How to render JPEG/PNG file data contained in Javascript variable? Is it possible ? What javascript libraries needed ? Browser in use is FF / IE.
Thanks
Modern browsers support inline images. So you could convert the binary data to a base64 encoded string and then append it to the DOM:
var img = document.createElement('img');
img.src = 'data:image/gif;base64,R0lGODlhEAAOALMAAOazToeHh0tLS/7LZv/0jvb29t/f3//Ub//ge8WSLf/rhf/3kdbW1mxsbP//mf///yH5BAAAAAAALAAAAAAQAA4AAARe8L1Ekyky67QZ1hLnjM5UUde0ECwLJoExKcppV0aCcGCmTIHEIUEqjgaORCMxIC6e0CcguWw6aFjsVMkkIr7g77ZKPJjPZqIyd7sJAgVGoEGv2xsBxqNgYPj/gAwXEQA7';
img.width = '16';
img.height = '14';
document.body.appendChild(img);
Related
I use 20 MB of text as String data inside a flutter Text() widget, But it did not increase the release app size.
APK size before adding 20MB of text data = 5.4MB
APK size After adding 20MB of text data = 5.4MB
(Note:- text data is not an unused value, It's used inside a flutter Text() widget)
Can I know, how flutter source code compression works or any information about this?
My guess is that the Dart language, and by extension Flutter, use powerful data compression algorithms that are built into the language by default, but there are also additional plugins.
All I could find:
An article on the "Medium" website about data compression
Some info about compression
Plugin for data compression
Dart Api Dev GZip included by default in language
Maybe with the help of this information you will find what you are looking for. And by the way, compare the sizes of installed applications, for sure an application with 20 MB of text will weigh more in its installed form.
Example code of powerful compression:
import 'dart:io';
import 'dart:convert';
main(List<String> arguments) {
String data = '';
for (int i = 0; i < 100000; i++) {
data = data + 'Hello world\r\n';
}
//Original Data
List<int> original = utf8.encode(data);
//Compress data
List<int> compressed = gzip.encode(original);
//Decompress
List<int> decompress = gzip.decode(compressed);
print('Original ${original.length} bytes');
print('Compressed ${compressed.length} bytes');
print('Decompressed ${decompress.length} bytes');
String decoded = utf8.decode(decompress);
assert(data == decoded);
}
Output:
Original 1300000 bytes
Compressed 2572 bytes
Decompressed 1300000 bytes
I've tried this way, and use it in FileImage but haven't found a rally point
Uint8List bytes = base64.decode(imageBase64);
File file = File.fromRawPath(bytes);
imageBase64 is the image url that has been encode.
The point of this thing is, i want to use it in FileImage or another widget image file but i don't want this image is saved to device and upload this file to the attachments file Rest API
can anyone help me.
If what you want to do once you have the bytes is to show the image, then you can use Image.memory.
var imageWidget = Image.memory(bytes);
OTOH If you're trying to upload the image, you don't need to convert it into file. You can use bytes directly assuming you can't upload it using base64 enconding. Package http
import 'package:http/http.dart';
...
//create multipart using filepath, string or bytes
MultipartFile multipartFile = MultipartFile.fromBytes(
'file',
byteData,
filename: fileName,
);
//add multipart to request
request.files.add(multipartFile);
var response = await request.send();
If you have an UintList8 you can use MemoryImage(bytes).
Uint8List bytes = base64.decode(imageBase64);
Image(image: MemoryImage(bytes));
How can I convert a PDF file into an image with Flutter?
I want to print the image to an ESC/POS printer using esc_pos_printer. This package won't accept PDFImage, it needs to be a Flutter Image.
I see plenty of PHP plugins that do this but nothing for Flutter.
edit: There is an answer to another question here which shows some code to decode an image from "pdf64" but I can't figure out exactly what "pdf64" is.
I created a PDF from html using flutter_html_to_pdflike this:
Directory appDocDir = await getApplicationDocumentsDirectory();
var targetPath = appDocDir.path;
var generatedPdfFile = await FlutterHtmlToPdf.convertFromHtmlContent(
htmlContent, targetPath, targetFileName);
generatedPdfFilePath = generatedPdfFile.path;
Now I need to know how to create a Flutter Image from that PDF or the bytecode to send raw to the printer.
You can use https://pub.dev/packages/printing:
await for (var page in Printing.raster(document)) {
final image = page.asImage();
...
}
This plugin can also convert your Html to Pdf with this:
final pdf = await Printing.convertHtml(
format: PdfPageFormat.a4,
html: '<html><body><p>Hello!</p></body></html>',
));
We are currently building a proof of concept to generate PDF/UA compliant PDF from from a CSS and html (xhtml) file using xslt. We are able tag the PDF and add the appropriate metadata information.
The last major issue we are unable to solve is embedding a standard PDF font zapfdinbats, which our accessibility assessment tool complains about - using PAC 2.0 along with adobe DC built in checker.
As you can see from the image below the other fonts we are using seems automatically get embedded using the xmlworker from our CSS.
I have also tried finding the font as indicated and found one, however, it doesn't seem to be the correct one.
