C / C++ / MFC

7-Jun-07 8:04

Hi,

I use CDC* pDC->DrawText(" number ") in OnDraw() to update text to a frame. I then call InvalidateRect(NULL,FALSE) to display the text. What is the better way of display text without calling InvalidateRect() because OnDraw() with InvalidateRect() slow down application quite a lot. Thanks.

Re: CDC DrawText [modified]

Matthew Faithfull7-Jun-07 8:19

Matthew Faithfull

7-Jun-07 8:19

If you're doing this right you should not have to call InvalidateRect(). OnDraw only gets called when some Rect is alreay invalid, that's why windows generated the WM_PAINT to get you to call OnDraw in the first place. If your text doesn't appear without this then something else is wrong.
I'm not sure what you mean by

gurucplusplus wrote:
update text to a frame

. With most windows you can call SetWindowText to set the text that's displayed. If this is a custom window class or an owner draw control then DrawText might be right Unsure | :~

Nothing is exactly what it seems but everything with seems can be unpicked.

Mark Salsbery7-Jun-07 8:19

7-Jun-07 8:19

You're causing ~~recursive~~ repeated calls to OnDraw() by calling InvalidateRect()
from within OnDraw(). That'll certainly slow things down Smile | :)

gurucplusplus wrote:
What is the better way of display text without calling InvalidateRect()

Don't call InvalidateRect()!

Mark

-- modified at 14:29 Thursday 7th June, 2007

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

gurucplusplus7-Jun-07 8:28

7-Jun-07 8:28

How can I update this text to graphic without calling invalidateRect()?

Mark Salsbery7-Jun-07 8:35

7-Jun-07 8:35

When you call DrawText, you ARE updating the text.

You use Invalidate methods to force a repaint from outside of OnPaint/OnDraw.

For example, if the text you are drawing changes as the result of some process in the application
and you want the window updated to reflect the change, then you'd call Invalidate. This will
mark the given area of the window as invalid. On the next WM_PAINT message (which will call
OnDraw() for CViews) you will call DrawText() with the updated text.

I hope that made sense Smile | :)

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

gurucplusplus7-Jun-07 8:52

7-Jun-07 8:52

So, If my text drawn changes I have to call invalidateRect to mark invalid for the next WM_PAINT message to update the text. Where should I call invalidaterect then? Not in ondraw()? thanks

Mark Salsbery7-Jun-07 9:11

7-Jun-07 9:11

gurucplusplus wrote:
If my text drawn changes I have to call invalidateRect to mark invalid for the next WM_PAINT message to update the text. Where should I call invalidaterect then?

Right. If the text characters never change (like pDC->DrawText("Text") then there's no reason
to ever call InvalidateRect() because every time the window needs repainting the text will
just be redrawn.
Now suppose you are drawing the text of a string that changes (pDC->DrawText(str)). The user
does something that causes the value of str to change and you want to reflect that change in the
window. Any time after you change str, call InvalidateRect() to mark the area as invalid. When
the resulting WM_PAINT is received by the window, CView::OnPaint() will call OnDraw(). In your
OnDraw() override, you call pDC->DrawText(str), drawing the new text on the window.

Also remember, WM_PAINT messages are LOW priority (they can get bumped to the back of the message
queue). If you need an instant update, like if the text string is changing as the result of a
timer (like in a clock implementation), then you can add a call to UpdateWindow() right after
the call to InvalidateRect(). This will cause a WM_PAINT to be sent immediately.

Remember that, when responding to WM_PAINT, it is your responsibility to validate the region
of the window that is invalid to prevent repeated WM_PAINT messages. Most of the time this
is done for us by MFC or the default window message handling. So if you invalidate regions of
a window while it's trying to validate it, the WM_PAINT messages keep coming.

If you want to see the recursive action/result of doing this in your OnDraw(), try this in your
OnDraw(). This consumes all the CPU time of one of my processors and renders dialog controls
useless:

Invalidate();
UpdateWindow();
return;

I'm actually surprised it doesn't crash Smile | :)

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

gurucplusplus7-Jun-07 9:57

CToolBar disable/enable buttons

7-Jun-07 9:57

Thanks.

Romiks7-Jun-07 7:45

7-Jun-07 7:45

Hi All,
I have used the code from
http://www.codeproject.com/docking/ctruecolortoolbar_update.asp article.
But I can't understand how to enable/disable buttons.
Please help me to do it Confused | :confused:

Thanks

Mark Salsbery7-Jun-07 7:52

7-Jun-07 7:52

One way is to use "command enablers"...

