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IViewObject interface

Enables an object to display itself directly without passing a data object to the caller. In addition, this interface can create and manage a connection with an advise sink so the caller can be notified of changes in the view object.

The caller can request specific representations and specific target devices. For example, a caller can ask for either an object's content or an iconic representation. Also, the caller can ask the object to compose a picture for a target device that is independent of the drawing device context. As a result, the picture can be composed for one target device and drawn on another device context. For example, to provide a print preview operation, you can compose the drawing for a printer target device but actually draw the representation on the display.

The IViewObject interface is similar to IDataObject; except that IViewObject places a representation of the data onto a device context while IDataObject places the representation onto a transfer medium.

Unlike most other interfaces, IViewObject cannot be marshaled to another process. This is because device contexts are only effective in the context of one process.

When to implement

Object handlers and in-process servers that manage their own presentations implement IViewObject for use by compound document containers. OLE provides an IViewObject implementation for its default object handler's cache.

When to use

You call IViewObject from a container application if you need to draw a contained object on a specific device context. For example, if you want to print the object to a printer, you call the Draw method in the IViewObject interface.

Members

The IViewObject interface inherits from the IUnknown interface. IViewObject also has these types of members:

Methods

The IViewObject interface has these methods.

MethodDescription
Draw

Draws a representation of the object onto the specified device context.

Freeze

Freezes the drawn representation of an object so that it will not change until a subsequent call to the Unfreeze method.

GetAdvise

Retrieves the advisory connection on the object that was used in the most recent call to SetAdvise.

GetColorSet

Retrieves the logical palette that the object is using for drawing.

SetAdvise

Establishes a connection between the view object and an advise sink so that the advise sink can be notified about changes in the object's view.

Unfreeze

Releases a drawing that was previously frozen using Freeze.

 

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

OleIdl.h

IDL

OleIdl.Idl

IID

IID_IViewObject is defined as 0000010d-0000-0000-C000-000000000046

 

 

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