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Acording to tutorial (A book: GDI+ Custom Controls With Visual CSharp 2005)I am reading, i have created Custom Control that is divered from Control.
I have overriden OnPaint event, and everytime i put base.OnPaint(e) into event, my IDE and app crashes. IDE crashed due to tempting to render a custom control. I am using VS 2008 SP1 and .NET framework 3.5 SP1.
Why does this happen? Is it required to put inside when diverting from Control class)
Edit: Found the problem. The problem was that I used base.OnPaint() inside event function. I needed to ovridde OnPaint
modified on Sunday, December 6, 2009 2:09 PM
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OnPaint() method actually raises the Paint event. By calling OnPaint() from a method bound to the Paint event, you actually set up an infinite loop causing a stack overflow that crashed the IDE.
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Hello,
I'm developing an app that localize WPF applications but When I try to serialize a class that contains a BAMLLOCALIZATIONDICTIONARY serialization failed because this class do not allow serialization.
Is there any way to serialize this class?
Thanks.
Dad
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You can not serialize a dictionary, if this is your dictionary, use KeyedCollection
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In our application , we are used datagridview drag and drop itself , i was did properly , But i want visualization of the drag . Now visual only a default cursor point only .. How can i do visual of these drag and drop. I am used C# Windows application
Thanks....
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Use the dragenter event to set the effect.
e.Effect = DragDropEffects.Move;
Never underestimate the power of human stupidity
RAH
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Hi everyone!
I have an app: draw a resizeable and draggable rectangle on form.
Now i want to modify it to draw a resizeable and draggable rectangle on picturebox not on Form to select area and crop image.
I tried a few ways but i can't. I'm newbie in C#. Please help me! Thank you so much!
Here's my code:
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;
namespace DragResizeRectangle
{
public partial class MainForm : Form
{
private RectangleF DragRect=new RectangleF(20, 20, 100, 80);
private System.Drawing.RectangleF[] Adornments = new RectangleF[0];
private bool MouseInRect = false;
private bool RectDragging = false;
private bool RectResizing = false;
private int ActiveAdornment = -1;
private Point MousePos;
private SolidBrush BackBrush;
private System.Drawing.Pen[] LinePen = new Pen[0];
public MainForm()
{
InitializeComponent();
}
void MainFormLoad(object sender, EventArgs e)
{
Adornments=new RectangleF[8];
LinePen=new Pen[2];
BackBrush = new SolidBrush(BackColor);
LinePen[0] = new Pen(ForeColor);
LinePen[1] = new Pen(ForeColor);
LinePen[1].DashPattern = new float[] { 5, 3 };
CalcAdornments();
SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.DoubleBuffer | ControlStyles.ResizeRedraw | ControlStyles.UserPaint, true);
}
private void CalcAdornments()
{
Adornments[0] = new RectangleF(DragRect.X - 4, DragRect.Y - 4, 8, 8);
Adornments[1] = new RectangleF(DragRect.X + DragRect.Width / 2 - 4, DragRect.Y - 4, 8, 8);
Adornments[2] = new RectangleF(DragRect.X + DragRect.Width - 4, DragRect.Y - 4, 8, 8);
Adornments[3] = new RectangleF(DragRect.X + DragRect.Width - 4, DragRect.Y + DragRect.Height / 2 - 4, 8, 8);
Adornments[4] = new RectangleF(DragRect.X + DragRect.Width - 4, DragRect.Y + DragRect.Height - 4, 8, 8);
Adornments[5] = new RectangleF(DragRect.X + DragRect.Width / 2 - 4, DragRect.Y + DragRect.Height - 4, 8, 8);
Adornments[6] = new RectangleF(DragRect.X - 4, DragRect.Y + DragRect.Height - 4, 8, 8);
Adornments[7] = new RectangleF(DragRect.X - 4, DragRect.Y + DragRect.Height / 2 - 4, 8, 8);
}
private void SetAdornmentCursor()
{
if (ActiveAdornment != -1) {
switch (ActiveAdornment) {
