Direct X 9.0 Color Spectrum?

[RogerThat123]

I have hooked endscene and I need to draw it here, my end scene is overriding a game call of duty 5 endscene. So I am drawing over it.

How would I go about creating a nice color spectrum such as

HRESULT APIENTRY my_EndScene( LPDIRECT3DDEVICE9 pDevice )
{
  //DRAW COLOR SPECTRUM HERE
}

I know how to draw it pixel by pixel, but that takes forever and it also slows down your frames per second very very much. So I think there is a built in function to do this for you...

[Syslock]

I have hooked endscene and I need to draw it here, my end scene is overriding a game call of duty 5 endscene. So I am drawing over it.

How would I go about creating a nice color spectrum such as

HRESULT APIENTRY my_EndScene( LPDIRECT3DDEVICE9 pDevice )
{
  //DRAW COLOR SPECTRUM HERE
}

I know how to draw it pixel by pixel, but that takes forever and it also slows down your frames per second very very much. So I think there is a built in function to do this for you...

Well, if it takes a long time to do it, just generate it in Photoshop or wherever beforehand and load it as a texture instead.
And use a compressed format like DDS, or a lossy format like JPG, if the texture is large.