Re: Scroll a CListCtrl? - C / C++ / MFC Discussion Boards

Omar Alvi3-Jul-03 9:45

3-Jul-03 9:45

Thanks, i know that there are some libraries available but actually i wanted to write my own class. Any help will be greatly appreciated.

Thank you

Scroll a CListCtrl?

Dominik Reichl2-Jul-03 9:40

Dominik Reichl

2-Jul-03 9:40

Hello,

I am trying to scroll a CListCtrl. I have the number of the item which should be displayed at the top (so not in the middle, the bottom or anything else...). If it is possible, the item should be on top (sure, if it's one of the last lines, this isn't possible).

I tried various ways but none of them worked.

1) I used EnsureVisible twice. First ensure that the last item is visible and then make a second call to the final item. I thought Windows would internally scroll to the end and then from the end up to the item. But it didn't work. Either it scrolled simply to the end, or it does nothing (randomly).

2) I tried to use the Scroll function, but it scrolls randomly Big Grin | :-D

Although I am pretty sure that I calculated the scroll amount correctly... Frown | :(

Do you have a short code snippet that scrolls to a specific item so it's at the top visible? How do you do it? Confused | :confused:

Thanks
-Dominik

_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??

Re: Scroll a CListCtrl?

basementman2-Jul-03 9:57

basementman

2-Jul-03 9:57

EnsureVisible has always worked for me in the past. Perhaps you should only call it once for the item that you really want to see.

onwards and upwards...

Re: Scroll a CListCtrl?

Ryan Binns3-Jul-03 1:39

Ryan Binns

3-Jul-03 1:39

You do realise that Scroll() scrolls in pixels, not in items, don't you?

Just checking Smile | :)

Ryan

Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2^nd April 2003, The Lounge)

Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"

Re: Scroll a CListCtrl?

Dominik Reichl3-Jul-03 3:45

Dominik Reichl

3-Jul-03 3:45

Yes, I realised that Scroll wants pixels Wink | ;)

It works now with EnsureVisible. I calculated the last item not correctly, I calculated the lastitem+1=count as last item Blush | :O

-Dominik

_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??

Re: Scroll a CListCtrl?

Ryan Binns3-Jul-03 4:03

Ryan Binns

3-Jul-03 4:03

Dominik Reichl wrote:
It works now with EnsureVisible

Cool | :cool:

Using Scroll() is just a PITA. How were you calculating the line height to do it? I probably would have used GetItemRect() and CRect::GetHeight().

Dominik Reichl wrote:
I calculated the lastitem+1=count as last item

Roll eyes | :rolleyes:

Yeah, that would stop it working Wink | ;)

Re: Scroll a CListCtrl?

Dominik Reichl3-Jul-03 5:56

Dominik Reichl

3-Jul-03 5:56

Ryan Binns wrote:
How were you calculating the line height to do it? I probably would have used GetItemRect() and CRect::GetHeight().

Nearly Wink | ;)

I've done exactly what you said, plus I added 1 to the item size because it looks like Windows adds a one-pixel line as spacer (at least on my Win98).

Big Grin | :-D

-Dominik

_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??

Re: Scroll a CListCtrl?

Ryan Binns3-Jul-03 14:55

Ryan Binns

3-Jul-03 14:55

Dominik Reichl wrote:
I've done exactly what you said, plus I added 1 to the item size because it looks like Windows adds a one-pixel line as spacer

Nope, Windows doesn't add a pixel to it. It's the stupid calculation that GetHeight() uses: (bottom - top). The actual height should be (bottom - top + 1). A rectangle where top=0 and bottom=1 is actually 2 pixels high, but GetHeight() returns 1. I don't know why CRect was written this way, but it was.

Ryan

Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2^nd April 2003, The Lounge)

Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"

Selecting multiple CEdit Boxes

K. Shaffer2-Jul-03 9:18

K. Shaffer

2-Jul-03 9:18

Is it possible to set the selection of text in two separate CEdit boxes at the same time? In order to highilght the first box, I use

m_approach1C.SetFocus();//set focus
m_approach1C.SetSel(0,-1);//select entire text

I must call SetFocus() for this to work, but I cannot set the focus to 2 CEdit boxes at the same time, so if I do this...

m_approach0C.SetFocus();//set focus to box 1
m_approach0C.SetSel(0,-1);//select all text in box 1
m_approach1C.SetSel(0,-1);//select all text in box 2

only the first CEdit control selects the text.

