C# Discussion Boards - CodeProject

Re: Determining the location of a DragDrop External to a form

Tristan Rhodes12-Dec-03 11:21

12-Dec-03 11:21

So how would I go about determining the target?

I was thinking of doing it by retrieving a file path from the destination, and constructing a file using a stream to that path. But you say that won't work.

How do I set up system hooks?

Cheers

Cata

Re: Determining the location of a DragDrop External to a form

Heath Stewart12-Dec-03 11:26

Heath Stewart

12-Dec-03 11:26

The target is responsible for unpacking the data based on clipboard formats it supports. There are no notifications for a drop target event.

As far as Windows hooks go, this would be an extremely difficult - and only hypothetically possible - process. You'd have to watch for particular messages but it would bog down the system incredibly for such a trivial end.

You should read about dragging and dropping in the Shell section of the Platform SDK on MSDN Online. Basically, all you can do is pack data into an IDataObject in .NET. To provide a stream or you have to resort to Win32's IDataObject (different than .NET's) and P/Invoke several methods (the ones that dragging and dropping, and the clipboard functions use internally in the .NET BCL) and create LOTS of structures. Reading about things like STGMEDIUM and FORMATETC should shed some light on this.

-----BEGIN GEEK CODE BLOCK-----
Version: 3.21
GCS/G/MU d- s: a- C++++ UL@ P++(+++) L+(--) E--- W+++ N++ o+ K? w++++ O- M(+) V? PS-- PE Y++ PGP++ t++@ 5 X+++ R+@ tv+ b(-)>b++ DI++++ D+ G e++>+++ h---* r+++ y+++
-----END GEEK CODE BLOCK-----

Re: Determining the location of a DragDrop External to a form

Tristan Rhodes12-Dec-03 11:35

Tristan Rhodes

12-Dec-03 11:35

Ok, thanks mate.

I will look it all up and figure things out.

Always the best way.

Smile | :)

Cata

Re: Determining the location of a DragDrop External to a form

Heath Stewart12-Dec-03 11:46

Heath Stewart

12-Dec-03 11:46

Yes it is. Unfortunately, solving your problem with Win32's drag-n-drop is not easy and reading about it is necessary before I could even explain half of the stuff to you (otherwise I end up writing a book! Poke tongue | ;-P

). So, while you can't be notified of drop operations in another app (unfortunately, this is a problem that many people have asked about), you can use native dragging and dropping to provide a stream when the other application asks for it - just make sure that you use common clipboard formats that the other app supports (like the Windows Shell supports the CF_HDROP while specifying TYMED_ISTREAM to pass a stream reference that the Shell can read, or something like that).

Determining a pc's memory & disk space

Manster12-Dec-03 4:34

Manster

12-Dec-03 4:34

Hi,
Can anyone tell me how I can determine how much memory, disk space, and free disk space are on a computer programmatically? This will be displayed on a windows form.

I'm thinking it's got to be in one of the dlls that come with windows, but I don't know which one and what functions to use.

Thanks!

Smile | :)

Re: Determining a pc's memory & disk space

Heath Stewart12-Dec-03 9:16

Heath Stewart

12-Dec-03 9:16

Instead of P/Invoking native methods, this is a perfect opportunity to use WMI (see the System.Management namespace). In fact, there's already several great tools to help you. This also allows you to query remote computers where the native functions won't always allow you to do that.

VS.NET makes it even easier. Show your Server Explorer tab, expand your computer, then Management Classes, then My Computer and select your computer. You'll notice the property grid has a lot of information you want. Simply drag that to your form and it creates an easy-to-use wrapper class for querying that management information. You can change the computer name and get that information for other computers as well.

For disk infomration, you should've noticed the Disk Volumes class right above My Computer. You can create a management class wrapper for that, too, and then specify the path and get the drive's information.

