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objectarx&dummies教程（九）—— interacting with autocad
objectarx&dummies教程（九）—— interacting with autocad
class 9 - interacting with autocad
hello,
on the last class i have presented how to perform selection sets. this class i will show how can you interact with autocad using global functions and acquiring information such as numbers, coordinates, system variables and much more.
invoking commands
objectarx provide us two global functions that allows us to invoke registered commands. this functionality is very handy and will help users to perform quick operations that don't require complex procedures. even this method is quite simple you should avoid using it in complex and huge operations. this method may also create problems when dealing with events handling.
the two provided functions are acedcmd() and acedcommand(). the first one invokes the command through a passed in resbuf list which will inform all command parameters. the second function will receive a variable number of parameters which will reproduce the way you fire the command from the prompt interface. below are these functions signature:
int acedcmd(const struct resbuf * rbp);
int acedcommand(int rtype, ... unnamed);
to build the resbuf list when using acedcmd() there is a utility function called acutbuildlist() which constructs this linked list easily. you just need to pass paired values with codes that describe the types and end the list with a 0 or rtnone value. another good practice is to clear the command prompt, calling acedcommand(rtnone) , after issued the command. don't forget to free memory used, when using resbuf pointers, through the acutrelrb() utility function to avoid memory leaks. there are several ways to use theses functions and i will show some of them below:
acedcmd():
a) moving the last created entity based on (0,0,0):
ads_point pt;
pt[0] = pt[1] = pt[2] = 0.0;
struct resbuf *mv;
mv = acutbuildlist(rtstr,"_move",rtstr,"_last",rtstr,"",
rtpoint,pt,rtstr,pause,0);
acedcmd(mv);
acedcommand(rtnone);
acutrelrb(mv);
b) calling a "redraw" native command:
struct resbuf *cmdlist;
cmdlist = acutbuildlist(rtstr, "_redraw", 0);
acedcmd(cmdlist);
acedcommand(rtnone);
acutrelrb(cmdlist);
acedcommand():
a) calling a zoom command and pausing for user input:
acedcommand(rtstr, "zoom", rtstr, pause, rtnone);
b) creating both a circle and a line entities:
acedcommand(rtstr, "circle", rtstr, "10,10",rtstr, pause,
rtstr, "line", rtstr, "10,10", rtstr, "20,20", rtstr, "", 0);
system variables
your application will probably need to access autocad system variables that can be read or write. objectarx provide two functions to deal with these variables using the resbuf structure to access and/or modify values. the function are called acedgetvar() and acedsetvar() and below are their signatures:
int acedgetvar(const char * sym,struct resbuf * result);
int acedsetvar(const char * sym,const struct resbuf * val);
the first parameter is the variable name the second the resbuf pointer to set / get information. the following example show how to change the fillet radius which is stored through a system variable:
struct resbuf rb, rb1;
acedgetvar("filletrad", &rb);
rb1.restype = rtreal;
rb1.resval.rreal = 1.0;
acedsetvar("filletrad", &rb1);
it is very important that you specify the correct type of resbuf item acquired.
in this case, the fillet radius is a real number which is rtreal type.
user input functions
there are additional global functions to allow interaction with users via command prompt interface. each of these functions could be used alone or with other ones. the following table shows what each function does:
acedgetint
gets an integer value
acedgetreal
gets a real value
acedgetdist
gets a distance
acedgetangle
gets an angle (oriented to 0 degrees specified by the angbase)
acedgetorient
gets an angle (oriented to 0 degrees at the right)
acedgetpoint
gets a point
acedgetcorner
gets the corner of a rectangle
acedgetkword
gets a keyword
acedgetstring
gets a string
each of these functions returns a int number as a result code that could be one of the following:
rtnorm
user entered a valid value
rterror
the function call failed
rtcan
user entered esc
rtnone
user entered only enter
rtrej
autocad rejected the request as invalid
rtkword
user entered a keyword or arbitrary text
autocad allows you to prevent invalid values when user respond to your input functions. this feature can be made through the acedinitget() function which can receive one or a combination of the following values:
rsg_nonull
disallow null input
rsg_nozero
disallow zero values
rsg_noneg
disallow negative values
rsg_nolim
do not check drawing limits, even if limcheck is on
rsg_dash
use dashed lines when drawing rubber-band line or box
rsg_2d
ignore
z
coordinate of 3d points (acedgetdist() only)
rsg_other
allow arbitrary input—whatever the user enters
the following example shows how to acquire a value greater than zero:
int age = -1;
acedinitget(rsg_nonull rsg_nozero rsg_noneg, null);
acedgetint("how old are you? ", &age);