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I am working on quite a large form that has become very slow to load, so i'm looking to take off some of the controls and have them loading on a background worker. The most used controls will remain, and a stack will be set up of controls to load in the background, loading the most recently requested control next.
As controls can only be added on the main thread there is also a queue of controls that have been loaded on the background worker and now need adding to the form. All of this works, the issue i have is it would be useful to keep a reference to each control, so you only load it once etc.
To stop code replication it would be great if i can create an object by sending in the System.Type of the object i want to make, the controlCollection it should be added to, some data it can use and the class/form level referance you want set to the control when it has loaded.
Most of this works, however, i cannot get the class level reference to point to object created on the background worker. I get the feeling it should be doable using byRef, but am not quite sure how. I'm thinking my C++ way of thinking is causing problems here, any advice would be appreciated.
Sorry for the large amount of code being posted, think it is all needed to solve the problem.
Public Class MyClass
'class level declaration of control to load on the background worker
Private _addresses As uscAddresses = Nothing
Public Function Addresses() As uscAddresses
If _addresses Is Nothing Then 'if its not been loaded we should put it on the top of the stack
'don't worry if it is already on the stack as it will not get loaded twice
_loadQueue.Push(New ComponentToLoad(GetType(uscAddresses), _addresses, Nothing, tpAddresses))
'if we are already running the background worker no need to start it a second time
If Not bgwLoader.IsBusy Then bgwLoader.RunWorkerAsync()
'ideally won't need this next bit in the final solution
While _addresses Is Nothing
'Application.DoEvents()
'Threading.Thread.Sleep(100)
End While
End If
Return _addresses
End Function
Structure ComponentToLoad
Public Type As System.Type 'type of object that we want to load
'**************************************************************
Public Target As UserControl 'the class level reference to use for the created object
'**************************************************************
Public Data As Object 'any data to pass to the object
Public Parent As Control 'the control to add the new object to after its created
Public Sub New(ByVal inType As System.Type, ByVal inTarget As UserControl, ByVal inData As Object, ByVal inParent As Control)
Type = inType
Target = inTarget
Data = inData
Parent = inParent
End Sub
End Structure
'runs as a stack so most recent request is delt with first
Private Shared _loadQueue As New Stack(Of ComponentToLoad)
'could use another stack but a queue will do, user should see little difference
Private Shared _controlsToAdd As New Queue(Of ComponentToLoad)
Private Sub MatterManager_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
'queue objects to load here if any are needed but not immediatly at form load
End Sub
'handles all loading, including checks that the object is not already loaded
Public Sub LoadControl(ByVal onUIThread As Boolean, ByRef inComponent As ComponentToLoad)
If onUIThread Then
'only add the control if its not there already
If Not DirectCast(inComponent.Parent, TabPage).Controls.Contains(inComponent.Target) Then
DirectCast(inComponent.Parent, TabPage).Controls.Add(inComponent.Target)
End If
Else
'only make the object if its not already made
If inComponent.Target Is Nothing Then
inComponent.Target = Activator.CreateInstance(inComponent.Type)
inComponent.Target.Dock = DockStyle.Fill
End If
'could pass the data in to the object here
End If
End Sub
Private Sub bgwLoader_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bgwLoader.DoWork
'check there is something in the queue
If _loadQueue.Count > 0 Then
'make reference to what we are loading so we can add it to the ui queue
Dim toLoad As ComponentToLoad = _loadQueue.Pop
'load it
LoadControl(False, toLoad)
'stick it on the ui addition queue
_controlsToAdd.Enqueue(toLoad)
End If
End Sub
Private Sub bgwLoader_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles bgwLoader.RunWorkerCompleted
While _controlsToAdd.Count > 0
'add all loaded controls
LoadControl(True, _controlsToAdd.Dequeue())
End While
If _loadQueue.Count > 0 AndAlso Not bgwLoader.IsBusy Then
'load the next object
bgwLoader.RunWorkerAsync()
End If
End Sub
End Class
modified on Wednesday, July 29, 2009 12:24 PM
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This sounds a bit like you are trying to solve a basic simple problem with a really really really complicated solution.
From the way you are trying to solve this problem now, I understand that even when the form is loaded completely, the user won't need all the controls all the time anyway.