BEGIN_MESSAGE_MAP(CMyFrameWnd, CFrameWnd)
...
ON_UPDATE_COMMAND_UI(ID_BUTTONID, OnUpdateButton)
...
END_MESSAGE_MAP()
 
void CMyFrameWnd::OnUpdateButton(CCmdUI* pCmdUI) 
{
   if (some_condition)
      pCmdUI->Enable(TRUE);
   else
      pCmdUI->Enable(FALSE);
}

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

Romiks7-Jun-07 19:41

7-Jun-07 19:41

Mark thanks for reply, but I have dialog based application, there is no ON_UPDATE_COMMAND_UI Frown | :(

Nelek8-Jun-07 3:09

Nelek

8-Jun-07 3:09

Then try in OnPaint.

if (condition)
button->EnableWindow (TRUE);
else
button->EnableWindow (FALSE);

is not the best way, but it will maybe work

NOTE: I have not read the article, so im not sure if I'm saying something catastrofical Wink | ;)

Greetings.

--------
M.D.V.

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?

Mark Salsbery8-Jun-07 4:32

8-Jun-07 4:32

Well, anytime after a toolbar is created and the buttons are added to it, you can enable and
diable buttons when you need to:

// Disable a button
m_ToolBar.GetToolBarCtrl().EnableButton(ID_BUTTON1, FALSE);

// Enable a button
m_ToolBar.GetToolBarCtrl().EnableButton(ID_BUTTON1, TRUE);

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

Romiks8-Jun-07 18:54

8-Jun-07 18:54

Mark, many thanks it works Smile | :)

, but button was not greyed Sniff | :^)

Mark Salsbery9-Jun-07 7:51

9-Jun-07 7:51

Romiks wrote:
but button was not greyed

Looking at the article, it looks like there's a separate image list for disabled.
Are the images in that image list the same as the regular images?

You could try omitting the last parameter in the call to LoadTrueColorToolBar() - the system
should do its default "greying" for disabled buttons.

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

Romiks11-Jun-07 20:38

11-Jun-07 20:38

Mark, many thanks for help. I have tried to omit the last parameter, but it doesn't work D'Oh! | :doh:

.
I will try to use CButton instead of tool bar.

Mark Salsbery12-Jun-07 6:28

12-Jun-07 6:28

So the buttons diable but they don't look disabled?

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

Romiks16-Jun-07 23:37

16-Jun-07 23:37

Hi Mark,
If I ommited the last parameter, buttons are not disabled. Frown | :(

Mark Salsbery17-Jun-07 7:29

17-Jun-07 7:29

I just downloaded the source - I'll take a look.

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

Mark Salsbery17-Jun-07 8:09

17-Jun-07 8:09

Ok..

It all works fine in the authors demo app.

The author actually omits the last parametr in the call to CTrueColorToolBar::LoadTrueColorToolBar
for the RIGHT toolbar. So, the right toolbar shows button bitmaps grayed by the system.

For the left toolbar he uses special bitmaps for disabled buttons that don't have any color,
just white/black/grays.

All the buttons except the first three on left and right are disabled. If you try to disable them
yourself they won't look any different Smile | :)

To enable them, you can add command enablers. For example, there's 9 buttons on the toolbars.
I enabled the 7th and 8th buttons like this (in MainFrm.cpp/.h):

// In MainFrm.h
 
// add these declarations to the CMainFrame class
afx_msg void OnUpdateButton32777(CCmdUI* pCmdUI);
afx_msg void OnUpdateButton32778(CCmdUI* pCmdUI);
 
 
// In MainFrm.cpp
 
// add this to CMainFrame message map
ON_UPDATE_COMMAND_UI(ID_BUTTON32777, OnUpdateButton32777)
ON_UPDATE_COMMAND_UI(ID_BUTTON32778, OnUpdateButton32778)
 
// add these handler methods
void CMainFrame::OnUpdateButton32777(CCmdUI* pCmdUI) 
{
	pCmdUI->Enable(TRUE);
}
 
void CMainFrame::OnUpdateButton32778(CCmdUI* pCmdUI) 
{
	pCmdUI->Enable(TRUE);
}

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

Romiks17-Jun-07 18:58

17-Jun-07 18:58

Ok...
I have dialog based MFC application Wink | ;)

There is no ON_UPDATE_COMMAND_UI command Frown | :(

Mark Salsbery18-Jun-07 4:29

18-Jun-07 4:29

Romiks wrote:
I have dialog based MFC application

Oh yeah, I forgot about that, sorry Blush | :O

Well I still go back to this:

// Disable button ID_BUTTON32777 in m_ToolBar
m_ToolBar.GetToolBarCtrl().EnableButton(ID_BUTTON32777, FALSE);

// Enable button ID_BUTTON32777 in m_ToolBar
m_ToolBar.GetToolBarCtrl().EnableButton(ID_BUTTON32777, TRUE);

I'm not sure why that doesn't work for you - I just tested it in a dialog toolbar here.

Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

Romiks18-Jun-07 5:52