Filling UserForm Controls
The vast majority of UserForms that are designed within Excel are used so users can easily select and input data. This also ensures that any entries that are entered into a spreadsheet are within the requirements needed. Possibly the best way to achieve both of these requirements is to supply a list of entries for the user to chose from. Excel has many Controls that can be placed on a UserForm that can make this not only easy for the user, but also for the designer of the UserForm. The two most useful Controls for this are the “ComboBox” and the “ListBox”. Let’s look at each of these Controls.
ComboBox
A
ComboBox is so called because it combines the features of two other Controls.
These are the TextBox and the ListBox. While it will allow a user to select an
existing entry from a list of entries, as with a ListBox, it will also allow the
user to enter a new entry, as with a TextBox.
The
default Property for a ComboBox is the Value property.
The
default Event for a ComboBox is the Click event.
A
ComboBox will only display one row of data at any one time unless the user
selects the drop arrow on the right of the ComboBox. The rows of data can then
be between 1 and the total number of rows in the ComboBox. The default is
eight. This is set by the ListRows
Property of the ComboBox.
ListBox
A
ListBox is quite similar to a ComboBox but has three important differences. The
first is that we can have a ListBox display a specified number of rows without
user intervention. The second is we can set a ListBox so that a user can select
more than one item at a time. The third is that a user cannot directly enter any
new values into the ListBox.
The
default Property for a ListBox is the Value property.
The
default Event for a ListBox is the Click event.
Which One To Use?
While
it is true that both the ListBox and the ComboBox have many similar Properties
and Events, there are times that a ListBox is called for and times when a
ComboBox is called for. It is up to us as the designer to make the correct
decision.
The fact that a ListBox can display more than one row at a time is really more of a cosmetic effect than anything else. So this should really be our last reason for using a ListBox over a ComboBox or vice versa. The two differences that should dictate our decision are:
Will
the user need to type in their own entries.
Will
the user need to be able to select more than one entry at a time.
If
the answer is yes to number one, then it’s a probably a ComboBox we need. If the answer
is yes to number two then it’s probably a ListBox we need.
Putting Data Into Our Controls
Once
we have made our decision on which Control we are going to use we next need to
decide which Method we are going to use to fill our Control with data. This is
usually quite a simple decision and we will nearly always use a range of
Worksheet cells to hold all our data and refer our Control to this range.
Ideally, the Worksheet we use should be hidden from view. We can do this via
Window>Hide or via VBA using the Worksheets Visible Property. eg;
Sheet1.Visible=xlVeryHidden
I would opt for the latter in most cases. As I have said, we will usually opt for storing our data within a range of cells. This means we can easily add data to the range either manually or via VBA. The other option we have is to use the AddItem Property and I will discuss this after we have looked at the method we would use to refer to a range of cells. This is done via the RowSource Property.
Row Source - Applies to both a ComboBox and ListBox
A
valid setting for the RowSource Property is a String. The String that we use
would be either a valid cell address or a valid range name.
ComboBox1.RowSource= "A1:A10"
ComboBox1.RowSource="Sheet2!A1:D10"
ComboBox1.RowSource="MyRange"
All
of the above are valid settings for the RowSource Property. The RowSource can be
set at either Run-time or Design-time. If the RowSource were set at Design-time
we would enter our String into the Property window of the ComboBox or ListBox
without quotation marks, eg;
A1:A10
Or
Sheet2!A1:D10
Or
MyRange
As you can see the range we specify can be either a single column or multiple columns. I will explain this further later on when we look at the column setting Properties of both Controls.
AddItem - Applies to both a ComboBox and ListBox
This Property can only be set at Run-time. If the ListBox or ComboBox has only one column then AddItem will add an item to the ListBox or ComboBox list. If the ListBox or ComboBox has more than one column then AddItem will add a new row to the ListBox or ComboBox list
The
syntax for the AddItem
Property Is: [
item [, varIndex]]
Both arguments are optional.
ComboBox1.AddItem "Horse", 5
The
AddItem is best suited if
You have only a short list of entries to add
For most other cases the RowSource Property is better suited.
When
To Put Data In Our Control?
Now
we have decided which Control to use and where our data is going to come from,
we next need to decide when we are going to fill our Control. We can have this
done at Run-time or Design-time. If our data were being read from a Worksheet
range we would most likely do this at Design-time. However if we are going to
use the AddItem method we will be filling our Control at Run-time. If this is
the case you will probably find that most often you will want the Control filled
with the relevant data whenever the UserForm that is housing our Control is Initialized
by the user. When this is the case, all we need to do is drop our code that will
fill our ListBox or ComboBox into the UserForm_Initialize() Event.
