| Microsoft DirectX 9.0 |
The Blt method performs a bit block transfer. This method is capable of synchronous or asynchronous blits, either video memory to video memory, video memory to system memory, system memory to video memory, or system memory to system memory. The blits can be performed using z information, alpha information, source color keys and destination color keys. Arbitrary stretching/shrinking will be performed if the source and destination rectangles are not the same size.
Normally, Blt will return immediately with an error if the blitter is busy and the blit could not be set up. The DDBLT_WAIT flag can be used to alter this behavior such that Blt will wait until the blit can be set up, or another error occurs, before returning.
Syntax
HRESULT Blt(
LPRECT lpDestRect,
LPDIRECTDRAWSURFACE lpDDSrcSurface,
LPRECT lpSrcRect,
DWORD dwFlags,
LPDDBLTFX lpDDBltFX
);
Parameters
lpDestRect
Points to a RECT structure that defines the upper left and lower right points of the rectangle on the destination surface which is to be blted to.
lpDDSrcSurface
Points to the IDirectDrawSurface interface of the DirectDrawSurface object. This is the source for the blit operation.
lpSrcRect
Points to a RECT structure that defines the upper left and lower right points of the rectangle on the source surface which is to be blted from.
dwFlags
Zero or more of the following values.
| Value | Description |
| DDBLT_ALPHADEST | Use the alpha information in the pixel format or the alpha channel surface attached to the destination surface as the alpha channel for this blit. |
| DDBLT_ALPHADESTCONSTOVERRIDE | Use the dwConstAlphaDest member in the DDBLTFX structure as the alpha channel for the destination surface for this blit. |
| DDBLT_ALPHADESTNEG | The NEG suffix indicates that the destination surface becomes more transparent as the alpha value increases. (0 is opaque) |
| DDBLT_ALPHADESTSURFACEOVERRIDE | Use the lpDDSAlphaDest member in the DDBLTFX structure as the alpha channel for the destination for this blit. |
| DDBLT_ALPHAEDGEBLEND | Use the dwAlphaEdgeBlend member in the DDBLTFX structure as the alpha channel for the edges of the image that border the color key colors. |
| DDBLT_ALPHASRC | Use the alpha information in the pixel format or the alpha channel surface attached to the source surface as the alpha channel for this blit. |
| DDBLT_ALPHASRCCONSTOVERRIDE | Use the dwConstAlphaSrc member in the DDBLTFX structure as the alpha channel for the source for this blit. |
| DDBLT_ALPHASRCNEG | The NEG suffix indicates that the source surface becomes more transparent as the alpha value increases. (0 is opaque) |
| DDBLT_ALPHASRCSURFACEOVERRIDE | Use the lpDDSAlphaSrc member in the DDBLTFX structure as the alpha channel for the source for this blit. |
| DDBLT_ASYNC | Do this blit asynchronously through the FIFO in the order received. If there is no room in the hardware FIFO fail the call. |
| DDBLT_COLORFILL | Uses the dwFillColor member in the DDBLTFX structure as the RGB color to fill the destination rectangle on the destination surface. |
| DDBLT_DDFX | Uses the dwDDFX member in the DDBLTFX structure to specify the effects to use for the blit. |
| DDBLT_DDROPS | Uses the dwDDROPS member in the DDBLTFX structure to specify the ROPS that are not part of the Win32 API. |
| DDBLT_KEYDEST | Use the color key associated with the destination surface. |
| DDBLT_KEYDESTOVERRIDE | Use the dckDestColorkey member in the DDBLTFX structure as the color key for the destination surface. |
| DDBLT_KEYSRC | Use the color key associated with the source surface. |
| DDBLT_KEYSRCOVERRIDE | Use the dckSrcColorkey member in the DDBLTFX structure as the color key for the source surface. |
| DDBLT_ROP | Use the dwROP member in the DDBLTFX structure for the raster operation for this blit. These ROPs are the same as the ones defined in the Win32 API. |
| DDBLT_ROTATIONANGLE | Use the dwRotationAngle member in the DDBLTFX structure as the angle (specified in 1/100th of a degree) to rotate the surface. |
| DDBLT_WAIT | Do not return immediately with the DDERR_WASSTILLDRAWING message if the bltter is busy -- wait until the blit can be set up or another error occurs. |
| DDBLT_ZBUFFER | Z-buffered blit using the z-buffers attached to the source and destination surfaces and the dwZBufferOpCode member in the DDBLTFX structure as the z-buffer opcode. |
| DDBLT_ZBUFFERDESTCONSTOVERRIDE | Z-buffered blit using the dwConstDest member and the dwZBufferOpCode member in the DDBLTFX structure as the z-buffer and z-buffer opcode respectively for the destination. |
| DDBLT_ZBUFFERDESTOVERRIDE | Z-buffered blit using the lpDDSDestZBuffer member and the dwZBufferOpCode member in the DDBLTFX structure as the z-buffer and z-buffer opcode respectively for the destination. |
| DDBLT_ZBUFFERSRCCONSTOVERRIDE | Z-buffered blit using the dwConstSrcZ member and the dwZBufferOpCode member in the DDBLTFX structure as the z-buffer and z-buffer opcode respectively for the source. |
| DDBLT_ZBUFFERSRCOVERRIDE | Z-buffered blit using the lpDDSSrcZBuffer member and the dwZBufferOpCode member in the DDBLTFX structure as the z-buffer and z-buffer opcode respectively for the source. |
lpDDBltFx
Pointer to a DDBLTFX structure
Return Values
| Value | Description |
| DD_OK | The method succeeded. |
| DDERR_GENERIC | Generic failure. |
| DDERR_INVALIDCLIPLIST | DirectDraw does not support the provided clip list. |
| DDERR_INVALIDOBJECT | DirectDraw received a pointer that was an invalid DirectDraw object. |
| DDERR_INVALIDPARAMS | One or more of the input parameters is invalid. |
| DDERR_INVALIDRECT | Rectangle provided was invalid. |
| DDERR_NOALPHAHW | Operation could not be carried out because there is no alpha accleration hardware present or available. |
| DDERR_NOBLTHW | No blitter hardware present. |
| DDERR_NOCLIPLIST | No clip list available. |
| DDERR_NODDROPSHW | No DirectDraw ROP hardware. |
| DDERR_SURFACELOST | Access to this surface is being refused because the surface memory is gone. The DirectDrawSurface object representing this surface should have Restore called on it. |
| DDERR_UNSUPPORTED | Action not supported. |
| DDERR_NOMIRRORHW | Operation could not be carried out because there is no hardware present or available. |
| DDERR_NORASTEROPHW | Operation could not be carried out because there is no appropriate raster op hardware present or available. |
| DDERR_NOROTATIONHW | Operation could not be carried out because there is no rotation hardware present or available. |
| DDERR_NOSTRETCHHW | Operation could not be carried out because there is no hardware support for stretching. |
| DDERR_SURFACEBUSY | Access to this surface is being refused because the surface is already locked by another thread. |
| DDERR_NOZBUFFERHW | Operation could not be carried out because there is no hardware support for z-buffer blitting. |
See Also