grayscale_fadein.shtml

mfc资源大全包含MFC编程各个方面的源码

					((peGray[j].peBlue -peOriginal[j].peBlue)*i)/nLoops;
			}

			// Draw the image again
			::SetDIBitsToDevice(pDC->m_hDC, xDest, yDest, nWidth, nHeight, 0, 
				0, 0, nHeight, lpDIBBits, (LPBITMAPINFO)hDIB, 
				DIB_RGB_COLORS);

			// Delay...
			Sleep(nDelay);
		}
	}
	else
	{
		// Any other scenario, simply draw the image 
		LPVOID lpDIBBits = (LPVOID)(bmInfo.bmiColors + nColors);
		::SetDIBitsToDevice(pDC->m_hDC, xDest, yDest, nWidth, nHeight, 0, 0, 0,
			nHeight, lpDIBBits, (LPBITMAPINFO)hDIB, DIB_RGB_COLORS);
	}
}
</FONT></TT></PRE>

<h4>Function 2: Fade from color to grayscale</h4>
The FadeColorToGrayScale () draws the device-independent bitmap (DIB) onto the device context as a full color image and then slowly changes it to a grayscale image. Since this function starts by drawing the image with a color palette it doesn't have to worry about two very different colors getting mapped to the same color as can happen if we start with a grayscale palette instead. This, of course, applies only displays that support a palette.


<PRE><TT><FONT COLOR="#990000">
// FadeColorToGrayScale	- Draws a bitmap in color slowly turns it to grayscale
// pDC				- Pointer to target device context
// hDIB				- Handle of device-independent bitmap
// xDest			- x-coordinate of upper-left corner of dest. rect. 
// yDest			- y-coordinate of upper-left corner of dest. rect. 
// nLoops			- How many loops to fade the image into color
// nDelay			- Delay in milli-seconds between each loop
//
void FadeColorToGrayScale( CDC *pDC, HANDLE hDIB, int xDest, int yDest, int nLoops, 
									int nDelay ) 
{
	CPalette pal;
	CPalette *pOldPalette;
	PALETTEENTRY peAnimate[256];
	PALETTEENTRY peGray[256];
	PALETTEENTRY peOriginal[256];

	BITMAPINFO &bmInfo = *(LPBITMAPINFO)hDIB ;
	
	int nColors = bmInfo.bmiHeader.biClrUsed ? bmInfo.bmiHeader.biClrUsed : 
					1 << bmInfo.bmiHeader.biBitCount;
	
	int nReservedColors = nColors > 236 ? 236 : nReservedColors;
	int nWidth = bmInfo.bmiHeader.biWidth;
	int nHeight = bmInfo.bmiHeader.biHeight;

	// Create the palette if needed
	if( pDC->GetDeviceCaps(RASTERCAPS) & RC_PALETTE && nColors <= 256 )
	{
		// The device supports a palette and bitmap has color table
		
		HPALETTE hPal = CreateReservedPalette(hDIB);
		pal.Attach( hPal );

		// Now save the original colors and get the grayscale colors
		pal.GetPaletteEntries(0, nReservedColors, (LPPALETTEENTRY)&peOriginal);
		for( int i=0; i < nReservedColors; i++)
		{
			long lSquareSum = peOriginal[i].peRed 
						* peOriginal[i].peRed
						+ peOriginal[i].peGreen 
						* peOriginal[i].peGreen
						+ peOriginal[i].peBlue 
						* peOriginal[i].peBlue;
			int nGray = (int)sqrt(((double)lSquareSum)/3);
			
			peGray[i].peRed = nGray;
			peGray[i].peGreen = nGray;
			peGray[i].peBlue = nGray;
		}


		
		// Select the palette
		pOldPalette = pDC->SelectPalette(&pal, FALSE);
		pDC->RealizePalette();

		// Draw the image 
		LPVOID lpDIBBits = (LPVOID)(bmInfo.bmiColors + nColors);
		
		::SetDIBitsToDevice(pDC->m_hDC, xDest, yDest, nWidth, nHeight, 0, 0, 0,
			nHeight, lpDIBBits, (LPBITMAPINFO)hDIB, DIB_RGB_COLORS);

