harumi 0.4.2

Overlay searchable CJK text on PDFs, extract text, merge/split pages — pure Rust, zero C dependencies
Documentation 
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
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386

use harumi::Document;
use lopdf;

const FONT: &[u8] = include_bytes!("fixtures/NotoSansJP-Regular.ttf");

// ---------------------------------------------------------------------------
// Cross-operator replace test helpers
// ---------------------------------------------------------------------------

/// Modify the first content stream on page 1 of a PDF, splitting the first
/// `<HEX> Tj` into two consecutive Tj operators at `split_at_char` CID chars.
/// Returns the modified PDF bytes. Used to simulate text split across multiple
/// Tj operators in the same BT/ET block (the cross-operator match scenario).
fn split_first_tj(pdf_bytes: &[u8], split_at_char: usize) -> Vec<u8> {
    let mut ldoc = lopdf::Document::load_from(pdf_bytes).unwrap();
    let page_id = *ldoc.get_pages().values().next().unwrap();

    let contents_val = {
        let obj = ldoc.get_object(page_id).unwrap();
        obj.as_dict().unwrap().get(b"Contents").unwrap().clone()
    };
    let stream_ids: Vec<lopdf::ObjectId> = match contents_val {
        lopdf::Object::Reference(id) => vec![id],
        lopdf::Object::Array(arr) => arr
            .into_iter()
            .filter_map(|o| if let lopdf::Object::Reference(id) = o { Some(id) } else { None })
            .collect(),
        _ => panic!("unexpected Contents type"),
    };

    for stream_id in stream_ids {
        let stream_obj = ldoc.get_object(stream_id).unwrap().clone();
        let Ok(stream) = stream_obj.as_stream() else { continue };
        let mut owned = stream.clone();
        if owned.dict.get(b"Filter").is_ok() {
            owned.decompress().ok();
        }
        let Ok(content_str) = std::str::from_utf8(&owned.content) else { continue };
        if let Some(new_content) = try_split_hex_tj(content_str, split_at_char) {
            ldoc.objects.insert(
                stream_id,
                lopdf::Object::Stream(lopdf::Stream::new(
                    lopdf::Dictionary::new(),
                    new_content.into_bytes(),
                )),
            );
            break;
        }
    }

    let mut out = Vec::new();
    ldoc.save_to(&mut out).unwrap();
    out
}

/// Find the first `<HEX> Tj` in `content` and split it at `split_at_char`
/// CID characters (each CID char = 4 hex digits). Returns `None` if no
/// suitable Tj is found or the split point is out of range.
fn try_split_hex_tj(content: &str, split_at_char: usize) -> Option<String> {
    let tj_idx = content.find("> Tj")?;
    let lt_idx = content[..tj_idx].rfind('<')?;
    let hex_str = &content[lt_idx + 1..tj_idx];
    if hex_str.len() % 4 != 0 || hex_str.is_empty() {
        return None;
    }
    let split_pos = split_at_char * 4;
    if split_pos == 0 || split_pos >= hex_str.len() {
        return None;
    }
    Some(format!(
        "{}<{}> Tj\n<{}> Tj{}",
        &content[..lt_idx],
        &hex_str[..split_pos],
        &hex_str[split_pos..],
        &content[tj_idx + 4..], // skip "> Tj"
    ))
}

/// Helper: create a minimal PDF with a known text run, save to bytes.
fn pdf_with_text(text: &str) -> Vec<u8> {
    let mut doc = Document::new((595.0, 842.0)).unwrap();
    let font = doc.embed_font(FONT).unwrap();
    doc.page(1).unwrap().add_invisible_text(text, font, [72.0, 700.0], 14.0).unwrap();
    doc.save_to_bytes().unwrap()
}

#[test]
fn replace_text_latin_present_in_output() {
    let bytes = pdf_with_text("Hello");

    let mut doc = Document::from_bytes(&bytes).unwrap();
    let font = doc.embed_font(FONT).unwrap();
    doc.page(1).unwrap().replace_text("Hello", "World", font).unwrap();
    let out = doc.save_to_bytes().unwrap();

    let check = Document::from_bytes(&out).unwrap();
    let frags = check.extract_text_runs(1).unwrap();
    let texts: Vec<&str> = frags.iter().map(|f| f.text.as_str()).collect();

