1# 卡片使用自定义绘制能力
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4ArkTS卡片开放了自定义绘制的能力，在卡片上可以通过[Canvas](../reference/apis-arkui/arkui-ts/ts-components-canvas-canvas.md)组件创建一块画布，然后通过[CanvasRenderingContext2D](../reference/apis-arkui/arkui-ts/ts-canvasrenderingcontext2d.md)对象在画布上进行自定义图形的绘制，如下示例代码实现了在画布的中心绘制了一个笑脸。
5
6```ts
7@Entry
8@Component
9struct CustomCanvasDrawingCard {
10  private canvasWidth: number = 0;
11  private canvasHeight: number = 0;
12  // 初始化CanvasRenderingContext2D和RenderingContextSettings
13  private settings: RenderingContextSettings = new RenderingContextSettings(true);
14  private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings);
15
16  build() {
17    Column() {
18      Row() {
19        Canvas(this.context)
20          .width('100%')
21          .height('100%')
22          .onReady(() => {
23            // 在onReady回调中获取画布的实际宽和高
24            this.canvasWidth = this.context.width;
25            this.canvasHeight = this.context.height;
26            // 绘制画布的背景
27            this.context.fillStyle = '#EEF0FF';
28            this.context.fillRect(0, 0, this.canvasWidth, this.canvasHeight);
29            // 在画布的中心绘制一个圆
30            this.context.beginPath();
31            let radius = this.context.width / 3;
32            let circleX = this.context.width / 2;
33            let circleY = this.context.height / 2;
34            this.context.moveTo(circleX - radius, circleY);
35            this.context.arc(circleX, circleY, radius, 2 * Math.PI, 0, true);
36            this.context.closePath();
37            this.context.fillStyle = '#5A5FFF';
38            this.context.fill();
39            // 绘制笑脸的左眼
40            let leftR = radius / 13;
41            let leftX = circleX - (radius / 2.3);
42            let leftY = circleY - (radius / 4.5);
43            this.context.beginPath();
44            this.context.arc(leftX, leftY, leftR, 0, 2 * Math.PI, true);
45            this.context.closePath();
46            this.context.strokeStyle = '#FFFFFF';
47            this.context.lineWidth = 15;
48            this.context.stroke();
49            // 绘制笑脸的右眼
50            let rightR = radius / 13;
51            let rightX = circleX + (radius / 2.3);
52            let rightY = circleY - (radius / 4.5);
53            this.context.beginPath();
54            this.context.arc(rightX, rightY, rightR, 0, 2 * Math.PI, true);
55            this.context.closePath();
56            this.context.strokeStyle = '#FFFFFF';
57            this.context.lineWidth = 15;
58            this.context.stroke();
59            // 绘制笑脸的鼻子
60            let startX = circleX;
61            let startY = circleY - 20;
62            this.context.beginPath();
63            this.context.moveTo(startX, startY);
64            this.context.lineTo(startX - 8, startY + 40);
65            this.context.lineTo(startX + 8, startY + 40);
66            this.context.strokeStyle = '#FFFFFF';
67            this.context.lineWidth = 15;
68            this.context.lineCap = 'round';
69            this.context.lineJoin = 'round';
70            this.context.stroke();
71            // 绘制笑脸的嘴巴
72            let mouthR = radius / 2;
73            let mouthX = circleX;
74            let mouthY = circleY + 10;
75            this.context.beginPath();
76            this.context.arc(mouthX, mouthY, mouthR, Math.PI / 1.4, Math.PI / 3.4, true);
77            this.context.strokeStyle = '#FFFFFF';
78            this.context.lineWidth = 15;
79            this.context.stroke();
80            this.context.closePath();
81          })
82      }
83    }.height('100%').width('100%')
84  }
85}
86```
87
88运行效果如下图所示。
89![WidgetCanvasDemo](figures/WidgetCanvasDemo.jpeg)