aboutsummaryrefslogtreecommitdiff
path: root/ext/js/comm/clipboard-reader.js
blob: b040d6ca139d78773996360f72e85ff864c468f9 (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
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
/*
 * Copyright (C) 2023-2024  Yomitan Authors
 * Copyright (C) 2020-2022  Yomichan Authors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

import {getFileExtensionFromImageMediaType} from '../media/media-util.js';

/**
 * Class which can read text and images from the clipboard.
 */
export class ClipboardReader {
    /**
     * Creates a new instances of a clipboard reader.
     * @param {{document: ?Document, pasteTargetSelector: ?string, richContentPasteTargetSelector: ?string}} details Details about how to set up the instance.
     */
    constructor({document = null, pasteTargetSelector = null, richContentPasteTargetSelector = null}) {
        /** @type {?Document} */
        this._document = document;
        /** @type {?import('environment').Browser} */
        this._browser = null;
        /** @type {?HTMLTextAreaElement} */
        this._pasteTarget = null;
        /** @type {?string} */
        this._pasteTargetSelector = pasteTargetSelector;
        /** @type {?HTMLElement} */
        this._richContentPasteTarget = null;
        /** @type {?string} */
        this._richContentPasteTargetSelector = richContentPasteTargetSelector;
    }

    /**
     * Gets the browser being used.
     * @type {?import('environment').Browser}
     */
    get browser() {
        return this._browser;
    }

    /**
     * Assigns the browser being used.
     */
    set browser(value) {
        this._browser = value;
    }

    /**
     * Gets the text in the clipboard.
     * @param {boolean} useRichText Whether or not to use rich text for pasting, when possible.
     * @returns {Promise<string>} A string containing the clipboard text.
     * @throws {Error} Error if not supported.
     */
    async getText(useRichText) {
        /*
        Notes:
            document.execCommand('paste') sometimes doesn't work on Firefox.
            See: https://bugzilla.mozilla.org/show_bug.cgi?id=1603985
            Therefore, navigator.clipboard.readText() is used on Firefox.

            navigator.clipboard.readText() can't be used in Chrome for two reasons:
            * Requires page to be focused, else it rejects with an exception.
            * When the page is focused, Chrome will request clipboard permission, despite already
              being an extension with clipboard permissions. It effectively asks for the
              non-extension permission for clipboard access.
        */
        if (this._isFirefox() && !useRichText) {
            try {
                return await navigator.clipboard.readText();
            } catch (e) {
                // Error is undefined, due to permissions
                throw new Error('Cannot read clipboard text; check extension permissions');
            }
        }

        const document = this._document;
        if (document === null) {
            throw new Error('Clipboard reading not supported in this context');
        }

        if (useRichText) {
            const target = this._getRichContentPasteTarget();
            target.focus();
            document.execCommand('paste');
            const result = /** @type {string} */ (target.textContent);
            this._clearRichContent(target);
            return result;
        } else {
            const target = this._getPasteTarget();
            target.value = '';
            target.focus();
            document.execCommand('paste');
            const result = target.value;
            target.value = '';
            return (typeof result === 'string' ? result : '');
        }
    }

    /**
     * Gets the first image in the clipboard.
     * @returns {Promise<?string>} A string containing a data URL of the image file, or null if no image was found.
     * @throws {Error} Error if not supported.
     */
    async getImage() {
        // See browser-specific notes in getText
        if (
            this._isFirefox() &&
            typeof navigator.clipboard !== 'undefined' &&
            typeof navigator.clipboard.read === 'function'
        ) {
            // This function is behind the Firefox flag: dom.events.asyncClipboard.read
            // See: https://developer.mozilla.org/en-US/docs/Web/API/Clipboard/read#browser_compatibility
            let items;
            try {
                items = await navigator.clipboard.read();
            } catch (e) {
                return null;
            }

            for (const item of items) {
                for (const type of item.types) {
                    if (!getFileExtensionFromImageMediaType(type)) { continue; }
                    try {
                        const blob = await item.getType(type);
                        return await this._readFileAsDataURL(blob);
                    } catch (e) {
                        // NOP
                    }
                }
            }
            return null;
        }

        const document = this._document;
        if (document === null) {
            throw new Error('Clipboard reading not supported in this context');
        }

        const target = this._getRichContentPasteTarget();
        target.focus();
        document.execCommand('paste');
        const image = target.querySelector('img[src^="data:"]');
        const result = (image !== null ? image.getAttribute('src') : null);
        this._clearRichContent(target);
        return result;
    }

    // Private

    /**
     * @returns {boolean}
     */
    _isFirefox() {
        return (this._browser === 'firefox' || this._browser === 'firefox-mobile');
    }

    /**
     * @param {Blob} file
     * @returns {Promise<string>}
     */
    _readFileAsDataURL(file) {
        return new Promise((resolve, reject) => {
            const reader = new FileReader();
            reader.onload = () => resolve(/** @type {string} */ (reader.result));
            reader.onerror = () => reject(reader.error);
            reader.readAsDataURL(file);
        });
    }

    /**
     * @returns {HTMLTextAreaElement}
     */
    _getPasteTarget() {
        if (this._pasteTarget === null) {
            this._pasteTarget = /** @type {HTMLTextAreaElement} */ (this._findPasteTarget(this._pasteTargetSelector));
        }
        return this._pasteTarget;
    }

    /**
     * @returns {HTMLElement}
     */
    _getRichContentPasteTarget() {
        if (this._richContentPasteTarget === null) {
            this._richContentPasteTarget = /** @type {HTMLElement} */ (this._findPasteTarget(this._richContentPasteTargetSelector));
        }
        return this._richContentPasteTarget;
    }

    /**
     * @template {Element} T
     * @param {?string} selector
     * @returns {T}
     * @throws {Error}
     */
    _findPasteTarget(selector) {
        if (selector === null) { throw new Error('Invalid selector'); }
        const target = this._document !== null ? this._document.querySelector(selector) : null;
        if (target === null) { throw new Error('Clipboard paste target does not exist'); }
        return /** @type {T} */ (target);
    }

    /**
     * @param {HTMLElement} element
     */
    _clearRichContent(element) {
        for (const image of element.querySelectorAll('img')) {
            image.removeAttribute('src');
            image.removeAttribute('srcset');
        }
        element.textContent = '';
    }
}