You could use the following native functions, but querying information for other computers isn't as easy (GetDiskFreeSpaceEx can use UNC paths, but they must have a trailing backslash (\) and require a share on the machine to query):

[DllImport("kernel32.dll", CharSet=CharSet.Auto)]
public static extern bool GetDiskFreeSpaceEx(string root,
  out long freeBytesToCaller,
  out long totalBytes,
  out long freeBytes);
 
[DllImport("kernel32.dll")]
public static extern void GlobalMemoryStatus(out MemoryStatus status);
 
[StructLayout(LayoutKind.Sequential)]
public struct MemoryStatus
{
  public int length;
  public int memoryLoad;
  public long totalPhysical;
  public long availablePhysical;
  public long totalPageFile;
  public long availablePageFile;
  public long totalVirtual;
  public long availableVirtual;
}

Re: Determining a pc's memory & disk space

Manster15-Dec-03 3:58

Manster

15-Dec-03 3:58

Heath,
Thanks for your help, but I can not find the System.Management namespace. Where is this namespace located and or how do I add it? I tried using System.Management; but that doesn't work.

Thanks

Re: Determining a pc's memory & disk space

Manster15-Dec-03 4:04

Manster

15-Dec-03 4:04

Sorry,
I figured out that I didn't add the reference. Hey, it's a Monday morning.

Thanks

Re: Determining a pc's memory & disk space

Jonathan Guidry12-Dec-03 9:37

Jonathan Guidry

12-Dec-03 9:37

Look at the System.Management namespace

ManagementObject disk = new ManagementObject("win32_logicaldisk.deviceid=\"c:\"");
disk.Get();
object freeSpace = disk.Properties["FreeSpace"].Value;

Jonathan

Alpha Texture Problems

12-Dec-03 2:01

I am running an application that uses a managed image list of icons pulled from the System kernel that uses extentions to look them up via a modified version Heath's little GetFileInfo source code.

The problem I have is, while my embeded resources, or any opened from the directory work fine in my XP visualStyle, with the alpha filtered ONLY at 32 bit ImageList settings, those that I pull from the system are still blocky and suffering from alpha textures showing up.

I am not sure what to do about this, I have written an algorythm to convert the pixels to RGB, but that leaves them on a black background. I don't understand why it occurs, as it does not occur else where.

Any ideas as to why?

Cheers

Cata

Re: Alpha Texture Problems

Heath Stewart12-Dec-03 4:32

Heath Stewart

12-Dec-03 4:32

By definition, alpha channels require 32-bit images because the first 24 bits are the colors (RGB) while the last 8 bits are the alpha channel.

As far as the problem goes, this has to do with the common controls version. If you use XP Visual Styles (either look at my article detailing this, or - for .NET 1.1 and up - call Application.EnableVisualStyles before calling Application.Run) most of the image handling code is redirected to common controls 6 (a side-by-side native assembly), which understands alpha channels. If not, the alpha channel gets converted to a close color like you've seen. .NET may understand alpha channels implicitly (which is why your embedded images with alpha channels work), but when pulling icons using file associations, you need enabled XP Visual Styles. This worked for me.

Re: Alpha Texture Problems

12-Dec-03 4:39

I've enabled the VisualStyles, with the DoEvents() methods.

Without those, even the embeded icons show the alpha texture.

I know it works, as the embedded icons, and those that I import from files (I unpacked the system icons from the DLL to experiment with them, and they work too), all come without the alpha.

What I don't understand is, when I construct the bitmaps from an icon handle, pulled from shell32, no matter what I do, the alpha is still there.

It's confusing me, because I can clearly see things working in some areas and others not.
I've set all my image lists to 32bit, and also added numerous 32bit reset points to test whether it was a drop in image quality that caused this. Still no luck.

Any ideas?

Cata

(I have a screen shot of the anomaly, if anyone wants a look. It's confusing indeed...)

SOLVED

Tristan Rhodes12-Dec-03 10:36

Tristan Rhodes

12-Dec-03 10:36

Ok, I found out that the problem lay in the extraction process.

Basicaly, when the icon is pulled from shell32, it was converted straight into a Bitmap, and then returned, before being added to the image list.

By leaving it as an Icon, and backing this up to the point where it is added to the image list, the Alpha is now recognised and removed. I guess that it looks for alpha in icons, but not in bitmaps.

Anyway, I am happy now.

