README.md: mention c++20 build option / impact

axxel · web-flow · commit bdb857efae30 · 2023-01-05T16:11:06.000+01:00
diff --git a/README.md b/README.md
@@ -8,8 +8,8 @@ It was originally ported from the Java [ZXing Library](https://github.com/zxing/
 
 ## Features
 
-* In pure C++17, no third-party dependencies (for the library)
-* Stateless, thread-safe readers/scanners and writers/generators
+* Written in pure C++17 (/C++20), no third-party dependencies (for the library itself)
+* Thread safe
 * Wrappers/Bindings for:
   * [Android](wrappers/android/README.md)
   * [iOS](wrappers/ios/README.md)
@@ -29,7 +29,10 @@ It was originally ported from the Java [ZXing Library](https://github.com/zxing/
 | DataBar        | DataBar Expanded  | PDF417             |
 |                | ITF               | MaxiCode (partial) |
 
-[Note: DataBar used to be called RSS. DataBar, MaxiCode and Micro QR Code are not supported for writing.]
+[Note:]
+ * DataBar used to be called RSS.
+ * DataBar, MaxiCode and Micro QR Code are not supported for writing.
+ * Building with C++20 (see [CMakeLists.txt](https://github.com/zxing-cpp/zxing-cpp/blob/d4b0f502775857f257d13efd25fb840ece1bca3e/CMakeLists.txt#L45)) changes the behaviour of the library: it then supports multi-symbol and position independent detection for DataMatrix. This comes at a noticable performace cost. To enable this in the Android library, one needs to use at least NDK [version 25](https://github.com/zxing-cpp/zxing-cpp/blob/d4b0f502775857f257d13efd25fb840ece1bca3e/wrappers/android/zxingcpp/build.gradle#L9).
 
 ## Getting Started
 