case 0:
Cursor = Cursors.SizeNWSE;
break;
case 1:
Cursor = Cursors.SizeNS;
break;
case 2:
Cursor = Cursors.SizeNESW;
break;
case 3:
Cursor = Cursors.SizeWE;
break;
case 4:
Cursor = Cursors.SizeNWSE;
break;
case 5:
Cursor = Cursors.SizeNS;
break;
case 6:
Cursor = Cursors.SizeNESW;
break;
case 7:
Cursor = Cursors.SizeWE;
break;
}
}
else {
Cursor = Cursors.Default;
}
}
void MainFormMouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left) {
if (MouseInRect & ActiveAdornment == -1) {
RectDragging = true;
MousePos = new Point(e.X, e.Y);
MousePos = PointToScreen(MousePos);
}
else if (ActiveAdornment != -1) {
RectResizing = true;
MousePos = new Point(e.X, e.Y);
MousePos = PointToScreen(MousePos);
}
}
}
void MainFormMouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left) {
Point CurrMouse = new Point(e.X, e.Y);
CurrMouse.X = Math.Max(0, Math.Min(CurrMouse.X, ClientSize.Width));
CurrMouse.Y = Math.Max(0, Math.Min(CurrMouse.Y, ClientSize.Height));
CurrMouse = PointToScreen(CurrMouse);
if (RectDragging) {
if (Math.Abs(CurrMouse.X - MousePos.X) > 2 | Math.Abs(CurrMouse.Y - MousePos.Y) > 2) {
DragRect.Offset(CurrMouse.X - MousePos.X, CurrMouse.Y - MousePos.Y);
DragRect.X = Math.Max(0, Math.Min(DragRect.X, ClientSize.Width - DragRect.Width));
DragRect.Y = Math.Max(0, Math.Min(DragRect.Y, ClientSize.Height - DragRect.Height));
MousePos = new Point(e.X, e.Y);
MousePos.X = Math.Max(0, Math.Min(MousePos.X, ClientSize.Width));
MousePos.Y = Math.Max(0, Math.Min(MousePos.Y, ClientSize.Height));
MousePos = PointToScreen(MousePos);
CalcAdornments();
Invalidate();
}
}
else if (RectResizing) {
if (ActiveAdornment != -1) {
if (Math.Abs(CurrMouse.X - MousePos.X) > 2 | Math.Abs(CurrMouse.Y - MousePos.Y) > 2) {
switch (ActiveAdornment) {
case 0:
DragRect.Height -= CurrMouse.Y - MousePos.Y;
if (!(DragRect.Height < 20)) {
DragRect.Y -= -CurrMouse.Y + MousePos.Y;
}
else {
DragRect.Height = 20;
}
DragRect.Width -= CurrMouse.X - MousePos.X;
if (!(DragRect.Width < 20)) {
DragRect.X -= -CurrMouse.X + MousePos.X;
}
else {
DragRect.Width = 20;
}
break;
case 1:
DragRect.Height -= CurrMouse.Y - MousePos.Y;
if (!(DragRect.Height < 20)) {
DragRect.Y -= -CurrMouse.Y + MousePos.Y;
}
else {
DragRect.Height = 20;
}
break;
case 2:
DragRect.Height -= CurrMouse.Y - MousePos.Y;
if (!(DragRect.Height < 20)) {
DragRect.Y -= -CurrMouse.Y + MousePos.Y;
}
else {
DragRect.Height = 20;
}
DragRect.Width += CurrMouse.X - MousePos.X;
DragRect.Width = Math.Max(20, DragRect.Width);
break;
case 3:
DragRect.Width += CurrMouse.X - MousePos.X;
DragRect.Width = Math.Max(20, DragRect.Width);
break;
case 4:
DragRect.Width += CurrMouse.X - MousePos.X;
DragRect.Width = Math.Max(20, DragRect.Width);
DragRect.Height += CurrMouse.Y - MousePos.Y;
DragRect.Height = Math.Max(20, DragRect.Height);
break;
case 5:
DragRect.Height += CurrMouse.Y - MousePos.Y;
DragRect.Height = Math.Max(20, DragRect.Height);
break;
case 6:
DragRect.Height += CurrMouse.Y - MousePos.Y;
DragRect.Height = Math.Max(20, DragRect.Height);
DragRect.Width -= CurrMouse.X - MousePos.X;
if (!(DragRect.Width < 20)) {
DragRect.X -= -CurrMouse.X + MousePos.X;
}
else {
DragRect.Width = 20;
}
break;
case 7:
DragRect.Width -= CurrMouse.X - MousePos.X;
if (!(DragRect.Width < 20)) {
DragRect.X -= -CurrMouse.X + MousePos.X;
}
else {
DragRect.Width = 20;
}
break;
}
MousePos = new Point(e.X, e.Y);
MousePos.X = Math.Max(0, Math.Min(MousePos.X, ClientSize.Width));
MousePos.Y = Math.Max(0, Math.Min(MousePos.Y, ClientSize.Height));
MousePos = PointToScreen(MousePos);
CalcAdornments();
Invalidate();
}
}
}
}
else {
MouseInRect = false;
ActiveAdornment = -1;
RectangleF tmprect = default(RectangleF);
int i = 0;
foreach (RectangleF tmprect_loopVariable in Adornments) {
tmprect = tmprect_loopVariable;
if (tmprect.Contains(e.X, e.Y)) {
MouseInRect = true;
ActiveAdornment = i;
SetAdornmentCursor();
Invalidate();
return;
}
i += 1;
}
if (DragRect.Contains(e.X, e.Y)) {
MouseInRect = true;
Cursor = Cursors.SizeAll;
Invalidate();
return;
}
Cursor = Cursors.Default;
Invalidate();
