C / C++ / MFC

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

6-Sep-07 8:03

The controls still flicker Frown | :-(

my overall process is:

<br />
//Dialog - prevent changes from being redrawn<br />
this->SetRedraw(FALSE);<br />
<br />
//invert parts of static image onthe Dialog, behind the controls<br />
pDC = this->GetDC();<br />
targetDC.CreateCompatibleDC(pDC);<br />
pOldTargetBmp = targetDC.SelectObject(&m_BmpTarget);<br />
targetDC.PatBlt(X,Y,iWidth,iHeight,DSTINVERT);<br />
targetDC.SelectObject(pOldTargetBmp);<br />
targetDC.DeleteDC();<br />
ReleaseDC(pDC);<br />
m_DialogStaticImage.SetBitmap(HBITMAP(m_BmpTarget));<br />
<br />
//redraw all controls to put them into foreground<br />
m_staticText.RedrawWindow(NULL,NULL,RDW_UPDATENOW);<br />
m_editBox.RedrawWindow(NULL,NULL,RDW_FRAME+RDW_INVALIDATE+RDW_UPDATENOW);<br />
.<br />
. about 15 controls<br />
.<br />
<br />
//Dialog - allow changes to be redrawn<br />
this->SetRedraw(TRUE);<br />
<br />
//no need to erase background since SetBitmap covered everything up<br />
this->Invalidate(FALSE);<br />
<br />
//show updated Dialog<br />
this->UpdateWindow();<br />

I was surprised that it would still flicker; I was hoping that all the graphics operations were done in memory, then simply shown when UpdateWindow was called - thus avoiding flicker.

Mark Salsbery6-Sep-07 8:22

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

6-Sep-07 8:22

I don't believe WM_SETREDRAW is supported by dialogs. You can try it on the individual controls though Smile | :)

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Mark Salsbery6-Sep-07 8:27

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ? [modified]

6-Sep-07 8:27

abiemann wrote:
I was surprised that it would still flicker; I was hoping that all the graphics operations were done in memory, then simply shown when UpdateWindow was called - thus avoiding flicker.

Nope. Looking more closely at your code, the only way you'll be able to prevent flicker
is to do the drawing offscreen yourself, then blt the whole thing to the dialog.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

abiemann6-Sep-07 8:33

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

6-Sep-07 8:33

Indeed, I was hoping that SetRedraw would implement double-buffering easily... but I found a good CP link that I'm studying now:

http://www.codeproject.com/gdi/flicker_free_intro.asp

EDIT:
I've compiled the "flicker free" project under VS8 and I see that the "Draw Area" flickers.

David Crow6-Sep-07 8:41

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

6-Sep-07 8:41

abiemann wrote:
//no need to erase background since SetBitmap covered everything up
this->Invalidate(FALSE);

You have a static control that is used to display a bitmap. Yes? Is it overlapping the other controls such that they are requiring this?

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

abiemann6-Sep-07 8:52

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

6-Sep-07 8:52

Yes, I have a static bitmap covering the entire Dialog window. Other controls (Buttons, Edit boxes) are ontop of this bitmap.

David Crow6-Sep-07 8:56

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

6-Sep-07 8:56

So are you rendering this image in the dialog's OnEraseBkgnd() method?

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

abiemann6-Sep-07 9:00

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

6-Sep-07 9:00

no I haven't touched the OnEraseBkgnd() or OnPaint methods.
The code above is processed whenever the user presses a key or lets go of a key.

(I haven't worked much with MFC, so I'm still learning)

David Crow6-Sep-07 10:20

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ? [modified]

6-Sep-07 10:20

abiemann wrote:
no I haven't touched the OnEraseBkgnd()...

Put your bitmap-rendering code in there and note the difference.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

abiemann6-Sep-07 13:08

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

6-Sep-07 13:08

Hi David,

I've made the change and the background bitmap doesn't flicker at all, however, the controls ontop of the bitmap still flicker.

This is the change I've made:

KeyHandler now triggers OnEraseBkgnd instead of performing PatBlt
When the user presses a key, the key's number is stored in a private member variable of the Dialog.
To subsequently make it update the background image, the Dialogs' key handler performs :

this->Invalidate(TRUE);<br />
this->UpdateWindow();

OnEraseBkgnd now does the PatBlt of the static image behind the controls
Next, OnEraseBkgnd(CDC* pDC) is processed.
this handler first checks that a key was pressed, if so, it performs the targetDC.PatBlt (I just use the pDC that's passed in) then it returns TRUE.
If no key was pressed then I let this handler perform the default CDialog::OnEraseBkgnd(pDC)

After this change I noticed that the individual controls no longer need their RedrawWindow() called, however, they still flicker (but the background static image doesn't flicker at all now).
I've also removed the SetRedraw() calls

-- modified at 19:14 Thursday 6th September, 2007

Mark Salsbery6-Sep-07 14:31

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

6-Sep-07 14:31

Did you try adding the WS_CLIPCHILDREN style to the dialog as suggested by WalderMort?

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

David Crow6-Sep-07 17:30

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

6-Sep-07 17:30

In other words, it works but it doesn't work. Confused | :confused:

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Hamid_RT6-Sep-07 7:33

Hamid_RT

6-Sep-07 7:33

Do you want to set some properties for a control?

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

abiemann6-Sep-07 7:39

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

6-Sep-07 7:39

No the properties won't change, but I'm calling quite a lot of RedrawWindow methods for the controls on the Dialog and I'm noticing that the bigger the controls, and the more there are, the more flicker I'm seeing.

Waldermort6-Sep-07 9:31

Waldermort

6-Sep-07 9:31

did you try the WS_CLIP_CHILDREN flag? This alone would reduce a hell of a lot of flicker.

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

Mark Salsbery6-Sep-07 9:45

Re: Is there an equivalent to SuspendLayout/ResumeLayout for a MFC Dialog ?

6-Sep-07 9:45

Good point! For whatever reason, when I see bitmap background code
I think skin, transparent controls, etc. For normal controls WS_CLIPCHILDREN
will work great! Smile | :)

Cheers,
Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

abiemann7-Sep-07 11:03

7-Sep-07 11:03

I've tried the following within ::OnInitDialog()

this->ModifyStyle(0, WS_CLIPCHILDREN);

but then nothing in the Dialog updates

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6-Sep-07 6:05

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