Locks a rectangle on a surface.
HRESULT LockRect( [out] D3DLOCKED_RECT *pLockedRect, [in] const RECT *pRect, [in] DWORD Flags );
- pLockedRect [out]
Pointer to a D3DLOCKED_RECT structure that describes the locked region.
- pRect [in]
Type: const RECT*
Pointer to a rectangle to lock. Specified by a pointer to a RECT structure. Specifying NULL for this parameter expands the dirty region to cover the entire surface.
- Flags [in]
Combination of zero or more locking flags that describe the type of lock to perform. For this method, the valid flags are:
You may not specify a subrect when using D3DLOCK_DISCARD. For a description of the flags, see D3DLOCK.
If the method succeeds, the return value is D3D_OK.
If the method fails, the return value can be D3DERR_INVALIDCALL or D3DERR_WASSTILLDRAWING.
If the D3DLOCK_DONOTWAIT flag is specified and the driver cannot lock the surface immediately, IDirect3DSurface9::LockRect will return D3DERR_WASSTILLDRAWING so that an application can use the CPU cycles while waiting for the driver to lock the surface.
The only lockable format for a depth-stencil surface is D3DFMT_D16_LOCKABLE. See D3DFORMAT.
For performance reasons, dirty regions are recorded only for level zero of a texture. Dirty regions are automatically recorded when IDirect3DSurface9::LockRect is called without D3DLOCK_NO_DIRTY_UPDATE or D3DLOCK_READONLY. See IDirect3DDevice9::UpdateTexture for more information.
A multisample back buffer cannot be locked.
This method cannot retrieve data from a surface that is is contained by a texture resource created with D3DUSAGE_RENDERTARGET because such a texture must be assigned to D3DPOOL_DEFAULT memory and is therefore not lockable. In this case, use instead IDirect3DDevice9::GetRenderTargetData to copy texture data from device memory to system memory.