Visual Basic

VB.Net WS_EX_LAYERED Forms

7-Dec-03 4:22

Having put your 4 Gig of memory method to the test I seem to have scratched the area of my hard disk, right around the place where the swap file seems to go Wink | ;-)

I am gonna go the C# route just to have a little utility function until my 2003 hits the front door carpet. I was using the div mul method of shifting up until now though and who cares if its 4 nano seconds slower than the C++ like bit shifts!

Ah well, all I have to do now is wait for the garbage collector to give me my 4 gig back hahaha 8-)

See Yah!

Nursey

andrew|5-Dec-03 4:32

5-Dec-03 4:32

Hello! Im new to these forums so please forgive me if I have posted in the wrong section for this.

Using winforms under vb.net, how does one set the GWL_EXSTYLE to include WS_EX_LAYERED? I need to set this
flag so that I may use UpdateLayeredWindow on the form. This is what I am using :

Dim lStyle As Long = GetWindowLong(Me.Handle.ToInt32, GWL_EXSTYLE)
lStyle = lStyle And WS_EX_LAYERED
Dim retval As Long = SetWindowLong(Me.Handle.ToInt32, GWL_EXSTYLE, lStyle)

I tried it after a .Show() call and in the _Load event as well.

Someone, please enlighten me! This is holding up my project atm. Thanks!

Edited by - andrew_ on 12/4/2003 8:09:57 PM

cnurse5-Dec-03 18:56

5-Dec-03 18:56

Andrew,

I sincerely hope this example, which I found for you, helps out...

Using Layered Windows

To have a dialog box come up as a translucent window, first create the dialog as usual. Then, on WM_INITDIALOG, set the layered bit of the window's extended style and call SetLayeredWindowAttributes with the desired alpha value. The code might look like this:

// Set WS_EX_LAYERED on this window
SetWindowLong(hwnd,
GWL_EXSTYLE,
GetWindowLong(hwnd, GWL_EXSTYLE) | WS_EX_LAYERED);

// Make this window 70% alpha
SetLayeredWindowAttributes(hwnd, 0, (255 * 70) / 100, LWA_ALPHA);
Note that the third parameter of SetLayeredWindowAttributes is a value that ranges from 0 to 255, with 0 making the window completely transparent and 255 making it completely opaque. This parameter mimics the more versatile BLENDFUNCTION of the AlphaBlend function.

To make this window completely opaque again, remove the WS_EX_LAYERED bit by calling SetWindowLong and then ask the window to repaint. Removing the bit is desired to let the system know that it can free up some memory associated with layering and redirection. The code might look like this:

// Remove WS_EX_LAYERED from this window styles
SetWindowLong(hwnd,
GWL_EXSTYLE,
GetWindowLong(hwnd, GWL_EXSTYLE) & ~WS_EX_LAYERED);

// Ask the window and its children to repaint
RedrawWindow(hwnd,
NULL,
NULL,
RDW_ERASE | RDW_INVALIDATE | RDW_FRAME | RDW_ALLCHILDREN);

Nursey

andrew|5-Dec-03 21:24

5-Dec-03 21:24

Nursey, thanks for trying address the issue at hand here.

My main objective is to draw to an offscreen DC and use UpdateLayeredWindow to render the form. Being VB.NET Winforms, I am not quite sure how one goes about handling the WM_CREATE, or WM_INITDIALOG messages. If this were VB6 or below I would have no problem with this.

The reason why I thought it would be worthwhile to pose the question is because I had checked the winform with spy++ and the WS_EX_LAYERED exstyle was not listed for the window.

If there is a setting or a way to assert the WX_EX_LAYERED exstyle to a winform without calling SetWindowLong (Which has no effect on the winform at all) please do let me know!

Thanks!

Dave Kreskowiak6-Dec-03 4:57

Dave Kreskowiak

6-Dec-03 4:57

Just for learning purposes ... What are you trying to do with the layered window? What is the goal of rendering the window offscreen?

SetWindowLong is the only way your going to set WS_EX_LAYERED, BUT what I noticed in your code is that your ANDing the value in. You must OR the value in to get it to work, at least in the examples I've found (see here[^])

RageInTheMachine9532

andrew|6-Dec-03 5:44

6-Dec-03 5:44

*headsmack* Youre absolutely right.

