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  • IViewObject Interface

    IViewObject Interface

     

    IID_IViewObject

    {0000010D-0000-0000-C000-000000000046}

     

     

    The 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.

     

    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.

     

     

    Methods in VTable order

    IUnknown Methods

    Description

    QueryInterface

    Returns pointers to supported interfaces.

    AddRef

    Increments reference count.

    Release

    Decrements reference count.

    IViewObject Methods

    Description

    Draw

    Draws a representation of the object onto a device context.

    GetColorSet

    Returns the logical palette the object uses for drawing.

    Freeze

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

    Unfreeze

    Unfreezes the drawn representation of an object.

    SetAdvise

    Sets up a connection between the view object and an advise sink so that the advise sink can receive notifications of changes in the view object.

    GetAdvise

    Returns the information on the most recent SetAdvise.

    出处:http://www.com.it-berater.org/COM/ole_and_data_transfer/interfaces/IViewObject.htm
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  • 原文地址:https://www.cnblogs.com/Chinasf/p/605697.html
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