About highlighting information
About properties
Every control in your DataWindow object has a set of properties
that determines
what the control looks like and where it is located. For example,
the values in a column of data display in a particular font and color,
in a particular location, with or without a border, and so on.
About modifying properties when designing
You define the appearance and behavior of these controls in DataWindow objects
in the DataWindow painter. As you do that, you are specifying the controls’ properties.
For example, when you place a border around a column, you are setting
that column’s Border property.
In most cases, the appearance and behavior of controls is
fixed; you do not want them to change at execution time. You make
headings bold when designing the headings and that’s the
way you want them to be at all times.
In the following DataWindow object, the Salary Plus Benefits column
has a Shadow box border around every data value in the column. To
display the border, you would set the border property for the column:
About modifying properties at execution time
In some cases, however, you might want some properties of
controls in DataWindow objects to be driven by the data, which is not known
when you are defining the DataWindow object in the painter. For these situations
you can define property conditional expressions,
which are expressions that are evaluated at execution time.
You can use these expressions to conditionally and dynamically
modify the appearance and behavior of your DataWindow object during execution.
The results of the expressions set the values of properties of controls
in the DataWindow object.
In the following DataWindow object, the Salary Plus Benefits column
has a Shadow box border highlighting each data value that is greater
than $60,000:
To control the display of the border, you would define a property
conditional expression for the column’s Border property.
When users run the DataWindow object, PowerBuilder changes the border
of individual data values based on your expressed condition (value
greater than $60,000).
About defining an expression
The following illustration shows the Salary_Plus_Benefits
column selected in the Design view. To the right of the Design view,
the Properties view shows properties for the column, including the
Border property. Next to the Border property is a little button
for accessing the dialog box where you enter the expression.
In this example you can see that the Border property is set
to NoBorder in the Properties view. However, the expression defined
for the property will override at execution time any border setting
made during design.
A closer look at the expression
The expression you enter almost always begins with If. Then
you specify three things: the condition, what happens if it’s
true, and what happens if it’s false. Parentheses surround
the three things and commas separate them:
|
1 |
If( <i>expression, </i><i>true, false</i> ) |
This is the expression used in the example. Because the expression
is for the Border property, the values for true and false indicate
particular borders. The value 1 means Shadow box border and the
value 0 means no border:
|
1 |
If(salary_plus_benefits > 60000, 1, 0) |
When users run the DataWindow object, PowerBuilder checks the
value in the computed column called salary_plus_benefits
to see if it is greater than 60,000. If it is (true), PowerBuilder will
display the value with the Shadow box border. If not (false), PowerBuilder will
display the value with no border.
About specifying properties
Usually you specify a number to indicate what you want for
a particular property. For example, the following list shows all
of the borders you can specify and the numbers you use. If you want
the border property to be Shadow box, you specify 1 in
the If statement, for either true or false.
- 0–None
- 1–Shadow
box - 2–Box
- 3–Resize
- 4–Underline
- 5–3D
Lowered - 6–3D
Raised
In the Properties view, the dropdown listboxes that list choices
for setting properties include the values that correspond to choices
in parentheses. This makes it easier to define an expression for
a property; you do not need to look up the values. For example,
if you want to specify the ResizeBorder in your expression, you
use the number 3, as shown in the dropdown listbox.
For details on the values of properties that
can be set using expressions, see “Supplying property values”. For complete information about what
the valid values are for all properties associated with a DataWindow object,
see the discussion of DataWindow object properties in the DataWindow Reference
or
online Help.
About modifying properties programmatically
You can also programmatically modify the properties of controls
in a DataWindow object during execution.
For more information, see the DataWindow
Reference
and the DataWindow Programmer’s
Guide
.