add comments abount defines

1 files changed, 7 insertions, 0 deletions

diff --git a/cqrlogo.c b/cqrlogo.c
index f1ef1ae..5ed5a4c 100644
--- a/cqrlogo.c
+++ b/cqrlogo.c
@@ -13,7 +13,14 @@
 #include <gdk-pixbuf/gdk-pixbuf.h>
 #include <qrencode.h>
 
+/* pixels are scaled up by this factor */
 #define QRCODE_SCALE	2
+/* error correction level used for QR code
+ * possible values: QR_ECLEVEL_L (lowest, about 7% error can be corrected)
+ *                  QR_ECLEVEL_M (about 15%)
+ *                  QR_ECLEVEL_Q (about 25%)
+ *                  QR_ECLEVEL_H (highest, about 30%)
+ * image size raises with higher levels */
 #define QRCODE_LEVEL	QR_ECLEVEL_L
 
 GdkPixbuf * encode_qrcode (char *text) {