Wouldn't it be easier to just rethink your GUI design? No program should need so many buttons, text boxes, or whatever, that an average PC starts having trouble loading the interface.
Even if you were to get your solution to work, your app would likely bring the PC to its knees anyway, by the time the background thread has finished loading all controls.
Try to combine controls, and reuse them, or to move certain secondary functionality (and the accompanying controls) to its own form, which you then open with a single button or automatically, as a result of another action taken or choice made.
My advice is free, and you may get what you paid for.
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While i understand your points, the application i am working on is a product that has been in development and use for many years, and i'm quite restricted in what i can do to change where information is displayed.
I think the C++ example of what i want is something like this:
#include <iostream>
#include <stdlib.h>
#include "objTest.h"
void main()
{
int toSet = 0;
objTest middleMan = objTest();
middleMan.setRef(&toSet);
middleMan.set(10);
std::cout<<toSet;
char c;
std::cin>>c;
}
#pragma once
class objTest
{
public:
objTest(void);
~objTest(void);
void setRef(int* newRef)
{
myVal = newRef;
}
void set(int newVal)
{
*myVal = newVal;
}
private:
int* myVal;
};
This is really quite simple and can be very powerful when used correctly, but i'm guessing not something that can be done in VB.
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I understand your problem. In this light, I think you are right, your C++ way of thinking is causing you problems. I honestly don't know whether this can be done in VB or not, but I am certain VB was never meant for application control on that level.
Considering that the GUI must be created on the main thread, and that all interaction between user and app also happens on the main thread, what exactly are you trying to achieve by loading the controls in groups? If you consider that a PC with a multi core CPU (which will actually handle two threads at the same time), should be strong enough to load your form the old way, and a single core processor will handle each thread alternatingly, so it won't really load any faster anyway, and loading controls in groups will limit the use of the loaded controls until all controls have been loaded?
How about creating and placing groups of controls at runtime, upon some mouse-over event or something? A bit like MS Office or the windows start menu.
My advice is free, and you may get what you paid for.
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the advantage i am looking to gain is that the main form would load up quicker, and allow interaction with the initially loaded controls, the ones that are used most. The less used but still required can be loaded say on the tab they are on being selected, however this means there will always be a wailt when the tab is clicked on, even if its a small wait.
If the controls are loaded in the background then they will be available. I agree that loading them when they are needed is a good solution, but if i could get them loaded while the app idles, or the user is doing other tasks it would just be a nice bonus.
GUI items don't need to be created on the main thread, the only action that must occur on the main thread is adding the created control to say a tab page's control collection. This may be because i am not declaring them as with events, but the way the form is used is 95% for displaying data, there is very little user interaction with the form which is why i can load them on the background worker.
Maybe its just me getting a little frustrated that VB won't let me implement whats in my head.
Thanks for the advice though.
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Jep, like I said, VB just isn't meant for control on that level. And if you are used to C++, and the level of control it affords, you are bound to feel some frustration every once in a while.
My advice is free, and you may get what you paid for.
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Well, the other problem you have, besides loading way too many controls on a form, is performance when the form has to redraw itself. A large number of controls simply takes longer and longer to render and gets worse as you add controls. You cannot move this to a background thread.
Back to your original problem, I don't really see this as a viable solution considering all controls have to be created on the UI thread. Creating them on a seperate thread causes problems for messages crossing thread boundries when they a dispatched from the app's message pump. You can very easily run into issues with your GUI that are funky and hard to replicated and diagnose.
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ok, i've got this all working now, i had to do something that i'm not massivly proud of, and i know its not very VB in its workings but here goes, just incase any one is in a similar situation. The issue i was having was that the reference in the structure would change to point at the newly created control, insted of pointing the class level object to point to the new control. I'm aware this is how things are designed to work, just lacks the ability to tell it how i want it working.
So i wrapped the control in a class, like so.
Class uscHolder
Public ctrl As UserControl
Public Sub New()
ctrl = Nothing
End Sub
End Class
That way the structure will not change its reference to the new object, that will always point at the class level object. That way setting the usercontrol in the wrapper class is applied every where.
Thanks agian for all the pointers, once i have a problem in my mind though even if its not the solution i use in the long run it will bug me untill i can think up a solution. When coding nothing should ever be impossible is a mindset i'm stuck with.