If I cannot do this, is there a way to change the background color of a CEdit box?

"Because without beer, things do not seem to go as well."

Kevin Shaffer
kshaff03@msn.com

Re: Selecting multiple CEdit Boxes

John R. Shaw2-Jul-03 11:16

John R. Shaw

2-Jul-03 11:16

Only one control (a.k.a. window) may have the focus at one time.

As for changing the background color, a search of code project should give you the answer. Try searching for things like the following: "edit control backgound color", "custum edit controls", "custum contols", and take a look at the totorials.

Trust in the code Luke. Yea right!

Re: Selecting multiple CEdit Boxes

Ryan Binns3-Jul-03 1:43

Ryan Binns

3-Jul-03 1:43

As John said, only one control can have the focus at once. Edit controls only show their selection when they have the focus, so if only one control can have focus, then only one edit control shows its text as selected. You can select text in both edit boxes, but only one will show up as selected.

kshaff03 wrote:
If I cannot do this, is there a way to change the background color of a CEdit box?

Yes. Handle WM_CTLCOLOR in your dialog. Look at the docs for more information. There are plenty of articles around as well.

Ryan

Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2^nd April 2003, The Lounge)

Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"

Having some trouble subclassing dynamically created CButtons

Flack2-Jul-03 8:57

Flack

2-Jul-03 8:57

Hello,

I was trying out one of the articles I read here about subclassing. The article can be found at http://www.codeproject.com/miscctrl/subclassdemo.asp#xx524121xx

I have subclassed CButton and have a new class, CMyButton. Now, I added all of the functionality that I want to CMyButton and want to subclass my CButtons.

In my app I have some CButtons that are dynamically created. The user hits "Add Button" in the menu and the button appears. This is what I tried to do in order to subclass the button:

//First the button is created (I am using an array of CButtons)<br />
m_buttons[m_numButtons].Create(Source,WS_VISIBLE|WS_TABSTOP|BS_FLAT|<br />
BS_PUSHBUTTON|BS_ICON|BS_VCENTER, r, MainWnd,IDC_MAIN_BUTTON + m_numButtons);<br />
<br />
//Now I try to subclass it<br />
CWnd *pWnd = GetDlgItem(IDC_MAIN_BUTTON + m_numButtons); <br />
ASSERT(pWnd && pWnd->GetSafeHwnd());<br />
m_btnMyButton.SubclassWindow(pWnd->GetSafeHwnd());<br />

However, the bold line gives me an assertion error in WinCore.cpp:
ASSERT(FromHandlePermanent(hWndNew) == NULL);
// Must not be already in permanent map

I read at Microsoft that this implies that the control that I am attempting to subclass has already been subclassed.

Does anyone know how I can resolve this problem?

Also, in CMyButton::DrawItem I have the button turn yellow, just as the article says. However, how can I make it so the button is drawn with all of the styles I have indicated when I created the button? What I have in DrawItem is exactly as in the article but button styles are not handled in the article. For example, I want a flat, icon button that is a tab stop, but the button is drawn as a usual button and unable to be tabbed to. What do I have to add to my DrawItem function to get it to make the button flat, display the icon, and be a tab stop and have any other styles that I added when I created the original CButton, before it was subclassed?

If you have any questions please let me know.

Thanx,
-Flack

Re: Having some trouble subclassing dynamically created CButtons

basementman2-Jul-03 9:38

basementman

2-Jul-03 9:38

I believe that your issue is that when you created the buttons via the CButton class, it already has it "subclassed" to MFC wndproc. Subclassing is used to hook windows that have already been created by other means.

onwards and upwards...

Re: Having some trouble subclassing dynamically created CButtons

Flack2-Jul-03 10:14

Flack

2-Jul-03 10:14

Thanx for the reply.

Would it then be possible for me to instead of have an array of CButtons and CButtons created dynamically, and then subclass them, to instead change it to an array of CMyButtons so I wouldnt have to subclass anything?

I tried this and the the buttons would draw and turn yellow when I hover over them with the mouse but the button styles I want are not drawn.

What would I have to do in order to make the buttons draw with the style I want? Im guessing Im missing something in CMyButton::DrawItem but I dont know what.

Any help is greatly appreciated.

