As you have seen earlier in this chapter, the GroupBox control can be used to logically bind a number of

Apress © 2003 (1200 pages)

controls (such as RadioButtons) to function as a collective. Closely related to the GroupBox is the Panel

This comprehensive text starts with a brief overview of the

control. Panels areC#alsolangusedage andto groupthen quicklyrelatedmcontrolsves to inkeya logicaltechnicalunitand. One difference is that the Panel type derives fromarchitethe ScrollableControltural issues for .class,NET developersand thus.it can support scroll bars, which is not possible with a GroupBox.

TablePanelsof Cocantentsbe used to conserve screen real estate. For example, if you have a group of controls that take C#upandthetheentire.NETbottomPlatform,halfSecondof a Form,Editionyou can contain them in a Panel that is half the size and set the IntroductiAutoScrolln property to true. In this way, the user can use the scroll bar(s) to view the hidden items. To

illustrate, let's update the previous TrackBar application. This time, each TrackBar is contained in a single

Part One - Introducing C# and the .NET Platform

Panel.Figure 15-17 shows the update.

Chapter 1 - The Philosophy of .NET

Chapter 2 - Building C# Applications

Part

Figure 15-17: Working with Panel types

Part Four - Leveraging the .NET Libraries

Chapter 12 - Object Serialization and the .NET Remoting Layer

The underlying code looks almost identical to that of manipulating a GroupBox. Begin by declaring a Panel

Chapter 13 - Building a Better Window (Introducing Windows Forms)

data member (panel1) and add each item using the Controls property, as shown here:

Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

// Configure the panel.

Chapter 16 - The System.IO Namespace panel1.AutoScroll = true;

Chapter 17 - Data Access with ADO.NET panel1.Controls.Add (this.label2);

Part Five - Web Applications and XML Web Services

panel1.Controls.Add (this.blueTrackBar);

Chapter 18 - ASP.NET Web Pages and Web Controls panel1.Controls.Add (this.label3);

Chapter 19 - ASP.NET Web Applications panel1.Controls.Add (this.greenTrackBar);

Chapter 20 - XML Web Services panel1.Controls.Add (this.redTrackBar);

Index

panel1.Controls.Add (this.label1);

List of Figures

List of Tables

SOURCE The Tracker application can be found under the Chapter 15 directory.

CODE

The UpDownC# andControls:the .NET PlatforDomainUpDown, Second Edition and NumericUpDown

Windows Forms provide two widgets that function as spin controls (also known as up/down controls). Like

Apress © 2003 (1200 pages)

the ComboBox and ListBox types, these new items also allow the user to choose an item from a range of

This comprehensive text starts with a brief overview of the

possible selectionsC#. Thelanguagedifferenceand thenis thatquicklywhenmovesusingtoakeyDomainUpDowntechnical and or NumericUpDown control, the information is selectedarchitecturalusing aissmallues forpair.NETof updevelopersand down. arrows. For example, check out Figure 15-18.

Table

C# and

Part

Chapter

Chapter

Part

Chapter 3 - C# Language Fundamentals

Figure 15-18: Working with UpDown types

Chapter 4 - Object-Oriented Programming with C#

ChapterGiven your5 -workExceptionswith previousand Object(andLifetimesimilar) types, you should find working with the UpDown widgets Chpainlesspter 6. The- InterfacesDomainUpDownand Collectionswidget allows the user to select from a set of string data. NumericUpDown

allows selections from a range of numeric data points. Each widget derives from a common direct base

Chapter 7 - Callback Interfaces, Delegat s, and Events

class: UpDownBase. Table 15-10 describes some important properties of this class.

Chapter 8 - Advanced C# Type Construction Techniques

Part Three - Programming with .NET Assemblies

Table 15-10: UpDownBase Properties

Chapter 9 - Understanding .NET Assemblies

List of Figures

The DomainUpDown control adds a small set of properties (Table 15-11) that allow you to configure and

List of Tables

manipulate the textual data in the widget.

