Work on range

ext/fg/js/range.js

@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2016  Alex Yatskov <alex@foosoft.net>
+ * Author: Alex Yatskov <alex@foosoft.net>
+ *
+ * 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 <http://www.gnu.org/licenses/>.
+ */
+
+
+class Range {
+    constructor(range) {
+        this.range = range;
+    }
+
+    text() {
+        return this.range.toString();
+    }
+
+    setLength(length) {
+        const node   = this.range.startContainer;
+        const offset = this.range.startOffset;
+
+        length = Math.min(node.length - offset, length);
+        if (length === 0) {
+            return null;
+        }
+
+        range.setEnd(node, offset + length);
+        return length;
+    }
+
+    paddedRect() {
+        const node        = this.range.startContainer;
+        const startOffset = this.range.startOffset;
+        const endOffset   = this.range.endOffset;
+
+        this.range.setStart(node, Math.max(0, startOffset - 1));
+        this.range.setEnd(node, Math.min(node.length, endOffset + 1));
+        const rect = range.getBoundingClientRect();
+        this.range.setStart(node, startOffset);
+        this.range.setEnd(node, endOffset);
+
+        return rect;
+    }
+
+    static fromPoint(point) {
+        const range = document.caretRangeFromPoint(point.x, point.y);
+        return range === null ? null : new Range(range);
+    }
+}