}
}
void MainFormMouseUp(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left) {
RectDragging = false;
RectResizing = false;
Invalidate();
}
}
void MainFormPaint(object sender, PaintEventArgs e)
{
Graphics g = e.Graphics;
g.FillRectangle(BackBrush, g.ClipBounds);
if (!MouseInRect) {
g.DrawRectangle(LinePen[0], DragRect.X, DragRect.Y, DragRect.Width, DragRect.Height);
}
else {
g.DrawRectangle(LinePen[1], DragRect.X, DragRect.Y, DragRect.Width, DragRect.Height);
g.FillRectangles(Brushes.White, Adornments);
g.DrawRectangles(Pens.Black, Adornments);
}
}
}
}
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Hi,
your code seems pretty clean, although probably too wieldy and not correct.
Unfortunately your text isn't clear, "I tried a few ways but i can't" doesn't even start to describe what is going on.
Here are some thoughts:
1. the code shown describes your Form, so calling Invalidate() will cause the entire Form to be repainted; when you draw on a Control (e.g. a PictureBox), you should invalidate that Control, and make sure it has a paint handler to paint its stuff itself.
What may be happening right now is one of these:
- you Invalidate the Form, it repaints with a rectangle on top of your PB, then the PB itself repaints;
- you Invalidate the Form, it repaints with the exception of the areas taken by its controls, then it does not repaint the controls, as you did not explicitly ask for that to happen (see Invalidate(boolean)).
2.
A PictureBox is a tricky (I would add "and stupid") Control; it knows how to resize the image it holds (SizeMode), however such resizing will not apply to what you draw on top of the PB. For applications like yours I tend to use a Panel, and paint the image myself, in the same paint handler that draws the rectangle, and with the same transformation settings.
3.
You should use mouse handlers that belong to the Control of interest, that would yield coordinates relative to that Control; IMO there probably is no need to call PointToScreen and the like.
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Hey all,
I came across one unusual behavior of Directory.Exists() method when I was testing user path input, I was trying with different inputs just to test the existence of the directory on my local drive. For negative test cases I provided the existing directory path and put two ".." at the end of directory path
e.g.
lets say I have "C:\CurrentDir" on my local drive
when I check the existence of directory using
bool isDirExist = Directory.Exists(@"C:\CurrentDir..");//".." are appended
surprisingly isDirExist is true 
when I try to access file contained in this directory it throws error......
it does not throw exception if I append only one "." [for @"C:\CurrentDir." +AnyFileName] 
Is this is bug in Directory.Exists method or anything else is happening behind the screen at OS level??
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SaveTigers wrote: surprisingly isDirExist is true
Directory.Exists is working as expected. You can't create a directory that ends with . (DOT) in windows. Windows will remove the dots automatically. So the function is not caring about the dots.
You can do something like.
string directoryToCheck = Path.GetFullPath(@"C:\CurrentDir..");
bool isDirExist = Directory.Exists(directoryToCheck);
Best wishes,
Navaneeth
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Hi all.
I would like to write a program that will function as a client on a remote computer. The idea is that at a given time i will be able to request specific actions from the client application. Remotely, of course.
Up to now i have considered two ways of doing this:
1. Use a DB on the server. The client will poll the DB for tasks at a standard rate and act as insrtucted there.
2. Use a web-service. The client will call a getTasks() method at a standard rate.
Both of these methods include polling the server at a fixed interval. This is necessary, since i need the client application to respond almost immediateley to server requests.