		// Now animate palette to set the image to grayscale
		for( i=1; i <= nLoops; i++ )
		{
			for (int j = 0; j< nColors; j++) 
			{  
				peAnimate[j].peRed = peOriginal[j].peRed - 
					((peOriginal[j].peRed -peGray[j].peRed)*i)/nLoops;
				peAnimate[j].peGreen = peOriginal[j].peGreen - 
					((peOriginal[j].peGreen-peGray[j].peGreen)*i)
						/nLoops;
				peAnimate[j].peBlue = peOriginal[j].peBlue  - 
					((peOriginal[j].peBlue -peGray[j].peBlue)*i)/nLoops;

				peAnimate[j].peFlags = peOriginal[j].peFlags;
			}

			pal.AnimatePalette(0, nColors, (LPPALETTEENTRY)&peAnimate);

			// Delay...
			Sleep(nDelay);
		}

		// Select the old palette back
		pDC->SelectPalette(pOldPalette, FALSE);
	}
	else if( (pDC->GetDeviceCaps(RASTERCAPS) & RC_PALETTE) == 0 && nColors <= 256 )
	{
		// Device does not supports palettes but bitmap has a color table
		// Modify the bitmaps color table directly

		// Get the original colors and the grayscale colors
		for( int i=0; i < nColors; i++)
		{
			// First save original colors
			peOriginal[i].peRed =   bmInfo.bmiColors[i].rgbRed ;
			peOriginal[i].peGreen = bmInfo.bmiColors[i].rgbGreen;
			peOriginal[i].peBlue =  bmInfo.bmiColors[i].rgbBlue ;

			long lSquareSum = bmInfo.bmiColors[i].rgbRed 
							* bmInfo.bmiColors[i].rgbRed
							+ bmInfo.bmiColors[i].rgbGreen 
							* bmInfo.bmiColors[i].rgbGreen
							+ bmInfo.bmiColors[i].rgbBlue 
							* bmInfo.bmiColors[i].rgbBlue;
			int nGray = (int)sqrt(((double)lSquareSum)/3);

			// Create a reference color table
			peGray[i].peRed = nGray;
			peGray[i].peGreen = nGray;
			peGray[i].peBlue = nGray;

		}

		// Let's draw the color image
		LPVOID lpDIBBits = (LPVOID)(bmInfo.bmiColors + nColors);
		::SetDIBitsToDevice(pDC->m_hDC, xDest, yDest, nWidth, nHeight, 0, 0, 0,
				nHeight, lpDIBBits, (LPBITMAPINFO)hDIB, DIB_RGB_COLORS);

		// Now change the image to grayscale
		for( i=1; i <= nLoops; i++ )
		{
			for (int j = 0; j< nColors; j++) 
			{  
				bmInfo.bmiColors[j].rgbRed   = peOriginal[j].peRed  - 
					((peOriginal[j].peRed -peGray[j].peRed)*i)/nLoops;
				bmInfo.bmiColors[j].rgbGreen = peOriginal[j].peGreen - 
					((peOriginal[j].peGreen-peGray[j].peGreen)*i)/
						nLoops;
				bmInfo.bmiColors[j].rgbBlue  = peOriginal[j].peBlue  - 
					((peOriginal[j].peBlue -peGray[j].peBlue)*i)/nLoops;
			}

			// Draw the image again
			::SetDIBitsToDevice(pDC->m_hDC, xDest, yDest, nWidth, nHeight, 0, 
				0, 0, nHeight, lpDIBBits, (LPBITMAPINFO)hDIB, 
				DIB_RGB_COLORS);

			// Delay...
			Sleep(nDelay);
		}
	}
	else
	{
		// Any other scenario, simply draw the image 
		LPVOID lpDIBBits = (LPVOID)(bmInfo.bmiColors + nColors);
		::SetDIBitsToDevice(pDC->m_hDC, xDest, yDest, nWidth, nHeight, 0, 0, 0,
			nHeight, lpDIBBits, (LPBITMAPINFO)hDIB, DIB_RGB_COLORS);
	}
}
</FONT></TT></PRE>


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