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This is my code for retrieving pictures, it was working before but then i accidentally deleted the table and i created it again with the same name and same fields. and now whenever i open the form with the picture, there was a message box error. it says Buffer cannot be null. Parameter name: buffer I don't know what i did wrong.
I have a web application on a Windows 2008 server. The web application opens another application interactively.The issue: If I am logged into the server, the web application runs without any problem. If I log-off, and try to use the web application, I get an error "Buffer cannot be null."If I log myself back into the server,go to another computer and try the web app, it will work fine.What security setting is causing this?
View 3 RepliesTo Double Buffer or not to Double Buffer this is the Question!I have a form with Protected Overrides Sub OnPaint that sets forms background to a gradient fill ,on top of that is a transparent richtext box.
Ok. now here`s the problem ,If i enable forms double buffering the transparent Rtb doesn't flicker when forms resized. but the forms drop shadow does flicker! ,its a boarderless form using CS_DROPSHADOW to draw the drop shadow Now if i disable double buffering the forms drop shadow doesn`t flicker but the transparent Rtb does ,any one have a clue how to get both to work in harmony !
The reply buffer is in ASCII value...but I need is HEX value.Is there any way that the reply buffer is in hex?
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Public Function read_write_string(ByVal devicehandle, ByVal command, ByVal commandlenght) As String
Dim inputReportBuffer(100) As Byte
unManagedBuffer = Marshal.AllocHGlobal(inputReportBuffer.Length)
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I have a problem that i cant solve i am trying to buffer 28 bytes from the com port into the array actual_packet_VPS1(30). It works with the counter set to 0 - 15 but doesnt work when we increase the counter size to 0 -28.
Private Sub MSComm5_OnComm(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles MSComm5.OnComm
Dim buffer As Object
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I have a need to double buffer a flowlayoutpanel. I have the form set to doublebuffered which is half the story but their is no property in the list to make the flowlayoutpanel do this (although MSDN states that it has this property) how i can set it to true for the panel?
View 5 RepliesIm trying to do a video player but i have to play this video from the buffer, is this possible.. Let me explain you much more complicated,a got a CryptoStream and im decryting the video
While lngBytesProcessed < lngFileLength
'Read file with the input filestream.
intBytesInCurrentBlock = fsInput.Read(bytBuffer, 0, 4096)
'Write output file with the cryptostream.
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This code writes my decryted or crypted video to a new file. However, i need to play the video file from the buffer(without copying to a new file), in other way it would be meaningless if i create a decryted file. in other words it would unsecure for me cuz if anyone can locate my temp directorey they can copy my decrypted video files.
Dim Fs as FileSystemObject
Dim TS as TextStream
Set Fs = CreateObject("Scripting.FileSystemObject")
Set Ts = fs.OpenTextFile(textFilePath, ForReading, False,
TristateUseDefault)
While not Ts.AtEndOfStream
Buffer=Ts.ReadLine
' Process the buffer
Wend
Ts.Close
Fs.Close
I tried to convert into c# but am getting ERROR like EOF expected, what I have to do?
I am using VB.net sockets to send a music file from one instance to another. It currently saves the file, but I do not want to be caught up in file-sharing, so I want to "save" it to a buffer, and when it gets to a particular percentage transferred, I want another thread to play the music file, deleting it from the buffer as it plays. I have the code to send it over the network, but I need to know how to keep it in a buffer and not save it as a file.
View 1 RepliesI've looked and looked + tryed debugging but I'm not getting anywhere fast I'm trying to import a usb radio driver and I'm 99% there. I can turn it on / off and get / set the freq.. but I'm struggling to get the rds name from it. The VB code for the function is
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I have been asked to improve the memory efficiency of an application that is used for high speed data acquisition. After running the VS memory profiler several times and scanning the projects for obvious issues I came to the following conclusion: despite using a fixed size circular buffer for storing acquired sample points, the RAM usage increases relative to the polling period. For example: polling data for one signal at 2 microseconds can use 5 times more memory (private bytes) than when running at 50 microseconds ... even though the buffer size is the same.
The circular buffer is an array of SamplePoint objects. Each of these objects contains an array of Shorts (16 bit) for corresponding data per signal and one date object (8 bytes) for the time stamp. For efficiency, the circular buffer is Redimmed only once every time it begins polling and filled with empty sample points which are then "assigned".