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Hi,I am junior .net developer I want to developer an application project for a given book let say having 500 pages.I want to search for a particular keyword in the book and the application should display the lines in the book that holds the word.
For instance assume the book like a bible, in which every verse has a unique number and found in a particular chapter of the book.So that a user can search based on the verse number and a particular word as well,then the application displays the verses that matches the word or the verse number.
I need help at the starting point of the application.Should I use database for storing the entire book verse by verse or either any other mechanism which is better for handling the entire book,so that I can write codes that searches the book.
Although may question is language independent, I am developing the application using dot net technologies vb/C#.if you give me your help specially based on these languages i would appreciate it.
Thanks for help
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Well, searching isn't all that difficult. The real question is, how is the book stored electronically? (pdf, txt, doc, dcx, etc.)
My advice is free, and you may get what you paid for.
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Hi,
I need a function in VB6.0 that formats a number and displays in full format.
Eg. FormatFunction(1,Formattype) - One
FormatFunction(222,Formattype) - Two Hundred and Twenty Two
Thanks in Advance.
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VB6 huu!!!!!  2009
huu!!!!!
why do you attemp to use vb6 in 2009 , microsoft has nothing to do with it again  well in C# your request is done this way
http://www.blackwasp.co.uk/NumberToWords.aspx[^]
in C++ like this
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
char *make_words(char *s, int ncomma);
char *insert_comma(long n, int *ncomma);
char *int2words(int n);
int main(void)
{
printf("100000000 = %s\n", int2words(100000000));
printf("10000000 = %s\n", int2words(10000000));
printf("1000000 = %s\n", int2words(1000000));
printf("100000 = %s\n", int2words(100000));
printf("10000 = %s\n", int2words(10000));
printf("1000 = %s\n", int2words(1000));
printf("100 = %s\n", int2words(100));
printf("10 = %s\n", int2words(10));
printf("1 = %s\n", int2words(1));
printf("\n");
printf("123456789 = %s\n\n", int2words(123456789));
printf("12345678 = %s\n\n", int2words(12345678));
printf("777777 = %s\n", int2words(777777));
printf("2005 = %s\n", int2words(2005));
printf("-273 = %s\n", int2words(-273));
getchar();
return 0;
}
char *make_words(char *s, int ncomma)
{
int i, len, rest = 0;
char *p = NULL;
static char zzz[256];
static char *ones[] = {"one ","two ","three ","four ",
"five ","six ","seven ","eight ","nine "};
static char *tens[] = {"ten ","eleven ","twelve ","thirteen ",
"fourteen ","fifteen ","sixteen ","seventeen ","eighteen ","nineteen "};
static char *twenties[] = {"","twenty ","thirty ","forty ",
"fifty ","sixty ","seventy ","eighty ","ninety "};
static char *hundreds[] = {
"hundred ","thousand ","million "};
memset(zzz, '\0', 256);
len = strlen(s);
for(i = 0; i < len; i++)
{
if ((p = strchr((s[i] == ',') ? &s[++i] : &s[i], ',')) == NULL)
{
p = &s[strlen(s)];
}
if (s[i] == '0')
{
continue;
}
if ((rest = (p - &s[i])) != 0)
{
if (rest == 3)
{
strcat(zzz, ones[s[i] - '0' - 1]);
strcat(zzz, hundreds[0]);
if (len == 7 && s[2] == '0') strcat(zzz, hundreds[1]);
if (len == 11 && s[2] == '0') strcat(zzz, hundreds[2]);
}
else if (rest == 2)
{
if (s[i] == '1')
{
strcat(zzz, tens[s[++i] - '0']);
rest--;
}
else
{
strcat(zzz, twenties[s[i] - '0' - 1]);
}
}
else
strcat(zzz, ones[s[i] - '0' - 1]);
}
if (rest == 1 && ncomma != 0)
{
strcat(zzz, hundreds[ncomma--]);
}
}
return zzz;
}
char *insert_comma(long n, int *ncomma)
{
static char zzz[30];
int i = 0;
char *p = &zzz[sizeof(zzz)-1];
*p = '\0';
*ncomma = 0;
do
{
if (i % 3 == 0 && i != 0)
{
*--p = ',';
++*ncomma;
}
*--p = (char)('0' + n % 10);
n /= 10;
i++;
} while(n != 0);
return p;
}
char *int2words(int n)
{
int nc;
char *ps, *zzz, *minus;
char *buffer;
buffer = (char *) malloc(256);
if (n < 0)
{
minus = "minus";
n = abs(n);
}
else
{
minus = "";
}
ps = insert_comma(n, &nc);
zzz = make_words(ps, nc);
sprintf(buffer,"%s %s", minus, zzz);
return buffer;
}
Good luck
Vuyiswa Maseko,
Few companies that installed computers to reduce the employment of clerks have realized their expectations.... They now need more and more expensive clerks even though they call them "Developers" or "Programmers."
