تفاعل المستخدم

• This chapter introduces the concept of user interaction, which involves users entering data or receiving messages.

Objectives

• Explain the meaning of user interaction.
• List five common properties of the TextBox control.
• Explain the meaning of a Method.
• Apply a Method to a desired object.
• Use the method to end the application.
• Explain the meaning of a message box.
• Show a message box to the user.
• Adjust the text that appears in the message box and the text in its title bar.
• Control the buttons that appear on the message box.
• Control the icons that appear on the message box.

User Interaction

• No application (program) exists without interacting with the user, whether by allowing them to enter data or by displaying messages such as alerts and warnings.
• Texts are among the most important inputs to the computer and their form can be controlled
• Texts also have operations that can be performed on them, as learned in Windows programs, such as copying, cutting, or pasting part of the text elsewhere.

Textbox Tool

• This tool was used in previous lessons.
• Used to allow the user to enter data through it, or it can be used to display data.
• Every tool (or object) has a set of properties, events, and methods that define its appearance, behavior, and functions

Properties

• After placing the TextBox tool on the Form, its shape and format can be controlled through properties such as whether it is a single-line or multi-line box
• It can be used for entering a password or the font that appears during writing.
• These properties can be adjusted during design through the properties box, or they can be adjusted from the code window using commands.

Common Textbox Properties

• RightToLeft: Determines the writing direction. Setting it to Yes makes the direction from right to left, and setting it to No makes it from left to right, which is the default.
• CharacterCasing: The default is Normal, meaning the letters appear in the same case as they are typed. If you want the letters to appear in uppercase, set the property to Upper, and to display them in lowercase, set it to Lower.
• Font: Used to adjust the font type, size, and formatting
• MaxLength: Used to set the maximum number of characters that the user can enter in the text box.
• MultiLine: To determine if the text box is a single line, set the property to False (the default). For multiple lines, set it to True.
• PasswordChar: Used to make the text box input appear as a password, i.e., symbols appear instead of the entered letters.
• ReadOnly: The default is False. To make the contents of the text box non-editable and only for reading, set this property to True.
• Scrollbars: Used to control the appearance of scrollbars
  • None: Means no scrollbars (default)
  • Horizontal: To display a horizontal scrollbar
  • Vertical: To display a vertical scrollbar
  • Both: To display a vertical and horizontal scrollbar.
• SelectedText: This property is not set, but rather used to find out the text that has been selected in the text box. This property is not available in the properties box, but can only be used by using the code.
• Text: To place the contents of the text box or to know its contents.
• TextAlign: To adjust the alignment of the contents of the text box.
  • This property can be set to Left, Right, or Center.
• TextLength: This property is also not available in the properties box, but rather used from the code. This property is used to find out the number of characters entered in the text.

Methods

• Control the shape of the tool or object
• There is a set of functions and actions that can be implemented on the Object and called Methods.
• Methods are used by writing code, not a special window like in properties.
• Methods are implemented during program execution, not at design time.
• General form of the code for using a method: ObjectName.Method;

Example

• ObjectName: name of the object
• Method: name of the method to be implemented on this object
• The Hide procedure hides the object, while the Show procedure displays it.
• Once you start typing in the code window, a box will appear showing a list of various elements such as properties and the names of the objects on the Form.
• To select the object directly from the list instead of typing it, press the Tab key from the keyboard (note the symbol that appears to the left of the names of the existing objects).
• After writing the name of the entity, and as soon as you write the dot (.) to start writing the name of the property or the procedure required, a list will appear with the names of the entity's properties and procedures that you can apply to it.

Common Methods

• AppendText: Used to add text to the text that already exists in the text box
• Clear: It clears the contents of the text box, For example Textbox1.Clear clears contents.
• Copy: Sends a copy of the part that has been selected in the text box.
• Cut: Sends the part.

Example

• Two previous actions are implemented on the object.
• For example you want to implement an action on the text inside a text box, convert it to uppercase.
• You are not dealing with a text-box object.
• You are dealing with the text, so apply the action to the text, and the text is the property of the text box: ObjectName.PropertyName.Method;
• Properties can be considered entities that have their special procedure.
• In the previous Textbox example, to convert the existing lowercase letters to uppercase, we use the ToUpper procedure, and the command form will be as follows, where we added the name of the Text property because this procedure is specific to the text entities: textBox1.Text.ToUpper();

Exercise

• Write a C#.NET program that contains two text boxes: one single-line and the other multi-line (Multiline).
• The program window also contains seven buttons to perform the required commands:
  • Append Text Button
  • Clear Button
  • Copy Button
  • Paste Button
  • Select All Button

Understanding Code

• The Copy button will not perform its function of copying the selected part to the Clipboard unless the special command for this is written in the button's Event Handler
• When writing the function, double click on copy to open the function
• Button (Copy) to perform the function of copying : txtFirstBox.Copy();

btnCopy click action

• The Click event is triggered when the item is first selected

btnCut click action

• Pastes the copied text to the second text box
  • txtSecondBox.Paste();

btnClear click action

• clear is to clear all the test
  • txtFirstBox.Clear(); txtSecondBox.Clear();

btnUpper click action

• Make all letters Capital letters
  • txtFirstBox.Text = txtFirstBox.Text.ToUpper();

btnLower click action

• Display the the contents of the txtFirstBox in lowercase letters
  • txtFirstBox.Text = txtFirstBox.Text.ToLower();

btnExit click action

• The command Application.Exit() can work on any class

Message Box

• Often appears in various applications
• Displays text and options such as (Yes/No)
• (Message box) show information about errors and prompts the user to complete a task

Common Command

• MessageBox.Show(Prompt , [Title] , [Buttons], [Icons])
  • Prompt : Text that is displayed to users
  • Title : Message box title
  • Buttons : Numbers/Text to represent

MessageBoxButtons

• Ok-Cancel, YesNo, and YesNoCancel

Message box icon

• Displays an icon in the message with a set format

Symbols (Message Box)

• Asterisk / Information
• Question
• Error
• Exclamation / Warning
• Hand / Stop