export class CrsClient {
|
/**
|
* @param config { {cloudKey: string, token: string, clientHost: string, jpegQuality: number} }
|
* @param canvas { HTMLCanvasElement }
|
*/
|
constructor(config, canvas) {
|
this.config = config;
|
this.canvas = canvas;
|
this.context = canvas.getContext('2d');
|
}
|
|
/**
|
* 发起一次CRS请求
|
* @param frame { {data: ArrayBuffer, height: number, width: number} } 相机帧
|
* @return {Promise}
|
*/
|
queryImage(frame) {
|
/*
|
* 从相机帧开始，发起一次CRS请求的步骤：
|
* 1. 将相机帧画到canvas上
|
* 2. 调用canvas.toDataURL得到JPEG图片的base64 (需要小程序基础库2.12.0及以上)
|
* 3. 填充请求参数
|
* 4. 发送CRS请求并返回
|
*/
|
let ctxImageData = this.context.createImageData(frame.width, frame.height); //#1
|
ctxImageData.data.set(new Uint8ClampedArray(frame.data)); //#1
|
this.context.putImageData(ctxImageData, 0, 0); //#1
|
let dataUrl = this.canvas.toDataURL("image/jpeg", this.config.quality); //#2
|
let base64 = dataUrl.substr(23); //#2 去除dataURL头，留下文件内容
|
|
const params = { //#3 添加cloudKey参数
|
image: base64,
|
notracking: "true",
|
appId: this.config.cloudKey,
|
};
|
|
return new Promise((resolve, reject) => { //#4 发送CRS请求
|
wx.request({
|
url: `${this.config.clientHost}/search/`,
|
method: 'post',
|
data: params,
|
header: {
|
'Authorization': this.config.token,
|
'content-type': 'application/json'
|
},
|
success: res => resolve(res.data),
|
fail: err => reject(err),
|
});
|
});
|
}
|
}
|