Regards

Cata

How to compile inline code documentation into assemblies?

Vasek12-Dec-03 1:43

Vasek

12-Dec-03 1:43

Hello!
I found that the inline code documentation defined on the classes and methods does not get compiled into assembly! When looking into object browser, the documentation is only visible for the items found under project node. When coding in the project referencing the library containing the documentation, I only get class/method/argument names but no single word in addition.

The MSDN documentation says that the /doc compiler option should be used to produce xml file which could be used by IntelliSense - the file should have the same name as the assembly produced. I tried it but with no the effect.

What do I do wrong?

Thanks for any suggestions.

Vasek
VB6, C#, MS DNA, MS.NET
Software Developer

Re: How to compile inline code documentation into assemblies?

Nigel Savidge12-Dec-03 2:01

Nigel Savidge

12-Dec-03 2:01

using: /doc:file

The file should have the same name as the assembly but with xml extension:

MyLib.dll
MyLib.xml

These should be kept together in the same folder.

Re: How to compile inline code documentation into assemblies?

Vasek15-Dec-03 7:15

Vasek

15-Dec-03 7:15

Hi, this exactly I made but I made it using IDE, I did not run compiler from the command line. There is /doc configuration option int the project setting. The file was created but the documentation was not inserted to the compiled file.

Could you tell me, whether the /doc: dicrective works for you?

Thanks

Vasek
VB6, C#, MS DNA, MS.NET
Software Developer

Re: How to compile inline code documentation into assemblies?

Nigel Savidge15-Dec-03 7:39

Nigel Savidge

15-Dec-03 7:39

Yes, I also do it using the IDE "XML Documentation File" setting and the documentation is put in the specified .xml documentation file. It is not supposed to be put in the compiled file.

reading from registry using Win API dll

Member 51467212-Dec-03 0:33

Member 514672

12-Dec-03 0:33

Hello,
I'm trying to use the Microsoft.Win32.Registry namespace for getting owner information from the registry. I found that this namespace isn't supported by .net compact framework and that i have to use Win Api functions and to import coredll .dll
But I don't know how can I fix my problem:

I have to
[DllImport("coredll.dll")]

and then to use RegCreateKeyEx(..) and RegCreateKeyEx(..)

LONG RegCreateKeyEx ( HKEY hKey, LPCWSTR lpSubKey, DWORD Reserved, LPWSTR lpClass, DWORD dwOptions, REGSAM samDesired, LPSECURITY_ATTRIBUTES lpSecurityAttributes,
PHKEY phkResult, LPDWORD lpdwDisposition );

LONG RegQueryValueEx( HKEY hKey, LPCWSTR lpValueName,
LPDWORD lpReserved, LPDWORD lpType, LPBYTE lpData, LPDWORD lpcbData );

but I don't know how to transform types of parameters for using this functions in c# and to use the macro like HKEY_CURRENT_USER

thank you for your time.

Ramona

Re: reading from registry using Win API dll

Heath Stewart12-Dec-03 4:25

Heath Stewart

12-Dec-03 4:25

Look at the System.Runtime.InteropServices.MarshalAsAttribute for some interformation. This should be pretty easy, though, and you should understand before proceeding. Basically, any handles become IntPtr, any strings become string (and in the DllImportAttribute you should specify the CharSet that's appropriate), DWORDs (and the like) become int, and structures must also be defined with appropriate attributes like StructLayoutAttribute. You should gain a good understanding of these. You also need to use the ref and out keywords appropriate based on the parameter type and the Platform SDK (PSDK) documentation ([in/out] translates to a ref, while [out] translates to an out).

As far as macros, you need to download and install the PSDK (if you didn't install it with VS.NET) and find it in the headers (the PSDK usually tells you what header it's in, otherwise search) and see what it's defined as.

Also, you could download a good decompiler like .NET Reflector[^] and look at the code for the Microsoft.Win32.Registry classes, structs, etc. This will give you some good idea of how Microsoft does it.

Create Server Event using code

AEKirin12-Dec-03 0:12

AEKirin

12-Dec-03 0:12

I need to 'associate' a Server Event to a Button via code. I built a Form, a Table, and a Button and I need to get a server event attached to the 'click' method for that button see code snippet below...

