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Flutter实现心碎的感觉

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:


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:


image.png

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:


image.png


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:
image.png

右边:
image.png


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。
xinsui.gif


我们把画笔进行填充将这个动画加入进来看下最终效果。

df5dbcbb-f36b-4f05-9613-0e94149d888f.gif
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)


最终代码:


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

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

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

late Animation<double> animation =
Tween<double>(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<double> 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;
}
}

小结


动画曲线Curves配合绘制可以实现很多好玩的东西,这个需要勤加练习方能掌握,仅将此心碎献给今天受伤的股民朋友们(ಥ﹏ಥ)


作者:老李code
来源:https://juejin.cn/post/7090457954415017991

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