Also, it seems that when we stop and run the application it hogs even more memory each time as though the Redim is not releasing the previous array. My questions boil down to the following: What is most memory efficient way of implementing a circular buffer containing managed objects which have arrays?Also, how and why is memory usage increasing with a fixed size array with different polling speeds? Does the garbage collector not have time? Do local variables get disposed of IMMEDIATELY when a sub or function exits?These are some of the doubts and concerns that I would like to rule out before proceeding.
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basically I'm sending and receiving both images, strings and files over a client/server connection. I can easily use a protocol for string commands but I cannot distinguish between the incoming data [if data is image or whatever and then follow onward instructions].So how do I make a packet using Dim buffer as byte()?
View 2 RepliesHow can I create a circular buffer on the heap in VB.NET ? This would be used for audio playback via P/Invoke to winmm.dll waveoutopen and waveoutwrite to support development of a software synth. I currently use the marshall class to build a regular array of bytes in the heap.
View 1 RepliesI've been trying to get the double buffer function working in VB.NET GDI+ for a space invaders game using the following command.[code]But because I am using a separate draw routine attached to a class it doesn't seem to work:[code]The aliens draw correctly but the images are very stuttery and double buffering doesn't seem to work.
View 1 RepliesI have connected to a host, but how do I find the correct buffer size? (The Buffer is currently set to 8k (8192))
Dim webget As New Net.Sockets.Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
webget.Connect(host, port)
webget.Send(data, 0, data.Length, SocketFlags.None)
Dim rData(8192) As Byte
webget.Receive(rData, rData.Length, 0)
I see this error page appears in some client access but some client didn't see this.
View 2 RepliesI'm currently working on a little software for my GPS and i havent touched VB in about 10 years so I'm trying to figure this out from scratch again pretty much. Anyway, I have this code to get the information from the GPS and parse it, the only problem is that It isn't getting all the code at once and then parsing, it is getting bits and pieces and only getting the RIGHT code from time to time..
Private Sub timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) _
Handles timer1.Tick
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I need to search a buffer for a string of characters.The buffer is essentially a binary file (it's an image) and contains lots of chr(0) characters.The string I need to locate also contains chr(0) characters. In fact it is the following string:
chr(100) & chr(0) & chr(0) & chr(163)
This is a marker in the image file for items I need to process.So I though I would do the following:
Dim sFileBuffer as String = system.io.file.readalltext("myimagefile")
Dim sLookFor as String = chr(100) & chr(0) & chr(0) & chr(163)
Dim iLocation as Integer = sFileBuffer.IndexOf(sLookFor)
The problem is that, although the characters in sLookFor definitely exist inside of sFileBuffer - IndexOf will always return -1 (not found).I tried the following:
Dim Marker() as Byte = {100, 0, 0 , 163}
Dim sLookFor as String = System.Text.Encoding.UTF8.GetString(Marker)
Dim sFileBuffer as String = system.io.file.readalltext("myimagefile", Encoding.UTF8)
Dim iLocation as Integer = sFileBuffer.IndexOf(sLookFor)
But this appears to only find occurrences of Chr(100) & Chr(0) - not the full 4 character sequence I desire. It appears to see the second Chr(0) as a termination of the search string.I think the sticking point here is the null. Yes - I can string.replace(chr(0), Chr(255)) in both the sLookFor and the sFileBuffer and adjust my search accordingly - but that seems like a mess to me.Is there not a way to search a buffer of binary data? I've tried working with byte arrays - but there appears to be no way to easily search for a sequence of byte values - just individual elements in the array.
I've managed to make an application at home using a serialport emulator and connector that will read text from a file on my desktop send it to com1 and then my connector program will merge com1 with com2. In short my program works at home but when I connect it to my device it appears the data in DataReceived is a fraction of what my simulator setup at home is producing, which apparently is completely normal according to all these threads I've read here.
