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Programming With the Mac OS 8.5 Window Manager

SetupWindowProxyDragImageRec

If you implement a custom window definition function, when the function TrackWindowProxyDrag is called, the Window Manager passes the message kWindowMsgSetupProxyDragImage in your window definition function's message parameter and passes a pointer to a structure of type SetupWindowProxyDragImageRec in the param parameter. Your window definition function is responsible for setting the contents of the SetupWindowProxyDragImageRec structure to contain data describing the proxy icon's drag image.

See Window Definition Message Constants and Window Definition Feature Constants for more details on the kWindowMsgSetupProxyDragImage message and the corresponding kWindowCanSetupProxyDragImage feature flag.

struct SetupWindowProxyDragImageRec
{
    GWorldPtr imageGWorld;
    RgnHandle imageRgn;
    RgnHandle outlineRgn;
};
typedef struct SetupWindowProxyDragImageRec SetupWindowProxyDragImageRec;

Field descriptions

imageGWorld
A pointer to the offscreen graphics world containing the drag image. The window definition function must allocate the offscreen graphics world, since the Window Manager has no way of knowing the appropriate size for the drag image. The Window Manager disposes of the offscreen graphics world.
imageRgn
A handle to a region containing the drag image. Only this portion of the offscreen graphics world referred to by the imageGWorld field is actually drawn. The Window Manager allocates and disposes of this region.
outlineRgn
A handle to a region containing an outline of the drag image, for use on monitors incapable of displaying the drag image itself. The Window Manager allocates and disposes of this region.
© 1999 Apple Computer, Inc. – (Last Updated 18 March 99)