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I have some DataGridViewComboBoxColumns in my datagridview. I have all of the code working correctly but I would like to find a way to have the CellValueChanged event fire when the new value is selected in the comboboxcolumn and not after a value is selected AND I click outside of that cell to commit it.
CleaKO
"Now, a man would have opened both gates, driven through and not bothered to close either gate." - Marc Clifton (The Lounge)
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The Cell value won't change until the cell loses focus. Until then, you're still editing it.
The Cell's value doesn't pickup the value of the ComboBox until focus is lost. This is when the SetValue method of the DataGridViewComboBoxCell is finally called, which sets the value of the DataGridViewCell, which fires the CellValueChanged event. The DataGridViewCombBoxCell doesn't expose any events itself, so I don't know how you're going to know when the ComboBox value changes.
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Hi ol
My name is yasin
i am currently developing an application in vbnet 2003
the requirements are as follows:
On the form will be located a number of points (no more than 4) through a light ray must pass. The light ray emerges in a specific direction from a fixed point.
Pls note the light ray is to be represented by a line
The light is deflected by reflection using a suitable number of plane mirrors.
Note that for a plane mirror the angle of reflection and the angle of incidence are equal.
The simulated system must allow the user to place simulated mirrors in the enclosed area to reflect the light ray to follow a path that will make the light ray illuminate all the designated fixed points.
this means dynamically placing lines (simulated mirrors) with mouse operations in the path of the simulated light beam; another line.
As soon as a mirror is placed then the light beam will be reflected and thus change course. Clearly the first attempt of placing the mirror is unlikely to direct the beam exactly as required so is essential that the mirror can be rotated about the point where the beam hits until the desired effect is achieved.
Once the simulation is showing the light beam passing through all the designated points then the system will report on the exact location and orientation of the mirrors.
At the moment i have managed through some research to create a label which can be moved around the form at runtime. the label will repersent the mirror. I even have the four fixed points and the source of the light ray on the form. By instantiating a class called clsBeam i can even draw the lines which will represent the the beam
Any ideas or even code on how to deflect the line (light ray) and how to rotate the label about the middle point will be highly appreciated.
Thanking you in advance.
Regards 
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Sounds like an interesting piece of homework. The deflection of the light, to do it correctly, would involve reading up on some physics. As for the rest, you should ask specific questions as you get stuck, rather than ask us to provide code for you.
Christian Graus - Microsoft MVP - C++
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
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Yasin786 wrote: Any ideas or even code on how to deflect the line (light ray)
This is simple Trigonometry, vector math. Open your math book from school.
Yasin786 wrote: how to rotate the label about the middle point will be highly appreciated
A don't think a label control is a good starting point for this control. You're going to need to move as well as rotate to any angle, so you're going to have to come up with a custom control for this.
You start by reading up on creating selectable and moveable graphics images here[^].
Or, if that's too much to go through, you can search for a graphics library that gives you this ability.
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Sounds like you are working in 2D and not 3D.
So it is a basic geometry exercise.
Once you have worked out how to design the geometry you may be more successful with getting help on the VB side.
I would suggest that you cut out pieces of paper, simulating the exercise, and work out the geometry then start mapping this to VB.
Good luck;)
You always pass failure on the way to success.
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Why would you need a Label?
If you want to draw a couple of lines, you can do that directly on a Form, or (and I prefer)
on a Panel. You can use different colors, line thicknesses, whatever to indicate rays,
mirrors, points, ...
So it all boils down to a couple of sine and cosine evaluations.
Luc Pattyn [Forum Guidelines] [My Articles]
this weeks tips:
- make Visual display line numbers: Tools/Options/TextEditor/...
- show exceptions with ToString() to see all information
- before you ask a question here, search CodeProject, then Google
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Hi,
I have a VB server application (driven from a set of ASP classic pages). To improve throughput of the VB app we have written a small component in c++ that runs multiple instances of the server app, and when it receives the requests from the ASP page it redirects them to which ever instance is free.
We've always been careful to maintain the base addresses of all our .dlls & .exes so they don't clash with each other, but my question is, that if I am running multiple instances of the VB .exe will it clash with itself and get rebased in memory and is there any way to prevent this? Or, will the .exe only be loaded once into memory and all instances access the same memory locations? And what about .dlls used by the .exe, will each only be loaded once, or per instance of the .exe?
Also, are there any good tools (preferably free) that I can use to look at what's actually happening when the exe/dlls get loaded?
Any advice would be really appreciated.
Simon
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Simon Stevens wrote: running multiple instances of the VB .exe will it clash with itself and get rebased in memory and is there any way to prevent this?
It's handled automatically. Even though making sure your base addresses don't stomp each other is kind of important, it's not necessary in most cases. Most DLL's don't need to be loaded at a specific address.
The default base address for .EXE's is 0x400000, DLL's is 0x100000000, IIRC.
