Neumorphism
cover

Flutter 绘制瓷砖线 Tiled Lines

前言

前几天发现了一个使用 <canvas> 绘制图形的教程 generative artistry 感觉很有意思,尝试用 Flutter 实现。本文实现第一篇教程的图形 Tiled Lines 效果如下。

创建画布

首先使用一个 Container 控件创建一个 320*320 大小的绘制区域,添加 CustomPaint 画布和一个继承 CustomPainter
的画笔 TiledLinesPainter。关于 CustomPaintCustomPainter 的知识可以查阅这篇文章 使用 Flutter 绘制图表(一)柱状图 📊

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
import 'package:flutter/material.dart';

class TiledLines extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Container(
width: 320.0,
height: 320.0,
decoration: BoxDecoration(
border: Border.all(
color: Colors.black,
width: 1.0,
),
),
child: CustomPaint(
painter: TiledLinesPainter(),
),
),
),
);
}
}

class TiledLinesPainter extends CustomPainter {
@override
void paint(Canvas canvas, Size size) {}

bool shouldRepaint(TiledLinesPainter oldDelegate) => false;
}

绘制线条

创建好画布后在 TiledLinesPainterpaint 方法里进行绘制。添加一个 _drawLine 方法用来绘制线条,绘制线条需要起始点和终止点,通过参数将数值传入。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
class TiledLinesPainter extends CustomPainter {
void _drawLine(
Canvas canvas,
double x,
double y,
double width,
double height,
) {
final Paint paint = Paint()
..strokeCap = StrokeCap.square
..strokeWidth = 2;

Offset p1 = Offset(x, y);
Offset p2 = Offset(x + width, y + height);

canvas.drawLine(p1, p2, paint);
}

@override
void paint(Canvas canvas, Size size) {
_drawLine(canvas, 0, 0, size.width, size.height);
}

bool shouldRepaint(TiledLinesPainter oldDelegate) => false;
}

加入随机性

使用 Random().nextBool() 方法创建一个随机的布尔值,在绘制线条之前改变起始点和终止点的坐标,这样 _drawLine 方法就有了绘制不同方向的线条的能力。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
void _drawLine(
Canvas canvas,
double x,
double y,
double width,
double height,
) {
final bool isLeftToRight = Random().nextBool();

final Paint paint = Paint()
..strokeCap = StrokeCap.square
..strokeWidth = 2;

Offset p1;
Offset p2;

if (isLeftToRight) {
p1 = Offset(x, y);
p2 = Offset(x + width, y + height);
} else {
p1 = Offset(x + width, y);
p2 = Offset(x, y + height);
}

canvas.drawLine(p1, p2, paint);
}

绘制更多的线条

可以绘制更多的线条喽!给 TiledLinesPainter 添加一个 step 属性,表示在画布上每隔多长距离绘制一条线。使用 step 将画布分割为多个小的方格,在每个小的方格里面绘制线条。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
class TiledLinesPainter extends CustomPainter {
final double step;

TiledLinesPainter(this.step);

void _drawLine(
Canvas canvas,
double x,
double y,
double width,
double height,
) {
final bool isLeftToRight = Random().nextBool();

final Paint paint = Paint()
..strokeCap = StrokeCap.square
..strokeWidth = 2;

Offset p1;
Offset p2;

if (isLeftToRight) {
p1 = Offset(x, y);
p2 = Offset(x + width, y + height);
} else {
p1 = Offset(x + width, y);
p2 = Offset(x, y + height);
}

canvas.drawLine(p1, p2, paint);
}

@override
void paint(Canvas canvas, Size size) {
for (double x = 0; x < size.width; x += step) {
for (double y = 0; y < size.height; y += step) {
_drawLine(canvas, x, y, step, step);
}
}
}

bool shouldRepaint(TiledLinesPainter oldDelegate) => false;
}

//...

TiledLinesPainter(20)

绘制边框和阴影

最后给画布添加边框和阴影效果,大功告成!👏 感谢阅读。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
import 'dart:math';
import 'package:flutter/material.dart';

class TiledLines extends StatelessWidget {
@override
Widget build(BuildContext context) {
List<BoxShadow> shadows = [];
double opacity = 0.1;

// 添加画布阴影
for (double i = 1; i <= 16; i++) {
opacity -= 0.01;
opacity = opacity > 0.01 ? opacity : 0.01;

shadows.add(
BoxShadow(
offset: Offset(-i, i),
color: Color.fromRGBO(0, 0, 0, opacity),
blurRadius: 2,
spreadRadius: 1,
),
);
}

return Scaffold(
body: Center(
child: Container(
width: 320.0,
height: 320.0,
decoration: BoxDecoration(
// 添加画布边框
border: Border.all(
color: Colors.black,
width: 20.0,
),
boxShadow: shadows,
),
child: Container(
color: Colors.white,
padding: const EdgeInsets.all(20.0),
child: CustomPaint(
painter: TiledLinesPainter(20),
),
),
),
),
);
}
}

class TiledLinesPainter extends CustomPainter {
final double step;

TiledLinesPainter(this.step);

void _drawLine(
Canvas canvas,
double x,
double y,
double width,
double height,
) {
// 创建随机性
final bool isLeftToRight = Random().nextBool();

final Paint paint = Paint()
..strokeCap = StrokeCap.square
..strokeWidth = 2;

Offset p1;
Offset p2;

// 设置线条的起始点和终止点
if (isLeftToRight) {
p1 = Offset(x, y);
p2 = Offset(x + width, y + height);
} else {
p1 = Offset(x + width, y);
p2 = Offset(x, y + height);
}

canvas.drawLine(p1, p2, paint);
}

@override
void paint(Canvas canvas, Size size) {
// 使用 step 分割画布,创建小的绘制方格
for (double x = 0; x < size.width; x += step) {
for (double y = 0; y < size.height; y += step) {
_drawLine(canvas, x, y, step, step);
}
}
}

bool shouldRepaint(TiledLinesPainter oldDelegate) => false;
}

参考

Tiled Lines

Buy Me A Coffee
← Flutter 绘制三角网格 Triangular Mesh 用 Flutter 实现探探卡片布局 →