September 30, 2013

ActiveX and AutoLISP Programming Tip 2

In this previous post, I provided the code for getting the AecArchBaseApplication object. This object provides access to a number of values that I previously obtained through DXF access to the dictionaries (which is no longer exposed). Assuming that you have saved the AecArchBaseApplication object to a variable called archBaseApp, the following code examples show how to obtain the noted objects and values:
;;; To get values from the currently active document, you need to get that
;;; object, which is stored in a property of the AecArchBaseApplication:
(setq docActive (vlax-get-property appAecArchBase 'ActiveDocument))

;;; With the active document in hand, you can get the AecArchBase 
;;; Preferences object:
(setq objAecArchBasePref
        (vlax-get-property docActive-AecArchBase 'Preferences)

;;; The AecArchBase Preferences object contains a number of values of
;;; interest, including those shown below.

;;; Model "tab" drawing scale:
(vlax-get-property objAecArchBasePref 'DatabaseScale)

;;; The auto-import Layer Standards/Layer Key Style file:
(vlax-get-property objAecArchBasePref 'LayerFile)

;;; The currently active Layer Key Style:
(vlax-get-property objAecArchBasePref 'LayerStandard)
;;; Yes, the property is named "LayerStandard", but the value stored
;;; is the current Layer Key Style, not the associated Layer Standard.

;;; The annotation plot size:
(vlax-get-property objAecArchBasePref 'TextHeight)

;;; Whether or not a DIMSCALE override is automatically created
;;; when you change scales and the current dimension style is not
;;; annnotative:
(vlax-get-property objAecArchBasePref 'CreateDimscaleOverride)

;;; The various units settings can be accessed through the Preferences
;;; object also, such as the current linear unit:
(vlax-get-property objAecArchBasePref 'LinearUnit)

Use vlax-dump-object on the AecArchBase Preferences object to see a list of all of the properties stored there.

In some cases, the values returned will be self-explanatory, such as the DatabaseScale, which is the scale factor associated with the current scale. For example, if the current model tab drawing scale is set to 1/4" = 1'-0", the DatabaseScale value will be 48.0. For items that are yes/no toggles, such as CreateDimscaleOverride, the value will be an integer. No (or false, or unchecked) is 0 (zero). Yes (or true, or checked) could be any other number, but is generally (always?) returned as -1 (negative one). Other values, such as LinearUnit, will seem more cryptic. If the current linear unit is set to "Inch", LinearUnit will return an integer value of 31. Properties such as LinearUnit return "enumerated values" (or "enums"), where each possible value is assigned a numeric value which may or may not have anything to do with the meaning it represents. The AutoCAD® Architecture Developer Help has a section that lists several of the enums used by AutoCAD Architecture and AutoCAD. Expand the AEC Base Automation Reference node and then the Enums node below that, and select the AecBuiltInUnit Enum for a listing of the various values and their meaning. As indicated in the image below, 31 is the enum for Inch.

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