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CImage::CreateEx 

Creates a CImage bitmap and attach it to the previously constructed CImage object.


BOOL CreateEx(
   int nWidth,
   int nHeight,
   int nBPP,
   DWORD eCompression,
   const DWORD* pdwBitmasks = NULL,
   DWORD dwFlags = 0 
) throw( );

Parameters

nWidth

The width of the CImage bitmap, in pixels.

nHeight

The height of the CImage bitmap, in pixels. If nHeight is positive, the bitmap is a bottom-up DIB and its origin is the lower left corner. If nHeight is negative, the bitmap is a top-down DIB and its origin is the upper left corner.

nBPP

The numbers of bits per pixel in the bitmap. Usually 4, 8, 16, 24, or 32. Can be 1 for monochrome bitmaps or masks.

eCompression

Specifies the type of compression for a compressed bottom-up bitmap (top-down DIBs cannot be compressed). Can be one of the following values:

  • BI_RGB   The format is uncompressed. Specifying this value when calling CImage::CreateEx is equivalent to calling CImage::Create.

  • BI_BITFIELDS   The format is uncompressed and the color table consists of three DWORD color masks that specify the red, green, and blue components, respectively, of each pixel. This is valid when used with 16- and 32-bpp bitmaps.

pdwBitfields

Only used if eCompression is set to BI_BITFIELDS, otherwise it must be NULL. A pointer to an array of three DWORD bitmasks, specifying which bits of each pixel are used for the red, green, and blue components of the color, respectively. For information on restrictions for the bitfields, see BITMAPINFOHEADER in the Platform SDK.

dwFlags

Specifies if the bitmap object has an alpha channel. Can be a combination of zero or more of the following values:

  • createAlphaChannel   Can only be used if nBPP is 32, and eCompression is BI_RGB. If specified, the created image has an alpha (transparency) value for each pixel, stored in the 4th byte of each pixel (unused in a non-alpha 32-bit image). This alpha channel is automatically used when calling CImage::AlphaBlend.

    NoteNote

    In calls to CImage::Draw, images with an alpha channel are automatically alpha blended to the destination.

TRUE if successful. Otherwise FALSE.

The following example creates a 100x100 pixel bitmap, using 16 bits to encode each pixel. In a given 16-bit pixel, bits 0-3 encode the red component, bits 4-7 encode green, and bits 8-11 encode blue. The remaining 4 bits are unused.

DWORD adwBitmasks[3] = { 0x0000000f, 0x000000f0, 0x00000f00 };
image.CreateEx( 100, 100, 16, BI_BITFIELDS, adwBitmasks, 0 );

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