I have Page X with a SignaturePad on my Xamarin.Forms app and I save the signature into the database in the following way:
if (!sp.IsBlank)
{
Stream image = await sp.GetImageStreamAsync(SignatureImageFormat.Png);
using (BinaryReader br = new BinaryReader(image))
{
br.BaseStream.Position = 0;
byte[] SignatureImage = br.ReadBytes((int)image.Length);
}
}
I save this byte array in my SQL database table. I navigate to a couple of other pages in my app and then go back to Page X and want to reload all the information into this page from the saved information in the database. How do I reload the Signature? Do I need to save the signature as strokes or points instead? How do I save strokes or points in the database? Some sample code would be really helpful
Thank you.
I'm using the Microsoft Bot Framework with Cognitive Services to generate images from a source image that the user uploads via the bot. I'm using C#.
The Cognitive Services API returns a byte[] or a Stream representing the treated image.
How can I send that image directly to my user? All the docs and samples seem to point to me having to host the image as a publically addressable URL and send a link. I can do this but I'd rather not.
Does anyone know how to simple return the image, kind of like the Caption Bot does?
You should be able to use something like this:
var message = activity.CreateReply("");
message.Type = "message";
message.Attachments = new List<Attachment>();
var webClient = new WebClient();
byte[] imageBytes = webClient.DownloadData("https://placeholdit.imgix.net/~text?txtsize=35&txt=image-data&w=120&h=120");
string url = "data:image/png;base64," + Convert.ToBase64String(imageBytes)
message.Attachments.Add(new Attachment { ContentUrl = url, ContentType = "image/png" });
await _client.Conversations.ReplyToActivityAsync(message);
The image source of HTML image elements can be a data URI that contains the image directly rather than a URL for downloading the image. The following overloaded functions will take any valid image and encode it as a JPEG data URI string that may be provided directly to the src property of HTML elements to display the image. If you know ahead of time the format of the image returned, then you might be able to save some processing by not re-encoding the image as JPEG by just returning the image encoded as base 64 with the appropriate image data URI prefix.
public string ImageToBase64(System.IO.Stream stream)
{
// Create bitmap from stream
using (System.Drawing.Bitmap bitmap = System.Drawing.Bitmap.FromStream(stream) as System.Drawing.Bitmap)
{
// Save to memory stream as jpeg to set known format. Could also use PNG with changes to bitmap save
// and returned data prefix below
byte[] outputBytes = null;
using (System.IO.MemoryStream outputStream = new System.IO.MemoryStream())
{
bitmap.Save(outputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
outputBytes = outputStream.ToArray();
}
// Encoded image byte array and prepend proper prefix for image data. Result can be used as HTML image source directly
string output = string.Format("data:image/jpeg;base64,{0}", Convert.ToBase64String(outputBytes));
return output;
}
}
public string ImageToBase64(byte[] bytes)
{
using (System.IO.MemoryStream inputStream = new System.IO.MemoryStream())
{
inputStream.Write(bytes, 0, bytes.Length);
return ImageToBase64(inputStream);
}
}
I'm using rad controls(charts and gridview) for developing an application,which i need to export the controls(each) into image.I have tried each control converting them into bytes format and send to webservice and converting them to images but sometime sending the byte data to service throws an error.Is any other way to convert each control into image.I have tried another way like.
Stream fileStream = File.OpenRead(#"\\HARAVEER-PC\TempImages\FlashPivot.png");
//PART 2 - use the stream to write the file output.
productChart.ExportToImage(fileStream, new Telerik.Windows.Media.Imaging.PngBitmapEncoder());
fileStream.Close();
It throwing me an error like cannot access to the folder TempImages.I have given sharing permissions to everyone but it doesn't access the folder.
Any solution is much appreciated.
private BitmapImage CreateChartImages()
{
Guid photoID = System.Guid.NewGuid();
string photolocation = #"D:\Temp\" + photoID.ToString() + ".jpg";
BitmapImage bi = new BitmapImage(new Uri(photolocation, UriKind.Absolute));
using (MemoryStream ms = new MemoryStream())
{
radChart.ExportToImage(ms, new PngBitmapEncoder());
bi.SetSource(ms);
}
return bi;
}
Could any1 please suggest a method by which i can store all my questions , Multiple Choice answers and the correct answer. So that i can call them and then display in a text box and radio buttons . And as when the user answers a question correctly i should be able to move to the next question.
This was my approach. Used data serialization, created a class with Data memebers which will store question id , questions and answers. then created an object for it in while page is loading. But i am unable to display the questions. Please help me out.
Depending on the number of questions, you might find it easier and faster to use a local database.
I am a little confused at your approach. Serialization by itself doesnt actually persist data. Perhaps that is your problem. I have found that storing the XML to IsolatedStorage is one of the easier ways to persist data.
I created an IsolatedStorage class that looks like this for saving an XDocument object.
public static void SaveDataToIsolatedStorage(string filePath, FileMode fileMode, XDocument xDoc)
{
using (IsolatedStorageFile storage = IsolatedStorageFile.GetUserStoreForApplication())
{
using (IsolatedStorageFileStream location = new IsolatedStorageFileStream(filePath, fileMode, storage))
{
System.IO.StreamWriter file = new System.IO.StreamWriter(location);
xDoc.Save(file);
}
}
}
Here is my reader.
private static XDocument ReadDataFromIsolatedStorageXmlDoc()
{
using (IsolatedStorageFile storage = IsolatedStorageFile.GetUserStoreForApplication())
{
if (!storage.FileExists(filePath))
{
return new XDocument();
}
using (var isoFileStream = new IsolatedStorageFileStream(filePath, FileMode.OpenOrCreate, storage))
{
using (XmlReader reader = XmlReader.Create(isoFileStream))
{
return XDocument.Load(reader);
}
}
}
}
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?