Speaker Name: Bill Kramer. Course: CP42-2 A Visual LISP Wizard's Into to Reactor Magic. Course Description

Transcription

1 Speaker Name: Bill Kramer Course: CP42-2 A Visual LISP Wizard's Into to Reactor Magic Course Description Visual LISP reactors are the tools by which event-driven applications are created. If you want to learn what an event-driven program is and how reactors fit in to the overall scheme, this class is for you. We'll look at the reactor system of AutoCAD that is available to the Visual LISP programmer, and discuss how to exploit this powerful system in your programs. CP42-2 1

2 A Visual LISP Wizard's Intro to Reactor Magic Bill Kramer AUTO-CODE MECHANICAL What are reactors? - Program modules that react to events - Data gathering tools - Data monitoring tools - When you write reactor programs, you are meddling in areas that will directly effect the operator of AutoCAD... Are you ready for this? - You should know Visual LISP - We will be covering the following: The concept of a reactor Coding reactors Setting up a reactor to run Practical aspects of reactors Concepts of Reactors - For every action there is a reaction - Actions are Events Keystroke Mouse activities Data change Object change and so much more! Programming a reactor is different - Process Programming Define a process (program Initiate the process Process runs and finishes Event driven programming - Event Driven Programming Define a process Relate the process to an event Wait for the event then run A Change in Strategy - Procedural programs CP42-2 2

3 Input * Process * Output - Event reactor programs NO INPUT Process quickly Change related objects or record event - Event reactors can cause events themselves Watch for endless loops - Reactors can cause events - Need to use various sentinels Global symbols Disable then re-enable reactors - Traps are found in Changing objects Creating new objects Reactor Concepts - Using the AutoCAD Object System Must use Object Variable types VL-LOAD-COM VLAX-ENAME->VLA-OBJECT Slowing down AutoCAD for your purpose Be quick about it! No control over sequence of reactor calls Be smart about it! What kind of reactors are there? - VLR objects vlr-acdb-reactor - Database reactor (add/change/remove entities vlr-command-reactor - Command system reactor vlr-docmanager-reactor - Document system reactor vlr-dwg-reactor - Drawing file I/O reactor vlr-dxf-reactor - Drawing file I/O reactor vlr-editor-reactor - Master reactor for command, dwg, dxf vlr-insert-reactor - Editor reactor for inserts - vlr-linker-reactor - ObjectARX load/unload reactor - vlr-lisp-reactor - Editor reactor for LISP watching vlr-miscellaneous-reactor - Some extras (layout change, pickfirst change vlr-mouse-reactor - Mouse click reactor vlr-object-reactor - Entity object specific reactor vlr-sysvar-reactor - Editor reactor for system variables vlr-toolbar-reactor - Toolbar changes vlr-undo-reactor - Undo system monitoring vlr-wblock-reactor - Writing a block to file CP42-2 3

4 vlr-window-reactor - Change in window size vlr-xref-reactor - Access to external reference block The coolest reactors - Database object related Vlr-acdb-Reactor Vlr-Object-Reactor - User control vlr-acdb-reactor vlr-command-reactor vlr-editor-reactor (covers many different types of events The Basic Rules - You cannot stop an event - If your activity results in another reactor it is your job to guard against it - User input and output is strongly discouraged - Be quick about it - Be smart about it Example reactor - Creating a reactor routine - Define function - two arguments The object causing the call back A list of parameters from AutoCAD - Object reactors have three arguments Owning object Object causing the call back List of parameters from AutoCAD Example - Reactor program to count commands - Builds list of (( Command name count... - Create startcounter and endcounter functions to control the reactor - Attach to the vlr-command-reactor object Learn what reactors are there - Command: (vlr-reaction-names - :vlr-command-reactor - (:VLR-unknownCommand - :VLR-commandWillStart - :VLR-commandEnded - :VLR-commandCancelled - :VLR-commandFailed CP42-2 4

5 CommandWillStart - This reactor sends the name of the command to be started. - Incoming parameter ( command name - Get the name, compare against save list Add one if found Add to list if not found Simple Command Reactor (defun CountCommands (CallerID plist (setq CN (car plist ;;get command name (if (assoc CN CounterList (setq CounterList (subst (cons CN (1+ (cdr (assoc CN CounterList (assoc CN CounterList CounterList (setq CounterList (cons (cons CN 1 CounterList ;;; (defun C:StartCounter ( (prompt "\ncounter reactor level 1 starting..." (setq mycommandreactor (vlr-command-reactor nil '((:vlr-commandwillstart. CountCommands (setq CounterList nil (prompt " condition GREEN" (princ ;;; (defun C:EndCounter ( (vlr-remove mycommandreactor ;;remove all reactors (prompt "\ncounter reactor stopped, list CounterList is:" (foreach Item CounterList (print Item (princ Database Reactors - Let s modify the concept a bit Instead of counting commands, Let s count the changes to the drawing itself. For that we use a database reactor Events include object erased object modified object appended CP42-2 5

