设置全局画笔透明度。
Number alpha
属性 | 类型 | 默认值 | 必填 | 说明 | 最低版本 |
|---|---|---|---|---|---|
| alpha | Number | 是 | 透明度取值范围： 0~1 ，0：表示完全透明，1：表示完全不透明 |
Page({
onLoad() {
const canvasContext = xhs.createCanvasContext('myCanvas');
canvasContext.setFillStyle('red');
canvasContext.fillRect(10, 10, 150, 100);
canvasContext.setGlobalAlpha(0.2);
canvasContext.setFillStyle('blue');
canvasContext.fillRect(50, 50, 150, 100);
canvasContext.setFillStyle('yellow');
canvasContext.fillRect(100, 100, 150, 100);
canvasContext.draw();
}
});
Page({
onLoad() {
const canvasContext = xhs.createCanvasContext('myCanvas');
canvasContext.setGlobalAlpha(0.2);
canvasContext.setFillStyle('red');
canvasContext.fillRect(10, 10, 150, 100);
canvasContext.setGlobalAlpha(1);
canvasContext.setFillStyle('blue');
canvasContext.fillRect(50, 50, 150, 100);
canvasContext.setGlobalAlpha(0.1);
canvasContext.setFillStyle('yellow');
canvasContext.fillRect(100, 100, 150, 100);
canvasContext.draw();
}
});