There may be times when you want to alter the list or even replace it with new data while the user has the UserForm open. If you do need to replace the list that is in a ListBox or ComboBox you must clear the old data out first, else you will end up with two lists within the same Control. The way we can do this is by using the Clear Method. One thing to be aware of with this Method is that a Run-time error will be generated if you attempt to use the Clear Method on a ListBox or ComboBox that does not contain any data or is Bound* to a Data source**.
Describes a control whose contents are associated with a particular data source, such as a cell or cell range in a worksheet.
**Data
Source
The
location of data to which a control is bound, for example, a cell in a
worksheet. The current value of the data source can be stored in the Value
property of a control. However, the control does not store the data; it only
displays the information that is stored in the data source.
ComboBox1.Clear
On Error GoTo 0
Lets now look at the settings we can use to specify the columns in our Control.
ColumnCount - Applies to both a ComboBox and ListBox
The
ColumnCount Property is used to specify how many columns will be displayed in
our ComboBox or ListBox.
A
valid setting for the ColumnCount Property is a “Long” equal to or greater
than -1. We can set the ColumnCount at both Run-time and Design-time.
If
our Control has an *unbound
Data source then the ColumnCount has a 10 column limit, ie; 0-9
unbound
is described by the Excel help as:
Describes
a control that is not related to a Worksheet cell. In contrast, a bound control
is a data source for a Worksheet cell that provides access to display and edit
the value of a control.
Once we have set our ColumnCount we may need to specify the width of each column. We do this by using the ColumnWidth Property.
ColumnWidth - Applies to both a ComboBox and ListBox
The
ColumnWidth Property is used to set the width of each column in a ListBox or
ComboBox that have a ColumnCount other than 0 (zero)
Settings
To separate column entries, use semicolons (;) as list separators. In Windows, use the list separator specified in the Regional Settings section of the Windows Control Panel to change this value.
Any or all of the ColumnWidths property settings can be blank. You create a blank setting by typing a list separator without a preceding value.
If you specify a –1 in the property page, the displayed value in the property page is a blank.
To calculate column widths when ColumnWidths is blank or –1, the width of the control is divided equally among all columns of the list. If the sum of the specified column widths exceeds the width of the control, the list is left-aligned within the control and one or more of the rightmost columns are not displayed. Users can scroll the list using the horizontal scroll bar to display the rightmost columns.
The minimum calculated column width is 72 points (1 inch). To produce columns narrower than this, you must specify the width explicitly.
Unless specified otherwise, column widths are measured in points. To specify another unit of measure, include the units as part of the values. The following examples specify column widths in several units of measure and describe how the various settings would fit in a three-column list box that is 4 inches wide.
Setting | Effect |
90;72;90 | The first column is 90 points (1.25 inch); the second column is 72 points (1 inch); the third column is 90 points. |
6 cm;0;6 cm | The first column is 6 centimeters; the second column is hidden; the third column is 6 centimeters. Because part of the third column is visible, a horizontal scroll bar appears. |
1.5 in;0;2.5 in | The first column is 1.5 inches, the second column is hidden, and the third column is 2.5 inches. |
2 in;;2 in | The first column is 2 inches, the second column is 1 inch (default), and the third column is 2 inches. Because only half of the third column is visible, a horizontal scroll bar appears. |
(Blank) | All three columns are the same width (1.33 inches). |
Remarks
In a combo box, the system displays the column designated by the TextColumn property in the text box portion of the control.
The other Property we will look at is the ColumnHeads Property.
ColumnHeads - Applies to both a ComboBox and ListBox
This
property allows us to have headings for the columns in a multi-column ComboBox
and ListBox.
A
valid setting for this is a Boolean (True or False). The default is False.
Let’s
assume we have headings on a Worksheet in the range A1:C1 and we have set the
ColumnHeads Property of a ListBox to True. To have our headings displayed in the
ListBox we would need to set the RowSource Property to:
ListBox1.RowSource="A2:C10"
In
other words we need to omit the first row when we fill our list then Excel will
use the row immediately above our RowSource as the headings.
Filling a ListBox and ComboBox Using Loops
While
using the RowSource Property referring to a range is the most likely way to fill
a ListBox and ComboBox and probably the easiest way. There are times when the
AddItem method is a better option and in some cases the only option. Let’s say
that you want to fill a ComboBox or ListBox with times that cover the previous
24 hour period at 15 minute intervals. You could of course use the NOW()
Function on a hidden Worksheet and increment it by the needed increment, ie;
A1
= NOW()
A2
=
A1+0.0104166666666667
A3=
A2+0.0104166666666667
And
so on……
This Loop will fill our ListBox with times that are incremented at 15 minute intervals over a 24 hour period. The code will only run when the UserForm that houses the ListBox is initialised. We could of course have the code run via a CommandButton or many other methods.
Summary
So
as you can see there does need to be some foresight as to which Control is best
suited to a particular situation. At times you may even use both the ComboBox
and ListBox.
©2002 ozgrid - microsoftexceltraining - David & Raina Hawley. All right reserved