If an EXE or DLL absolutely has to be loaded at a specific address (which is rarely ever required) and that space isn't available, it's just not loaded. If it can be loaded anywhere (the default Link configuration), and the base address isn't available, it'll be rebased automatically.
Though, there are performance benefits to specifying your own default base addresses. If there is a collision, the DLL that is being loaded is moved to a free block in the address space. Moving code around is an expensive operation. So if a DLL gets used by multiple processes, the base address that's good for one process might not be so good for another!
As for loading multiple copies of your .EXE. Since each process gets it's own virtual address space (about 4GB worth), it thinks it is the only process loaded in Windows. So even though you have lots of processes running, each one thinks it's the only process running.
When the .EXE is launched, it's loaded, by default, at 0x400000. Launch another .EXE and it gets loaded at the same address, but in another virtual address space. If you launch the same .EXE again, it also gets it's own virtual address space, but another copy of the code is NOT loaded. The code for each process is mapped into each virtual address space, as needed. So, if you launch 16 copies of Notepad, only one copy of the code stays in memory and that code gets mapped into the virtual address space of each process.
The same is also true for DLL's.
This "mapping" is why you can load the same .EXE or .DLL multiple times, but only keep a single copy of the code in memory. Though, say you have a .DLL being used by two different process and each has to load the .DLL at a different address?? Easy. Each address space maintains its own map of code in the .DLL. Each map does any rebasing of the code required to get it to fit where the address space allows.
You can read more about it here[^].
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Cheers Dave, that clears things up a bit. I hadn't realised that each .exe was getting it's own address space, that does make more sense now I think about it.
So all I need to worry about is my .dll's clashing with other .dll's that are loaded by my .exe into it's own virtual address space.
Brilliant, Cheers.
Simon
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Not really. Any rebasing happens automagically. The biggest performance hit is going to come when the DLL is loaded for the first time. After that, where the DLL lands in the address space is usually where it stays for the lifetime of the process its loaded into.
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Right, so for example, I've got a.exe which loads b.dll, c.dll. For optimum performance, I just need to change the base addresses of b.dll and c.dll so they don't clash with each other, which will prevent any rebasing and any performance loss.
Simon
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Thank you. 
Simon
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Class Class1<br />
Public Field1 as Integer<br />
End Class
I'm sure that many coders want browse Class1.Field1 in designer property grid , why Microsoft doesn't support it ?
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I think the clue is in the word "Property"
Steve Jowett
-------------------------
Sometimes a man who deserves to be looked down upon because he is a fool, is only despised only because he is an 'I.T. Consultant'
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Ky Nam wrote: I'm sure that many coders want browse Class1.Field1 in designer property grid
Speak for yourself. I don't want it to.
Ky Nam wrote: why Microsoft doesn't support it ?
Because exposing fields as public is bad practice...? You're supposed to be exposing PRIVATE fields through nice little public Property accessors.
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hey guy
if u r in ur home u follow ur home,s rule not to other,s same
like when u work in microsoft it has also there rule
ok don,t ask this type of question.
read it private, public, partial property to set the class
byeeeee
hope u understand
lucky
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Speaking of rules...
Do NOT use SMS Speak in the fourms. It makes your posts quite difficult to read. You've got a 101+ key keyboard in front on your, use it!
Lucky Sheikh wrote: hope u understand:
Barely, just barely.
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I am having a problem with changing an image using the "Image.FromFile(Path)" method. On startup, everything works fine, but as soon as I use the "openFileDialog" box, the system won't open the selected image any longer.
Every time the mouse hovers over a button, I want it to change the image of the button. This works even after opening another form and closing it again. But as soon as I select an image using the "openFileDialog" box then the system crashes out every time I hover over one of the buttons that I want the image changed.
After using the "OpenFileDialog" box, I dispose of it, in an attempt for it not to clash with Hover methods.
What can I do to avoid this problem?
  
Evan Saunders
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i think after ur code, try the picturebox.load before anything
phatkin
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after which code, the "OpenFileDialog" or the "image.fromfile()" for the hover?
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after image.from file,
my VS got corrupted on ma vista so cant check for u today but i hope it works or sam1 else helps u
phatkin
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EvanSaunders wrote: then the system crashes out every time I hover over one of the buttons
What buttons?? In the OpenFileDialog??
EvanSaunders wrote: that I want the image changed.
The OpenFileDialog doesnt' fire off any events, so I don't know where you're changing whatever image.
What's the exception that's thrown?? Does your entire system crash (Windows), or just your app??
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I have the buttons in my main menu...(the openfiledialog box is in a form opened by the main menu)
I choose an imagefile from the opendialog box to load an image on another form for another task, but as soon as I do this, and go back to the main menu, my main menu hover buttons won't change images any longer.
The exception thrown is that my created system crashes with the exception that the image path doesn't exist. Strange exception seeing that it loaded before...
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