Rich text editor for Flutter
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import 'dart:math' as math;
import 'package:flutter_quill/models/quill_delta.dart';
import '../style.dart';
import 'embed.dart';
import 'line.dart';
import 'node.dart';
/* A leaf node in document tree */
abstract class Leaf extends Node {
Object _value;
Object get value => _value;
Leaf.val(Object val) : _value = val;
factory Leaf(Object data) {
if (data is Embeddable) {
return Embed(data);
}
String text = data as String;
assert(text.isNotEmpty);
return Text(text);
}
@override
void applyStyle(Style value) {
assert((value.isInline || value.isIgnored || value.isEmpty),
'Unable to apply Style to leaf: $value');
super.applyStyle(value);
}
@override
Line? get parent => super.parent as Line?;
@override
int get length {
if (_value is String) {
return (_value as String).length;
}
// return 1 for embedded object
return 1;
}
@override
Delta toDelta() {
var data = _value is Embeddable ? (_value as Embeddable).toJson() : _value;
return Delta()..insert(data, style.toJson());
}
@override
void insert(int index, Object data, Style? style) {
assert(index >= 0 && index <= length);
Leaf node = Leaf(data);
if (index < length) {
splitAt(index)!.insertBefore(node);
} else {
insertAfter(node);
}
node.format(style);
}
@override
void retain(int index, int? len, Style? style) {
if (style == null) {
return;
}
int local = math.min(length - index, len!);
int remain = len - local;
Leaf node = _isolate(index, local);
if (remain > 0) {
assert(node.next != null);
node.next!.retain(0, remain, style);
}
node.format(style);
}
@override
void delete(int index, int? len) {
assert(index < length);
int local = math.min(length - index, len!);
Leaf target = _isolate(index, local);
Leaf? prev = target.previous as Leaf?;
Leaf? next = target.next as Leaf?;
target.unlink();
int remain = len - local;
if (remain > 0) {
assert(next != null);
next!.delete(0, remain);
}
if (prev != null) {
prev.adjust();
}
}
@override
void adjust() {
if (this is Embed) {
return;
}
Text node = this as Text;
// merging it with previous node if style is the same
Node? prev = node.previous;
if (!node.isFirst && prev is Text && prev.style == node.style) {
prev._value = prev.value + node.value;
node.unlink();
node = prev;
}
// merging it with next node if style is the same
Node? next = node.next;
if (!node.isLast && next is Text && next.style == node.style) {
node._value = node.value + next.value;
next.unlink();
}
}
Leaf? cutAt(int index) {
assert(index >= 0 && index <= length);
Leaf? cut = splitAt(index);
cut?.unlink();
return cut;
}
Leaf? splitAt(int index) {
assert(index >= 0 && index <= length);
if (index == 0) {
return this;
}
if (index == length) {
return isLast ? null : next as Leaf?;
}
assert(this is Text);
String text = _value as String;
_value = text.substring(0, index);
Leaf split = Leaf(text.substring(index));
split.applyStyle(style);
insertAfter(split);
return split;
}
void format(Style? style) {
if (style != null && style.isNotEmpty) {
applyStyle(style);
}
adjust();
}
Leaf _isolate(int index, int length) {
assert(
index >= 0 && index < this.length && (index + length <= this.length));
Leaf target = splitAt(index)!;
target.splitAt(length);
return target;
}
}
class Text extends Leaf {
Text([String text = ''])
: assert(!text.contains('\n')),
super.val(text);
@override
String get value => _value as String;
@override
String toPlainText() {
return value;
}
@override
Node newInstance() {
return Text();
}
}
/// An embedded node such as image or video
class Embed extends Leaf {
Embed(Embeddable data) : super.val(data);
@override
Embeddable get value => super.value as Embeddable;
@override
String toPlainText() {
return '\uFFFC';
}
@override
Node newInstance() {
throw UnimplementedError();
}
}