Now ,I have a problem with d3d programming.I want to use d3d to display a image on the screeen.Although I have set the colorkey as 0xffff00ff, but the image is always in black box.
My code is as the following:

//set the render state

m_pD3dDevice->SetRenderState(D3DRS_ALPHABLENDENABLE,TRUE);
m_pD3dDevice->SetRenderState(D3DRS_SRCBLEND,D3DBLEND_SRCALPHA);
m_pD3dDevice->SetRenderState(D3DRS_DESTBLEND,D3DBLEND_INVSRCALPHA);

//create a surface and load the image

HRESULT hResult=D3DXGetImageInfoFromFile(imageFile,&imageInfo);
if(S_OK!=hResult)
return NULL;
hResult=m_pD3dDevice->CreateOffscreenPlainSurface(imageInfo.Width,
imageInfo.Height,D3DFMT_A8R8G8B8,D3DPOOL_DEFAULT,
&surface/*m_pSurface[m_nSurfaceUsed]*/,NULL);

if(S_OK!=hResult)
return NULL;
hResult=D3DXLoadSurfaceFromFile(surface/*m_pSurface[m_nSurfaceUsed]*/,NULL,NULL,
imageFile,NULL,D3DX_DEFAULT,colorKey,NULL); //i have sat the colorkey as 0xffff00ff
hResult=m_pD3dDevice->StretchRect(surface,res,m_pBackBuffer,dest,D3DTEXF_NONE);



i know that i can use another metohd to display this image ,such as IDXSprite,but i always want to know why my code doesnt work .
where is woring or the StretchRect function doesnt support the transprarency color ? anybody can help me?Thanks!

StretchRect() does a simple texture copy and ignores the alpha channel. You probably want to use ID3DXSprite to draw your image.

StretchRect() does a simple texture copy and ignores the alpha channel. You probably want to use ID3DXSprite to draw your image.

Thank you very much!I have considered it but not for sure.I just want to use a simple method and i think DirectDraw was in my mind.