flutter-quill/lib/widgets/proxy.dart

import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';

import 'box.dart';

class BaselineProxy extends SingleChildRenderObjectWidget {
  final TextStyle textStyle;
  final EdgeInsets padding;

  BaselineProxy({Key key, Widget child, this.textStyle, this.padding})
      : super(key: key, child: child);

  @override
  RenderBaselineProxy createRenderObject(BuildContext context) {
    return RenderBaselineProxy(
      null,
      textStyle,
      padding,
    );
  }

  @override
  void updateRenderObject(
      BuildContext context, covariant RenderBaselineProxy renderObject) {
    renderObject
      ..textStyle = textStyle
      ..padding = padding;
  }
}

class RenderBaselineProxy extends RenderProxyBox {
  RenderBaselineProxy(
    RenderParagraph child,
    TextStyle textStyle,
    EdgeInsets padding,
  )   : _prototypePainter = TextPainter(
            text: TextSpan(text: ' ', style: textStyle),
            textDirection: TextDirection.ltr,
            strutStyle:
                StrutStyle.fromTextStyle(textStyle, forceStrutHeight: true)),
        super(child);

  final TextPainter _prototypePainter;

  set textStyle(TextStyle value) {
    assert(value != null);
    if (_prototypePainter.text.style == value) {
      return;
    }
    _prototypePainter.text = TextSpan(text: ' ', style: value);
    markNeedsLayout();
  }

  EdgeInsets _padding;

  set padding(EdgeInsets value) {
    assert(value != null);
    if (_padding == value) {
      return;
    }
    _padding = value;
    markNeedsLayout();
  }

  @override
  double computeDistanceToActualBaseline(TextBaseline baseline) =>
      _prototypePainter.computeDistanceToActualBaseline(baseline) +
          _padding?.top ??
      0.0;

  @override
  performLayout() {
    super.performLayout();
    _prototypePainter.layout();
  }
}

class EmbedProxy extends SingleChildRenderObjectWidget {
  EmbedProxy(Widget child) : super(child: child);

  @override
  RenderEmbedProxy createRenderObject(BuildContext context) =>
      RenderEmbedProxy(null);
}

class RenderEmbedProxy extends RenderProxyBox implements RenderContentProxyBox {
  RenderEmbedProxy(RenderBox child) : super(child);

  @override
  List<TextBox> getBoxesForSelection(TextSelection selection) {
    if (!selection.isCollapsed) {
      return <TextBox>[
        TextBox.fromLTRBD(0.0, 0.0, size.width, size.height, TextDirection.ltr)
      ];
    }

    double left = selection.extentOffset == 0 ? 0.0 : size.width;
    double right = selection.extentOffset == 0 ? 0.0 : size.width;
    return <TextBox>[
      TextBox.fromLTRBD(left, 0.0, right, size.height, TextDirection.ltr)
    ];
  }

  @override
  double getFullHeightForCaret(TextPosition position) => size.height;

  @override
  Offset getOffsetForCaret(TextPosition position, Rect caretPrototype) {
    assert(position.offset != null &&
        position.offset <= 1 &&
        position.offset >= 0);
    return position.offset == 0 ? Offset.zero : Offset(size.width, 0.0);
  }

  @override
  TextPosition getPositionForOffset(Offset offset) =>
      TextPosition(offset: offset.dx > size.width / 2 ? 1 : 0);

  @override
  TextRange getWordBoundary(TextPosition position) =>
      TextRange(start: 0, end: 1);

  @override
  double getPreferredLineHeight() {
    return size.height;
  }
}

class RichTextProxy extends SingleChildRenderObjectWidget {
  final TextStyle textStyle;
  final TextDirection textDirection;
  final double textScaleFactor;
  final Locale locale;
  final StrutStyle strutStyle;
  final TextWidthBasis textWidthBasis;
  final TextHeightBehavior textHeightBehavior;

  @override
  RenderParagraphProxy createRenderObject(BuildContext context) {
    return RenderParagraphProxy(null, textStyle, textDirection, textScaleFactor,
        strutStyle, locale, textWidthBasis, textHeightBehavior);
  }