    // Replacement text must appear
    assert!(
        texts.iter().any(|&t| t.contains("World")),
        "expected 'World' in extracted text, got: {:?}",
        texts
    );
    // Original text must be gone
    assert!(
        !texts.iter().any(|&t| t.contains("Hello")),
        "expected 'Hello' to be gone, got: {:?}",
        texts
    );
}

#[test]
fn replace_text_no_match_is_noop() {
    let bytes = pdf_with_text("Alpha");

    let mut doc = Document::from_bytes(&bytes).unwrap();
    let font = doc.embed_font(FONT).unwrap();
    doc.page(1).unwrap().replace_text("Beta", "Gamma", font).unwrap();
    let out = doc.save_to_bytes().unwrap();

    let check = Document::from_bytes(&out).unwrap();
    let frags = check.extract_text_runs(1).unwrap();
    let texts: Vec<&str> = frags.iter().map(|f| f.text.as_str()).collect();

    assert!(
        texts.iter().any(|&t| t.contains("Alpha")),
        "expected 'Alpha' to remain, got: {:?}",
        texts
    );
    assert!(
        !texts.iter().any(|&t| t.contains("Gamma")),
        "expected 'Gamma' to be absent, got: {:?}",
        texts
    );
}

#[test]
fn replace_text_cjk() {
    let bytes = pdf_with_text("日本語");

    let mut doc = Document::from_bytes(&bytes).unwrap();
    let font = doc.embed_font(FONT).unwrap();
    doc.page(1).unwrap().replace_text("日本語", "英語", font).unwrap();
    let out = doc.save_to_bytes().unwrap();

    let check = Document::from_bytes(&out).unwrap();
    let frags = check.extract_text_runs(1).unwrap();
    let texts: Vec<&str> = frags.iter().map(|f| f.text.as_str()).collect();

    assert!(
        texts.iter().any(|&t| t.contains("英語")),
        "expected '英語' in extracted text, got: {:?}",
        texts
    );
    assert!(
        !texts.iter().any(|&t| t.contains("日本語")),
        "expected '日本語' to be gone, got: {:?}",
        texts
    );
}

#[test]
fn replace_preserve_font_success() {
    // Two runs ensure both glyph sets land in the same font subset.
    let mut doc = Document::new((595.0, 842.0)).unwrap();
    let font = doc.embed_font(FONT).unwrap();
    doc.page(1).unwrap().add_invisible_text("Alpha", font, [72.0, 700.0], 14.0).unwrap();
    doc.page(1).unwrap().add_invisible_text("Beta", font, [72.0, 680.0], 14.0).unwrap();
    let bytes = doc.save_to_bytes().unwrap();

    let mut doc2 = Document::from_bytes(&bytes).unwrap();
    doc2.page(1).unwrap().replace_text_preserve_font("Alpha", "Beta").unwrap();
    let out = doc2.save_to_bytes().unwrap();

    let check = Document::from_bytes(&out).unwrap();
    let frags = check.extract_text_runs(1).unwrap();
    let all: String = frags.iter().map(|f| f.text.as_str()).collect::<Vec<_>>().join("");
    assert!(all.contains("Beta"), "expected 'Beta' in: {:?}", all);
    assert!(!all.contains("Alpha"), "expected 'Alpha' gone from: {:?}", all);
}

#[test]
fn replace_preserve_font_missing_glyph_returns_err() {
    // Only "Hello" glyphs (H,e,l,o) are in the subset; "World" needs W,r,d which are absent.
    // Error is now returned eagerly at replace_text_preserve_font() call time, not at save().
    let bytes = pdf_with_text("Hello");

    let mut doc = Document::from_bytes(&bytes).unwrap();
    let result = doc.page(1).unwrap().replace_text_preserve_font("Hello", "World");
    assert!(result.is_err(), "expected Err for char not in font subset, got Ok");
}

