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-rw-r--r--cqrlogo.c21
1 files changed, 14 insertions, 7 deletions
diff --git a/cqrlogo.c b/cqrlogo.c
index d547ffc..6ff68de 100644
--- a/cqrlogo.c
+++ b/cqrlogo.c
@@ -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));
}
}