在 Custom TG2480H 打印机上打印徽标答案

【问题标题】：Printing a logo on a Custom TG2480H printer在 Custom TG2480H 打印机上打印徽标
【发布时间】：2017-06-28 12:43:29
【问题描述】：

我正在使用 Custom TG2480-H 打印机打印收据。除了徽标之外，我的所有收据都可以使用。

我有一个单色的.bmp 文件，它代表徽标并具有正确的尺寸。

我正在检索文件，使用不同的响应类型：

this.http.get('/assets/images/brand/logo-bnw.bmp', {
  responseType: ResponseContentType.Blob
}).subscribe((response: Response) => {
  console.log('Blob bytes', this.kiowarePrintService.getBytesFromText(response.text()));
});
this.http.get('/assets/images/brand/logo-bnw.bmp', {
  responseType: ResponseContentType.Text
}).subscribe((response: Response) => {
  console.log('Text bytes', this.kiowarePrintService.getBytesFromText(response.text()));
});
this.http.get('/assets/images/brand/logo-bnw.bmp', {
  responseType: ResponseContentType.ArrayBuffer
}).subscribe((response: Response) => {
  console.log('ArrayBuffer bytes', this.kiowarePrintService.getBytesFromText(response.text()));
});

这是ResponseContentType 上的文档以及它可以具有的不同值。

这是getBytesFromText的代码：

getBytesFromText(text: string) {
    const bytes: number[] = [];
    for (let i = 0; i < text.length; i++) {
      bytes.push(text.charCodeAt(i));
    }
    return bytes;
  }

将响应转换为字节会打印这些值：

Blob bytes (2) [123, 125]

Text bytes (951) [66, 77, 65533, 3, 0, 0, 0, 0, 0, 0, 62, 0, 0, 0, 40, 0, 0, 0, 120, 0, 0, 0, 56, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 65533, 3, 0, 0, 65533, 14, 0, 0, 65533, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 65533, 65533, 65533, 0, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 0, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 0, 65533, 65533, 65533, 65533, 65533, 65533…]

ArrayBuffer bytes (479) [19778, 958, 0, 0, 0, 62, 0, 40, 0, 120, 0, 56, 0, 1, 1, 0, 0, 896, 0, 3780, 0, 3780, 0, 0, 0, 0, 0, 0, 0, 65535, 255, 65535, 65535, 65535, 65535, 65535, 65535, 65535, 255, 65535, 65535, 65535, 65535, 65535, 65535, 65535, 255, 65535, 65535, 65535, 65535, 65535, 65535, 65535, 255, 65535, 65535, 65535, 65535, 65535, 65535, 65535, 255, 65535, 65535, 65535, 65535, 65535, 65535, 65535, 255, 65535, 65535, 65535, 65535, 65535, 65535, 65535, 255, 65535, 65535, 65535, 65535, 65535, 65535, 65535, 255, 65535, 65535, 65535, 65535, 65535, 65535, 65535, 255, 65535, 65535, 65535, 65535, 65535…]

这些似乎都是错误的，Blob 字节的数量太少了，另外两个都包含大于字节的数字 (>255)。

无论如何，我都尝试将这些字节发送到打印机，结果如下：

Blob 不打印任何内容
Text
ArrayBuffer

编辑：尝试添加 'content-type': 'image/bmp' 标头：

    const headers: Headers = new Headers({'Content-Type': 'image/bmp'});
    const options: RequestOptions = new RequestOptions({headers: headers});
    this.http.get('/assets/images/brand/logo-bnw.bmp', options).subscribe((response: Response) => {
      console.log('image/bmp bytes', this.kiowarePrintService.getBytesFromText(response.text()));
    });

记录这个：

image/bmp bytes (951) [66, 77, 65533, 3, 0, 0, 0, 0, 0, 0, 62, 0, 0, 0, 40, 0, 0, 0, 120, 0, 0, 0, 56, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 65533, 3, 0, 0, 65533, 14, 0, 0, 65533, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 65533, 65533, 65533, 0, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 0, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 65533, 0, 65533, 65533, 65533, 65533, 65533, 65533…]

看起来和文本响应一样

【问题讨论】：

您是说您已尝试“将这些字节发送到打印机”。你用了什么方法？您是使用 window.print() 还是创建了其他浏览器插件？

标签： angular typescript printing bitmap bytebuffer

【解决方案1】：

您正在对所有返回类型使用 response.text()。对于二进制数据，您应该将其保存为 blob。您可以使用

访问底层字节而无需转换为文本

response.arrayBuffer()

这应该会为您提供您期望的正确字节数组。

这个问题也很相关：Get Image or byte data with http

最佳答案采取的做法是：

var blob = new Blob([new Uint8Array(response._body)]

【讨论】：