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How can a TextBox or RichTextBox buffer size be set? I have data that goes to a TextBox continuously, but I want to set a maximum size of buffer for the TextBox. I read in one forum someone suggesting to set the TextBox MaxLength property, but the questioner replied that he had tried this, and when the MaxLength was reached no further data input was possible, and what he wanted was the situation where new data could still come in, but the oldest data was then deleted, i.e a rolling buffer, which is precisely
View 3 RepliesI built a console application that reads a directory of files, builds a 'put' statement for each file and submits each statement to a webservice. Then, it reads the webservice output (for each statement), parses it for a specific string, builds a 'get'statement and submits the 'get' to the webservice (for each file).Then, the application reads the 'get' output stream and writes a file (to the local file system) for each file that was submitted, using a streamwriter.I have encountered an issue where some files are unable to be written to the local file system by the streamwriter.After much testing I have figured out that any file exceeding 4096 bytes will cause the application to hang where streamwriter should write the output to file.I have tried the syntax below to increase the size of the streamwriter buffer however, it doesn't seem to be working.I do need to mention that I am an extreme novice with VB or any other language and have, for the most part written this module from research and code samples.I should mention that this module does work for any file that is less than 4096 bytes in size.
View 6 Replies(First time trying to do socket programming ) I'm trying to read a large buffer using sockets. Is there anything wrong with this psudo code?
DO
mySocket.Receive(buff) ' temporary buffer, discard the data
WHILE (mySocket.Available > 0)
it terminates after the first iteration because, I suppose, it reads the data faster than the sender is sending it, and Socket.Available will be 0 (if i break the debugger and step through it, it receives the whole buffer). How can i make the Receive call block until more data is available? (I've tried setting Socket.ReceiveTimeout, but it doesn't seem to do any good)
I am trying to communicate with an Extech 421509 Thermometer via the serial port.Since I do not know VB very well I first wrote the program in LabVIEW to make sure I knew how to write the program, once I was successful with that I tried to write the code in VB.I am mostly successful with that except that in VB my buffer will be read 4 or 5 times and then there is nothing on my buffer. In LabVIEW I do not have this problem as I write to the buffer I can immediately read from the buffer.
Imports System
Imports System.IO.Ports
Imports System.Threading[code]....
I found this function from the net. But I have a problem with the reply buffer. The reply buffer is in ASCII value...but I need is HEX value. Is there any way that the reply buffer is in hex?
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I am trying to empty my input buffer when I open up the serial port using this code but its not working any suggestions? Mainly just look at the last line [code]
View 6 Replieschange my MDIClient's background image I've decided that painting over it is the best way to go (because of scaling). Problem is, when the form (and the MDIClient) get scaled/resized, there's massive flicker even with the ControlStyles and form double buffering.
Public Class frmMain
Dim BGimage As Image
Sub New()
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I'm receiving tons of statistics data that I need to insert into the db.I would like to implement some kind of Queue or FIFO class that keeps all the dataand when it reaches to a specific count (buffer), it will send that data to the SQL through bulk insert. This should be thread-safe.
View 3 RepliesI have a standard WMA stream, streaming in constantly via the internet. I need to write an application to stream this audio, and looks for any periods of 'silence'. When it detects silence, it runs an event.
For the purposes of this, silence is defined as three seconds of zero-level audio. The stream keeps going in a technical sense, but there is no audible noise coming through it.
However, I want the program to detect the silence while it is still in the 'buffer'. That is, the user won't hear this silence before the program detects it is there.
The audio shouldn't stop as it is analysing this silence - it needs to keep playing the audio constantly to the user.
I'm open to using whatever suitable API is out there - such as BASS, or the Windows Media extensions built into the dot net platform.
where I'm going wrong with my circular DirectSound Capture buffer here? If I just capture sound into a big non-circular buffer it works fine, but with a 1 second (44100 bytes) buffer and a 100ms timer to poll the read position it goes haywire. No error messages, just long blocks of zeros with short bursts of valid data. calculation of the number of bytes to read and/or the read position.
Here is the code. gBuffer is defined elsewhere as a big byte array. In this example I am just trying to copy the captured sound data from the small temporary byte array (tempBuffer) into the big gBuffer byte array. Obviously this must be done so that every byte is read and copied into the byte array with no gaps or duplication of values. Timer1 is set to 100mS:
Dim McaptureBuffer As CaptureBuffer
Dim MiLastReadPos As Integer
Dim MiBufferOffset As Integer
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Does reading the serial port empty the buffer?
View 2 Replies