I want to split a file ( a docx file) and use the individual fragments of the file to encode a QRCode such that when the qrcodes are read in sequence, it reproduces the original file.
I was able to split the file and create a bunch of QRCodes but when attempted to recreate the file, the Decoder throws the following Error Message.
"Invalid number of finder pattern detected"
I am using http://www.codeproject.com/KB/cs/qrcode.aspx library.
My encoder code
private List Encode(String content, Encoding encoding, int
System.Drawing.Color qrCodeBackgroundColor,
QRCodeCapacity,System.Drawing.Color qrCodeBackgroundColor,System.Drawing.Color
qrCodeForegroundColor,int qrCodeScale, int NoOfQRcodes)
{
List<Bitmap> _qrcodesImages = new List<Bitmap>();
byte[] _filebytearray = encoding.GetBytes(content);
for (int k = 0,l=0; k < NoOfQRcodes; k++)
{
byte[] _tempByteArray = _filebytearray.Skip(l).Take(QRCodeCapacity).ToArray();
bool[][] matrix = calQrcode(_tempByteArray);
SolidBrush brush = new SolidBrush(qrCodeBackgroundColor);
Bitmap image = new Bitmap((matrix.Length * qrCodeScale) + 1, (matrix.Length * qrCodeScale) + 1);
Graphics g = Graphics.FromImage(image);
g.FillRectangle(brush, new Rectangle(0, 0, image.Width, image.Height));
brush.Color = qrCodeForegroundColor;
for (int i = 0; i < matrix.Length; i++)
{
for (int j = 0; j < matrix.Length; j++)
{
if (matrix[j][i])
{
g.FillRectangle(brush, j * qrCodeScale, i * qrCodeScale, qrCodeScale, qrCodeScale);
}
}
}
_qrcodesImages.Add(image);
l += QRCodeCapacity;
}
return _qrcodesImages;
}
Related
I have been trying for hours to figure out why my code is not working. Basically, I have an image. I load its bytes into dart as a list of Uint8List. Then, I replace the values of the list with some other values. The problem is that after replacing the values, when I call the File().writeAsBytes() function, the image is CORRUPTED. Don't know why this is happening. Tried doing everything I could.
var b = File("assets/1K91k (1).jpg").readAsBytesSync();
void main() {
runApp(const MyApp());
for (int i = 0; i < b.length; i++) {
double check = b[i] / 255;
if (check > 0.8) {
b[i] = 255;
} else {
b[i] = 2;
}
}
File("/home/kq1231/Desktop/test.jpg")
..createSync()
..writeAsBytesSync(b);
}
I tried converting the b list to a Uint8List but to no avail.
Feels funny to answer my own question but here's how it got working:
import 'package:image/image.dart' as image;
import 'dart:io';
image.Image prettify(String fileName, String exportPath, String imageName,
double threshold, int blurRadius) {
var b = image.decodeImage(File(fileName).readAsBytesSync());
b = image.gaussianBlur(b!, blurRadius);
for (int i = 0; i < b.width; i++) {
for (int j = 0; j < b.height; j++) {
var pix = b.getPixel(i, j);
if ((image.getBlue(pix) + image.getRed(pix) + image.getGreen(pix)) /
(255 * 3) >
threshold) {
b.setPixel(i, j, 0xffffff);
} else {
b.setPixel(i, j, 0);
}
}
}
File("$exportPath/$imageName")
..createSync()
..writeAsBytesSync(image.encodePng(b));
return b;
}
This is a function called prettify. It applies a specific operation to a given image. First, decode the image. Then, loop through each pixel, average the R, G and B values to get the grayscale value (get the value of the pixel using image.getPixel() and set its value using image.setPixel()). Then, encode it back to .png format and save it.
Note that image is the name of the library imported.
I am converting an IBrowserfile to a stream of 6gig. I am trying to hash the file in chunks but getting the Out Of Memory exception,
public static async Task<byte[]> hashmultiblock(Stream stream)
{
int chunckSize = 30000000;
int totalChunks = (int)(stream.Length / chunckSize);
if (stream.Length % chunckSize != 0)
totalChunks++;
using (SHA256 hashAlgorithm = SHA256.Create())
{
int offset = 0;
for (int i = 0; i < totalChunks; i++)
{
long position = (i * (long)chunckSize);
int toRead = (int)Math.Min(stream.Length - position + 1, chunckSize);
byte[] buffer = new byte[toRead];
if (i == totalChunks)
hashAlgorithm.TransformFinalBlock(buffer.ToArray(), 0, toRead);
else
hashAlgorithm.TransformBlock(buffer.ToArray(), 0, toRead, null, -1);
}
return hashAlgorithm.Hash;
}
}
I need to use Bitmap class from System.Drawing.Bitmap, this is a function that works fine on windows Platform. But after I tried to run on Xamarin Forms, and installed nuget package System.Drawing, the program compiles correctly without errors.
