双缓冲不好用，请各位大侠帮忙

[kg200704]

我把文字首先描画到双缓冲的屏外位图上，然后再将该位图描画到屏幕上，但是屏幕上显示一片空白，不知道是怎么回事，以下是我的代码，请各位帮帮忙，谢谢！！

CFbsBitmap* iOffScrnBmp;
CFbsBitmapDevice* iOffScrnBmpDevice;
CFbsBitGc* iOffScrnContext;

iOffScrnBmp = new (ELeave) CFbsBitmap;
User::LeaveIfError(iOffScrnBmp->Create(Size(), EColor4K));

iOffScrnBmpDevice = CFbsBitmapDevice::NewL(iOffScrnBmp);
User::LeaveIfError(iOffScrnBmpDevice->CreateContext(iOffScrnContext));

void MyContainer::Draw(const TRect& aRect) const
{
//clear buffer
iOffScrnContext->Clear(Rect());

//draw something in the buffer
iOffScrnContext->SetPenStyle(CGraphicsContext::ESolidPen);
iOffScrnContext->SetPenColor(TRgb(0x266D03));
iOffScrnContext->UseFont(CEikonEnv::Static()->SymbolFont());

iOffScrnContext->DrawText(_L("we had joy we had fun we had seasons in the sun"));
iOffScrnContext->DiscardFont();

//draw bitmap to screen
iOffScrnContext->BitBlt(TPoint(0, 0), iOffScrnBmp);
}

[lspo816]

http://discussion.forum.nokia.com/forum/showthread.php?t=85386

Hope this can help

[Atoric]

Try
iFbsBitGc = CFbsBitGc::NewL(); //graphic context
iBmpDevice = CFbsBitmapDevice::NewL(iOffScreenBitmap);
iFbsBitGc->Activate(iBmpDevice);
iFbsBitGc->SetBrushColor( KRgbBlack );
iFbsBitGc->Clear();

[Atoric]

好像，你的Bitblt不是在屏幕上绘图，而是在离屏环境下绘图吧

[kg200704]

还是有问题，画不上去。不过还是要谢谢楼上的指点。

[knowledge_Is_Life]

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[meiZiNick]

什么呀