C / C++ / MFC

Remi Morin26-Oct-01 8:33

Remi Morin

26-Oct-01 8:33

Hi,
for the flickering problem you may use a memory device, a bitmap in memory that you attach to a CDC, then from thisd CDC you copy over the CDC* pDC. else you can, before drawing access to the "screen bitmap" and use it... but I've never do It. There are good tutorial in the Graphics section who may contain theses information

Remi Morin
Rmorin@Operamail.com
Remi.Morin@Lyrtech.com

Christian Graus26-Oct-01 11:04

Christian Graus

26-Oct-01 11:04

Hi all, I am trying to make a custom drawing package in an MDI app.

I've done the same thing and pretty much had to learn how to do it as I went. If you're using GDI ( i.e. not GDI+), buy Windows Graphics Programming by Feng Yuan. Hell, buy it anyway, I still refer to it .

I have managed to load a bitmap into the child window using OnDraw and the CDC* pDC.

First things first. Do NOT use CBitmap, it is a device dependant bitmap. In order to be able to edit and save differing bitmap bit depths instead of just ones the same depth as the screen res, use a DIBSection wrapper like the one Chris Maunder wrote which is in the bitmaps section on the site.

I have also managed to get it to draw various lines to the screen when the users chooses the appropriate menu (yay ). However, these lines are drawn onto the CDC* pDC, is this the best way (I am getting flickering upon resizing of the child window)? or can you draw onto the CBitmap itself?

The only way to draw onto a bitmap is through a CDC unless you're planning to access the bits directly. As has been said, you fix the flicker by drawing to a memory DC and then drawing direct to the screen in one blt. I also killed OnEraseBackground because I was drawing over the whole surface myself anyhow, and that goes a long way to killing flicker.

The main focus of my problem is the fact I need to have low-level access to the pixel colours (in Delphi I was using scanline to scan whole lines of them into a PByteArray) so that I can change the ones that interest me, and leave the ones that don`t.

Using a DIBSection solves this problem - you will have access to the underlying bits in order to do whatever you pretty much like. You'll figure this out quickly anyhow, but I'll mention that Windows stores colours in BGR format.

Finally, what would be the best way to go about creating a layered approach, so that when I draw the lines etc. I don`t actually affect the underlying bitmap? would creating a new DC and drawing onto this, before outputting to the screen solve this? Anyway, I appreciate any help you could give on this guys,

In that case you could store the lines drawn in a path and actually draw them to the screen DC instead of the one holding the original bitmap. I did something like this for the line/shape tools ( where you stretch out a shape and it doesn't become a permanent addition until you let go of the mouse ) -> when the mouse button was pressed I started drawing onto the memDC before blting it to the screen, when you lifted the mouse I drew to the DC that held the bitmap, thus making a permanent change.

Christian

After all, there's nothing wrong with an elite as long as I'm allowed to be part of it!! - Mike Burston Oct 23, 2001

Chambers27-Oct-01 0:07

Chambers

27-Oct-01 0:07

Thanks for responses guys. I have used a memDC to draw on and then blt it to the screen CDC*, however, I still have flicker (only when resizing the window, I can move the child about and its fine), I think it may be something to do with OnEraseBackground do you think you can tell me how to kill it (do I just override it and then fail to do anything in the function call?). Many thanks again for the responses I got, they were superb. Big Grin | :-D

Cheers,
Alan;P

AEGC

ON_UPDATE_COMMAND_UI problem...

Christian Graus27-Oct-01 0:32

Christian Graus

27-Oct-01 0:32

You should simply return TRUE to indicate that you've handled the message, don't do anything else or call the base method.

Christian

After all, there's nothing wrong with an elite as long as I'm allowed to be part of it!! - Mike Burston Oct 23, 2001

Remi Morin26-Oct-01 3:50

Remi Morin

26-Oct-01 3:50

I used the ON_UPDATE_COMMAND_UI message in a DialogBar to display button, this fonction do nothing. It is only usefull to avoid my DialogBar to grayed my button so the message map look like this

BEGIN_MESSAGE_MAP(CVBurnBar, CDialogBar)
	//{{AFX_MSG_MAP(CVBurnBar)
        //...other message handler
	ON_UPDATE_COMMAND_UI(IDC_Up_Normalize_AxisY, OnUpdateButton)
	ON_UPDATE_COMMAND_UI(IDC_Bottom_Normalize_AxisY, OnUpdateButton)
	ON_UPDATE_COMMAND_UI(IDC_Bottom_Adjust_Y, OnUpdateButton)
	ON_UPDATE_COMMAND_UI(IDC_Up_Adjust_Y, OnUpdateButton)
	//}}AFX_MSG_MAP
	ON_MESSAGE(WM_INITDIALOG,OnInitDialog)
END_MESSAGE_MAP()

and the function

void CVBurnBar::OnUpdateButton(CCmdUI* /* pCmdUI*/) 
{}

but theses message handler are called very often... what can I do to avoid this function to be call so often? Is there an other way to display button NOT GRAYED in a dialog bar whitout using the ON_UPDATE_COMMAND_UI.
when I do MyButton.EnableWindow(true) if the ON_UPDATE_COMMAND_UI is not define for this button it is automatically grayed after 1/10 of a second...

What I wan't is to display and grayed my button when I want...

any idea?

