颤动的pdf生成图像太慢 [英] Flutter pdf generation too slow with image
问题描述
im正在扑朔迷离地在pdf生成器应用程序上工作，但是当我想将图像添加到pdf时，花费的时间也太长了，我想知道如何添加多个图像.
im working on a pdf generator app in flutter, but when i want to add an image to the pdf, it takes too long also i wanted to know how it is possible to add multiple images.
Im使用3个库，图像选择器-pdf-打印
Im using 3 libraries, image picker - pdf - printing
这是我的代码:
Future getImage() async {
var image = await ImagePicker.pickImage(source: ImageSource.gallery);
final tempDir = await getTemporaryDirectory();
final path = tempDir.path;
int rand = new Math.Random().nextInt(10000000);
imge.Image imagee = imge.decodeImage(image.readAsBytesSync());
imge.Image smallerImage = imge.copyResize(imagee, 500);
setState(() {
var _image = new File('$path/img_$rand.jpg')..writeAsBytesSync(imge.encodeJpg(smallerImage, quality: 85));
_sharePdf(_image);
});
}
PDFDocument _generateDocument(File _image) {
final pdf = new PDFDocument(deflate: zlib.encode);
final page = new PDFPage(pdf, pageFormat: PDFPageFormat.LETTER);
final g = page.getGraphics();
final font = new PDFFont(pdf);
final top = page.pageFormat.height;
print(top);
imge.Image img = imge.decodeImage(_image.readAsBytesSync());
PDFImage image = new PDFImage(
pdf,
image: img.data.buffer.asUint8List(),
width: img.width,
height: img.height);
g.drawImage(image, 100.0, top - 150.0, 80.0, 100.0);
return pdf;
}
void _sharePdf(File _image) {
print("Share ...");
final pdf = _generateDocument(_image);
// Calculate the widget center for iPad sharing popup position
final RenderBox referenceBox =
shareWidget.currentContext.findRenderObject();
final topLeft =
referenceBox.localToGlobal(referenceBox.paintBounds.topLeft);
final bottomRight =
referenceBox.localToGlobal(referenceBox.paintBounds.bottomRight);
final bounds = new Rect.fromPoints(topLeft, bottomRight);
Printing.sharePdf(document: pdf, bounds: bounds);
}
然后我调用函数getImage().
Then im calling the function getImage().
我选择图像后，需要花费2-3分钟的时间，所有内容都会冻结，然后您可以共享pdf！
After i pick the image it takes 2-3 minutes in which everything freezes then you can share the pdf!
推荐答案
用于iOS和Android的Flutter_html_to_pdf插件，用于从HTML生成PDF文件.
flutter_html_to_pdf plugin for iOS and Android for generating PDF files from HTML.
使用:
https://pub.dev/packages/flutter_html_to_pdf
代替:
首先，在您的pubspec.yaml文件中添加flutter_html_to_pdf作为依赖项.
First, add flutter_html_to_pdf as a dependency in your pubspec.yaml file.
dependencies:
flutter_html_to_pdf: ^0.5.2
现在在Dart代码中，您可以使用:
Now in your Dart code, you can use:
import 'package:flutter_html_to_pdf/flutter_html_to_pdf.dart';
用法#
var htmlContent =
"""
<!DOCTYPE html>
<html>
<head>
<style>
table, th, td {
border: 1px solid black;
border-collapse: collapse;
}
th, td, p {
padding: 5px;
text-align: left;
}
</style>
</head>
<body>
<h2>PDF Generated with flutter_html_to_pdf plugin</h2>
<table style="width:100%">
<caption>Sample HTML Table</caption>
<tr>
<th>Month</th>
<th>Savings</th>
</tr>
<tr>
<td>January</td>
<td>100</td>
</tr>
<tr>
<td>February</td>
<td>50</td>
</tr>
</table>
<p>Image loaded from web</p>
<img src="https://i.imgur.com/wxaJsXF.png" alt="web-img">
</body>
</html>
""";
var targetPath = "/your/sample/path";
var targetFileName = "example_pdf_file"
var generatedPdfFile = await FlutterHtmlToPdf.convertFromHtmlContent(
htmlContent, targetPath, targetFileName);
您还可以传递内部带有HTML内容的File对象作为参数
You can also pass File object with HTML content inside as parameter
var file = File("/sample_path/example.html");
var generatedPdfFile = await FlutterHtmlToPdf.convertFromHtmlFile(
file, targetPath, targetFileName);
甚至只是该文件的路径
var filePath = "/sample_path/example.html";
var generatedPdfFile = await FlutterHtmlToPdf.convertFromHtmlFilePath(
filePath, targetPath, targetFileName);
图片如果要将设备中的本地图片添加到HTML，则需要将图片的路径作为src值传递.
Images If you want to add local image from device to your HTML you need to pass path to image as src value.
<img src="file:///storage/example/your_sample_image.png" alt="web-img">
或者如果要使用图像File对象
or if you want to use the image File object
<img src="${imageFile.path}" alt="web-img">
对于多张图片，您可以添加多个标签，例如:
And for Multiple images you can add multiple tags like:
<img src="your source" alt="your alternative">
<img src="your source" alt="your alternative">
<img src="your source" alt="your alternative">
<img src="your source" alt="your alternative">
<img src="your source" alt="your alternative">
这篇关于颤动的pdf生成图像太慢的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