  RichTextProxy(
      RichText child,
      this.textStyle,
      this.textDirection,
      this.textScaleFactor,
      this.locale,
      this.strutStyle,
      this.textWidthBasis,
      this.textHeightBehavior)
      : assert(child != null),
        assert(textStyle != null),
        assert(textDirection != null),
        assert(locale != null),
        assert(strutStyle != null),
        super(child: child);

  @override
  void updateRenderObject(
      BuildContext context, covariant RenderParagraphProxy renderObject) {
    renderObject.textStyle = textStyle;
    renderObject.textDirection = textDirection;
    renderObject.textScaleFactor = textScaleFactor;
    renderObject.locale = locale;
    renderObject.strutStyle = strutStyle;
    renderObject.textWidthBasis = textWidthBasis;
    renderObject.textHeightBehavior = textHeightBehavior;
  }
}

class RenderParagraphProxy extends RenderProxyBox
    implements RenderContentProxyBox {
  RenderParagraphProxy(
    RenderParagraph child,
    TextStyle textStyle,
    TextDirection textDirection,
    double textScaleFactor,
    StrutStyle strutStyle,
    Locale locale,
    TextWidthBasis textWidthBasis,
    TextHeightBehavior textHeightBehavior,
  )   : _prototypePainter = TextPainter(
            text: TextSpan(text: ' ', style: textStyle),
            textAlign: TextAlign.left,
            textDirection: textDirection,
            textScaleFactor: textScaleFactor,
            strutStyle: strutStyle,
            locale: locale,
            textWidthBasis: textWidthBasis,
            textHeightBehavior: textHeightBehavior),
        super(child);

  final TextPainter _prototypePainter;

  set textStyle(TextStyle value) {
    assert(value != null);
    if (_prototypePainter.text.style == value) {
      return;
    }
    _prototypePainter.text = TextSpan(text: ' ', style: value);
    markNeedsLayout();
  }

  set textDirection(TextDirection value) {
    assert(value != null);
    if (_prototypePainter.textDirection == value) {
      return;
    }
    _prototypePainter.textDirection = value;
    markNeedsLayout();
  }

  set textScaleFactor(double value) {
    assert(value != null);
    if (_prototypePainter.textScaleFactor == value) {
      return;
    }
    _prototypePainter.textScaleFactor = value;
    markNeedsLayout();
  }

  set strutStyle(StrutStyle value) {
    assert(value != null);
    if (_prototypePainter.strutStyle == value) {
      return;
    }
    _prototypePainter.strutStyle = value;
    markNeedsLayout();
  }

  set locale(Locale value) {
    if (_prototypePainter.locale == value) {
      return;
    }
    _prototypePainter.locale = value;
    markNeedsLayout();
  }

  set textWidthBasis(TextWidthBasis value) {
    assert(value != null);
    if (_prototypePainter.textWidthBasis == value) {
      return;
    }
    _prototypePainter.textWidthBasis = value;
    markNeedsLayout();
  }

  set textHeightBehavior(TextHeightBehavior value) {
    if (_prototypePainter.textHeightBehavior == value) {
      return;
    }
    _prototypePainter.textHeightBehavior = value;
    markNeedsLayout();
  }

  @override
  RenderParagraph get child => super.child;

  @override
  double getPreferredLineHeight() {
    return _prototypePainter.preferredLineHeight;
  }

  @override
  Offset getOffsetForCaret(TextPosition position, Rect caretPrototype) =>
      child.getOffsetForCaret(position, caretPrototype);

  @override
  TextPosition getPositionForOffset(Offset offset) =>
      child.getPositionForOffset(offset);

  @override
  double getFullHeightForCaret(TextPosition position) =>
      child.getFullHeightForCaret(position);

  @override
  TextRange getWordBoundary(TextPosition position) =>
      child.getWordBoundary(position);

  @override
  List<TextBox> getBoxesForSelection(TextSelection selection) =>
      child.getBoxesForSelection(selection);

  @override
  performLayout() {
    super.performLayout();
    _prototypePainter.layout(
        minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
  }
}