1 files changed, 122 insertions, 0 deletions
diff --git a/ext/fg/js/text-source-element.js b/ext/fg/js/text-source-element.js
new file mode 100644
index 00000000..16ac5cd5
--- /dev/null
+++ b/ext/fg/js/text-source-element.js
@@ -0,0 +1,122 @@
+/*
+ * Copyright (C) 2016-2020  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/>.
+ */
+
+class TextSourceElement {
+    constructor(element, fullContent=null, startOffset=0, endOffset=0) {
+        this._element = element;
+        this._fullContent = (typeof fullContent === 'string' ? fullContent : TextSourceElement.getElementContent(element));
+        this._startOffset = startOffset;
+        this._endOffset = endOffset;
+        this._content = this._fullContent.substring(this._startOffset, this._endOffset);
+    }
+
+    get element() {
+        return this._element;
+    }
+
+    get fullContent() {
+        return this._fullContent;
+    }
+
+    get startOffset() {
+        return this._startOffset;
+    }
+
+    get endOffset() {
+        return this._endOffset;
+    }
+
+    clone() {
+        return new TextSourceElement(this._element, this._fullContent, this._startOffset, this._endOffset);
+    }
+
+    cleanup() {
+        // NOP
+    }
+
+    text() {
+        return this._content;
+    }
+
+    setEndOffset(length, fromEnd=false) {
+        if (fromEnd) {
+            const delta = Math.min(this._fullContent.length - this._endOffset, length);
+            this._endOffset += delta;
+            this._content = this._fullContent.substring(this._startOffset, this._endOffset);
+            return delta;
+        } else {
+            const delta = Math.min(this._fullContent.length - this._startOffset, length);
+            this._endOffset = this._startOffset + delta;
+            this._content = this._fullContent.substring(this._startOffset, this._endOffset);
+            return delta;
+        }
+    }
+
+    setStartOffset(length) {
+        const delta = Math.min(this._startOffset, length);
+        this._startOffset -= delta;
+        this._content = this._fullContent.substring(this._startOffset, this._endOffset);
+        return delta;
+    }
+
+    getRect() {
+        return this._element.getBoundingClientRect();
+    }
+
+    getWritingMode() {
+        return 'horizontal-tb';
+    }
+
+    select() {
+        // NOP
+    }
+
+    deselect() {
+        // NOP
+    }
+
+    equals(other) {
+        return (
+            typeof other === 'object' &&
+            other !== null &&
+            other instanceof TextSourceElement &&
+            this._element === other.element &&
+            this._fullContent === other.fullContent &&
+            this._startOffset === other.startOffset
+        );
+    }
+
+    static getElementContent(element) {
+        let content;
+        switch (element.nodeName.toUpperCase()) {
+            case 'BUTTON':
+                content = element.textContent;
+                break;
+            case 'IMG':
+                content = element.getAttribute('alt') || '';
+                break;
+            default:
+                content = `${element.value}`;
+                break;
+        }
+
+        // Remove zero-width non-joiner
+        content = content.replace(/\u200c/g, '');
+
+        return content;
+    }
+}