matrix-qrcode: Modify the QR code generation so mobile clients can decode

matrix_qrcode/src/utils.rs

@@ -17,7 +17,7 @@ use std::convert::TryInto;
 use base64::{decode_config, encode_config, STANDARD_NO_PAD};
 #[cfg(feature = "decode_image")]
 use image::{ImageBuffer, Luma};
-use qrcode::QrCode;
+use qrcode::{bits::Bits, EcLevel, QrCode, Version};
 
 #[cfg(feature = "decode_image")]
 use crate::error::DecodingError;
@@ -73,7 +73,21 @@ pub(crate) fn to_qr_code(
     shared_secret: &str,
 ) -> Result<QrCode, EncodingError> {
     let data = to_bytes(mode, flow_id, first_key, second_key, shared_secret)?;
-    Ok(QrCode::new(data)?)
+
+    // Mobile clients seem to have trouble decoding the QR code that gets
+    // generated by `QrCode::new()` it seems to add a couple of data segments
+    // with different data modes/types. The parsers seem to assume a single
+    // data type and since we start with an ASCII `MATRIX` header the rest of
+    // the data gets treated as a string as well.
+    //
+    // We make sure that there isn't an ECI bit set and we just push the bytes,
+    // this seems to help since the decoder doesn't assume an encoding and
+    // treats everything as raw bytes.
+    let mut bits = Bits::new(Version::Normal(7));
+    bits.push_byte_data(&data)?;
+    bits.push_terminator(EcLevel::L)?;
+
+    Ok(QrCode::with_bits(bits, EcLevel::L)?)
 }
 
 #[cfg(feature = "decode_image")]