Here is a sample of our code
private static ReturnValue CreateFromHtml(string html)
{
ReturnValue Result = new ReturnValue();
var stream = new MemoryStream();
using (var doc = new Document(PageSize.LETTER))
{
using (var ms = new MemoryStream())
{
using (var writer = PdfWriter.GetInstance(doc, ms))
{
writer.CloseStream = false;
writer.SetPdfVersion(PdfWriter.PDF_VERSION_1_7);
//TAGGED PDFVERSION_1_7
//Make document tagged
writer.SetTagged();
//===============
//PDF/UA
//Set document metadata
writer.ViewerPreferences = PdfWriter.DisplayDocTitle;
doc.AddLanguage("en-US");
doc.AddTitle("document title");
writer.CreateXmpMetadata();
doc.Open();
var embedfont = HttpContext.Current.Server.MapPath("~/scripts/ZapfDingbats.ttf");
var fontProv = new XMLWorkerFontProvider();
fontProv.DefaultEncoding = "UTF-8";
fontProv.Register(embedfont);
//Testing zapfDingbats font
Font font = FontFactory.GetFont(embedfont, BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
Paragraph p1 = new Paragraph("Testing of Fonts", font);
doc.Add(p1);
//end font processing
var tagProcessors = (DefaultTagProcessorFactory)Tags.GetHtmlTagProcessorFactory();
tagProcessors.RemoveProcessor(HTML.Tag.IMG);
tagProcessors.AddProcessor(HTML.Tag.IMG, new CustomImageTagProcessor());
var cssFiles = new CssFilesImpl();
cssFiles.Add(XMLWorkerHelper.GetInstance().GetDefaultCSS());
var cssResolver = new StyleAttrCSSResolver(cssFiles);
var charset = Encoding.UTF8;
var context = new HtmlPipelineContext(new CssAppliersImpl(new XMLWorkerFontProvider()));
context.SetAcceptUnknown(true).AutoBookmark(true).SetTagFactory(tagProcessors);
var htmlPipeline = new HtmlPipeline(context, new PdfWriterPipeline(doc, writer));
var cssPipeline = new CssResolverPipeline(cssResolver, htmlPipeline);
var worker = new XMLWorker(cssPipeline, true);
var xmlParser = new XMLParser(true, worker, charset);
using (var sr = new StringReader(html))
{
xmlParser.Parse(sr);
doc.Close();
ms.Position = 0;
ms.CopyTo(stream);
stream.Position = 0;
}
}
}
}
// get bytes from stream
Result.Data = stream.ToArray();
// success
Result.Success = true;
return Result;
}
Maybe there is something in the CSS we need to do (our CSS is quite large f
iText only ships with the Adobe Font Metrics (AFM) file of Zapfdingbats. This means that you can't embed that font unless you provide the corresponding PostScript Font Binary (PFB) file. This PFB file can't be shipped with iText because iText doesn't have a license to do so.
The first step to solve this, is to:
purchase a Zapfdingbats license so that you get the PFB (If I recall correctly, it's a font owned by Adobe), or
use an alternative font when you want to insert special characters (check boxes, phone symbols,...) into your text (e.g. purchase a license for the AdobePiStd font that was used as a substitution font and use that font instead of Zapfdingbats).
In your case, you provided a font ZapfDingbats.ttf which you register with the XMLWorkerFontProvider. When you register this font, it can be recognized through an alias. If ZapfDingbats.ttf isn't picked up by XML Worker, there is probably a mismatch between the name of the font used in the PDF and the alias that was used when ZapfDingbats.ttf was registered.
What is the font name used for ZapfDingbats in the CSS? You should register ZapfDingbats using that name as alias.
I'm trying to use the share() method, including an image, but I'm having trouble supplying the proper path to the image. Where should I put the image file, and what is the path (putting in the default package and trying "jar:///myimage.png" didn't work), and why is this not documented clearly?
image can be stored in storage which is following path for window
C:\Users\userName.cn1
and the image can be read by using following codes
InputStream is = Storage.getInstance().createInputStream("tizbn.JPG");
EncodedImage i = EncodedImage.create(is, is.available());
Loading image from default folder
Image i =EncodedImage.create("/tizbn.png");
Loading image From Theme
EncodedImage current = (EncodedImage) fetchResourceFile().getImage("tizbn.png");
The share API works with https://www.codenameone.com/javadoc/com/codename1/io/FileSystemStorage.html[FileSystemStorage] and not with https://www.codenameone.com/javadoc/com/codename1/io/Storage.html[Storage].
You need to save the file into a file system path which is always an absolute path, we recommend using the app home to store files. There is a sample in the developer guide section on the ShareButton covering this:
Form hi = new Form("ShareButton");
ShareButton sb = new ShareButton();
sb.setText("Share Screenshot");
hi.add(sb);
Image screenshot = Image.createImage(hi.getWidth(), hi.getHeight());
hi.revalidate();
hi.setVisible(true);
hi.paintComponent(screenshot.getGraphics(), true);
String imageFile = FileSystemStorage.getInstance().getAppHomePath() + "screenshot.png";
try(OutputStream os = FileSystemStorage.getInstance().openOutputStream(imageFile)) {
ImageIO.getImageIO().save(screenshot, os, ImageIO.FORMAT_PNG, 1);
} catch(IOException err) {
Log.e(err);
}
sb.setImageToShare(imageFile, "image/png");