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4/8/2010

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

Syntax 

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

Parameters

pUnk

[in] Pointer to the IUnknowninterface on the view object that is to be drawn.

dwAspect

[in] Specifies how the object is to be represented.

Representations include the following:

  • Content

  • An icon

  • A thumbnail

  • A printed document

Valid values are taken from the enumeration DVASPECT. For more information, see DVASPECT.

hdcDraw

[in] Handle to the device context (DC) on which to draw.

Cannot be a metafile device context.

lprcBounds

[in] Long pointer to a RECTstructure specifying the rectangle where the object should be drawn.

This parameter is converted to a RECTLstructure and passed to IViewObject::Draw.

Return Value

The following HRESULT values can be returned.

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 IViewObjectinterface.

E_INVALIDARG

The function has failed.

E_OUTOFMEMORY

The function has failed.

Remarks

Passing invalid (and under some circumstances NULL) pointers into this function causes an unexpected termination of the application.

The OleDrawhelper function calls the QueryInterfacemethod for the object specified ( pUnk), asking for an IViewObjectinterface on that object. Then, OleDrawconverts the RECTstructure to a RECTLstructure, and calls IViewObject::Drawas follows.

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

Do not use OleDrawto draw into a metafile because it does not specify the lprcWBoundsparameter required for drawing into metafiles.

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

Requirements

Header ole2.h
Library ole32.lib
Windows Embedded CE Windows CE 2.0 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also