基于Flutter制作一个心碎动画特效

来源：脚本之家时间：2022-04-25 17:46:35

前言

继续动画探索，今天用Flutter制作一个心碎的感觉，灵感来源于今天的股市，哎，心哇凉哇凉的。废话不多说，开始。

效果图先上：

实现步骤

1、绘制一个心

首先我们使用两段三阶贝塞尔曲线制作一个心型，这里因为需要实现心碎的效果，所以我们需要将心的两段用两段路径path进行绘制出来，效果：

绘制代码：

canvas.translate(size.width / 2, size.height / 2);
Paint paint = Paint();
paint
  ..style = PaintingStyle.stroke
  ..strokeWidth = 2
  ..color = Colors.black87;
Path path = Path();
path.moveTo(0, 0);
path.cubicTo(-200, -80, -60, -240, 0, -140);
path.close();
Path path2 = Path();
canvas.save();
canvas.drawPath(
    path,
    paint
    ..color = Colors.red
      ..style = PaintingStyle.stroke);
canvas.restore();
path2.cubicTo(200, -80, 60, -240, 0, -140);
path2.close();
canvas.drawPath(
    path2,
    paint..color = Colors.black87);

2、绘制心的裂痕

我们看到心确实分成两半了，但是中间还缺少裂痕，接下来我们就绘制心碎的裂痕，也很简单，在两段路径path闭合前进行绘制线，效果：

绘制代码：

path.relativeLineTo(-10, 30);
path.relativeLineTo(20, 5);
path.relativeLineTo(-20, 30);
path.relativeLineTo(20, 20);
path.relativeLineTo(-10, 20);
path.relativeLineTo(10, 10);

path2.relativeLineTo(-10, 30);
path2.relativeLineTo(20, 5);
path2.relativeLineTo(-20, 30);
path2.relativeLineTo(20, 20);
path2.relativeLineTo(-10, 20);
path2.relativeLineTo(10, 10);

OK，我们已经看到心已经有了裂痕，如何心碎，只需将画布进行翻转一定角度即可，这里我们将画布翻转45°，看下效果：

左边：

右边：

3、加入动画

已经有心碎的感觉了，接下来加入动画元素让心碎的过程动起来。

思路：我们可以想一下，心碎的过程是什么样子，心的颜色慢慢变灰，心然后慢慢裂开，下方的动画运动曲线看起来更符合心碎的过程，里面有不舍，不甘，但最后心还是慢慢的碎了。

我们把画笔进行填充将这个动画加入进来看下最终效果。

是不是心碎了一地。

知识点：这里我们需要找到红色和灰色的RGB色值，通过Color.fromRGBO(r, g, b, opacity)方法赋值颜色的色值。然后通过动画值改变RGB的值即可。这里我使用的色值是：

红色：Color.fromRGBO(255, 0, 0, 1)灰色：Color.fromRGBO(169, 169, 169, 1)

完整代码

class XinSui extends StatefulWidget {
  const XinSui({Key? key}) : super(key: key);

  @override
  _XinSuiState createState() => _XinSuiState();
}

class _XinSuiState extends State with SingleTickerProviderStateMixin {
  late AnimationController _controller =
      AnimationController(vsync: this, duration: Duration(milliseconds: 4000))
        ..repeat();
  late CurvedAnimation cure =
      CurvedAnimation(parent: _controller, curve: Curves.bounceInOut);

  late Animation animation =
      Tween(begin: 0.0, end: 1.0).animate(cure);

  @override
  Widget build(BuildContext context) {
    return Container(
      child: CustomPaint(
        size: Size(double.infinity, double.infinity),
        painter: _XinSuiPainter(animation),
      ),
    );
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }
}

class _XinSuiPainter extends CustomPainter {
  Animation animation;

  _XinSuiPainter(this.animation) : super(repaint: animation);

  @override
  void paint(Canvas canvas, Size size) {
    canvas.translate(size.width / 2, size.height / 2);
    Paint paint = Paint();
    paint
      ..style = PaintingStyle.stroke
      ..strokeWidth = 2
      ..color = Colors.black87;
    Path path = Path();
    path.moveTo(0, 0);
    path.cubicTo(-200, -80, -60, -240, 0, -140);
    path.relativeLineTo(-10, 30);
    path.relativeLineTo(20, 5);
    path.relativeLineTo(-20, 30);
    path.relativeLineTo(20, 20);
    path.relativeLineTo(-10, 20);
    path.relativeLineTo(10, 10);
    path.close();
    Path path2 = Path();
    canvas.save();
    canvas.rotate(-pi / 4 * animation.value);
    canvas.drawPath(
        path,
        paint
        ..color = Colors.red
          ..color = Color.fromRGBO(
              255 - (86 * animation.value).toInt(),
              (animation.value * 169).toInt(),
              (animation.value * 169).toInt(),
              1)

          ..style = PaintingStyle.fill);
    canvas.restore();
    path2.cubicTo(200, -80, 60, -240, 0, -140);
    path2.relativeLineTo(-10, 30);
    path2.relativeLineTo(20, 5);
    path2.relativeLineTo(-20, 30);
    path2.relativeLineTo(20, 20);
    path2.relativeLineTo(-10, 20);
    path2.relativeLineTo(10, 10);
    path2.close();
    canvas.rotate(pi / 4 * animation.value);
    canvas.drawPath(
        path2,paint);
  }
  @override
  bool shouldRepaint(covariant _XinSuiPainter oldDelegate) {
    return oldDelegate.animation != animation;
  }
}