C#/VB.NET/ASP.NET/SQL7/2000/2005/2008
http://www.vuyiswamaseko.somee.com
http://www.vuyiswamaseko.tiyaneProperties.co.za
vuyiswa@its.co.za
http://www.itsabacus.co.za/itsabacus/
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Have you tried to write a function to do this?
Try, and if you still need help, post your code.
Tim
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Since this is such a common homework question, it's very unlikely you're going to get anyone to write it for you. You need to write this yourself, and when you get stuck , then ask questions about the specific problem you're having.
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The fact that your school is teaching you VB6, means that they are out of touch and not a good place for you to be. VB6 is long dead. It has little to no value in the workplace. There's more existing VB6 programmers than there are legacy apps that need work.
Christian Graus
Driven to the arms of OSX by Vista.
Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.
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Hi,
I have several collections which are used many times within my application. These collections (which are mainly generic lists) are collections of user-defined objects populated with data from a database, objects instantiated form classes such as regions, ethnicities, disabilities etc.
Is it a good idea to build these collections when the application starts and hold them in memory while the application is running, or would it be better to build them when required then release them when done resulting in many database calls.
Thanks in advance.
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Retaining the lists in memory, I do it all the time. How do you deal with the user adding to the list.
I have a static class MasterTables with a property for each table, in the getter if there is no table I get the data from the database, this requires 1 call.
If the user changes the master table data I simply set the mastertable property to null, next time it is requested a new copy is loaded.
This gets away from the initial hit when starting the app, loading all those master tables can be a noticable delay on the load. I know it can be done in a non ui thread but the master tables style suits me admirably.
Never underestimate the power of human stupidity
RAH
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Ok great, thanks for the tip, sounds like a good idea and one I will definately use 
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One consideration to make, if you edit the data, your local copy is still valid, but if many users use the program and they have a locally stored copy that is different to yours things get out of sync. You can keep a record of when you last loaded the table from the database, and also a record in the database of the last time the data was updated. This will mean you have to check you have the latest version each time, which is a database call, but you will only get the data if it has changed since you last got it.
Only really an issue with a multi user application.
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Ok thanks, good point!
It is a multi-user application, however the lists in question are probably not going to get modified very often. The lists hold data such as ethnicities, regions etc, which are fairly static.
But thanks for pointing that out, something I hadn't considered but will bear in mind in the future 
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While this is what I call a "technical" issue I have not seen it become a problem in a practical sense (I also currently don't work on transactional systems either). I find that master file information is rarely updated once the system is set up and if I enforce a daily restart it pretty much eliminates the problem. I also tells the users it is a potential issues so they are aware of it.
Never underestimate the power of human stupidity
RAH
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Hi,
Any one can tell me. how to import table from sqlserver 2000 data base to sqlserver 2000 database only table,stored procedure and views with out any data.
Thanking for future help
Regards
K. Rajesh Kumar
i am a fresher in software development i have so many doubts in .net so i need to ca
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This question plainly has nothign to do with VB.NET. You can right click and ask SQL Server to generate SQL to recreate the DB. Ideally, you should create a DB by writing scripts which you store in source control and can then run on any DB you like in the future.
Christian Graus
Driven to the arms of OSX by Vista.
Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.
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Use a script, you can generate the script from query analyser.
And CG is correct, this belongs in the Database forum.
Never underestimate the power of human stupidity
RAH
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I'm doing an application regarding status of garment production..I use RD ID reader to count each process in garment production. It use USB interface up to 50 device attached in 1 computer. How can I differentiate every 50 input that are coming in almost 1 second?
I know that every USB hardware has unique ID or port that can be used to differentiate their input. But how to implement it in Visual Basic Programming Language?
Thanx b4 for your kind answer
Hermawan
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