Lesson 14 - Other Windows Forms Controls

In the previous lesson, Basic Windows Forms Controls, we described several basic form controls, these were Button, Label, TextBox, NumericUpDown, ComboBox, ListBox, and CheckBox. In today's C# .NET tutorial, we're going to continue the Toolbox tour.

RadioButton

RadioButton is very similar to CheckBox. The difference is that only one RadioButton inside the current container can be checked at a time. If you have more of them and check one, the others will be unchecked. So we can always choose only one from a set of options. We usually use RadioButton controls when there are only a few options available and a ListBox wouldn't look nice on the form.

Properties

• Checked (bool) - If the value is true, the RadioButton is checked.
• Appearance - If set to Button, the RadioButton will be rendered as an ordinary button (i.e. the Button). A checked RadioButton will look like a pressed button, others will look like unpressed ones.
• Image - If we use Appearance = Button, we can set an icon to the button easily.
• TextAlign - Aligns the label text to the check button.
• ImageAlign - Aligns the image.
• TextImageRelation - Here we can set the relation between the text and the image. The text can be displayed over the picture, but it can also be above it, below it, etc.

Events

• CheckedChanged - Is triggered when the RadioButton is checked or unchecked.

GroupBox

If some controls on the form are logically related, we can place them in a container. The container is a control that can contain other controls inside. We can simply put those controls into it in the designer. One of the containers in .NET is GroupBox. Try to create a GroupBox and put several controls in it. Then when you move it, you'll see those controls are moving along with it.

Beside making the form more readable, inserting controls into containers has other benefits as well. For example, we can hide the container (set Visible to false) and it'll disappear along with its contents. We can easily access the controls inside the container using its Controls collection and a loop. And last but not least, we can put RadioButton controls in it, of which only one can be selected at a time. More RadioButton controls can be checked at a time if they are in different containers.

Properties

• Text - The group title.
• Controls - The collection of all the components inside this group.

Events

No important events.

Panel

Panel is another container control. It behaves the same as the GroupBox, except that its border isn't displayed by default. This allows us to group form controls for inner purposes of the application, without the user noticing it. A typical example is putting e.g. 20 TextBox controls with different values into a Panel, then iterating through its Controls collection and setting the Text value to each. Without the panel, getting to the TextBox controls would be more difficult, and perhaps we'd accidentally rewrite all the controls on the form.

Properties

• BorderStyle - The visual style of the panel's border. We can set None, FixedSingle and Fixed3D.
• Controls - The collection of all controls inside the panel.

Events

No important events.

FlowLayoutPanel

FlowLayoutPanel arranges form controls for us. While in the normal panel we have to set their positions manually, FlowLayoutPanel doesn't use their positions, but displays the controls as they go instead, from left to right, from top to bottom. This can often be useful.

Properties

• FlowDirection - We can set in which direction the controls should be displayed. The Panel can display them both from right to left, or even vertically in both directions.
• BorderStyle - The style of the border. We can set None, FixedSingle, and Fixed3D.

Events

No important events.

PictureBox

PictureBox is an image, more specifically an image control. It's useful for improving the application design. It's also a common practice to not assign the image to it, but draw something instead (e.g. a graph).

Properties

• Image - The image.
• SizeMode - The display mode of the image. The Normal mode displays the image as it is, StretchImage stretches it over the entire PictureBox, regardless of the aspect ratio, the AutoSize sets the PictureBox size to the size of the image, CenterImage centers the image, and finally, Zoom resizes the image respecting the aspect ratio.

Events

• Paint - This event is triggered when the image is to be redrawn (that is, when the form asks for the image to be redrawn. This happens when the form is created or when another window is moved over the form). Inside the handler method, we usually draw our own graphics on the image's canvas, using the methods of the Graphics property of the e handler method parameter. We've already tried it several times during this course.

DateTimePicker

DateTimePicker allows us to enter date and time with dignity. It's certainly worth using this control for this purpose, it's easy for the user and for us as well. We don't have to parse values from a TextBox, which spares us from handling input errors, and at the same time the operating system solves entering the value for us. It provides us a nice calendar to enter the date and time.

Properties

• Format - Selects the output format. We can choose between the long and short date formats, time format, and even our own format, but we won't deal with this one here.

Here's how the time picker looks like:

• ShowUpDown (bool) - Specifies whether to display the UpDown (arrows that are particularly useful for time entering) or the DropDown calendar (which is perfect for date entering).
• Value - The entered value.

Events

• ValueChanged - Occurs when the user changes the value.

MonthCalendar

The calendar allows us to display days of a month, to select them and render some as bold. We can use it as part of some agenda app.

Properties

• BoldedDays (DateTime[]) - A DateTime array of the days that will be rendered as bold. For example, we highlight the days we have an appointment on this way.
• MonthlyBoldedDays (DateTime[]) - Similar as the above, bold days can be specified regardless of the month, so they'll appear bold in every month.
• AnnuallyBoldedDays - Again, similar as the above, but the days will appear bold every year, so they year doesn't matter.
• CalendarDimensions - The number of months displayed vertically and horizontally.
• ShowToday (bool) - Allows us to turn off the bottom bar with today's date.
• ShowTodayCircle (bool) - Allows us to turn off the circle highlighting of today.
• ShowWeekNumbers (bool) - Displays week numbers.

Events

• DateChanged - Occurs when the date selection (or date range) has changed or when we move to the next / previous month using the arrows.
• DateSelected - Occurs when the date selection (or date range) has changed.

That's all for today. In the next lesson, Windows Forms - Dialogs, we'll continue with our review of the .NET controls.