Remi Morin
Rmorin@Operamail.com
Remi.Morin@Lyrtech.com

Tomasz Sowinski26-Oct-01 4:01

Tomasz Sowinski

26-Oct-01 4:01

If you want your button to stay active all the time, do not create ON_UPDATE_COMMAND_UI - just ON_COMMAND handler. MFC scans through message maps during each idle cycle, which happens very often indeed. However, you shouldn't be worried much about that - it works the same way for toolbars, for example.

Tomasz Sowinski -- http://www.shooltz.com

Chambers26-Oct-01 4:08

Chambers

26-Oct-01 4:08

You should be using ON_UPDATE_COMMAND_UI_RANGE(IDC_Up_Normalise_AxisY, IDC_Up_Adjust_Y, OnUpdateButton) provided the command IDs use that range. This maps the button handlers to the same function(OnUpdateButton), something it looks like your trying to do. The function does nothing because you haven`t said for it to do anything! I think that in the CVBurnBar function, if you change the parameter to (CCmdUI* pCmdUI) i.e no comments, then you should have control to change the button i.e gray it out etc (using pCmdUI->thefunctionyouwant). Also make sure the afx_msg void OnUpdateButton in the header file is changed to reflect this. To stop the button being grayed out at the start all you need to do is add a message map for ON_COMMAND_RANGE(IDC_Up_Normalise_AxisY, IDC_Up_Adjust_Y, TheFunctionYouWantToCallWhenButtonIsClicked). hope this helped slightly. Big Grin | :-D

AEGC

Carlos Antollini26-Oct-01 4:12

Carlos Antollini

26-Oct-01 4:12

From MSDN: (TN031: Control Bars)

CCmdUI Support for CDialogBar

Dialog bar buttons should be updated through the ON_UPDATE_COMMAND_UI handler mechanism. At idle time, the dialog bar will call the ON_UPDATE_COMMAND_UI handler with the command ID of all the buttons that have a ID >= 0x8000 (that is, in the range of command IDs).

The ON_UPDATE_COMMAND_UI handler can call:

Enable: to enable or disable the button.

SetText: to change the text of the button.
Customization can be done through standard window manager APIs.

Best Regards...

Carlos Antollini.
Green Alien | [Alien]

Today Is Friday!!! Beer | [beer]

for All!!!

Date and Time Picker Control

Carlos Antollini26-Oct-01 4:17

Carlos Antollini

26-Oct-01 4:17

You tried with

void CVBurnBar::OnUpdateButton(CCmdUI* /* pCmdUI*/) 
{
 CCmdUI->Enable();
}

Carlos Antollini.

Steve Thresher26-Oct-01 3:43

Steve Thresher

26-Oct-01 3:43

Does anybody have any ideas on how to make the control read only. There doesn't appear to be a window style to do it. If you disable the window it still looks the same but you can't click the drop down arrow.

Any suggestions would be appreciated.

Steve.

Listview Custom Draw

Paul C26-Oct-01 1:11

26-Oct-01 1:11

Anyone know how to determine the font that a custom draw listview item is using?

#realJSOP26-Oct-01 1:24

#realJSOP

26-Oct-01 1:24

In the OnInitialUpdate function, you could call GetFont() and then analyze the members of the pointer it returns (CFont*). Something like this:

CFont* font = GetFont();
if (font)
{
   LOGFONT lf;
   font->GetLogFont(&lf);
   TRACE("Typeface name of font = %s\n", lf.lfFaceName);
}

To hell with those thin-skinned pillow-biters. - Me, 10/03/2001

Paul C26-Oct-01 1:32

26-Oct-01 1:32

I am not using MFC so how would I do this just using the windows API? I am actually trying to determine whether the item is bold or not in the Outlook Express message list. Thank you for your response.

#realJSOP26-Oct-01 3:35

#realJSOP

26-Oct-01 3:35

WM_GETFONT
An application sends a WM_GETFONT message to a control to retrieve the font with which the control is currently drawing its text.

To send this message, call the SendMessage function with the following parameters.

SendMessage(
(HWND) hWnd, // handle to destination window
WM_GETFONT, // message to send
(WPARAM) wParam, // not used; must be zero
(LPARAM) lParam // not used; must be zero
);
Parameters
This message has no parameters.

Return Values
The return value is a handle to the font used by the control, or NULL if the control is using the system font.

Requirements
Windows NT/2000 or later: Requires Windows NT 3.1 or later.
Windows 95/98/Me: Requires Windows 95 or later.
Header: Declared in Winuser.h; include Windows.h.

After you get the HFONT, you can probably build a logfont to retrieve the info.

To hell with those thin-skinned pillow-biters. - Me, 10/03/2001

Paul C26-Oct-01 4:04

26-Oct-01 4:04

That method will return the listview font not the font of the item.

Tomasz Sowinski26-Oct-01 2:38

Tomasz Sowinski

26-Oct-01 2:38

Custom-draw listview is free to choose as many fonts as it wants for painting different parts of the item area (in such case it skips the default drawing completely). Are you subclassing the listview in question?

Tomasz Sowinski -- http://www.shooltz.com

Paul C26-Oct-01 3:12

26-Oct-01 3:12

No I am not subclassing the listview but using hooks.

Tomasz Sowinski26-Oct-01 3:35

Tomasz Sowinski

26-Oct-01 3:35

Well, assuming that this control only sets the font and lets COMCTL32 draw the items, you may try to install WH_CALLWNDPROCRET hook and inspect the font selected into DC after NM_CUSTOMDRAW. You'll have to check for correct custom-draw stage, probably CDDS_ITEMPREPAINT.

BTW: why do you need this functionality?

Tomasz Sowinski -- http://www.shooltz.com

Paul C26-Oct-01 4:07