i want to display an image stored in mysql database
the problem is that i can't convert the blob format into a Uint8list ; i searched and found soulitions but none of them works
Grab the blob from JSON:
var blob = yourJSONMapHere['yourJSONKeyHere'];
var image = BASE64.decode(blob); // image is a Uint8List
Now, use image in a Image.memory
new Container( child: new Image.memory(image));
this soulition didn't work because base64.decode need a string source not a blob file to convert
Don't know if it is relatable to this particular case but had similar issue with Cloud Firestore.
Created blob for storing in this way:
Blob myBlob = Blob(await audioFile.readAsBytes());
saved to Firestore in one field as usual
Then tried to read it back and couldn't figure it out how to get Uint8List from blob I get back from Firestore.
my solution:
//extract blob from field of Firestore document
Blob audioBlob = audioDocFromDb.get("fieldName");
//use .bytes on blob from this source
//package:cloud_firestore_platform_interface/src/blob.dart
Uint8List audioBytes = audioBlob.bytes;
this worked for me.
In my case I was packing up recorded audio and trying to play it back.
I had this problem too, i know the solution now, after many attempts:
Dont forget to upvote!
Uint8List image = Uint8List.fromList(blob.toBytes());
Image.memory(image);
This function has always saved me for getting bytes from a file that is uploaded to a URL.
import 'package:http/http.dart' as http;
// urlImageBlob is the URL where our file is hosted.
Uint8List fileBytes = await http.readBytes(Uri.parse(urlImageBlob));
// Display if are image.
Image.memory(fileBytes);
I am developing an app that allows a user to fill metadata to an image from UI like:
Name
Location
Maker Notes
....
Is there any way to do it in Flutter?
You can check by http://metapicz.com/#landing with any image URL
If you only need mobile support, there's a new package that can do this for you.
You add it as a dependency and then...
final exif = await Exif.fromPath(file.path);
final attributes = await exif!.getAttributes();
attributes['UserComment'] = "This file was edited by FlutterApp!";
final result = await exif.writeAttributes(attributes);
Is possible to load an image (logo) before loading the original image using Universal Image Loader?
How would be the implementation in this case?
Thanks in advance.
Using DisplayImageOptions in the field 'showImageOnLoading':
IMAGE_OPTIONS = new DisplayImageOptions.Builder() //
.showImageOnLoading(R.drawable.loader) //
.resetViewBeforeLoading(false) //
.bitmapConfig(Config.RGB_565) //
.imageScaleType(ImageScaleType.IN_SAMPLE_INT) //
.delayBeforeLoading(500) //
.cacheOnDisc(true) //
.cacheInMemory(true) //
.build();
After using the ImagesService to transform an uploaded image, I would like to store it back into a new Blob file and make it available through getServingUrl() as provided by the ImagesService.
Storing the image in a new AppEngineFile as described here works fine and I am able to open and view it locally using the dev server.
However when passing the blobKey for the new AppEngineFile to ImagesService.getServingUrl() a
java.lang.IllegalArgumentException: Could not read blob.
exception is thrown. Any ideas what the problem could be? This is the code I use to transform and store an uploaded image (blobKey and blobInfo correspond to the uploaded file, not the newly created one).
/* Transform image in existing Blob file */
Image originalImage = ImagesServiceFactory.makeImageFromBlob(blobKey);
Transform verticalFlip = ImagesServiceFactory.makeVerticalFlip();
ImagesService imagesService = ImagesServiceFactory.getImagesService();
Image newImage = imagesService.applyTransform(verticalFlip, originalImage);
/* Store newImage in an AppEngineFile */
FileService fileService = FileServiceFactory.getFileService();
AppEngineFile file = fileService.createNewBlobFile(blobInfo.getContentType());
FileWriteChannel writeChannel = fileService.openWriteChannel(file, true);
ByteBuffer buffer = ByteBuffer.wrap(newImage.getImageData());
writeChannel.write(buffer);
/* closeFinally assigns BlobKey to new file object */
writeChannel.closeFinally();
BlobKey newBlobKey = fileService.getBlobKey(file);
Edit:
The above code is correct, the problem was storing a String representation of the new blob key using newBlobKey.toString() instead of newBlobKey.getKeyString().
