using BitBlt for preview DC

[Hamid Taebi]

Flicker free drawing without using double buffer[^] GDI Topics: Flicker-Free Drawing[^] Flicker free drawing using memory DC[^].

Of one Essence is the human race thus has Creation put the base One Limb impacted is sufficient For all Others to feel the Mace (Saadi )

[_T No name]

i think u didnt get me.. i have used memDC fot flicker free drwaing but it does not work in case PrintPreview. I have used BitBlt for copying from memDC to pDC. But not in case of print preivw. if i do drawing does not come properly. i think there is some problem with BitBlt in case of preview DC. thanks

[Code o mat]

What exactly do you mean by

_T("No name") wrote:

drawing does not come properly

? Maybe put up some code or -don't know if it is possible or allowed or a nice thing to do- screenshots or maybe links to screenshots for us to see what you mean.

> The problem with computers is that they do what you tell them to do and not what you want them to do. < > Life: great graphics, but the gameplay sux. <

[Nishad S]

_T("No name") wrote:

my drawing coming distorted

What you meant by distorted? You may try SetStretchBltMode, with HALFTONE, then use StretchBlt. (If my guess is correct... :) )

- ns -

[_T No name]

void CCalendarControlView::DrawOnDC(CDC * pDC, int isPrinting) { if (pDC->IsKindOf(RUNTIME_CLASS(CPreviewDC))) { memDC.CreateCompatibleDC(pDC); bmp.CreateCompatibleBitmap(pDC, rc.Width(),rc.height()); memDC.SelectObject(&bmp); pMemDC = &memDC; } //Now m doing some drawing on pMemDc and at last after drawing for display pDC->BitBlt(0,0,rc.Width(),rc.Height(),pMemDC,SRCCOPY); } and onPrintPreviewButtton() { AFXPrintPreview(this); } m doing this getting correct drawig in case of niormal display but not in case or print preivew.

[_T No name]

i tried this also this didnt help. i have uploaded the code i think this will help u thx

[Code o mat]

Explain what your print preview looks like. You could try using SetAttribDC[^] or SetOutputDC[^], but without seeing your results i am just guessing around.

> The problem with computers is that they do what you tell them to do and not what you want them to do. < > Life: great graphics, but the gameplay sux. <

[_T No name]

i was getting some thing earlier. but now with the code i have given u m nt getting nything. on Print preview it just comes while page. did u got the code write in that code i have just written the case of preview DC thanx

[Code o mat]

Pardon?

> The problem with computers is that they do what you tell them to do and not what you want them to do. < > Life: great graphics, but the gameplay sux. <

[_T No name]

did u get the code i have pasted. i m nt getting wt u have understood and wt u didnt. void CCalendarControlView::OnFilePrintPreview() { AFXPrintPreview(this); } CRect rc = rcClient; void CCalendarControlView::DrawOnDC(CDC * pDC, int isPrinting) { memDC.CreateCompatibleDC(pDC); bmp.CreateCompatibleBitmap(pDC, rc.Width(), rc.Height()); memDC.SelectObject(&bmp); pMemDC = &memDC; } //Now drawinf something on pMemDC //Now BitBlt pDC->BitBlt(0, 0, rc.Width(), rc.Height(), pMemDC, 0, 0, SRCCOPY); this works fine in case of display in window but nuthing comes on OnFilePrintPreview() if ny prob in getting code please let me knw.. thanx for ur effort

[Code o mat]

Google doesn't bring up much for AFXPrintPreview, and i don't know it. Are you sure your drawing code gets called when you call that AFXPrintPreview method?

> The problem with computers is that they do what you tell them to do and not what you want them to do. < > Life: great graphics, but the gameplay sux. <

[_T No name]

ya i m sure as it works perfectly in case i do not use memery dc in case of print preview and directly do the drawing on display dc. actually it is given in mfc itself all the code DoPrintPreview and CPrintDialog etc code has been written and these functions is being called. if it works in case display dc i dnt knw why it doesnt work in case of memory dc and copying to display dc thanks for ur effort.

[Code o mat]

Your problem might be the rectangle you use for the drawing. Could it be that your buffer bitmap does not get the right size? Also, doing a print preview isn't exactly the same as drawing on the screen, as far as i know, since printers have different page sizes, DPIs, whatevers, if i were you i would try experimenting with that SetAttribDC[^], try doing MemDC.SetAttribDC(pDC) before you start drawing and MemDC.ReleaseAttribDC()[^] afterwards and see if anything changes.

> The problem with computers is that they do what you tell them to do and not what you want them to do. < > Life: great graphics, but the gameplay sux. <

[_T No name]

well i did that also but that didnt help. even wt u r telling can be a case but how to get correct size i just have the info that in case if print preview the pDC i get in OnDraw() is the one with m_bPrinting = 1 means its a printer dc. it might be due to AFXPrintPreview() it runs some code written in mfc itself in viewcore.cpp viewprev.cpp. u might have these files also if u have latest visual studio at C:\Program Files\Microsoft Visual Studio 9.0\VC\atlmfc\src\mfc ny idea how can i check the size m passing to buffer dc is correct or not thanks

[Code o mat]

Try using CDC::GetDeviceCaps[^], giving it maybe HORZRES and VERTRES or so to get the size of the DC's surface, or maybe HORZSIZE and VERTSIZE. Just note something, when using printer DC's, the size of the surface might be HUGE. Actually, do you really need to draw your print preview on a buffer?

> The problem with computers is that they do what you tell them to do and not what you want them to do. < > Life: great graphics, but the gameplay sux. <

[_T No name]

i have did this. even though prob is same nothing is coming. i have to use buffer as there is so much flicering comin in print preview window as resizing and all due to direct drawing on display dc. if (pDC->IsKindOf(RUNTIME_CLASS(CPreviewDC))) { //using buffer and copying from mem DC to preview DC causes problem. so //we directly draw on preview DC during preview. memDC.CreateCompatibleDC(pDC); bmp.CreateCompatibleBitmap(pDC, pDC->GetDeviceCaps(HORZRES), pDC->;GetDeviceCaps(VERTRES)); memDC.SelectObject(&bmp); memDC.SetAttribDC(pDC->;GetSafeHdc()); //pMemDC = pDC; pMemDC = &memDC; }

[Code o mat]

Does BitBlt succeed at all?

> The problem with computers is that they do what you tell them to do and not what you want them to do. < > Life: great graphics, but the gameplay sux. <

[_T No name]

yes it does in both the case (display and print preview) the rc i m passing to bitblt and CreateCompatibleBmp is of 6400 ,4900 i think this is the one u were talking abt so its correct right ?? in case of printing m already setting m_rcPrintrect as above size