const {ccclass, property} = cc._decorator;

@ccclass

export default class TD extends cc.Component {

    @property(cc.Camera)

    spC: cc.Camera = null as any;

    // onLoad () {}

    async jietu () {

        let width = this.node.width;

        let height = this.node.height;

        //截图的本质是创建一个canvas，然后通过canvas生成图片材质

        this.spC.node.x = 0;

        this.spC.node.y = 0;

        let canvas = document.createElement('canvas');

        canvas.width = width;

        canvas.height = height;

        let ctx = canvas.getContext('2d');

        let gpTexture = new cc.RenderTexture(); //绘制

        //@ts-ignore

        gpTexture.initWithSize(width, height, cc.game._renderContext.STENCIL_INDEX8);

        this.spC.targetTexture = gpTexture;

        this.spC.render(this.node);//相机绘制，将屏幕上的内容更新到renderTexture中

        let data = gpTexture.readPixels();//读取renderTexture中的数据

        let rowBytes = width * 4;

        for (let row = 0; row < height; row++) {

            let srow = height - 1 - row;

            let imageData = ctx.createImageData(width, 1);

            let start = srow * width * 4;

            for (let i = 0; i < rowBytes; i++) {

                imageData.data[i] = data[start + i];

            }

            ctx.putImageData(imageData, 0, row);

        }

        if (CC_WECHATGAME) {

            //@ts-ignore

            let _tempFilePath = await canvas.toTempFilePathSync(

                {

                    x: 0,

                    y: 0,

                    width: width,

                    height: height,

                    destWidth: 380,

                    destHeight: 380,

                    fileType: 'png',

                    quality: 1

                });

            //显示图片

            wx.previewImage({

                urls: [_tempFilePath]

            })

        }

    }

    // update (dt) {}

}

我是要对某个节点截图 但是要截图的部分 透明区域应该是透明的才对 但是现在显示的图片 透明区域是黑色的