method_channel.dart
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/*
* Copyright (C) 2017, David PHAM-VAN <dev.nfet.net@gmail.com>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import 'dart:async';
import 'dart:typed_data';
import 'package:flutter/rendering.dart' show Rect;
import 'package:flutter/services.dart';
import 'package:pdf/pdf.dart';
import 'callback.dart';
import 'interface.dart';
import 'print_job.dart';
import 'printer.dart';
import 'printing_info.dart';
import 'raster.dart';
const MethodChannel _channel = MethodChannel('net.nfet.printing');
/// An implementation of [PrintingPlatform] that uses method channels.
class MethodChannelPrinting extends PrintingPlatform {
MethodChannelPrinting() : super() {
_channel.setMethodCallHandler(_handleMethod);
}
static final Map<int, PrintJob> _printJobs = <int, PrintJob>{};
static int _jobIndex = 0;
/// Callbacks from platform plugins
static Future<dynamic> _handleMethod(MethodCall call) async {
switch (call.method) {
case 'onLayout':
final PrintJob job = _printJobs[call.arguments['job']];
try {
final PdfPageFormat format = PdfPageFormat(
call.arguments['width'],
call.arguments['height'],
marginLeft: call.arguments['marginLeft'],
marginTop: call.arguments['marginTop'],
marginRight: call.arguments['marginRight'],
marginBottom: call.arguments['marginBottom'],
);
final Uint8List bytes = await job.onLayout(format);
if (bytes == null) {
throw 'onLayout returned null';
}
return Uint8List.fromList(bytes);
} catch (e) {
return e.toString();
}
break;
case 'onCompleted':
final bool completed = call.arguments['completed'];
final String error = call.arguments['error'];
final PrintJob job = _printJobs[call.arguments['job']];
if (completed == false && error != null) {
job.onCompleted.completeError(error);
} else {
job.onCompleted.complete(completed);
}
break;
case 'onHtmlRendered':
final PrintJob job = _printJobs[call.arguments['job']];
job.onHtmlRendered.complete(call.arguments['doc']);
break;
case 'onHtmlError':
final PrintJob job = _printJobs[call.arguments['job']];
job.onHtmlRendered.completeError(call.arguments['error']);
break;
case 'onPageRasterized':
final PrintJob job = _printJobs[call.arguments['job']];
final PdfRaster raster = PdfRaster(
call.arguments['width'],
call.arguments['height'],
call.arguments['image'],
);
job.onPageRasterized.add(raster);
break;
case 'onPageRasterEnd':
final PrintJob job = _printJobs[call.arguments['job']];
job.onPageRasterized.close();
_printJobs.remove(job.index);
break;
}
}
static PrintJob _newPrintJob(PrintJob job) {
job.index = _jobIndex++;
_printJobs[job.index] = job;
return job;
}
@override
Future<PrintingInfo> info() async {
_channel.setMethodCallHandler(_handleMethod);
Map<dynamic, dynamic> result;
try {
result = await _channel.invokeMethod(
'printingInfo',
<String, dynamic>{},
);
} catch (e) {
print('Error getting printing info: $e');
return PrintingInfo.unavailable;
}
return PrintingInfo.fromMap(result);
}
@override
Future<bool> layoutPdf(
LayoutCallback onLayout,
String name,
PdfPageFormat format,
) async {
final PrintJob job = _newPrintJob(PrintJob(
onCompleted: Completer<bool>(),
onLayout: onLayout,
));
final Map<String, dynamic> params = <String, dynamic>{
'name': name,
'job': job.index,
'width': format.width,
'height': format.height,
'marginLeft': format.marginLeft,
'marginTop': format.marginTop,
'marginRight': format.marginRight,
'marginBottom': format.marginBottom,
};
await _channel.invokeMethod<int>('printPdf', params);
try {
return await job.onCompleted.future;
} finally {
_printJobs.remove(job.index);
}
}
@override
Future<Printer> pickPrinter(Rect bounds) async {
final Map<String, dynamic> params = <String, dynamic>{
'x': bounds.left,
'y': bounds.top,
'w': bounds.width,
'h': bounds.height,
};
final Map<dynamic, dynamic> printer = await _channel
.invokeMethod<Map<dynamic, dynamic>>('pickPrinter', params);
if (printer == null) {
return null;
}
return Printer(
url: printer['url'],
name: printer['name'],
model: printer['model'],
location: printer['location'],
);
}
@override
Future<bool> directPrintPdf(
Printer printer,
LayoutCallback onLayout,
String name,
PdfPageFormat format,
) async {
final PrintJob job = _newPrintJob(PrintJob(
onCompleted: Completer<bool>(),
));
final Uint8List bytes = await onLayout(format);
if (bytes == null) {
return false;
}
final Map<String, dynamic> params = <String, dynamic>{
'name': name,
'printer': printer.url,
'doc': Uint8List.fromList(bytes),
'job': job.index,
};
await _channel.invokeMethod<int>('directPrintPdf', params);
final bool result = await job.onCompleted.future;
_printJobs.remove(job.index);
return result;
}
@override
Future<bool> sharePdf(
Uint8List bytes,
String filename,
Rect bounds,
) async {
final Map<String, dynamic> params = <String, dynamic>{
'doc': Uint8List.fromList(bytes),
'name': filename,
'x': bounds.left,
'y': bounds.top,
'w': bounds.width,
'h': bounds.height,
};
return await _channel.invokeMethod<int>('sharePdf', params) != 0;
}
@override
Future<Uint8List> convertHtml(
String html, String baseUrl, PdfPageFormat format) async {
final PrintJob job = _newPrintJob(PrintJob(
onHtmlRendered: Completer<Uint8List>(),
));
final Map<String, dynamic> params = <String, dynamic>{
'html': html,
'baseUrl': baseUrl,
'width': format.width,
'height': format.height,
'marginLeft': format.marginLeft,
'marginTop': format.marginTop,
'marginRight': format.marginRight,
'marginBottom': format.marginBottom,
'job': job.index,
};
await _channel.invokeMethod<void>('convertHtml', params);
final Uint8List result = await job.onHtmlRendered.future;
_printJobs.remove(job.index);
return result;
}
@override
Stream<PdfRaster> raster(
Uint8List document,
List<int> pages,
double dpi,
) {
final PrintJob job = _newPrintJob(PrintJob(
onPageRasterized: StreamController<PdfRaster>(),
));
final Map<String, dynamic> params = <String, dynamic>{
'doc': Uint8List.fromList(document),
'pages': pages,
'scale': dpi / PdfPageFormat.inch,
'job': job.index,
};
_channel.invokeMethod<void>('rasterPdf', params);
return job.onPageRasterized.stream;
}
}