lib/web_ui/lib/src/engine/surface/painting.dart

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// @dart = 2.6
part of engine;

/// Implementation of [ui.Paint] used by the HTML rendering backend.
class SurfacePaint implements ui.Paint {
  SurfacePaintData _paintData = SurfacePaintData();

  @override
  ui.BlendMode get blendMode => _paintData.blendMode ?? ui.BlendMode.srcOver;

  @override
  set blendMode(ui.BlendMode value) {
    if (_frozen) {
      _paintData = _paintData.clone();
      _frozen = false;
    }
    _paintData.blendMode = value;
  }

  @override
  ui.PaintingStyle get style => _paintData.style ?? ui.PaintingStyle.fill;

  @override
  set style(ui.PaintingStyle value) {
    if (_frozen) {
      _paintData = _paintData.clone();
      _frozen = false;
    }
    _paintData.style = value;
  }

  @override
  double get strokeWidth => _paintData.strokeWidth ?? 0.0;

  @override
  set strokeWidth(double value) {
    if (_frozen) {
      _paintData = _paintData.clone();
      _frozen = false;
    }
    _paintData.strokeWidth = value;
  }

  @override
  ui.StrokeCap get strokeCap => _paintData.strokeCap;

  @override
  set strokeCap(ui.StrokeCap value) {
    if (_frozen) {
      _paintData = _paintData.clone();
      _frozen = false;
    }
    _paintData.strokeCap = value;
  }

  @override
  ui.StrokeJoin get strokeJoin => _paintData.strokeJoin;

  @override
  set strokeJoin(ui.StrokeJoin value) {
    if (_frozen) {
      _paintData = _paintData.clone();
      _frozen = false;
    }
    _paintData.strokeJoin = value;
  }

  @override
  bool get isAntiAlias => _paintData.isAntiAlias;

  @override
  set isAntiAlias(bool value) {
    if (_frozen) {
      _paintData = _paintData.clone();
      _frozen = false;
    }
    _paintData.isAntiAlias = value;
  }

  @override
  ui.Color get color => _paintData.color;

  @override
  set color(ui.Color value) {
    if (_frozen) {
      _paintData = _paintData.clone();
      _frozen = false;
    }
    _paintData.color =
        value.runtimeType == ui.Color ? value : ui.Color(value.value);
  }

  @override
  bool get invertColors {
    return false;
  }

  @override
  set invertColors(bool value) {}

  static const ui.Color _defaultPaintColor = ui.Color(0xFF000000);

  @override
  ui.Shader get shader => _paintData.shader;

  @override
  set shader(ui.Shader value) {
    if (_frozen) {
      _paintData = _paintData.clone();
      _frozen = false;
    }
    _paintData.shader = value;
  }

  @override
  ui.MaskFilter get maskFilter => _paintData.maskFilter;

  @override
  set maskFilter(ui.MaskFilter value) {
    if (_frozen) {
      _paintData = _paintData.clone();
      _frozen = false;
    }
    _paintData.maskFilter = value;
  }

  @override
  ui.FilterQuality get filterQuality => _paintData.filterQuality;

  @override
  set filterQuality(ui.FilterQuality value) {
    if (_frozen) {
      _paintData = _paintData.clone();
      _frozen = false;
    }
    _paintData.filterQuality = value;
  }

  @override
  ui.ColorFilter get colorFilter => _paintData.colorFilter;

  @override
  set colorFilter(ui.ColorFilter value) {
    if (_frozen) {
      _paintData = _paintData.clone();
      _frozen = false;
    }
    _paintData.colorFilter = value;
  }

  // TODO(flutter_web): see https://github.com/flutter/flutter/issues/33605
  @override
  double get strokeMiterLimit {
    return null;
  }

  @override
  set strokeMiterLimit(double value) {
    assert(value != null);
  }

  @override
  ui.ImageFilter get imageFilter {
    // TODO(flutter/flutter#35156): Implement ImageFilter.
    return null;
  }

  @override
  set imageFilter(ui.ImageFilter value) {
    // TODO(flutter/flutter#35156): Implement ImageFilter.
  }

  // True if Paint instance has used in RecordingCanvas.
  bool _frozen = false;

  // Marks this paint object as previously used.
  SurfacePaintData get paintData {
    // Flip bit so next time object gets mutated we create a clone of
    // current paint data.
    _frozen = true;
    return _paintData;
  }

  @override
  String toString() {
    final StringBuffer result = StringBuffer();
    String semicolon = '';
    result.write('Paint(');
    if (style == ui.PaintingStyle.stroke) {
      result.write('$style');
      if (strokeWidth != null && strokeWidth != 0.0)
        result.write(' $strokeWidth');
      else
        result.write(' hairline');
      if (strokeCap != null && strokeCap != ui.StrokeCap.butt)
        result.write(' $strokeCap');
      semicolon = '; ';
    }
    if (isAntiAlias != true) {
      result.write('${semicolon}antialias off');
      semicolon = '; ';
    }
    if (color != _defaultPaintColor) {
      if (color != null)
        result.write('$semicolon$color');
      else
        result.write('${semicolon}no color');
      semicolon = '; ';
    }
    result.write(')');
    return result.toString();
  }
}

/// Private Paint context data used for recording canvas commands allowing
/// Paint to be mutated post canvas draw operations.
class SurfacePaintData {
  ui.BlendMode blendMode;
  ui.PaintingStyle style;
  double strokeWidth;
  ui.StrokeCap strokeCap;
  ui.StrokeJoin strokeJoin;
  bool isAntiAlias = true;
  ui.Color color;
  ui.Shader shader;
  ui.MaskFilter maskFilter;
  ui.FilterQuality filterQuality;
  ui.ColorFilter colorFilter;

  // Internal for recording canvas use.
  SurfacePaintData clone() {
    return SurfacePaintData()
      ..blendMode = blendMode
      ..filterQuality = filterQuality
      ..maskFilter = maskFilter
      ..shader = shader
      ..isAntiAlias = isAntiAlias
      ..color = color
      ..colorFilter = colorFilter
      ..strokeWidth = strokeWidth
      ..style = style
      ..strokeJoin = strokeJoin
      ..strokeCap = strokeCap;
  }

  @override
  String toString() {
    if (!assertionsEnabled) {
      return super.toString();
    } else {
      final StringBuffer buffer = StringBuffer('SurfacePaintData(');
      if (blendMode != null) {
        buffer.write('blendMode = $blendMode; ');
      }
      if (style != null) {
        buffer.write('style = $style; ');
      }
      if (strokeWidth != null) {
        buffer.write('strokeWidth = $strokeWidth; ');
      }
      if (strokeCap != null) {
        buffer.write('strokeCap = $strokeCap; ');
      }
      if (strokeJoin != null) {
        buffer.write('strokeJoin = $strokeJoin; ');
      }
      if (color != null) {
        buffer.write('color = ${colorToCssString(color)}; ');
      }
      if (shader != null) {
        buffer.write('shader = $shader; ');
      }
      if (maskFilter != null) {
        buffer.write('maskFilter = $maskFilter; ');
      }
      if (filterQuality != null) {
        buffer.write('filterQuality = $filterQuality; ');
      }
      if (colorFilter != null) {
        buffer.write('colorFilter = $colorFilter; ');
      }
      buffer.write('isAntiAlias = $isAntiAlias)');
      return buffer.toString();
    }
  }
}