Table 15-11: DomainUpDown Properties

The NumericUpDown type is just as simple (Table 15-12).

C# and the .NET Platform, Second Edition

Chapter 8 - Advanced C# Type Construction Techniques

// Configure DomainUpDown widget.

Part Three - Programming with .NET Assemblies

domainUpDown.Sorted = true;

Chapter 9 - Understanding .NET Assemblies domainUpDown.Wrap = true;

Chapter 10 - Processes, AppDomains, Contexts, and Threads

domainUpDown.Items.AddRange (new object[4] { "Another Boring String named B",

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

"Boring String A", "BORING String C", "Final Boring string (D)"});

Part Five - Web Applications and XML Web Services

The Click event handler for the Form's Button type simply asks each type for its current value and places it

Chapter 18 - ASP.NET Web Pages and Web Controls

in the appropriate Label as a formatted string, as shown here:

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

protected void btnGetSelections_Click (object sender, System.EventArgs e)

Index

{

List of Figures

// Get info from updowns...

List of Tables lblCurrSel.Text =

string.Format("String: {0}\nNumber: {1}", domainUpDown.Text, numericUpDown.Value);

}

Of course, the DomainUpDown and NumericUpDown types support a number of events. If you ever need to capture when the selection changes, you can use SelectedItemChanged (for DomainUpDown types) or ValueChanged (for NumericUpDown types). Here is an example:

// Intercept the SelectedItemChanged event.

domainUpDown.SelectedItemChanged

+= new EventHandler (domainUpDown_SelectedItemChanged);

...

// Handle the event.

protected void domainUpDown_SelectedItemChanged (object sender,

Apress © 2003 (1200 pages)

this.Text = "You changed the string value...";

}This comprehensive text starts with a brief overview of the C# language and then quickly moves to key technical and architectural issues for .NET developers.

SOURCE The UpAndDown application is included under the Chapter 15 directory.

Table of Contents

CODE

C# and the .NET Platform, Second Edition

Introduction

Part One - Introducing C# and the .NET Platform

Chapter 1 - The Philosophy of .NET

Chapter 2 - Building C# Applications

Part Two - The C# Programming Language

Chapter 3 - C# Language Fundamentals

Chapter 4 - Object-Oriented Programming with C#

Chapter 5 - Exceptions and Object Lifetime

Chapter 6 - Interfaces and Collections

Chapter 7 - Callback Interfaces, Delegates, and Events

Chapter 8 - Advanced C# Type Construction Techniques

Part Three - Programming with .NET Assemblies

Chapter 9 - Understanding .NET Assemblies

Chapter 10 - Processes, AppDomains, Contexts, and Threads

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Part Four - Leveraging the .NET Libraries

Chapter 12 - Object Serialization and the .NET Remoting Layer

Chapter 13 - Building a Better Window (Introducing Windows Forms)

Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables

Working withC# andthetheErrorProvider.NET latform, Second Edition

Most Windows Forms applications will need to validate user input in one way or another. This is especially

Apress © 2003 (1200 pages)

true with dialog boxes, as you should inform users if they make a processing error before continuing

This comprehensive text starts with a brief overview of the forward. (I'll examineC# languagedialog boxandprogrammingthen quickly moveslater intothiskeychaptertechnical.) and

architectural issues for .NET developers.

The ErrorProvider type can be used to provide a visual cue of user input error. For example, assume you have a Form containing a TextBox and Button widget. If the user enters more than five characters in the

TableTextBox,of Contentsthe error information shown in Figure 15-19 is displayed.

C# and the .NET Platform, Second Edition

Introduction

Part

Chapter

Chapter

Part

Chapter

ChapterFigure4 - 15Object-19:-TheOri ntedErrorProviderProgrammingactionw th C#

Chapter 5 - Exceptions and Object Lifetime

Chapter 6 - Interfaces and Collections

Here, you have detected that the user entered more than five characters and responded by placing a

Chapter 7 - Callback Interfaces, Delegates, and Events

small error icon (!) next to the TextBox object. When the user places the cursor over this icon, the

Chapter 8 - Advanced C# Type Construction Techniques

descriptive error text appears as a pop-up. Also, this ErrorProvider is configured to cause the icon to blink

Part Three - Programming with .NET Assemblies

a number of times to strengthen the visual cue (which, of course, you can't see without running the

Chapter 9 - Understanding .NET Assemblies application).

