Advanced Windows Forms Controls in .NET framework

Creation QR Code 2d barcode in .NET framework Advanced Windows Forms Controls

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3. Which of the following is NOT a valid setting for the View property of the ListView control A. LargeIcon B. Details C. Tree D. SmallIcon

Allowing users to select or choose from a set of options, set dates, and work with images are common scenarios for user interface design. In this lesson, you will learn to use value-setting controls such as CheckBox, RadioButton, and TrackBar and date-set ting controls such as DateTimePicker and MonthCalendar; and you will learn to work with images using the ImageList component and the PictureBox control.

After this lesson, you will be able to:

Set two or more mutually exclusive options in the user interface using a RadioButton. Use the CheckBox control to indicate whether a condition is on or off. Allow navigation through a large amount of information or visually adjust a numeric setting using a TrackBar. Allow the user to select a single item from a list of dates or times using the DateTimePicker control. Present an intuitive graphical interface for users to view and set date information using the MonthCalendar. Add images to or remove images from the ImageList component. Display graphics using the PictureBox control.

Value-setting controls allow the user to set values or pick options from a preset list in the user interface. The CheckBox control allows a user to select or deselect particular options in a non-exclusive manner, while the RadioButton allows you to present a range of options to the user, only one of which can be selected. The TrackBar control allows the user to rapidly set a value in a graphical interface.

The CheckBox control is a very familiar control to users. It allows the user to mark a check box next to a label to indicate acceptance or rejection of the option presented. CheckBox controls function in a non-exclusive manner you can have multiple CheckBox controls on a single form, and any combination of them can be checked or unchecked at a single time. Table 3-10 shows important properties of the CheckBox control.

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Description Determines whether the CheckBox is automatically checked when the text is clicked. Gets or sets whether the CheckBox is checked. Returns the CheckState of the control. Possible values for this property are Checked, Unchecked, and Indeterminate. The text displayed next to the check box. Determines whether the CheckBox control allows two check states or three.

The most common usage for the CheckBox control is to allow the user to make a binary decision about an option by either checking the box or not checking it. Typi cally, the check box is used for non-exclusive options; that is, checking a particular check box usually does not affect the state of other text boxes. Figure 3-7 shows an example of a hypothetical pizza order form. Radio buttons are used to choose between the exclusive options Pizza or Calzone, and CheckBox controls are used to select toppings for the pizza or calzone that is selected.

Figure 3-7

You can programmatically determine if a CheckBox control is checked by accessing the Checked property. This property will return True if the control is checked and False if the control is unchecked or indeterminate. A less common use for the CheckBox is to allow the user to choose between three set tings: Checked, Unchecked, or Indeterminate. This can be useful to indicate to the user that a conscious decision must be made for each option rather than simply setting a default option. You enable three-state CheckBox controls by setting the ThreeState

property to True. This allows the user to cycle through the three states, rather than just the two, for the check box. You can determine the state of the check box by accessing the CheckState property. Note that you can set the CheckState property to Indeterminate at design time even if you set the ThreeState property to False. This causes the CheckBox controls to start in the indeterminate state, but once the user makes a selection, they must be either checked or unchecked; in this case, the user is not allowed to reset the check box to indeterminate.