BOOL BitBlt(hDestDC,X,Y,nWidth,nHeight,hSrcDC,XSrc,YSrc,dwRop)
This function moves a bitmap from the source device given by the hSrcDC parameter to the destination device given by the hDestDC parameter. The XSrc and YSrc parameters specify the origin on the source device of the bitmap that is to be moved. The X, Y, nWidth, and nHeight parameters specify the origin, width, and height of the rectangle on the destination device that is to be filled by the bitmap. The dwRop parameter (raster operation) defines how the bits of the source and destination are combined.
| Parameter | Type/Description |
| hDestDC | HDC Identifies the device context that is to receive the bitmap. | |
| X | int Specifies the logical x-coordinate of the upper-left corner of the destination rectangle. | |
| Y | int Specifies the logical y-coordinate of the upper-left corner of the destination rectangle. | |
| nWidth | int Specifies the width (in logical units) of the destination rectangle and source bitmap. | |
| nHeight | int Specifies the height (in logical units) of the destination rectangle and source bitmap. | |
| hSrcDC | HDC Identifies the device context from which the bitmap will be copied. It must be NULL if the dwRop parameter specifies a raster operation that does not include a source. | |
| XSrc | int Specifies the logical x-coordinate of the upper-left corner of the source bitmap. | |
| YSrc | int Specifies the logical y-coordinate of the upper-left corner of the source bitmap. | |
| dwRop | DWORD Specifies the raster operation to be performed. Raster-operation codes define how the graphics device interface (GDI) combines colors in output operations that involve a current brush, a possible source bitmap, and a destination bitmap. For a list of raster-operation codes, see Table R.1, “Raster Operations.” |
The return value specifies whether the bitmap is drawn. It is nonzero if the bitmap is drawn. Otherwise, it is zero.
GDI transforms the nWidth and nHeight parameters, once by using the destination display context, and once by using the source display context. If the resulting extents do not match, GDI uses the StretchBlt function to compress or stretch the source bitmap as necessary. If destination, source, and pattern bitmaps do not have the same color format, the BitBlt function converts the source and pattern bitmaps to match the destination. The foreground and background colors of the destination are used in the conversion.
If BitBlt converts monochrome bitmaps to color, it sets white bits (1) to the background color and black bits (0) to the foreground color. The foreground and background colors of the destination device context are used. To convert color to monochrome, BitBlt sets pixels that match the background color to white (1), and sets all other pixels to black (0). The foreground and background colors of the color-source device context are used.
The foreground color is the current text color for the specified device context, and the background color is the current background color for the specified device context.
Not all devices support the BitBlt function. For more information, see the RC_BITBLT raster capability in the GetDeviceCaps function, later in this chapter.
Table R.1 lists the various raster-operation codes for the dwRop parameter:
Table R.1 Raster Operations
| Code | Description |
| BLACKNESS | Turns all output black. |
| DSTINVERT | Inverts the destination bitmap. |
| MERGECOPY | Combines the pattern and the source bitmap using the Boolean AND operator. |
| MERGEPAINT | Combines the inverted source bitmap with the destination bitmap using the Boolean OR operator. |
| NOTSRCCOPY | Copies the inverted source bitmap to the destination. |
| NOTSRCERASE | Inverts the result of combining the destination and source bitmaps using the Boolean OR operator. |
| PATCOPY | Copies the pattern to the destination bitmap. |
| PATINVERT | Combines the destination bitmap with the pattern using the Boolean XOR operator. |
| PATPAINT | Combines the inverted source bitmap with the pattern using the Boolean OR operator. Combines the result of this operation with the destination bitmap using the Boolean OR operator. |
| SRCAND | Combines pixels of the destination and source bitmaps using the Boolean AND operator. |
| SRCCOPY | Copies the source bitmap to the destination bitmap. |
| SRCERASE | Inverts the destination bitmap and combines the result with the source bitmap using the Boolean AND operator. |
| SRCINVERT | Combines pixels of the destination and source bitmaps using the Boolean XOR operator. |
| SRCPAINT | Combines pixels of the destination and source bitmaps using the Boolean OR operator. |
| WHITENESS | Turns all output white. |