如何将文本和图像文件合并为一个图像文件？
如何将文本和图像文件合并为一个图像文件？
提问于 2022-03-16 22:09:10
下面是函数中的代码片段，该函数将生成的QR代码(使用qr_flutter包)上载到firebase存储区；然后获取防火墙存储url以保存在上载到firebase防火墙的自定义模型中(未显示)。
这很好，但是我想上传一个由上面的标题文本和下面的地址文本所限制的QR代码组成的文件。(本质上是带有子标题、qrFile、address的列)。
我的问题是:如何将文本和qrFile合并成一个图像文件，我可以将其上传到防火墙存储中？
String qrString = 'qr_data_here';
final qrValidationResult = QrValidator.validate(
data: qrString,
version: QrVersions.auto,
errorCorrectionLevel: QrErrorCorrectLevel.L,
);
if (qrValidationResult.status == QrValidationStatus.valid) {
final qrCode = qrValidationResult.qrCode;
const String title = 'title_name_here';
final String address = 'address_here';
final painter = QrPainter.withQr(
qr: qrCode!,
color: const Color(0xFF000000),
gapless: true,
embeddedImageStyle: null,
embeddedImage: null,
);
Directory tempDir = await getTemporaryDirectory();
String tempPath = tempDir.path;
final ts = DateTime.now().millisecondsSinceEpoch.toString();
String path = '$tempPath/$ts.png';
// ui is from import 'dart:ui' as ui;
final picData =
await painter.toImageData(2048, format: ui.ImageByteFormat.png);
// writeToFile is seen in code snippet below
await writeToFile(
picData!,
path,
);
} else {
genericErrorDialog(context);
}
// qrStorage is a reference to a folder in firebase storage
await qrStorage.child('name_here').putFile(qrFile);
var url =
await qrStorage.child('name_here').getDownloadURL(); late File qrFile;
Future<void> writeToFile(ByteData data, String path) async {
final buffer = data.buffer;
qrFile = await File(path).writeAsBytes(
buffer.asUint8List(data.offsetInBytes, data.lengthInBytes));
}回答 1
Stack Overflow用户
回答已采纳
发布于 2022-03-17 20:01:51
一种解决方案是使用屏幕截图包(https://pub.dev/packages/screenshot)。这个包有一个函数，可以将小部件保存为图像(而不显示在屏幕上)，如下所示。
ScreenshotController screenshotController = ScreenshotController();
await screenshotController
.captureFromWidget(CustomWidget())
.then((capturedImage) async {
await do_something_with_capturedImage_here();
});由于它与我的问题具体相关；下面是生成qr代码的代码，将它与文本放在一个小部件(需要更多的格式)中，然后将小部件保存为图像文件并上传到firebase。
String qrString = 'qr_data_here';
final qrValidationResult = QrValidator.validate(
data: qrString,
version: QrVersions.auto,
errorCorrectionLevel: QrErrorCorrectLevel.L,
);
if (qrValidationResult.status == QrValidationStatus.valid) {
final qrCode = qrValidationResult.qrCode;
const String title = 'title_name_here';
final String address = 'address_here';
final painter = QrPainter.withQr(
qr: qrCode!,
color: const Color(0xFF000000),
gapless: true,
embeddedImageStyle: null,
embeddedImage: null,
);
Directory tempDir = await getTemporaryDirectory();
String tempPath = tempDir.path;
final ts = DateTime.now().millisecondsSinceEpoch.toString();
String path = '$tempPath/$ts.png';
// ui is from import 'dart:ui' as ui;
final picData =
await painter.toImageData(2048, format: ui.ImageByteFormat.png);
// writeToFile is seen in code snippet below
await writeToFile(
picData!,
path,
);
await screenshotController
.captureFromWidget(Column(
children: [
Text(title),
Image.file(qrFile),
Text(address),
],
))
.then((capturedImage) async {
await widgetToImageFile(capturedImage);
});
} else {
genericErrorDialog(context);
}
// qrStorage is a reference to a folder in firebase storage
await qrStorage.child('name_here').putFile(fullQrFile);
var url =
await qrStorage.child('name_here').getDownloadURL();ScreenshotController screenshotController = ScreenshotController();
late File qrFile;
late File fullQrFile;
Future<void> writeToFile(ByteData data, String path) async {
final buffer = data.buffer;
qrFile = await File(path).writeAsBytes(
buffer.asUint8List(data.offsetInBytes, data.lengthInBytes));
}
Future<void> widgetToImageFile(
Uint8List capturedImage,
) async {
Directory newTempDir = await getTemporaryDirectory();
String newTempPath = newTempDir.path;
final newTs = DateTime.now().millisecondsSinceEpoch.toString();
String path = '$newTempPath/$newTs.png';
fullQrFile = await File(path).writeAsBytes(capturedImage);
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/71504797
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