#[test]
fn replace_preserve_font_cjk() {
    // Include both strings so all glyphs are in the subset.
    let mut doc = Document::new((595.0, 842.0)).unwrap();
    let font = doc.embed_font(FONT).unwrap();
    doc.page(1).unwrap().add_invisible_text("日本語", font, [72.0, 700.0], 14.0).unwrap();
    doc.page(1).unwrap().add_invisible_text("英語", font, [72.0, 680.0], 14.0).unwrap();
    let bytes = doc.save_to_bytes().unwrap();

    let mut doc2 = Document::from_bytes(&bytes).unwrap();
    doc2.page(1).unwrap().replace_text_preserve_font("日本語", "英語").unwrap();
    let out = doc2.save_to_bytes().unwrap();

    let check = Document::from_bytes(&out).unwrap();
    let frags = check.extract_text_runs(1).unwrap();
    let all: String = frags.iter().map(|f| f.text.as_str()).collect::<Vec<_>>().join("");
    assert!(all.contains("英語"), "expected '英語' in: {:?}", all);
    assert!(!all.contains("日本語"), "expected '日本語' gone from: {:?}", all);
}

#[test]
fn replace_text_returns_match_count() {
    let bytes = pdf_with_text("Hello");

    let mut doc = Document::from_bytes(&bytes).unwrap();
    let font = doc.embed_font(FONT).unwrap();
    let count = doc.page(1).unwrap().replace_text("Hello", "World", font).unwrap();
    assert_eq!(count, 1, "expected 1 match, got {count}");
}

#[test]
fn replace_text_no_match_returns_zero() {
    let bytes = pdf_with_text("Hello");

    let mut doc = Document::from_bytes(&bytes).unwrap();
    let font = doc.embed_font(FONT).unwrap();
    let count = doc.page(1).unwrap().replace_text("NoSuchText", "World", font).unwrap();
    assert_eq!(count, 0, "expected 0 matches, got {count}");
}

#[test]
fn replace_preserve_font_returns_count() {
    let mut doc = Document::new((595.0, 842.0)).unwrap();
    let font = doc.embed_font(FONT).unwrap();
    doc.page(1).unwrap().add_invisible_text("Alpha", font, [72.0, 700.0], 14.0).unwrap();
    doc.page(1).unwrap().add_invisible_text("Beta", font, [72.0, 680.0], 14.0).unwrap();
    let bytes = doc.save_to_bytes().unwrap();

    let mut doc2 = Document::from_bytes(&bytes).unwrap();
    let count = doc2.page(1).unwrap().replace_text_preserve_font("Alpha", "Beta").unwrap();
    assert_eq!(count, 1, "expected 1 match, got {count}");
    // no match → 0
    let count2 = doc2.page(1).unwrap().replace_text_preserve_font("NoSuchText", "Beta").unwrap();
    assert_eq!(count2, 0, "expected 0 matches, got {count2}");
}

#[test]
fn can_replace_text_counts_without_mutating() {
    let bytes = pdf_with_text("Hello");

    // page() requires &mut self even for read-only ops (PageHandle design)
    let mut doc = Document::from_bytes(&bytes).unwrap();
    let count = doc.page(1).unwrap().can_replace_text("Hello", "Hello").unwrap();
    assert_eq!(count, 1, "expected 1 match, got {count}");

    // Document was not mutated: original text is still there after save
    let out = doc.save_to_bytes().unwrap();
    let check = Document::from_bytes(&out).unwrap();
    let frags = check.extract_text_runs(1).unwrap();
    let texts: Vec<&str> = frags.iter().map(|f| f.text.as_str()).collect();
    assert!(
        texts.iter().any(|&t| t.contains("Hello")),
        "can_replace_text should not modify the document; 'Hello' should still be present"
    );
}

#[test]
fn can_replace_text_missing_glyph_returns_err() {
    let bytes = pdf_with_text("Hello");

    let mut doc = Document::from_bytes(&bytes).unwrap();
    let result = doc.page(1).unwrap().can_replace_text("Hello", "World");
    assert!(result.is_err(), "expected Err for char not in font subset");
}