Why would you want to do that? Once you transform an image it is cached and anyway it is always fast. If you really feel you want to save it just use urlfetch to read the data and store them in the BlobStore ;-)
The following works fine when executed at the end of the code posted in the question:
String url = imagesService.getServingUrl(newBlobKey)
The URL can then be used to scale and crop the new image as described in the docs
http://code.google.com/appengine/docs/java/images/overview.html#Transforming_Images_from_the_Blobstore
I have an existing PDF and I can use FdFWriter to input to text boxes. It works well. Now I have an image. I have read the documentation and looked at many examples but they all create new documents and insert an image. I want to take an existing PDF and insert an image into either an image field or as the icon image of a button. I have tried but it corrupts the document.
I need to be able to take an existing document and put an image on it. I do not want to open, read, replace, and delete the original. This original changes and the name "original" only means the source file in this context. There are many PDF files like this that need an image.
Thank you for any help.
Edit - I am very thankful for the code below. It works great, but the problem for me is that the existing PDF has digital signatures on it. When the document is copied like this (into result.pdf) those signatures, while still present, have a different byte count or other item that is corrupted. This means the signatures, while they show up on result.pdf, have an icon next to them that state "invalid signature."
In case it matters I am using a Topaz signature pad to create my signatures, which has it's own security. Merely copying the PDF will not corrupt it but the process below will.
I am trying to put the image on the existing document, not a copy of it, which in this case matters.
Also, by signature, I mean handwritten, not pin numbers.
Thank you again.
EDIT - Can PdfSignatureAppearance be used for this?
EDIT - I seem to be able to do it with:
var stamper = new PdfStamper(reader, outputPdfStream,'1',true);
If you want to change the contents of an existing PDF file and add extra content such as watermarks, pagenumbers, extra headers, PdfStamper is the object you need. I have successfully used the following code to insert an image into an existing pdf file to a given absolute position:
using System.IO;
using iTextSharp.text;
using iTextSharp.text.pdf;
class Program
{
static void Main(string[] args)
{
using (Stream inputPdfStream = new FileStream("input.pdf", FileMode.Open, FileAccess.Read, FileShare.Read))
using (Stream inputImageStream = new FileStream("some_image.jpg", FileMode.Open, FileAccess.Read, FileShare.Read))
using (Stream outputPdfStream = new FileStream("result.pdf", FileMode.Create, FileAccess.Write, FileShare.None))
{
var reader = new PdfReader(inputPdfStream);
var stamper = new PdfStamper(reader, outputPdfStream);
var pdfContentByte = stamper.GetOverContent(1);
Image image = Image.GetInstance(inputImageStream);
image.SetAbsolutePosition(100, 100);
pdfContentByte.AddImage(image);
stamper.Close();
}
}
}
When you insert the image you have the possibility to resize it. You can take a look at transformation matrix in the iTextSharp documentation.
Here is a similar example whichi inserts an image on the page using the stamper:
Gmane iTex Mailing List Post
I could solve my problem by simply adding following lines to my signing code to add image
var image = iTextSharp.text.Image.GetInstance(#"C:\Users\sushil\Documents\sansign.jpg");
appearance.Acro6Layers = true;
appearance.SignatureGraphic = image;
appearance.SignatureRenderingMode = PdfSignatureAppearance.RenderingMode.GRAPHIC_AND_DESCRIPTION;
As I was signing document with visible digital signature , now I can have both image and digital signature properties side by side
in the .net core6 that uses DDD try this declare class in Infrastructure Layer
using System.IO;
using iTextSharp.text;
using iTextSharp.text.pdf;
public async Task<string> SignatureToPdf(string pathPdfFile, string
pathSignatureImage, string pathOutputName)
{
var webRootPath = hostingEnvironment.ContentRootPath;
if (!File.Exists(Path.Combine(webRootPath, pathPdfFile))) return
null;
await using Stream inputPdfStream =
new FileStream(Path.Combine(webRootPath, pathPdfFile),
FileMode.Open, FileAccess.Read, FileShare.Read);
await using Stream inputImageStream =
new FileStream(Path.Combine(webRootPath, pathSignatureImage), FileMode.Open, FileAccess.Read, FileShare.Read);
await using Stream outputPdfStream =
new FileStream(Path.Combine(webRootPath, pathOutputName),
FileMode.Create, FileAccess.Write, FileShare.None);
var reader = new PdfReader(inputPdfStream);
var stamper = new PdfStamper(reader, outputPdfStream);
var pdfContentByte = stamper.GetOverContent(1);
var image = Image.GetInstance(inputImageStream);
image.SetAbsolutePosition(100, 100);
pdfContentByte.AddImage(image);
stamper.Close();
return "ok";
}
pdftk can do this. It's not a library but you can easily call it from your code as a .exe.
See stamp and background commands:
http://www.pdflabs.com/docs/pdftk-man-page/
ref: How to do mail merge on top of a PDF?