Re: Background image becomes dark after adding watermark, need help.

From:

"Jeff Partch" <jeffp@mvps.org>

Newsgroups:

microsoft.public.vc.mfc

Date:

Sun, 4 May 2008 07:31:48 -0500

Message-ID:

<OmdwULerIHA.2520@TK2MSFTNGP02.phx.gbl>

I think the specific problem you're asking about is a result of your
function never copying the original bitmap to the new bitmap, but you really
need to rethink the whole thing: there's no parameter validation, no error
checking, hard-wired coordinates, failures to deselect objects, and what
seems to me to be a misguided division of responsibilities. And those calls
to DeleteDC at the end imply that you have never even glanced at the
documentation.

--
Jeff Partch

"beginnercsharp" <huzhou1238@yahoo.com.cn> wrote in message
news:83629459-f956-4295-92e6-0618cdcc0ffb@b5g2000pri.googlegroups.com...

I want to add text on bitmap,the following is the implementation.
After adding text watermark, I find text watermark is added on the
bitmap, while the bitmap is complete dark.The bitmap I used is not a
dark image. That is to say,generating bitmap only contain
watermark,not including original bitmap information.I still don't find
the bug to the function and do hope someone could give me some
clues,thanks in advance.

//pBitmap: the original bitmap
//BitmapNew: the bitmap created after processed the original bitmap
//iSize: text font size
//strText: text stuff
//color: text color
void AddTextWatermark(CBitmap *pBitmap,CBitmap &BitmapNew,int
iSize,LPCSTR strText,COLORREF color)
{
CDC dcSrc,dcDst ;
       int nWidth, nHeight ;

       BITMAP pBitMap ;
       pBitmap->GetBitmap(&pBitMap) ;

//FONT
CFont textFont;
textFont.CreatePointFont(iSize,strText);

       nWidthOld = pBitMap.bmWidth ;
       nHeightOld = pBitMap.bmHeight ;

        // Create DC
       dcSrc.CreateCompatibleDC((CDC*)NULL);
       dcDst.CreateCompatibleDC((CDC*)NULL);

       // Source Bitmap
       dcSrc.SelectObject(pBitmap);

       // New Bitmap
       BitmapNew.CreateCompatibleBitmap(&dcSrc,nWidth,nHeight);

       // add watermarker on Bitmap
       dcDst.SelectObject(&BitmapNew);
dcDst.SelectObject(&textFont);
dcDst.SetTextColor(color);
dcDst.SetBkMode(TRANSPARENT);
dcDst.TextOut(70,8,strText); //Position:(10,15)

       // Free Resource
      dcSrc.DeleteDC() ;
      dcDst.DeleteDC() ;
}