summaryrefslogtreecommitdiff
path: root/hocr/hocr.go
blob: 0c1295cb655a1467c57e06cc4b43e707b775352e (plain)
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
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
package hocr

// TODO: separate out linedetail to a general structure that can incorporate
//       line-conf-buckets too, in a different file (and rename package to
//       something more generic). Do this using the CopyableLine interface
// TODO: Parse line name to zero pad line numbers, so they come out in the correct order

import (
	"encoding/xml"
	"image"
	"image/png"
	"io"
	"regexp"
	"strconv"
	"strings"
)

// TODO: move the linedetail stuff out to a separate file, and create a new
//       CopyableLine implementing struct for ocropy, which will just store
//       a file location
type LineDetail struct {
	Name string
	Avgconf float64
	Img CopyableLine
	Text string
	Hocrname string
}

type CopyableLine interface {
	CopyLineTo(io.Writer) (error)
}

type ImgDirect struct {
	img image.Image
}

func (i ImgDirect) CopyLineTo(w io.Writer) (error) {
	err := png.Encode(w, i.img)
	if err != nil {
		return err
	}
	return nil
}

type LineDetails []LineDetail

// Used by sort.Sort.
func (l LineDetails) Len() int { return len(l) }

// Used by sort.Sort.
func (l LineDetails) Less(i, j int) bool {
	return l[i].Avgconf < l[j].Avgconf
}

// Used by sort.Sort.
func (l LineDetails) Swap(i, j int) { l[i], l[j] = l[j], l[i] }

type Hocr struct {
	Lines []OcrLine `xml:"body>div>div>p>span"`
}

type OcrLine struct {
	Class string `xml:"class,attr"`
	Id string `xml:"id,attr"`
	Title string `xml:"title,attr"`
	Words []OcrWord `xml:"span"`
	Text string `xml:",chardata"`
}

type OcrWord struct {
	Class string `xml:"class,attr"`
	Id string `xml:"id,attr"`
	Title string `xml:"title,attr"`
	Chars []OcrChar `xml:"span"`
	Text string `xml:",chardata"`
}

type OcrChar struct {
	Class string `xml:"class,attr"`
	Id string `xml:"id,attr"`
	Title string `xml:"title,attr"`
	Chars []OcrChar `xml:"span"`
	Text string `xml:",chardata"`
}

// Returns the confidence for a word based on its x_wconf value
func wordConf(s string) (float64, error) {
	re, err := regexp.Compile(`x_wconf ([0-9.]+)`)
	if err != nil {
		return 0.0, err
	}
	conf := re.FindStringSubmatch(s)
	return strconv.ParseFloat(conf[1], 64)
}

func boxCoords(s string) ([4]int, error) {
	var coords [4]int
	re, err := regexp.Compile(`bbox ([0-9]+) ([0-9]+) ([0-9]+) ([0-9]+)`)
	if err != nil {
		return coords, err
	}
	coordstr := re.FindStringSubmatch(s)
	for i := range coords {
		c, err := strconv.Atoi(coordstr[i+1])
		if err != nil {
			return coords, err
		}
		coords[i] = c
	}
	return coords, nil
}

func noText(s string) bool {
	t := strings.Trim(s, " \n")
	return len(t) == 0
}

func Parse(b []byte) (Hocr, error) {
	var hocr Hocr

	err := xml.Unmarshal(b, &hocr)
	if err != nil {
		return hocr, err
	}

	return hocr, nil
}

func GetLineDetails(h Hocr, i image.Image, name string) (LineDetails, error) {
	lines := make(LineDetails, 0)

	for _, l := range h.Lines {
		totalconf := float64(0)
		num := 0
		for _, w := range l.Words {
			c, err := wordConf(w.Title)
			if err != nil {
				return lines, err
			}
			num++
			totalconf += c
		}

		coords, err := boxCoords(l.Title)
		if err != nil {
			return lines, err
		}

		var line LineDetail
		line.Name = l.Id
		line.Avgconf = (totalconf/float64(num)) / 100
		linetext := ""

		linetext = l.Text
		if(noText(linetext)) {
			linetext = ""
			for _, w := range l.Words {
				if(w.Class != "ocrx_word") {
					continue
				}
				linetext += w.Text + " "
			}
		}
		if(noText(linetext)) {
			linetext = ""
			for _, w := range l.Words {
				if(w.Class != "ocrx_word") {
					continue
				}
				for _, c := range w.Chars {
					if(c.Class != "ocrx_cinfo") {
						continue
					}
					linetext += c.Text
				}
				linetext += " "
			}
		}
		line.Text = strings.TrimRight(linetext, " ")
		line.Text += "\n"
		line.Hocrname = name
		var imgd ImgDirect
		imgd.img = i.(*image.Gray).SubImage(image.Rect(coords[0], coords[1], coords[2], coords[3]))
		line.Img = imgd
		lines = append(lines, line)
	}
	return lines, nil
}