通过

OleDraw

  • 项目

This helper function provides a convenient way to draw objects by encapsulating the IViewObject::Draw method and other related maintenance functions for the drawing rectangle.

WINOLEAPI OleDraw(
  IUnknown* pUnk, 
  DWORD dwAspect, 
  HDC hdcDraw, 
  LPCRECT lprcBounds
);

Parameters

  • pUnk
    [in] Pointer to the IUnknown interface on the view object that is to be drawn.
  • dwAspect
    [in] Specifies how the object is to be represented. Representations include content, an icon, a thumbnail, or a printed document. Valid values are taken from the enumeration DVASPECT. See DVASPECT for more information.
  • hdcDraw
    [in] Handle to the device context (DC) on which to draw. Cannot be a metafile device context.
  • lprcBounds
    [in] Long pointer to a RECT structure specifying the rectangle in which the object should be drawn. This parameter is converted to a RECTL structure and passed to IViewObject::Draw.

Return Values

The following table shows the HRESULT values that can be returned by this function.

Value Description
S_OK Object was successfully drawn.
OLE_E_BLANK No data to draw from.
E_ABORT The draw operation was aborted.
VIEW_E_DRAW An error occurred in drawing.
OLE_E_INVALIDRECT The rectangle is invalid.
DV_E_NOIVIEWOBJECT The object does not support the IViewObject interface.
E_INVALIDARG The function has failed.
E_OUTOFMEMORY The function has failed.

Remarks

Passing into this function any invalid and, under some circumstances, NULL pointers will result in unexpected termination of the application.

The OleDraw helper function calls the QueryInterface method for the object specified (pUnk), asking for an IViewObject interface on that object. Then, OleDraw converts the RECT structure to a RECTL structure, and calls IViewObject::Draw as follows.

lpViewObj->Draw(dwAspect,-1,0,0,0,hdcDraw,&rectl,0,0,0);

Do not use OleDraw to draw into a metafile because it does not specify the lprcWBounds parameter required for drawing into metafiles.

To determine whether the platform supports this function, see Determining Supported COM APIs.

Requirements

OS Versions: Windows CE 2.0 and later.
Header: Ole2.h.
Link Library: Ole32.lib.

See Also

IViewObject::Draw | DVASPECT | RECTL | IUnknown | DVASPECT | RECT | IViewObject | QueryInterface | Determining Supported COM APIs

Last updated on Wednesday, April 13, 2005

© 2005 Microsoft Corporation. All rights reserved.