#[test]
fn replace_multiple_on_same_page() {
    // Two distinct runs on the same page, both get replaced
    let mut doc = Document::new((595.0, 842.0)).unwrap();
    let font = doc.embed_font(FONT).unwrap();
    doc.page(1).unwrap().add_invisible_text("Foo", font, [72.0, 700.0], 14.0).unwrap();
    doc.page(1).unwrap().add_invisible_text("Bar", font, [72.0, 680.0], 14.0).unwrap();
    let bytes = doc.save_to_bytes().unwrap();

    let mut doc2 = Document::from_bytes(&bytes).unwrap();
    let font2 = doc2.embed_font(FONT).unwrap();
    doc2.page(1).unwrap().replace_text("Foo", "Baz", font2).unwrap();
    doc2.page(1).unwrap().replace_text("Bar", "Qux", font2).unwrap();
    let out = doc2.save_to_bytes().unwrap();

    let check = Document::from_bytes(&out).unwrap();
    let frags = check.extract_text_runs(1).unwrap();
    let all_text: String = frags.iter().map(|f| f.text.as_str()).collect::<Vec<_>>().join("");

    assert!(all_text.contains("Baz"), "expected Baz in: {:?}", all_text);
    assert!(all_text.contains("Qux"), "expected Qux in: {:?}", all_text);
    assert!(!all_text.contains("Foo"), "expected Foo gone: {:?}", all_text);
    assert!(!all_text.contains("Bar"), "expected Bar gone: {:?}", all_text);
}

// ---------------------------------------------------------------------------
// Cross-operator replace tests
// ---------------------------------------------------------------------------

#[test]
fn replace_text_cross_operator() {
    // "Hello" is split into two consecutive Tj ops in the same BT/ET block:
    //   <Hel_gids> Tj   <lo_gids> Tj
    // replace_text("Hello", "World") must span the operator boundary.
    let split_bytes = split_first_tj(&pdf_with_text("Hello"), 3);

    let mut doc = Document::from_bytes(&split_bytes).unwrap();
    let font = doc.embed_font(FONT).unwrap();
    let count = doc.page(1).unwrap().replace_text("Hello", "World", font).unwrap();
    assert_eq!(count, 1, "cross-op replace must find exactly 1 match");

    let out = doc.save_to_bytes().unwrap();
    let check = Document::from_bytes(&out).unwrap();
    let all: String = check
        .extract_text_runs(1)
        .unwrap()
        .iter()
        .map(|f| f.text.as_str())
        .collect::<Vec<_>>()
        .join("");
    assert!(all.contains("World"), "expected 'World' in: {:?}", all);
    assert!(!all.contains("Hello"), "expected 'Hello' gone from: {:?}", all);
}

#[test]
fn can_replace_text_cross_operator_count() {
    // can_replace_text must count matches that span multiple Tj operators.
    let split_bytes = split_first_tj(&pdf_with_text("Hello"), 3);

    let mut doc = Document::from_bytes(&split_bytes).unwrap();
    let count = doc
        .page(1)
        .unwrap()
        .can_replace_text("Hello", "Hello")
        .unwrap();
    assert_eq!(count, 1, "can_replace_text must count cross-op matches");
}

#[test]
fn replace_preserve_font_cross_operator() {
    // Both "Hello" and "World" must be in the font subset so that
    // replace_text_preserve_font can encode "World" with the existing font.
    let mut doc = Document::new((595.0, 842.0)).unwrap();
    let font = doc.embed_font(FONT).unwrap();
    doc.page(1)
        .unwrap()
        .add_invisible_text("Hello", font, [72.0, 700.0], 14.0)
        .unwrap();
    doc.page(1)
        .unwrap()
        .add_invisible_text("World", font, [72.0, 680.0], 14.0)
        .unwrap();
    let initial = doc.save_to_bytes().unwrap();

    // Split "Hello"'s Tj — both BT/ET blocks share one lopdf stream object.
    let split_bytes = split_first_tj(&initial, 3);

    let mut doc2 = Document::from_bytes(&split_bytes).unwrap();
    let count = doc2
        .page(1)
        .unwrap()
        .replace_text_preserve_font("Hello", "World")
        .unwrap();
    assert_eq!(count, 1, "preserve_font cross-op must find exactly 1 match");

    let out = doc2.save_to_bytes().unwrap();
    let check = Document::from_bytes(&out).unwrap();
    let all: String = check
        .extract_text_runs(1)
        .unwrap()
        .iter()
        .map(|f| f.text.as_str())
        .collect::<Vec<_>>()
        .join("");
    assert!(all.contains("World"), "expected 'World' in: {:?}", all);
    assert!(!all.contains("Hello"), "expected 'Hello' gone from: {:?}", all);
}