Thanx,
-Flack

Re: Having some trouble subclassing dynamically created CButtons

Ryan Binns2-Jul-03 16:08

Ryan Binns

2-Jul-03 16:08

Flack wrote:
Would it then be possible for me to instead of have an array of CButtons and CButtons created dynamically, and then subclass them, to instead change it to an array of CMyButtons so I wouldnt have to subclass anything?

Yes, this is the right way to do it.

Flack wrote:
What would I have to do in order to make the buttons draw with the style I want? Im guessing Im missing something in CMyButton::DrawItem but I dont know what.

All your drawing code is in CMyButton::DrawItem(). If you comment out everything in this function, then nothing will get drawn. Just make sure you are drawing the right thing Smile | :)

.

Ryan

Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2^nd April 2003, The Lounge)

Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"

Create and Access Hardware?

Selevercin2-Jul-03 8:28

Selevercin

2-Jul-03 8:28

This is a large question, but I wish to know if it's possible to create hardware and then access it through VC++? Perhaps make an LED light up through an USB port... I can't seem to find anything on the internet about this, does anyone know if it's even possible?

Again, I know it's a big question, but I'm just curiuos... Thanks!

If you have a problem with my spelling, just remember that's not my fault. I (as well as everyone else who learned to spell after 1976) blame it on Robert A. Kolpek for U.S. Patent 4,136,395.

Re: Create and Access Hardware?

John M. Drescher2-Jul-03 8:51

John M. Drescher

2-Jul-03 8:51

Selevercin wrote:
can't seem to find anything on the internet about this, does anyone know if it's even possible?

Of course this is possible but there is a lot of work involved. You must write a driver. Windows 9X drivers are completly different from windows NT drivers.

John

Re: Create and Access Hardware?

Selevercin2-Jul-03 9:13

Selevercin

2-Jul-03 9:13

Hmmm... thanks for replying. Is there information on this somewhere?

Selevercin

If you have a problem with my spelling, just remember that's not my fault. I (as well as everyone else who learned to spell after 1976) blame it on Robert A. Kolpek for U.S. Patent 4,136,395.

Re: Create and Access Hardware?

John M. Drescher2-Jul-03 9:18

John M. Drescher

2-Jul-03 9:18

I'm sorry I don't know of any good sources of info on this kind of thing. In the past we have investigated doing stuff like this but we thought that it would be too time consuming for what we got out of it..

John

Re: Create and Access Hardware?

David Crow2-Jul-03 10:01

David Crow

2-Jul-03 10:01

Selevercin wrote:
Is there information on this somewhere?

Possibly here:

http://flounder.com/books.htm#Developing%20Windows%20NT%204.0%20Device%20Drivers

Re: Create and Access Hardware?

Selevercin2-Jul-03 10:54

Selevercin

2-Jul-03 10:54

Thanks for the help... I think it's going to be too complex and time consuming to actually do it though.

Thanks again,

Nic

If you have a problem with my spelling, just remember that's not my fault. I (as well as everyone else who learned to spell after 1976) blame it on Robert A. Kolpek for U.S. Patent 4,136,395.

Re: Create and Access Hardware?

David Crow2-Jul-03 16:54

David Crow

2-Jul-03 16:54

Yes, device drivers are no small undertaking.

Re: Create and Access Hardware?

jhwurmbach3-Jul-03 1:19

jhwurmbach

3-Jul-03 1:19

There is an article written in German here[^]which describes a DIY USB-interface. You can even buy the pieces and build it yourself.

If any german article does help you, the article seems to be very good.

My opinions may have changed, but not the fact that I am right.

Re: Create and Access Hardware?

Trollslayer2-Jul-03 11:14

Trollslayer

2-Jul-03 11:14

There is a way, and that is to used a serial interface (maybe with a USB to serial converter if you want) and control the handshake lines. This won't provide many lines, but is cheap and fast with a little bit of level shifting hardware.
Use one of the serial classes in http://www.codeproject.com/system/[^] that can directly control and read these lines.

Elaine Rose | [Rose]

The tigress is here Big Grin | :-D

Re: Create and Access Hardware?

Selevercin2-Jul-03 12:33

Selevercin

2-Jul-03 12:33

I'm sorry, but "handshake lines"? I'm completely new to this sort of thing...

Thanks!

If you have a problem with my spelling, just remember that's not my fault. I (as well as everyone else who learned to spell after 1976) blame it on Robert A. Kolpek for U.S. Patent 4,136,395.

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