在我的 NativeScript-Vue 应用程序中,我需要将 PDF 文档打印到蓝牙打印机,并接收回调,无论打印成功还是取消。插件nativescript-printer在 iOS 上可以完美处理它,但在 Android 上它不会返回回调 (the feature is not implemented) 。该插件使用类 PrintHelper ,它有一个回调,在成功和取消时都会被调用,不带参数和返回。
看来唯一的解决办法就是通过类PrintManager来实现打印。一些来源:
- Printing custom documents | Android Developers
- An Android Custom Document Printing Tutorial
- Printing PDF directly using PrintManager Android 4.4
- How to Print PDF using Android 4.4 Printing framework (有很多赞成票,这似乎是最好的答案)
这就是我尝试过的。 onWrite
和 onLayout
可以工作,但是 onStart
和 onFinish
(这是我的目标)永远不会被调用。
import * as application from "tns-core-modules/application";
function printPdf(pdfFilePath) { // path: "/data/user/0/com.myapp.test/cache/pdf/document1.pdf"
let printManager = application.android.foregroundActivity.getSystemService(android.content.Context.PRINT_SERVICE);
let jobName = "PrintPdf";
let PrintPDFAdapter = android.print.PrintDocumentAdapter.extend({
onStart() {
console.log("on start);
},
onWrite(pages, destination, cancellationSignal, callback) {
let input;
let output;
try {
input = new java.io.FileInputStream(new java.io.File(pdfFilePath));
output = new java.io.FileOutputStream(destination.getFileDescriptor());
let buf = new Array.create("byte", 1024);
let bytesRead;
while ((bytesRead = input.read(buf)) > 0) {
output.write(buf, 0, bytesRead);
}
callback.onWriteFinished(new android.print.PageRange(0, 0));
} catch (e){
console.error(e);
} finally {
try {
input.close();
output.close();
} catch (e) {
console.error(e);
}
}
},
onLayout(oldAttributes, newAttributes, cancellationSignal, callback, extras){
try {
if (cancellationSignal.isCanceled()) {
callback.onLayoutCancelled();
return;
}
let pdi = new android.print.PrintDocumentInfo.Builder("print_output.pdf").setContentType(android.print.PrintDocumentInfo.CONTENT_TYPE_DOCUMENT).build();
callback.onLayoutFinished(pdi, true);
} catch (e) {
console.error(e);
}
},
onFinish() {
console.log("on finish");
}
});
let pda = new PrintPDFAdapter();
printManager.print(jobName, pda, null);
}
最佳答案
printManager.print()
返回一个 PrintJob 对象,该对象公开了当前的打印状态。这不太好,但这是我的解决方法:
function printPDF(pdfFilePath) {
// above code
let printJob = printManager.print(jobName, pda, null);
let onFinish = function(status) {
resolve(status);
clearInterval(interval);
}
let interval = setInterval(() => {
let state = printJob.getInfo().getState();
console.log(state);
if (state === 6) onFinish("print failed");
if (state === 7) onFinish("print cancelled");
if (state === 5) onFinish("print completed");
}, 500);
}
如果 PrintJob 状态卡在排队或阻塞状态,我可能会在时间间隔上实现超时。
关于NativeScript中PDF打印的Android实现,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/61099335/