Chapter 10 - Processes, AppDomains, Contexts, and Threads

ChapterIf you wish11 -toTypesupportReflection,this typeLateofBinding,input validation,and Attributethe first-BasedstepProgrammingis to understand the properties of the

PartControlFourclass- Leveraging(Table 15the-13.NET). Libraries

Chapter 12 - Object Serialization and the .NET Remoting Layer

Table 15-13: Control Properties

Ch pter 13 - Buildi g a Better Window (Introducing Windows Forms)

Chapter 14 - A Better Painting Framework (GDI+)

Control Meaning in Life

Chapter 15 - Programming with Windows Forms Controls

Property

Chapter 16 - The System.IO Namespace

List of Figures

Every GUI widget can set the CausesValidation property to true or false. (The default is false.) If you set

List of Tables

this bit of state data to true, the control forces the other controls on the Form to validate themselves when it receives focus (provided the CausesValidation property is also set to true).

Once a validating control has received focus, the Validating and Validated events are fired for each control. It is in the scope of the Validating event handler in which you configure a corresponding ErrorProvider. Optionally, the Validated event can be handled to determine when the control has finished its validation cycle.

To begin, assume you have set the CausesValidation property to true for the Button and TextBox and have added a member variable of type ErrorProvider. Here is the configuration code:

// Configure the error provider.

errorProvider1.DataMember = "";

errorProvider1.DataSource = null;

errorProvider1.ContainerControl = null;

errorProvider1.BlinkStyle = System.Windows.Forms.ErrorBlinkStyle.AlwaysBlink;

errorProvider1.BlinkRate = 500;

C# and the .NET Platform, Second Edition

The ErrorProviderApresstype has© 2003a small(1200 pages)set of members. The most important item for your purposes is the BlinkStyle property,Thiswhichcomprehensivecan be settextto anystartsof thewithvaluesbriefofoverviewthe ErrorBlinkStyleof the enumeration described in Table 15-14. C# language and then quickly moves to key technical and

architectural issues for .NET developers.

Table 15-14: ErrorBlinkStyle Properties

Chapter 5 - Exceptions and Object Lifetime

Chapter 6 - Interfaces and Collections

The ErrorProvider also has additional members beyond BlinkStyle and BlinkRate. For example, if you wish

Chapter 7 - Callback Interfaces, Delegates, and Events

to associate a custom icon to the error, you can do so using the Icon property. Nevertheless, once you

Chapter 8 - Advanced C# Type Construction Techniques

have configured how the ErrorProvider looks and feels, you bind the error to the TextBox within the scope

Part Three - Programming with .NET Assemblies

of its Validating event handler, as shown here:

Chapter 9 - Understanding .NET Assemblies

Chapter 10 - Processes, AppDomains, Contexts, and Threads

protected void txtInput_Validating (object sender, CancelEventArgs e)

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

{

Part Four - Leveraging the .NET Libraries

// Check if the text length is greater than 5.

Chapter 12 - Object Serialization and the .NET Remoting Layer if(txtInput.Text.Length > 5)

Chapter 13 - Building a Better Window (Introducing Windows Forms)

{

Chapter 14 - A Better Painting Framework (GDI+)

errorProvider1.SetError(txtInput, "Can't be greater than 5!");

Chapter 15 - Programming with Windows Forms Controls

}

Chapter else16 - The//SystemThings.IO NaremespaceOK, don't show anything.

Chapter 17 - DataerrorProvider1Access w th ADO..SetError(txtInput,NET "");

Part} Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

SOURCE The ErrorProvider application is included under the Chapter 15 directory.

Index

CODE

List of Figures

List of Tables