注意其中的PowerOn()給相機上電
3.調用Observer的PowerOnComplete()函數通知系統上電完成
void CImageCapturerEngine::PowerOnComplete(TInt aError)
{
TInt err = aError;
if(aError == KErrNone)
{
TCameraInfo info;
iCamera->CameraInfo(info);
if ((info.iOptionsSupported&TCameraInfo::EContrastSupported)!=0)
{
TRAP(err, iCamera->SetContrastL(CCamera::EContrastAuto));
}

TRAP(err,StartViewFinderL());
if(err==KErrNone)
{
TRAP(err,PrepareImageCaptureL(KDefaultImageFormat));
}
}
if(err!=KErrNone)
{
iObserver.OnError(aError);
}
}
4.設置對比度，預覽圖像
void CImageCapturerEngine::ViewFinderFrameReady(CFbsBitmap& aFrame)
{
iObserver.OnFrame(aFrame);
}

5.準備捕捉圖像
void CImageCapturerEngine::ImageReady(CFbsBitmap* aBitmap,HBufC8* /*aData*/,TInt aError)
{
if(aError == KErrNone)
{
iObserver.OnImage(aBitmap);
}
else
{
iObserver.OnError(aError);
}
}

6.重要的函數：開始預覽圖像和停止預覽
void CImageCapturerEngine::StartViewFinderL()
{
TSize imageSize(KDefaultImageWidth,KDefaultImageHeight);

if(iCamera->ViewFinderActive())
{
// iObserver.OnError(KErrAlreadyActive)
}
else
{
iCamera->StartViewFinderBitmapsL(imageSize);
}
if(!iCamera->ViewFinderActive())
{
// iObserver.OnError(KErrNotActivated);
}
}

void CImageCapturerEngine::StopViewFinder()
{
iCamera->StopViewFinder();
}

7.捕捉圖像
void CImageCapturerEngine::CaptureImage()
{
iCamera->CaptureImage();
}

補充：
（1）iCamera->SetContrastL(CCamera::EContrastAuto));
EContrastAuto-自動設置
還可以設置-100到100之間的值