1 files changed, 113 insertions, 0 deletions
diff --git a/ext/fg/js/source-range.js b/ext/fg/js/source-range.js
new file mode 100644
index 00000000..c4cabf4b
--- /dev/null
+++ b/ext/fg/js/source-range.js
@@ -0,0 +1,113 @@
+/*
+ * 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.rng = range;
+    }
+
+    text() {
+        return this.rng.toString();
+    }
+
+    setLength(length) {
+        const end = Range.seekEnd(this.rng.startContainer, this.rng.startOffset + length);
+        this.rng.setEnd(end.node, end.offset);
+    }
+
+    containsPoint(point) {
+        const rect = this.getPaddedRect();
+        return point.x >= rect.left && point.x <= rect.right;
+    }
+
+    getRect() {
+        return this.rng.getBoundingClientRect();
+    }
+
+    getPaddedRect() {
+        const range       = this.rng.cloneRange();
+        const startOffset = range.startOffset;
+        const endOffset   = range.endOffset;
+        const node        = range.startContainer;
+
+        range.setStart(node, Math.max(0, startOffset - 1));
+        range.setEnd(node, Math.min(node.length, endOffset + 1));
+
+        return range.getBoundingClientRect();
+    }
+
+    select() {
+        const selection = window.getSelection();
+        selection.removeAllRanges();
+        selection.addRange(this.rng);
+    }
+
+    deselect() {
+        const selection = window.getSelection();
+        selection.removeAllRanges();
+    }
+
+    compareOrigin(range) {
+        return range.rng.compareBoundaryPoints(Range.START_TO_START, this.rng);
+    }
+
+    static seekEnd(node, length) {
+        const state = {node, offset: 0, length};
+
+        if (!Range.seekEndRecurse(node, state)) {
+            return {node: state.node, offset: state.offset};
+        }
+
+        for (let sibling = node.nextSibling; sibling !== null; sibling = sibling.nextSibling) {
+            if (!Range.seekEndRecurse(sibling, state)) {
+                return {node: state.node, offset: state.offset};
+            }
+        }
+
+        for (let sibling = node.parentElement.nextSibling; sibling !== null; sibling = sibling.nextSibling) {
+            if (!Range.seekEndRecurse(sibling, state)) {
+                return {node: state.node, offset: state.offset};
+            }
+        }
+
+        return {node: state.node, offset: state.offset};
+    }
+
+    static seekEndRecurse(node, state) {
+        if (node.nodeType === 3) {
+            const consumed = Math.min(node.length, state.length);
+            state.node = node;
+            state.offset = consumed;
+            state.length -= consumed;
+        } else {
+            for (let i = 0; i < node.childNodes.length; ++i) {
+                if (!Range.seekEndRecurse(node.childNodes[i], state)) {
+                    break;
+                }
+            }
+        }
+
+        return state.length > 0;
+    }
+
+    static fromPoint(point) {
+        const range = document.caretRangeFromPoint(point.x, point.y);
+        return range === null ? null : new Range(range);
+    }
+}