HDevelop User's Manual

2.5. OPERATOR WINDOW 51
Please refer to the following rules on how parameters obtain their values and how you may
specify them:
Iconic input parameters:
These are the only parameters that do not have any defaults. You have to make sure that
there is an input. Possible inputs are iconic variables of the corresponding list. If there is
no need to execute the operator immediately, you may even specify new variable names,
i.e., names, that do not already exist in the variable window, but will be instantiated
later by adding further operators to the program. In any case you have to specify iconic
parameters exclusively with variable names. It is not possible to use expressions.
Iconic output parameters:
These parameters contain default variables, which have the same names as the parameters
themselves. If a variable with the same name as the output parameter is already
being used, a number is added to the name to make it unique. Because the parameter
names characterize the computed result very well, you may adopt these default names in
many cases. Besides this, you are free to choose arbitrary names either by yourself or by
opening the list (see above). If you use a variable that already has a value, this value is
deleted during execution before overwriting it with new results. It is possible to specify a
variable both in an input and output position.
Control input parameters:
These parameters normally possess a default value. In particular, this is to support novices
selecting an appropriate value. As an alternative, you may use the text field’s button to
open a combo box and to select a value suggestion. In addition, this combo box contains
a list of variables that contain values of the required type. A restriction of proposed
variables is especially used for parameters that contain data like file, frame grabber, or
ocr handles.
Input control parameters may contain constants, variables, and expressions. Common
types are integer numbers (ÒØÖ), floating point numbers (ÖÐ), boolean values
(ØÖÙ and Ð×) and character strings (×ØÖÒ). You are able to use multiple values
of these types at once. This is done by using the tuple type. This is an enumeration of
values, separated by commas and enclosed in brackets. Furthermore, you may build up
expressions with these values. The possibilities of using tuples are very extensive. You
may use expressions in HDevelop similar to the use of expressions in C or in Pascal. You
will find a more detailed description in section 3.5.
Control output parameters:
These parameters are handled in the same way as output object parameters. Their defaults
are variables, named with their parameter names. Other possibilities to obtain a
control output variable name are either using the combo box or specifying variable names
manually. You cannot use any expressions for these parameters, either.
After discussing what can be input for different parameters, it is explained how this is done.
Nevertheless, you have to keep in mind that you need to modify a parameter only, if it contains
no values or if you are not satisfied with the HALCON default values.
Text input:
To specify a parameter using your keyboard is the simplest but not the most often used
HALCON 6.0