ABAP_to_the_Future

10
ALV SALV Reporting Framework
Each of the methods called in Listing 10.8 are discussed next; you’ll see how
they’re defined in the abstract interface and implemented in the concrete class.
Optimizing the Column Width
The method OPTIMIZE_COLUMN_WIDTHS has no parameters, because what it does is
very straightforward. Ninety-nine times ou t of 100, your report will have columns
such as customer names, and more often than not the longest customer
name in the report will not be long enou gh to fill the entire length of the customer
name field in the data dictionary. To avoid empty space in the report and
to get the maximum number of columns on one screen to prevent the users having
to scroll to the right (they hate doing that), you can tell the view technology to
work out the maximum length needed fo r each column dynamically at runtime
based on the actual contents of the table to be displayed.
Note
There are rare occasions when it’s vital that you maintain total control over how wide
each column is, and in such cases you do not want to call this method.
Setting the Column Attributes
The SET_COLUMN_ATTRIBUTES_METHOD is probably the most commonly used
method for making applicatio n-specific changes; it’s a way to define the special
attributes of the various columns in the internal table to be displayed. As you can
see in Figure 10.7, this consists of a number of optional input parameters that
control the following elements:
왘 The identity of the column in question. Todefine this, you pass in the field (column)
name, which is the name of the field in the internal table structure. You
have to have the table name as an optional parameter as well, because the interface
has to cater to several UI technologies. One of which, CL_GUI_ALV_GRID,
cannot live without the field name—so you have to pander to the lowest common
denominator.
왘 Whether the user can double-click on a column value and trigger an action,
such as viewing the underlying business document (a hotspot).
왘 Whether the column is hidden by default and the user can choose to display it
or whether the column is never to be displayed under any circumstances (socalled
technical columns, which are only used internally by the program).
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