IDirect3DSurface9::LockRect method (d3d9helper.h)

Locks a rectangle on a surface.

Syntax

HRESULT LockRect(
  [out] D3DLOCKED_RECT *pLockedRect,
  [in]  const RECT     *pRect,
  [in]  DWORD          Flags
);

Parameters

[out] pLockedRect

Type: D3DLOCKED_RECT*

Pointer to a D3DLOCKED_RECT structure that describes the locked region.

[in] pRect

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.

[in] Flags

Type: DWORD

Combination of zero or more locking flags that describe the type of lock to perform. For this method, the valid flags are:

• D3DLOCK_DISCARD
• D3DLOCK_DONOTWAIT
• D3DLOCK_NO_DIRTY_UPDATE
• D3DLOCK_NOSYSLOCK
• D3DLOCK_READONLY

Return value

Type: HRESULT

If the method succeeds, the return value is D3D_OK.

If the method fails, the return value can be D3DERR_INVALIDCALL or D3DERR_WASSTILLDRAWING.

Remarks

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 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.

Requirements

See also

IDirect3DSurface9

IDirect3DSurface9::UnlockRect