But when running program I receive an error. Somehow seems to point to System.Drawing from windows, not the System.Drawing from the nuget package.
What I need to do is, get Photo from Camera and print it.
Below is the code to print. Problem is with "Bitmap" converter.
Tried several nuget packages, none worked:
System.Drawing.Common
Fast-Bitmap
Bitmap.Net
public byte[] PrintImage(byte[] PHOTO)
{
Bitmap bmp;
using (var ms = new MemoryStream(PHOTO))
{
bmp = new Bitmap(ms);
}
BitmapData data = GetBitmapData(bmp);
BitArray dots = data.Dots;
byte[] width = BitConverter.GetBytes(data.Width);
int offset = 0;
MemoryStream stream = new MemoryStream();
BinaryWriter bw = new BinaryWriter(stream);
// center command
bw.Write(27);
bw.Write('a');
bw.Write(1);
// print image
bw.Write((char)0x1B);
bw.Write('#');
bw.Write((char)0x1B);
bw.Write('3');
bw.Write((byte)24);
while (offset < data.Height)
{
bw.Write((char)0x1B);
bw.Write('*'); // bit-image mode
bw.Write((byte)33); // 24-dot double-density
bw.Write(width[0]); // width low byte
bw.Write(width[1]); // width high byte
for (int x = 0; x < data.Width; ++x)
{
for (int k = 0; k < 3; ++k)
{
byte slice = 0;
for (int b = 0; b < 8; ++b)
{
int y = (((offset / 8) + k) * 8) + b;
// Calculate the location of the pixel.
// It'll be at (y * width) + x.
int i = (y * data.Width) + x;
// If the image is shorter than 24 dots.
bool v = false;
if (i < dots.Length)
{
v = dots[i];
}
slice |= (byte)((v ? 1 : 0) << (7 - b));
}
bw.Write(slice);
}
}
offset += 24;
bw.Write((char)0x0A);
}
// Restore the line spacing to the default of 30 dots.
bw.Write((char)0x1B);
bw.Write('3');
bw.Write((byte)30);
bw.Flush();
byte[] bytes = stream.ToArray();
return bytes; // logo + Encoding.Default.GetString(bytes);
}
public BitmapData GetBitmapData(Bitmap bmp) // (string bmpFileName)
{
//using (var bitmap = (Bitmap)Bitmap.FromFile(bmpFileName))
using (var bitmap = bmp)
{
var threshold = 127;
var index = 0;
double multiplier = 570; // this depends on your printer
double scale = (double)(multiplier / (double)bitmap.Width);
int xheight = (int)(bitmap.Height * scale);
int xwidth = (int)(bitmap.Width * scale);
var dimensions = xwidth * xheight;
var dots = new BitArray(dimensions);
for (var y = 0; y < xheight; y++)
{
for (var x = 0; x < xwidth; x++)
{
var _x = (int)(x / scale);
var _y = (int)(y / scale);
var color = bitmap.GetPixel(_x, _y);
var luminance = (int)(color.R * 0.3 + color.G * 0.59 + color.B * 0.11);
dots[index] = (luminance < threshold);
index++;
}
}
return new BitmapData()
{
Dots = dots,
Height = (int)(bitmap.Height * scale),
Width = (int)(bitmap.Width * scale)
};
}
}
public class BitmapData
{
public BitArray Dots
{
get;
set;
}
public int Height
{
get;
set;
}
public int Width
{
get;
set;
}
}
Error occurs when function is called as:
byte[] _buffer = PrintImage(FOTO);
The error:
"Could not resolve type with token 01000119 from typeref (expected class 'System.Drawing.Bitmap' in assembly 'System.Drawing.Common, Version=4.0.1.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51')"
in my C# window application i want to read the text & images from ABC.pdf but its password protected.please help me to solve this issue.
