Lecture 5 COMMON CONTROLS

Transcription

1 Lecture 5 COMMON CONTROLS

2 1. The ListBox Class Represents a box that contains a list of items. The following are its some of its more important properties: MultiColumn This is a Boolean that indicates whether the listbox has more than one column. Its default value is False. ColumnWidth In a multicolumn listbox, this property represents the width of each column in pixels. By default, If the value of this property is zero, it makes each column have a default width. Sorted

3 The ListBox Class It has a Count property that returns the number of items in the ListBox and an Item property that returns the item object in a certain index position. The class has the following methods: Add: Adds an item to the ListBox object. Its syntax is: ListBox1.Items.Add(item) AddRange: Adds one or more items to the ListBox object. Its most common syntax is: ListBox1.Items.AddRange() Clear: Clears the ListBox, removing all the items. Its syntax is: ListBox1.Items.Clear() Contains: Checks whether an item can be found in the list of items. Its syntax is: ListBox1.Items.Contains()

4 2. The ComboBox Class Similar to the ListBox class and has properties and methods similar to those of the ListBox class. The following are examples of properties that are specific to the ComboBox class: DropDownStyle Displaymember

5 IndexOf: Returns the index of a particular item. Insert: Inserts an item into the ListBox at the specified index position. Remove: Removes the item that is passed as an argument to this method from the ListBox. RemoveAt: Removes an item at the specified index position.

6 Checkbox and Radio Button Both used when you intend to allow the user to Both used when you intend to allow the user to input between options. Use checkbox if you want to allow the user the option to select more than one option Use radio button if you want to allow the use to select only one option out of the list.

7 Progress Bar A few properties It is used to provide visual feedback to your users about the status of some task. It shows a bar that fills in from left to right as the operation progresses. S.N Property Description 1 AllowDrop Overrides Control.AllowDrop. 2 BackgroundImage Gets or sets the background image for the ProgressBar control. 3 BackgroundImageL ayout Gets or sets the layout of the background image of the progress bar. 4 CausesValidation Gets or sets a value indicating whether the control, when it receives focus, causes validation to be performed on any controls that require validation.

8 S.N Method Name & Description Increment Increments the current position of the ProgressBar control by specified amount. PerformStep Increments the value by the specified step. ResetText Resets the Text property to its default value. ToString Returns a string that represents the progress bar control. A few common methods Some events S.N Event Description 1 BackgroundImage Changed 2 BackgroundImage LayoutChanged 3 CausesValidationC hanged Occurs when the value of the BackgroundImage property changes. Occurs when the value of the BackgroundImageLayout property changes. Occurs when the value of the CausesValidation property changes. 4 Click Occurs when the control is clicked.

9 Data Grid view Displays and enables data manipulation of a series of rows and columns representing records and fields from a Recordset object.

10 Menu Strip, ToolStrip Context Menu and Status Strip MenuStrip - this lets you build a menu that lies underneath the title panel. ContextMenuStrip - this lets you build a context-sensitive menu, one that appears whenever you right-click on something that has a context sensitive menu attached to it. Typically a MenuStrip is used to give access to functionality common to the whole application. A ContextMenuStrip is used to give access to a focused area of functionality. Context Menu Strip

11 Unlike menu strip control, the context menu can have only one Menu with one or more menu items in it. Menu items to the context menu are added in the way you do it for the menu strips. The important step is assigning the context menu to the form and you can do that by using the contextmenu property of the windows form. One difference between the MenuStrip and the ToolStrip is the fact that the top-level menu headings in the MenuStrip are all ToolStripMenuItem objects, hence The MenuStrip derives from ToolStrip. A StatusStrip displays window status. Usually placed at the bottom of the window/form. Typically provides ProgressBar, DropdownButton, SplitButton, and Label features

12 Timer It allows you to set a time interval to execute an event after that interval continuously. It is useful when you want to execute certain applications after a certain interval. Say you want to create a backup of your data processing in every hour. You can make a routine which will take the backup and call that routine on Timer's event and set timer interval for an hour. Tick Start Stop Close AutoReset Interval Enabled This event occurs when the Interval has elapsed. Starts raising the Tick event by setting Enabled to true. Stops raising the Tick event by setting Enabled to false. Releases the resources used by the Timer. Indicates whether the Timer raises the Tick event each time the specified Interval has elapsed or whether the Tick event is raised only once after the first interval has elapsed. Indicates the interval on which to raise the Tick event. Indicates whether the Timer raises the Tick event.

13 TabControl By using a tab control, an application can define multiple pages for the same area of a window or dialog box. Each page consists of a certain type of information or a group of controls that the application displays when the user selects the corresponding tab.

14 Picture Box The PictureBox control is used for displaying images on the form. The Image property of the control allows you to set an image both at design time or at run time.

15 Date time picker The DateTimePicker control displays date and/or time information and acts as the interface through which users can modify date and time information. The control's display consists of fields that are defined by the control's format string. When the DateTimePicker is dropped down, a MonthView calendar is displayed.

16 Practice questions Question 1: a) Create a VB program made up of a text box, a command button and a list box. When the command button is clicked, the text contained within the text box is added to the listbox. b) Add a command button and a label to the form. When button 2 is pressed, the index position of the item in the textbox in the listbox is shown on a label

17 Question 2 Create an application containing a command button and a progress bar. i. When the command button is clicked, the progress bar advances by a limited interval. ii. Alter the program, an put the progress bar on a Splash ii. Alter the program, an put the progress bar on a Splash Screen, so that it imitates a loading application or program.

18 Question 3 a) Create a windows application to display a clock through a text box b) A multiplication application

19 Question 4 txtpv txtir txtny cmdcalc The program above is a simple calculator that is used to determine the future value of a given amount of money that is invested today. Implement the program above, displaying the results in a label.