Creating Custom Object Snap Modes

Custom object snap modes allow the developer to set the following attributes:

• Keyword

  The custom object snap keyword that the user types in to activate the object snap. Both local and global keywords must be specified.

• Protocol extension class

  A pointer to the class that performs the per-entity processing of the object snap mode.

• Glyph

  The custom glyph for the object snap mode.

• ToolTip string

  The default ToolTip string for the custom object snap mode.

For more information on setting these attributes, see the ObjectARX Reference.

A custom object snap mode is defined by registering an instance of the AcDbCustomOsnapMode class with the custom object snap manager, described in the previous section.

When a custom object snap mode is used, AutoCAD ^® takes the class object returned by AcDbCustomOsnapMode::entityOsnapClass(), looks up the corresponding protocol extension object for the picked entity, and invokes AcDbCustomOsnapInfo::getOsnapInfo() to obtain the points or lines associated with that entity and object snap mode. If the final candidate point is associated with that object snap mode, AutoCAD displays the glyph object from the instance returned by AcDbCustomOsnapMode::glyph() and the ToolTip string returned by AcDbCustomOsnapMode::tooltipString().