Creating User Controls
Creating User Controls
A set of controls provided by the .NET Framework is quite broad and, for most applications scenarios, perhaps sufficient. However, for scenarios when you will need to either tweak the prebuilt controls or create new controls by aggregating multiple simpler controls, the Windows Forms application model allows developers to create their own controls by subclassing the UserControl class. For instance, consider Listing 7.8, where a Phone control is created by using a set of TextBox and Label controls. The control also has its own property (Phone, read-only in this case) that provides the entered phone number. As shown in Figure 7.12, User control design and development is fully available within the Visual Studio .NET designer environment. Listing 7.8 User Controls using System; using System.Collections; using System.ComponentModel; using System.Drawing; using System.Data; using System.Windows.Forms; namespace WindowsControlLibrary1 { public class PhoneControl : UserControl { public String Phone { get { return "("+areaCodeBox.Text+") "+phoneNoBox1.Text+"-" +phoneNoBox2.Text; } } private Label areaCodeLabel; private Label phoneNumberLabel; private TextBox phoneNoBox1; private TextBox phoneNoBox2; private TextBox areaCodeBox; private System.ComponentModel.Container components = null; public PhoneControl() { InitializeComponent(); } protected override void Dispose( bool disposing ) { if( disposing ) { if( components != null ) components.Dispose(); } base.Dispose( disposing ); } private void InitializeComponent() { this.areaCodeLabel = new Label(); this.areaCodeBox = new TextBox(); this.phoneNoBox1 = new TextBox(); this.phoneNumberLabel = new Label(); this.phoneNoBox2 = new TextBox(); this.SuspendLayout(); // // areaCodeLabel // this.areaCodeLabel.Location = new Point(8, 16); this.areaCodeLabel.Name = "areaCodeLabel"; this.areaCodeLabel.Size = new Size(72, 20); this.areaCodeLabel.TabIndex = 0; this.areaCodeLabel.Text = "Area Code"; // // areaCodeBox // this.areaCodeBox.Location = new Point(96, 16); this.areaCodeBox.MaxLength = 3; this.areaCodeBox.Name = "areaCodeBox"; this.areaCodeBox.Size = new Size(32, 20); this.areaCodeBox.TabIndex = 1; this.areaCodeBox.Text = ""; // // phoneNoBox1 // this.phoneNoBox1.Location = new Point(96, 40); this.phoneNoBox1.MaxLength = 3; this.phoneNoBox1.Name = "phoneNoBox1"; this.phoneNoBox1.Size = new Size(32, 20); this.phoneNoBox1.TabIndex = 2; this.phoneNoBox1.Text = ""; // // phoneNumberLabel // this.phoneNumberLabel.Location = new Point(8, 40); this.phoneNumberLabel.Name = "phoneNumberLabel"; this.phoneNumberLabel.Size = new Size(80, 20); this.phoneNumberLabel.TabIndex = 2; this.phoneNumberLabel.Text = "Phone Number"; // // phoneNoBox2 // this.phoneNoBox2.Location = new Point(144, 40); this.phoneNoBox2.MaxLength = 4; this.phoneNoBox2.Name = "phoneNoBox2"; this.phoneNoBox2.Size = new Size(40, 20); this.phoneNoBox2.TabIndex = 3; this.phoneNoBox2.Text = ""; // // PhoneControl // this.Controls.Add(this.phoneNoBox2); this.Controls.Add(this.phoneNoBox1); this.Controls.Add(this.phoneNumberLabel); this.Controls.Add(this.areaCodeBox); this.Controls.Add(this.areaCodeLabel); this.Name = "PhoneControl"; this.Size = new Size(200, 72); this.Load += new System.EventHandler(this.PhoneControl_Load); this.ResumeLayout(false); } } } Figure 7.12. Phone User control. Using User ControlsAfter they are developed, user controls can be used within a Windows Forms application, shown in Listing 7.9 (developed using any .NET supported programming language), by adding the reference of the control library to the application (Figure 7.13). In Visual Studio .NET, you can add a reference to a related Windows controls project, and the user controls will be available for use visually using drag and drop under the My User controls Toolbox palette. Listing 7.9 Using User Controls using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; namespace UsingUserControls { public class Form1 : Form { private Button ShowButton; private Label PhoneLabel; private WindowsControlLibrary1.PhoneControl phoneControl; private Label label1; private System.ComponentModel.Container components = null; public Form1() { InitializeComponent(); } protected override void Dispose( bool disposing ) { if( disposing ) { if (components != null) { components.Dispose(); } } base.Dispose( disposing ); } private void InitializeComponent() { this.phoneControl = new WindowsControlLibrary1.PhoneControl(); this.ShowButton = new Button(); this.PhoneLabel = new Label(); this.label1 = new Label(); this.SuspendLayout(); // // phoneControl // this.phoneControl.Location = new Point(96, 8); this.phoneControl.Name = "phoneControl"; this.phoneControl.Size = new Size(200, 72); this.phoneControl.TabIndex = 0; // // ShowButton // this.ShowButton.Location = new Point(48, 112); this.ShowButton.Name = "ShowButton"; this.ShowButton.Size = new Size(192, 24); this.ShowButton.TabIndex = 1; this.ShowButton.Text = "Show Phone No"; this.ShowButton.Click += new EventHandler(ShowButton_Click); // // PhoneLabel // this.PhoneLabel.Location = new Point(8, 168); this.PhoneLabel.Name = "PhoneLabel"; this.PhoneLabel.Size = new Size(272, 24); this.PhoneLabel.TabIndex = 2; this.PhoneLabel.TextAlign = ContentAlignment.MiddleCenter; // // label1 // this.label1.Location = new Point(8, 0); this.label1.Name = "label1"; this.label1.Size = new Size(80, 80); this.label1.TabIndex = 3; this.label1.Text = "Phone No:"; this.label1.TextAlign = ContentAlignment.MiddleCenter; // // Form1 // this.AutoScaleBaseSize = new Size(5, 13); this.ClientSize = new Size(292, 197); this.Controls.Add(this.label1); this.Controls.Add(this.PhoneLabel); this.Controls.Add(this.ShowButton); this.Controls.Add(this.phoneControl); this.Name = "Form1"; this.Text = "Form1"; this.ResumeLayout(false); } [STAThread] static void Main() { Application.Run(new Form1()); } private void ShowButton_Click(object sender, System.EventArgs e) { PhoneLabel.Text = phoneControl.Phone; } } } Figure 7.13. Using Phone User controls. Third-party User ControlsA key reason for the existence of the User Control framework is to create a marketplace of user controls. Third-party independent software vendors can develop controls based on their core expertise (for instance, reporting controls, charting controls, and so on) and then make them available either commercially or using the Open Source licensing model. Users can then use these prebuilt sets of controls in their own applications and concentrate their efforts on developing business applications rather than spending months of effort in developing core controls.
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