height * sizeof (png_byte *)); for (y = 0; y < bitmap->height; ++y) { - png_byte *row = png_malloc (png_ptr, sizeof (uint8_t) * bitmap->width); - row_pointers[y] = row; + /* we need to round up, need a complete byte for less than eight bits */ + row_pointers[y] = png_malloc (png_ptr, (sizeof(uint8_t) * bitmap->width + 7) / 8); for (x = 0; x < bitmap->width; ++x) { - *row++ = bitmap->pixel[y * bitmap->width + x]; + /* bit are written in reverse order! */ + bit = 7 - (x % 8); + byte = x / 8; + if (bitmap->pixel[y * bitmap->width + x]) + row_pointers[y][byte] |= 1 << (bit); + else + row_pointers[y][byte] &= ~(1 << (bit)); } } |