The thing is, i don't want these applications to interfere with the user's use-experience. I don't want him to feel that he has my application running in the background and polling every now and then.
So:
Are my concerns justified?
If so, what would you suggest as a substitute?
If not, which of the above would you suggest?
Thanks for reading all the way down here. I will really appreciate your responses.
SummerBulb.
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I'd suggest you to got with choice 2. Use a web service or WCF to communicate with DB. This avoid tight coupling of client application with database.
SummerBulb wrote: I don't want him to feel that he has my application running in the background and polling every now and then.
So users won't be using your application directly? If not, you can start it and keep it in "System tray". Have a thread which does the polling.
Best wishes,
Navaneeth
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N a v a n e e t h wrote: Have a thread which does the polling
I don't mind having the application in the background. My dillemma is concerning the CPU, memory and internet bandwidth.
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SummerBulb wrote: My dillemma is concerning the CPU, memory and internet bandwidth.
It'd be a premature optimization. I'd suggest to make the application working first. Profile it and see whether it requires optimizations. BTW, you can consider few things when you develop.
1 - Ensure calls to Dispose() for all disposable objects - CLR manages the memory quite well and you don't have to worry much about it. Few classes in the .NET framework implements IDisposable and make sure you call Dispose() method on it to avoid resource leaks.
2 - Don't send unnecessary informations over the wire - I have found WCF services perform better than SOAP based web services. But you need to understand how WCF does the communication. When you send large objects/collections, it will be slow. So make sure you send only the necessary information.
Once you done with the application, profile it and find out the areas that can be optimized further.
Best wishes,
Navaneeth
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Thank you very much for your replies.
Does the WCF differ much from the SOAP? (this must sound like a very silly question to someone whoe knows them both well...)
modified on Sunday, December 6, 2009 4:51 AM
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SummerBulb wrote: Does the WCF differ much from the SOAP?
Yes. SOAP is a protocol where WCF is a framework for creating service oriented applications. WCF can communicate using SOAP protocol if needed. Here[^] is a good MSDN article on WCF's capabilities.
Best wishes,
Navaneeth
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What's the "fixed interval"?
If "almost immediately" is less than 5 minutes, consider to could connect to a server, stay connected, and receive an event when there's a new task. No polling required, tasks arrive immediately.
If you're using WCF, you can do this Duplex Services[^].
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I've had good success with having a Windows Service poll a database to get information on tasks to perform.
It could use a Web Service to access the database.
You can also define a custom action for the Windows Service that will allow the server to trigger the action of the client.
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I am working on a Invoice Application in which a user can enter in the invoice line items by selecting the item number from a combobox within a DataGridView. I am looking for some sample code to do the following:
1. load a combox within a datagridview from a table
2. load other fields (item descr, item price from combobox table)
As always, thanks for the advice.
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Try google. Copy and paste your first question into it's text box, and press search. It finds your answer, and even offers to correct your spelling at the same time!
Repeat.
No trees were harmed in the sending of this message; however, a significant number of electrons were slightly inconvenienced.
This message is made of fully recyclable Zeros and Ones
"Rumour has it that if you play Microsoft CDs backwards you will hear Satanic messages.Worse still, is that if you play them forwards they will install Windows"
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I have an object named 'dv'
'dv' has a string property named 'refNumber'
There is also a string 'altString' = "refNumber"
Is there a way to use 'altString' to get that property from 'dv'?
string newString = dv.??altString??
-- should set newString the same as --
string newString = dv.refNumber
Thanks for your suggestions.
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Reflection can do this. Use System.Reflection name space. You'd do something like (not tested)
PropertyInfo property = (PropertyInfo) dv.GetMembers().SingleOrDefault(info =>
info.MemberType == MemberTypes.Property &&
info.Name == altString);
string newString = string.Empty;
if (property != null)
newString = (string) property.GetValue(dv, null);
Best wishes,
Navaneeth
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Thank you. Please forgive my ignorance, but where does 'refNumber' occur in your reply?
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BDJones wrote: but where does 'refNumber' occur in your reply?
Quote Selected Text
You said it will be in altString variable. I am using that variable to compare against name. You can replace it with "refNumber" if you wish to.
Best wishes,
Navaneeth
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