change NEEDS_RESULT_CALLBACK to accept closures

This resolves issue #2.
This is a breaking change, and should necessitate moving to v0.3.0

FIXES: #2

src/lib.rs

@@ -8,7 +8,7 @@ mod exceptions;
 pub mod maxicode;
 pub mod qrcode;
 
-use std::collections::HashMap;
+use std::{collections::HashMap, rc::Rc};
 
 pub use exceptions::Exceptions;
 
@@ -40,7 +40,7 @@ pub use encode_hints::*;
  *
  * @see DecodeHintType#NEED_RESULT_POINT_CALLBACK
  */
-pub type RXingResultPointCallback = fn(&dyn ResultPoint);
+pub type RXingResultPointCallback = Rc<dyn Fn(&dyn ResultPoint)>;
 
 mod decode_hints;
 pub use decode_hints::*;

src/multi/qrcode/detector/multi_detector.rs

@@ -45,7 +45,7 @@ impl<'a> MultiDetector<'_> {
         let resultPointCallback = if let Some(DecodeHintValue::NeedResultPointCallback(cb)) =
             hints.get(&DecodeHintType::NEED_RESULT_POINT_CALLBACK)
         {
-            Some(*cb)
+            Some(cb.clone())
         } else {
             None
         };

src/qrcode/detector/qrcode_detector.rs

@@ -84,7 +84,7 @@ impl<'a> Detector<'_> {
             hints.get(&DecodeHintType::NEED_RESULT_POINT_CALLBACK)
         {
             // if let DecodeHintValue::NeedResultPointCallback(cb) = nrpc {
-            Some(*cb)
+            Some(cb.clone())
             // } else {
             //     None
             // }
@@ -97,7 +97,7 @@ impl<'a> Detector<'_> {
         //     (RXingResultPointCallback) hints.get(DecodeHintType.NEED_RESULT_POINT_CALLBACK);
 
         let mut finder =
-            FinderPatternFinder::with_callback(self.image.clone(), self.resultPointCallback);
+            FinderPatternFinder::with_callback(self.image.clone(), self.resultPointCallback.clone());
         let info = finder.find(hints)?;
 
         self.processFinderPatternInfo(info)
@@ -479,7 +479,7 @@ impl<'a> Detector<'_> {
             alignmentAreaRightX - alignmentAreaLeftX,
             alignmentAreaBottomY - alignmentAreaTopY,
             overallEstModuleSize,
-            self.resultPointCallback,
+            self.resultPointCallback.clone(),
         );
         alignmentFinder.find()
     }