PdfReader reader = new PdfReader(#"E:\ABC.pdf");
int intPageNum = reader.NumberOfPages;
string[] words;
string line;
for (int i = 1; i <= intPageNum; i++)
{
var text = PdfTextExtractor.GetTextFromPage(reader, i, new LocationTextExtractionStrategy());
words = text.Split('\n');
for (int j = 0, len = words.Length; j < len; j++)
{
line = Encoding.UTF8.GetString(Encoding.UTF8.GetBytes(words[j]));
label1.Text = label1.Text + "\n" + line;
}
}
Is there any way that I can detect color pages in a PDF file?
For example I have a PDF file with 5 pages, and the first and last page are in color. How can I detect the color pages? Can iText do it?
Now my solution is to convert PDF to images and then detect images color or black&white, but it takes too long time to do it, I need a fast way.
Convert pdf to image by Adobe Acrobat Code as fellows
public static void ConvertPDF2Image(string pdfInputPath, string imageOutputPath,
string imageName, int startPageNum, int endPageNum, ImageFormat imageFormat, double resolution)
{
Acrobat.CAcroPDDoc pdfDoc = null;
Acrobat.CAcroPDPage pdfPage = null;
Acrobat.CAcroRect pdfRect = null;
Acrobat.CAcroPoint pdfPoint = null;
// Create the document (Can only create the AcroExch.PDDoc object using late-binding)
// Note using VisualBasic helper functions, have to add reference to DLL
pdfDoc = (Acrobat.CAcroPDDoc)Microsoft.VisualBasic.Interaction.CreateObject("AcroExch.PDDoc", "");
// validate parameter
if (!pdfDoc.Open(pdfInputPath)) { throw new FileNotFoundException(); }
if (!Directory.Exists(imageOutputPath)) { Directory.CreateDirectory(imageOutputPath); }
if (startPageNum <= 0) { startPageNum = 1; }
if (endPageNum > pdfDoc.GetNumPages() || endPageNum <= 0) { endPageNum = pdfDoc.GetNumPages(); }
if (startPageNum > endPageNum) { int tempPageNum = startPageNum; startPageNum = endPageNum; endPageNum = startPageNum; }
if (imageFormat == null) { imageFormat = ImageFormat.Jpeg; }
if (resolution <= 0) { resolution = 1; }
// start to convert each page
for (int i = startPageNum; i <= endPageNum; i++)
{
pdfPage = (Acrobat.CAcroPDPage)pdfDoc.AcquirePage(i - 1);
pdfPoint = (Acrobat.CAcroPoint)pdfPage.GetSize();
pdfRect = (Acrobat.CAcroRect)Microsoft.VisualBasic.Interaction.CreateObject("AcroExch.Rect", "");
int imgWidth = (int)((double)pdfPoint.x * resolution);
int imgHeight = (int)((double)pdfPoint.y * resolution);
pdfRect.Left = 0;
pdfRect.right = (short)imgWidth;
pdfRect.Top = 0;
pdfRect.bottom = (short)imgHeight;
// Render to clipboard, scaled by 100 percent (ie. original size)
// Even though we want a smaller image, better for us to scale in .NET
// than Acrobat as it would greek out small text
pdfPage.CopyToClipboard(pdfRect, 0, 0, (short)(100 * resolution));
IDataObject clipboardData = Clipboard.GetDataObject();
if (clipboardData.GetDataPresent(DataFormats.Bitmap))
{
Bitmap pdfBitmap = (Bitmap)clipboardData.GetData(DataFormats.Bitmap);
pdfBitmap.Save(Path.Combine(imageOutputPath, imageName) + i.ToString() + "." + imageFormat.ToString(), imageFormat);
pdfBitmap.Dispose();
}
}
pdfDoc.Close();
Marshal.ReleaseComObject(pdfPage);
Marshal.ReleaseComObject(pdfRect);
Marshal.ReleaseComObject(pdfDoc);
Marshal.ReleaseComObject(pdfPoint);
}
////detect image Color or black and white as fellows
Bitmap box1 = new Bitmap(PictureBox1.Image);
Color c = new Color()
int rr, gg, bb;
for(int i=0;i<PictureBox1.Width;i++){
for(int j=0;j<PictureBox1.Height;j++){
c= box1.GetPixel(i,j);
rr= c.R; gg=c.g;bb=c.B;
if（c ==Color.Black||c= Color.White）{
MessageBox.Show("black and white dot")
}
else {
if(rr==gg==bb){
MessageBox.Show("Gray dot");
}
else {
MessageBOx.Show("Color dot")；
}
}
}
}