HtmlForm frmROPtbl = new HtmlForm();
frmROPtbl.Attributes.Add("runat", "server");

Table maintable = new Table();
maintable.Width = Unit.Percentage(100);
TableRow hdrRow = new TableRow();
TableCell hdrCell0 = new TableCell();
TableCell hdrCell1 = new TableCell();
hdrRow.Width = Unit.Percentage(100);
hdrCell0.Width = Unit.Percentage(50);
hdrCell1.Width = Unit.Percentage(50);
Label hdrLabel = new Label();
hdrLabel.ID = "lblCustomerDesc".ToString();
hdrLabel.Width = Unit.Pixel(360);

Button btnToExcel = new Button();
btnToExcel.ID = "btnToExcel";
btnToExcel.CssClass ="Button".ToString();
btnToExcel.Text = "To Excel";
btnToExcel.Click += new System.EventHandler(this.btnToExcel_Click);

btnToExcel.Attributes.Add("runat", "server");
//* Attach a Server Event to this Button

hdrCell0.Controls.Add(hdrLabel);
hdrCell1.Controls.Add(btnToExcel);

hdrRow.Cells.Add (hdrCell0);
hdrRow.Cells.Add (hdrCell1);
...

Thanks
Andy
(Andrew.Kirin@verizon.net)

Re: Create Server Event using code

Heath Stewart12-Dec-03 4:15

Heath Stewart

12-Dec-03 4:15

What do you mean by "server" event? Adding the Click event handler automatically renders the correct HTML. If you want the server to watch for something to happen, you can't for so many reasons:

HTTP is by nature non-stateful.
ASP.NET runs server-side and generates client-side code (HTML, Javascript, images, etc.) that the browser downloads to the user's machine.
These two do not maintain persistent communications.
The only way the client can alert the server of a change is by making a new request to get the file (without the use of ActiveX, Java Applets, or using javascript with special automation objects that are different from browser to browser and sometimes not available at all).

-----BEGIN GEEK CODE BLOCK-----
Version: 3.21
GCS/G/MU d- s: a- C++++ UL@ P++(+++) L+(--) E--- W+++ N++ o+ K? w++++ O- M(+) V? PS-- PE Y++ PGP++ t++@ 5 X+++ R+@ tv+ b(-)>b++ DI++++ D+ G e++>+++ h---* r+++ y+++
-----END GEEK CODE BLOCK-----

my fatherland

duaneye200311-Dec-03 23:23

duaneye2003

11-Dec-03 23:23

http://www.china-vips.com/bbs/dispbbs.asp?BoardID=12&id=12866&replyID=82911&star=1&skin=

village in my fatherland.
my broken heart

Static libraries and C#

Severino11-Dec-03 22:20

Severino

11-Dec-03 22:20

Hello,

I would like to know if there is some way to use a static library (a .LIB developed using C++) from C#.
Any idea?

Regards

Severino

Re: Static libraries and C#

Heath Stewart12-Dec-03 4:05

Heath Stewart

12-Dec-03 4:05

Isn't possible. .NET uses assemblies that contain dependency references, assembly attributes, modules (what actually contain the code), embedded resources, and a manifest that lists it all.

This does imply, however, that you could write a library and compile it as a module (only possible with the command-line compiler, csc.exe (C# compiler) using the /t:module parameter. You can then compile an assembly that contains your code plus this module. It's not quite the same thing, but the result is pretty much the same. Again, this is only available with the command-line compiler. VS.NET doesn't support this.

Doing things this way will result in an assembly with two different modules. There is an article at an old hang-out that describes writing assemblies with modules in different languages. The principal is the same even if you use the same language, though: http://www.devhood.com/tutorials/tutorial_details.aspx?tutorial_id=466[^].

Re: Static libraries and C#

Eric Gunnerson (msft)12-Dec-03 13:31

Eric Gunnerson (msft)

12-Dec-03 13:31

Two options:

1) Compile it into a DLL.
2) Write a wrapper using Managed C++.

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