6 Start by attaching functions Attach the function symbols to the reactor events (vlr-acdb-reactor nil '((:vlr-objectmodified. CountChanges (:vlr-objectappended. CountNew (:vlr-objecterased. CountDels Set up global variables - Save the reactor link object created (setq mydatabasereactor (vlr-acdb-reactor... - Set up the counting variables For modify, append, delete - Define the functions themselves These are simple! (defun CountChanges (CallerID plist (setq ModCounter (1+ ModCounter (defun CountNew (CalledID plist (setq NewCounter (1+ NewCounter (defun CountDels (CallerID plist (setq DelCounter (1+ DelCounter (defun C:StopCounter2 ( (vlr-remove mydatabasereactor (prompt (strcat "New objects = " (itoa NewCounter "\nmodified = " (itoa ModCounter "\ndeleted = " (itoa DelCounter (prompt "\nreactor level 2 stopped." (princ (defun C:StartCounter2 ( (prompt "\ncounter reactor level 2 coming on line..." (setq ModCounter 0 NewCounter 0 DelCounter 0 mydatabasereactor (vlr-acdb-reactor nil '((:vlr-objectmodified. CountChanges (:vlr-objectappended. CountNew (:vlr-objecterased. CountDels CP42-2 6

7 (prompt "GREEN" (princ Command and database events - You can t stop it! But you can counter negative effects - Be quick! It runs for EVERY transaction - Be silent! Prompts and inputs are a nuisance Entity Base Reactions - Often best for special entities Application specific data houses Dimensions and related text Smart objects - VLR-OBJECT-REACTOR Attach entity object reference with list of events Object Based Reactors - Use VLR-REACTION-NAMES with :VLR-OBJECT-REACTOR for listing. :VLR-canceled - operation was canceled :VLR-copied - object has been copied :VLR-erased - object has been erased :VLR-unerased - object has been un-erased :VLR-goodbye - object is about to be removed from memory :VLR-openedForModify - object open for changes :VLR-modified - object has been changed :VLR-subObjModified - sub-entity changed :VLR-modifyUndone - modifications have been undone :VLR-modifiedXData - extended data has changed :VLR-unappended - object detached from database :VLR-reappended - object re-attached to database :VLR-objectClosed - modifications completed Object Based Reactors - Use to link entity objects vlr-object-reactor List of entity object references Associated data, if any Reactor event links to functions as nested list Object based event functions CP42-2 7

8 - Object event handling functions have three arguments Object reference of entity causing call back Object reference of the reactor Parameter list (often contains nothing called only when one of the related objects is changed Who called? - The first parameter is the entity object reference of the entity that caused the callback to take place. This is the entity that changed Entity object is read only Related to who else? - Ask the reactor object (VLR-OWNERS <object reference> returns a list of entity object references same ones from VLR-OBJECT-REACTOR call Data returned is a LIST Use = to test equality with other object references A Simple Example - Text object linked to line object display length of line when changed - Object reactor tied to line and text when line changed, can locate text when text changes, do nothing first question is one of set up Setting up the data - Operator selects a line object - Operator selects a point for text placement - Compute line length, generate text object - Given both line and text object references, Create a VLR-OBJECT-REACTOR link Use the event :VLR-modified C:BINDLEN example Bind TEXT string object to LINE object so that every time the line changes, the string data is updated reflecting the current length of the line. (defun C:BINDLEN (/ EN EL PT Lobj Tobj (setq EN (entsel "\npick a line object: " (if (and EN (= CP42-2 8

9 (cdr (assoc 0 (setq EL (entget (car EN "LINE" (progn (setq PT (getpoint "\nlocate text point for length: " (if PT (progn (setq Lobj (vlax-ename->vla-object (car EN Tobj (vla-addtext (ModelSpace (strcat "Length = " (rtos (vla-get-length Lobj (vlax-3d-point PT (Getvar "TEXTSIZE" (vlr-object-reactor (list Lobj Tobj nil '((:vlr-modified. LineChange (defun ModelSpace ( (vla-get-modelspace (vla-get-activedocument (vlax-get-acad-object That's It! - That s all there is to setting it up. - Now on to the call back function Logic is as follows if calling object is line get object reference of related text change text value for new length The Callback Function ;; ;; Reactor Program LineChange ;; (defun LineChange (ObjID ;Object ID of reacting object CallerID ;Object ID of reactor object PList ;Parameter list (if (= (vlax-get ObjID "ObjectName" ;was it the line that called? "AcDbLine" (progn CP42-2 9

10 (setq DD (vla-get-length ObjID ;Get the length of the line TX (vlr-owners CallerID ;Get the Object IDs of the reactor TX (if (= ObjID (nth 0 TX ;is first one line? (nth 1 TX ;then get the second one (text (nth 0 TX ;otherwise get the text one (vla-put-textstring TX ; Change the text string value for the text object (strcat "Length = " (rtos DD 2 3 ;end line type check Cleaning up our mess - (VLR-REMOVE <object> use reactor object reference as argument - (VLR-REMOVE-ALL kills them all off - (vlr-remove-all :vlr-<type>-reactor kills them all off for a given type Between drawing sessions? - Reactors need to be started - LSP code for reactors needs to be loaded - Can add to automatic load list in AutoCAD Add to start up suite in APPLOAD Use a dictionary to save object links Or attach extended data Or save to a database Reactor Programming - Event driven applications - Can expand existing applications - Not difficult to create Easy to get lost though Many options to consider sometimes - Work well with interactive CAD applications Event Programming - Need to start by establishing linkage of function with event - Events are associated with reactor objects - Event callback functions need to be: Quick, efficient, clean - Object based event callbacks can only read the object that called CP