1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160

use image::DynamicImage;
use image::GrayImage;

use failure::Error;

use crate::decode::{Decode, QRDecoder};
use crate::detect::{Detect, LineScan, Location};
use crate::extract::{Extract, QRExtractor};
use crate::prepare::{BlockedMean, Prepare};

use crate::util::qr::{QRData, QRError, QRLocation};

/// Struct to hold logic to do the entire decoding
pub struct Decoder<IMG, PREPD> {
    prepare: Box<dyn Prepare<IMG, PREPD>>,
    detect: Box<dyn Detect<PREPD>>,
    qr: ExtractDecode<PREPD, QRLocation, QRData, QRError>,
}

impl<IMG, PREPD> Decoder<IMG, PREPD> {
    /// Do the actual decoding
    ///
    /// Logic is run in the following order:
    /// * prepare
    /// * detect
    /// * per detected code the associated extract and decode functions
    pub fn decode(&self, source: IMG) -> Vec<Result<String, Error>> {
        let prepared = self.prepare.prepare(source);
        let locations = self.detect.detect(&prepared);

        if locations.is_empty() {
            return vec![];
        }

        let mut all_decoded = vec![];

        for location in locations {
            match location {
                Location::QR(qrloc) => {
                    let extracted = self.qr.extract.extract(&prepared, qrloc);
                    let decoded = self.qr.decode.decode(extracted);

                    all_decoded.push(decoded.or_else(|err| Err(Error::from(err))));
                }
            }
        }

        all_decoded
    }
}

/// Create a default Decoder
///
/// It will use the following components:
///
/// * prepare: BlockedMean
/// * detect: LineScan
/// * extract: QRExtractor
/// * decode: QRDecoder
///
/// This is meant to provide a good balance between speed and accuracy
pub fn default_decoder() -> Decoder<DynamicImage, GrayImage> {
    default_builder().build()
}

/// Builder struct to create a Decoder
///
/// Required elements are:
///
/// * Prepare
/// * Detect
/// * Extract
/// * Decode
pub struct DecoderBuilder<IMG, PREPD> {
    prepare: Option<Box<dyn Prepare<IMG, PREPD>>>,
    detect: Option<Box<dyn Detect<PREPD>>>,
    qr: Option<ExtractDecode<PREPD, QRLocation, QRData, QRError>>,
}

impl<IMG, PREPD> DecoderBuilder<IMG, PREPD> {
    /// Constructor; all fields initialized as None
    pub fn new() -> DecoderBuilder<IMG, PREPD> {
        DecoderBuilder {
            prepare: None,
            detect: None,
            qr: None,
        }
    }

    /// Set the prepare implementation for this Decoder
    pub fn prepare(
        &mut self,
        prepare: Box<dyn Prepare<IMG, PREPD>>,
    ) -> &mut DecoderBuilder<IMG, PREPD> {
        self.prepare = Some(prepare);
        self
    }

    /// Set the detect implementation for this Decoder
    pub fn detect(&mut self, detect: Box<dyn Detect<PREPD>>) -> &mut DecoderBuilder<IMG, PREPD> {
        self.detect = Some(detect);
        self
    }

    /// Set the extact and decode implementations for this Decoder for QR codes
    pub fn qr(
        &mut self,
        extract: Box<dyn Extract<PREPD, QRLocation, QRData, QRError>>,
        decode: Box<dyn Decode<QRData, QRError>>,
    ) -> &mut DecoderBuilder<IMG, PREPD> {
        self.qr = Some(ExtractDecode { extract, decode });
        self
    }

    /// Build actual Decoder
    ///
    /// # Panics
    ///
    /// Will panic if any of the required components are missing
    pub fn build(self) -> Decoder<IMG, PREPD> {
        if self.prepare.is_none() {
            panic!("Cannot build Decoder without Prepare component");
        }

        if self.detect.is_none() {
            panic!("Cannot build Decoder without Detect component");
        }

        Decoder {
            prepare: self.prepare.unwrap(),
            detect: self.detect.unwrap(),
            qr: self.qr.unwrap(),
        }
    }
}

/// Create a default DecoderBuilder
///
/// It will use the following components:
///
/// * prepare: BlockedMean
/// * locate: LineScan
/// * extract: QRExtractor
/// * decode: QRDecoder
///
/// The builder can then be customised before creating the Decoder
pub fn default_builder() -> DecoderBuilder<DynamicImage, GrayImage> {
    let mut db = DecoderBuilder::new();

    db.prepare(Box::new(BlockedMean::new(5, 7)));
    db.detect(Box::new(LineScan::new()));
    db.qr(Box::new(QRExtractor::new()), Box::new(QRDecoder::new()));

    db
}

struct ExtractDecode<PREPD, LOC, DATA, ERROR> {
    extract: Box<dyn Extract<PREPD, LOC, DATA, ERROR>>,
    decode: Box<dyn Decode<DATA, ERROR>>,
}