1 files changed, 244 insertions, 0 deletions
diff --git a/ext/fg/js/source.js b/ext/fg/js/source.js
new file mode 100644
index 00000000..3b6ecb2a
--- /dev/null
+++ b/ext/fg/js/source.js
@@ -0,0 +1,244 @@
+/*
+ * Copyright (C) 2016-2017  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/>.
+ */
+
+
+/*
+ * TextSourceRange
+ */
+
+class TextSourceRange {
+    constructor(range, content='') {
+        this.range = range;
+        this.content = content;
+    }
+
+    clone() {
+        return new TextSourceRange(this.range.cloneRange(), this.content);
+    }
+
+    text() {
+        return this.content;
+    }
+
+    setEndOffset(length) {
+        const state = TextSourceRange.seekForward(this.range.startContainer, this.range.startOffset, length);
+        this.range.setEnd(state.node, state.offset);
+        this.content = state.content;
+        return length - state.remainder;
+    }
+
+    setStartOffset(length) {
+        const state = TextSourceRange.seekBackward(this.range.startContainer, this.range.startOffset, length);
+        this.range.setStart(state.node, state.offset);
+        this.content = state.content;
+        return length - state.remainder;
+    }
+
+    containsPoint(point) {
+        const rect = this.getPaddedRect();
+        return point.x >= rect.left && point.x <= rect.right;
+    }
+
+    getRect() {
+        return this.range.getBoundingClientRect();
+    }
+
+    getPaddedRect() {
+        const range = this.range.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.range);
+    }
+
+    deselect() {
+        const selection = window.getSelection();
+        selection.removeAllRanges();
+    }
+
+    equals(other) {
+        return other.range && other.range.compareBoundaryPoints(Range.START_TO_START, this.range) === 0;
+    }
+
+    static shouldEnter(node) {
+        if (node.nodeType !== 1) {
+            return false;
+        }
+
+        const skip = ['RT', 'SCRIPT', 'STYLE'];
+        if (skip.includes(node.nodeName)) {
+            return false;
+        }
+
+        const style = window.getComputedStyle(node);
+        const hidden =
+            style.visibility === 'hidden' ||
+            style.display === 'none' ||
+            parseFloat(style.fontSize) === 0;
+
+        return !hidden;
+    }
+
+    static seekForward(node, offset, length) {
+        const state = {node, offset, remainder: length, content: ''};
+        if (!TextSourceRange.seekForwardHelper(node, state)) {
+            return state;
+        }
+
+        for (let current = node; current !== null; current = current.parentElement) {
+            for (let sibling = current.nextSibling; sibling !== null; sibling = sibling.nextSibling) {
+                if (!TextSourceRange.seekForwardHelper(sibling, state)) {
+                    return state;
+                }
+            }
+        }
+
+        return state;
+    }
+
+    static seekForwardHelper(node, state) {
+        if (node.nodeType === 3 && node.parentElement && TextSourceRange.shouldEnter(node.parentElement)) {
+            const offset = state.node === node ? state.offset : 0;
+            const remaining = node.length - offset;
+            const consumed = Math.min(remaining, state.remainder);
+            state.content = state.content + node.nodeValue.substring(offset, offset + consumed);
+            state.node = node;
+            state.offset = offset + consumed;
+            state.remainder -= consumed;
+        } else if (TextSourceRange.shouldEnter(node)) {
+            for (let i = 0; i < node.childNodes.length; ++i) {
+                if (!TextSourceRange.seekForwardHelper(node.childNodes[i], state)) {
+                    break;
+                }
+            }
+        }
+
+        return state.remainder > 0;
+    }
+
+    static seekBackward(node, offset, length) {
+        const state = {node, offset, remainder: length, content: ''};
+        if (!TextSourceRange.seekBackwardHelper(node, state)) {
+            return state;
+        }
+
+        for (let current = node; current !== null; current = current.parentElement) {
+            for (let sibling = current.previousSibling; sibling !== null; sibling = sibling.previousSibling) {
+                if (!TextSourceRange.seekBackwardHelper(sibling, state)) {
+                    return state;
+                }
+            }
+        }
+
+        return state;
+    }
+
+    static seekBackwardHelper(node, state) {
+        if (node.nodeType === 3 && node.parentElement && TextSourceRange.shouldEnter(node.parentElement)) {
+            const offset = state.node === node ? state.offset : node.length;
+            const remaining = offset;
+            const consumed = Math.min(remaining, state.remainder);
+            state.content = node.nodeValue.substring(offset - consumed, offset) + state.content;
+            state.node = node;
+            state.offset = offset - consumed;
+            state.remainder -= consumed;
+        } else if (TextSourceRange.shouldEnter(node)) {
+            for (let i = node.childNodes.length - 1; i >= 0; --i) {
+                if (!TextSourceRange.seekBackwardHelper(node.childNodes[i], state)) {
+                    break;
+                }
+            }
+        }
+
+        return state.remainder > 0;
+    }
+}
+
+
+/*
+ * TextSourceElement
+ */
+
+class TextSourceElement {
+    constructor(element, content='') {
+        this.element = element;
+        this.content = content;
+    }
+
+    clone() {
+        return new TextSourceElement(this.element, this.content);
+    }
+
+    text() {
+        return this.content;
+    }
+
+    setEndOffset(length) {
+        switch (this.element.nodeName) {
+            case 'BUTTON':
+                this.content = this.element.innerHTML;
+                break;
+            case 'IMG':
+                this.content = this.element.getAttribute('alt');
+                break;
+            default:
+                this.content = this.element.value;
+                break;
+        }
+
+        this.content = this.content || '';
+        this.content = this.content.substring(0, length);
+
+        return this.content.length;
+    }
+
+    setStartOffset(length) {
+        return 0;
+    }
+
+    containsPoint(point) {
+        const rect = this.getRect();
+        return point.x >= rect.left && point.x <= rect.right;
+    }
+
+    getRect() {
+        return this.element.getBoundingClientRect();
+    }
+
+    select() {
+        // NOP
+    }
+
+    deselect() {
+        // NOP
+    }
+
+    equals(other) {
+        return other.element === this.element && other.content === this.content;
+    }
+}