harmony 鸿蒙卡片使用自定义绘制能力
卡片使用自定义绘制能力
ArkTS卡片开放了自定义绘制的能力,在卡片上可以通过Canvas组件创建一块画布,然后通过CanvasRenderingContext2D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。
@Entry
@Component
struct CanvasCard {
private canvasWidth: number = 0;
private canvasHeight: number = 0;
// 初始化CanvasRenderingContext2D和RenderingContextSettings
private settings: RenderingContextSettings = new RenderingContextSettings(true);
private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings);
build() {
Column() {
Row() {
Canvas(this.context)
.margin('5%')
.width('90%')
.height('90%')
.onReady(() => {
console.info('[ArkTSCard] onReady for canvas draw content');
// 在onReady回调中获取画布的实际宽和高
this.canvasWidth = this.context.width;
this.canvasHeight = this.context.height;
// 绘制画布的背景
this.context.fillStyle = '#EEF0FF';
this.context.fillRect(0, 0, this.canvasWidth, this.canvasHeight);
// 在画布的中心绘制一个圆
this.context.beginPath();
let radius = this.context.width / 3;
let circleX = this.context.width / 2;
let circleY = this.context.height / 2;
this.context.moveTo(circleX - radius, circleY);
this.context.arc(circleX, circleY, radius, 2 * Math.PI, 0, true);
this.context.closePath();
this.context.fillStyle = '#5A5FFF';
this.context.fill();
// 绘制笑脸的左眼
let leftR = radius / 13;
let leftX = circleX - (radius / 2.3);
let leftY = circleY - (radius / 4.5);
this.context.beginPath();
this.context.arc(leftX, leftY, leftR, 0, 2 * Math.PI, true);
this.context.strokeStyle = '#FFFFFF';
this.context.lineWidth = 15;
this.context.stroke();
// 绘制笑脸的右眼
let rightR = radius / 13;
let rightX = circleX + (radius / 2.3);
let rightY = circleY - (radius / 4.5);
this.context.beginPath();
this.context.arc(rightX, rightY, rightR, 0, 2 * Math.PI, true);
this.context.strokeStyle = '#FFFFFF';
this.context.lineWidth = 15;
this.context.stroke();
// 绘制笑脸的鼻子
let startX = circleX;
let startY = circleY - 20;
this.context.beginPath();
this.context.moveTo(startX, startY);
this.context.lineTo(startX - 8, startY + 40);
this.context.lineTo(startX + 8, startY + 40);
this.context.strokeStyle = '#FFFFFF';
this.context.lineWidth = 15;
this.context.lineCap = 'round'
this.context.lineJoin = 'round'
this.context.stroke();
// 绘制笑脸的嘴巴
let mouthR = radius / 2;
let mouthX = circleX;
let mouthY = circleY + 10;
this.context.beginPath();
this.context.arc(mouthX, mouthY, mouthR, Math.PI / 1.4, Math.PI / 3.4, true);
this.context.strokeStyle = '#FFFFFF';
this.context.lineWidth = 15;
this.context.stroke();
this.context.closePath();
})
}
}.height('100%').width('100%')
}
}
运行效果如下图所示。
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