IViewObjectEx::QueryHitRect method (ocidl.h)

Článek
10/13/2021

Indicates whether any point in a rectangle is within a given drawing aspect of an object.

Syntax

HRESULT QueryHitRect(
  [in]  DWORD   dwAspect,
  [in]  LPCRECT pRectBounds,
  [in]  LPCRECT pRectLoc,
  [in]  LONG    lCloseHint,
  [out] DWORD   *pHitResult
);

Parameters

[in] dwAspect

The requested drawing aspect.

[in] pRectBounds

An object bounding rectangle in client coordinates of the containing window. This rectangle is computed and passed by the container so that the object can meaningfully interpret the hit location.

[in] pRectLoc

The hit test rectangle, specified in HIMETRIC units, relative to the top-left corner of the object.

[in] lCloseHint

The suggested distance, in HIMETRIC units, that the container considers close. This value is a hint, and objects can interpret it in their own way. Objects can also use this hint to roughly infer output resolution to choose expansiveness of hit test implementation.

[out] pHitResult

A pointer to returned information about the hit expressed as the HITRESULT enumeration values.

Return value

This method returns S_OK on success. Other possible return values include the following.

Return code	Description
E_FAIL	This method is not implemented for the requested aspect. Use DVASPECT_CONTENT instead.

Remarks

Containers may need to test whether an object overlaps a given drawing aspect of another object. They can determine whether the objects overlap by requesting a region or at least a bounding rectangle of the aspect in question. However, a quicker way to do this is to call IViewObjectEx::QueryHitRect to ask the object whether a given rectangle intersects one of its drawing aspects.

Note Unlike IViewObjectEx::QueryHitPoint, this method does not return HITRESULT_TRANSPARENT or HITRESULT_CLOSE. It is strictly hit or miss, returning HITRESULT_OUTSIDE if no point in the rectangle is hit and HITRESULT_HIT if at least one point in the rectangle is a hit.

Notes to Implementers

An object supporting IViewObjectEx is required to implement this method at least for the DVASPECT_CONTENT aspect. The object should not take any other action in response to this method other than to return the information; there should be no side-effects. If there is any ambiguity about whether a point is a hit, for instance due to coordinates not converting exactly, the object should return HITRESULT_HIT whenever any point in the rectangle might be a hit on the object. That is, it is permissible to claim a hit for a point that is not actually rendered, but never correct to claim a miss for any point that is in the rendered image of the object.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	ocidl.h

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