As for your question of why... If you draw to an offscreen DC, maintain a background color (which in this case is argb(0,0,0,0)) of the DC, pass it to UpdateLayeredWindow with the right params, it will render the window for you and continue to handle the wm_paint messages that come in, until you remove the ws_ex_layered style and re-add it (in which case you need to call your fuction which draws offscreen again...). Its a great lil bit o' magic, and it allows you to have a window, for example, based on a PNG with alpha channel support.

Thanks for bringing that ANDing to my attention though!

UPDATE:
I stumbled upon an article which stated that Integers in vb.net are Longs in vb6. I had to modify the declares for SetWindowLong and GetWindowLong so that the params used Integers and returned Integers instead of Longs. Once I changed this, and used the ORing instead of the ANDing, everything worked as it should have.

Thanks again for the help guys!

cnurse6-Dec-03 22:52

MSScriptControl and VB.Net Control Events

6-Dec-03 22:52

Andrew...this is a comment to you, because we all get code blindness, but the rest of us have learned a very valuable lesson from Rage, read the code brothers, be the code. I just had the urge to assume I could grab you a quick example and let you go from there. If I had read the code properly then I too would have learned somthing 8-)

say la vee as people who talk foreign languages phonetically would say.

Chris.

Nursey

andrew|5-Dec-03 4:29

How can I integrated a combobox ?

5-Dec-03 4:29

I am attempting to add a form or control as an object to my instance of the MSScriptControl, where the control or form will extend its events to the loaded script...

oScripting.AddObject("Window", Me, True)
oScripting.State = MSScriptControl.ScriptControlStates.Connected

That is supposed to add the object and attach its members and events... but it doesnt fire the event within the script..

Sub Window_Click()
Msgbox "clicked"
End Sub

I have also tried;

Sub Window_Click(sender, e)
Msgbox "clicked"
End Sub

Please advise! I would very much like to know what I am doing wrong!

jlizardo5-Dec-03 3:29

jlizardo

5-Dec-03 3:29

Hi everyone;

I have a problem about what can I integrate a Combo box who's list is link with a table (called department) but the text of the combo is link with other table (called user).

Table 1 = user
Field 1 = User
Field 2 = DeptCode

Table 2 = Department
Field = DeptCode
Field = DeptDescription

I other words, I have a form presenting the user informtion (this information is from the table user), but the field called deptCode in user table. I want present every time the records is changed the dept description from table department.

(I think all of that is without Coding)

Please me on that...

Johnny

Johnny Lizardo

How to Stop a Big Loop

rrocha25-Dec-03 0:06

rrocha2

5-Dec-03 0:06

Hi everyone ...

When i am inside a big loop in VB6 (for .. to; if .. then; while .. wend) the form stops responding.

How can I make a stop button in the form ??

Thank you Wink | ;)

,

Rodrigo

Re: How to Stop a Big Loop

Ian Darling5-Dec-03 0:19

Ian Darling

5-Dec-03 0:19

You need to provide a means to break the loop. This is an example (untested), but you should get the idea:

dim StopButtonPressed as Boolean

sub MyLongLoopSubroutine()
 StopButtonPressed = false
 while (MyCondition = true ) and (StopButtonPressed = false)
  ' do loop stuff here
  ' DoEvents allows the UI and other windows messages to get through
  DoEvents
 wend
end sub

sub StopButton_Click()
 StopButtonPressed = true
end sub

Bear in mind you need to be careful when using DoEvents to keep a user interface responsive, as any actions the user has may interfere with the loop you're running.

--
Ian Darling
"The moral of the story is that with a contrived example, you can prove anything." - Joel Spolsky

My Computer Shell Extension

MusclePup4-Dec-03 22:58

MusclePup

4-Dec-03 22:58

If anyone can give me clues on how to add an icon to the WinXP My Computer that directly access a program.

Eg... Accessing a custom FTP program like a disk drive under My Computer.

Visual Studio Freezing.

cnurse4-Dec-03 21:40