Mirroring in the .NET Framework | Developing International Software

Glossary

ADO.NET: Stands for Microsoft ActiveX Data Objects for the .NET Framework. A set of classes that expose data-access services to the .NET programmer. ADO.NET supplies a rich set of components for creating distributed, data-sharing applications. It is an integral part of the .NET Framework, providing access to relational data, Extensible Markup Language (XML) integration, and application data.
Web Forms: Generally applies to the design-time technology that enables the authoring of ASP.NET pages in a visual designer.

The remainder of this chapter shows how to mirror Web Forms, Windows Forms, and message boxes. As was true for Web content, the DIR attribute can be used for mirroring text in Web Forms. The RightToLeft property-from the Control class-is valuable for providing RTL support for Windows Forms, whereas the MessageBox class supports RTL and mirroring for message boxes. In the sections that follow, you will learn how to take advantage of this support.

Mirrored Web Forms

In Microsoft Visual Studio .NET, you can create ASP.NET applications by using either Microsoft Visual Basic .NET or Microsoft Visual C# .NET. The guidelines that you should follow are basically the same as those you have just seen for mirroring Web content. When you design Arabic Web Forms pages, the best way to make text flow from right to left is to use the DIR attribute. As with Web content, this attribute is usually placed in the <HTML> tag or the <BODY> tag. Controls and HTML elements on the page then inherit the specified direction.

You can set the DIR attribute at a DOCUMENT object level. All the controls on the form will inherit the same settings. However, the DIR attribute can be used individually with other tags such as <TABLE> and in Web Forms controls, as in the following example, which allows items to be displayed from right to left:

 <TABLE dir="rtl" ...> <asp:TextBox dir="rtl" ...>

Mirrored Windows Forms

Glossary

Multiple-document interface (MDI): A UI in an application that allows the user to have more than one document open at the same time.
Windows Forms Designer: Provides a rapid development solution for creating Windows applications. It is the locus of visual, client-based forms design. Using the designer, you can add components, data controls, or Windows-based controls to a form.
Windows Forms controls: Reusable components that encapsulate UI functionality and are used in client-side Windows applications. Not only do Windows Forms provide many ready-to-use controls, they also provide the infrastructure for developing your own controls.

Windows applications created in the .NET Framework allow you to access operating-system services and to take advantage of other benefits that your user's computing environment provides. Also, you can access data using ADO.NET. Additionally, GDI+ allows you to do advanced drawing and painting within your forms. (For more information on GDI+, see Chapter 13, "Graphics Device Interface Plus.") Finally, your Windows applications can make calls to methods exposed through XML Web services.

Windows Forms can be standard windows, multiple-document interface (MDI) windows, dialog boxes, or display surfaces for graphical routines. The easiest way to define the UI for a form is to place controls on its surface. Forms are objects that have several functions. The objects expose properties that define the forms' appearance, methods which define their behavior, and events which define their interaction with the user. Windows Forms are controls because they inherit from the Control class. This class has a key property for RTL support-the RightToLeft property-which specifies whether the text is displayed from right to left. The form itself supports the RightToLeft property, as do all your controls.

The RightToLeft property takes one of the following values, as shown in Table 8-1.

Table 8-1 Values for the RightToLeft property.

Value	Description
Inherit	The direction in which the text is rendered is inherited from the parent control.
No	The text is rendered from left to right. This is the default value.
Yes	The text is rendered from right to left.

The effect of the RightToLeft property can differ slightly from one control to another, as shown later in Table 8-2 below. In the Form object, when you set the RightToLeft property to Yes, text displayed in the form's title bar is right-aligned and has an RTL reading order.

What about design time? The Windows Forms Designer takes into account the effects of the RightToLeft property on controls. For example, when you set the RightToLeft property of the form to Yes, the property automatically updates the display of the form in the designer, so that the form's caption appears in the title bar right-aligned, as at run time. When the RightToLeft property value is set to RightToLeft.Yes, the horizontal alignment of the control's elements is reversed, yet the elements' alignment values are unchanged. For example, in a TextBox control with the TextAlign property value of HorizontalAlignment.Left, text is displayed right-aligned, but the property value remains HorizontalAlignment.Left. However, if the RightToLeft property value is set to RightToLeft.Yes and if the TextAlign property is set to HorizontalAlignment.Right, the text is displayed left-aligned.

Windows Forms don't support mirroring directly, as they do the RightToLeft property. Instead, you create your own controls to be displayed as you need. You can develop your own RTLTreeview control, for example, which inherits from the Treeview control and changes its style to be mirrored.

On some occasions, you might want to create a basic form with settings and properties such as a watermark or a certain control layout that you will then use again within a project. Each new form can contain modifications to the original form template. The solution is to use Windows Forms inheritance, which is a feature offered with the .NET Framework class library. For example, using inheritance you can build your own mirrored form by inheriting from the System.Windows.Forms.Form class and changing the window style of System.-Windows.Forms.Form.

Table 8-2 on the following page explains how the RightToLeft property affects the Windows Forms controls and which of them need to be mirrored. The common effect of setting the RightToLeft property to Yes on all controls is that the base-text embedding (in other words, the overall direction of text rendering) is assumed to be right to left. Table 8-2 explains how the RightToLeft property affects the Windows Forms controls and indicates which of them need mirroring.

Table 8-2 Explains how the RightToLeft property affects the Windows Forms controls and indicates which of them need mirroring.

Control or Component	Right-to-Left Effect	Require Mirroring
Button	Sets the RTL reading order.	No
CheckBox	The check box is displayed on the right side of the text.	No
CheckedListBox	All the check boxes are displayed on the right side of the text.	No
ColorDialog	Not affected; depends on the language of the operating system.	No
ComboBox	Items in combo-box control are right-aligned.	No
ContextMenu	Appears right-aligned with RTL reading order.	No
DataGrid	Appears right-aligned with RTL reading order.	No
DateTimePicker	Not affected; depends on the language of the operating system.	No
DomainUpDown	Left-aligns the up and down buttons.	No
ErrorProvider	Not supported.	No
FontDialog	Depends on the language of the operating system.	No
GroupBox	The caption of the GroupBox is displayed right-aligned and allows all the contained controls to inherit this property.	No
VScrollBar	Displayed on the left side rather than right side of scrollable controls.	No
HScrollBar	Start with the scroll box right-aligned.	No
ImageList	Not required.	No
Label	Displayed right-aligned.	No
LinkLabel	Displayed right-aligned.	No
ListBox	Items in list box control are right-aligned.	No
ListView	Sets the reading order to RTL, while the elements stay left-aligned.	Yes
MainMenu	Displayed right-aligned with RTL reading order, during run time only and not in design time.	No
MonthCalendar	Not affected; depends on the language of the operating system.	No
NotifyIcon	Not supported.	No
NumericUpDown	Up and down buttons are left-aligned.	No
OpenFileDialog	Not affected; depends on the language of the operating system.	No
PageSetupDialog	Not affected; depends on the language of the operating system.	No
Panel	Allows all the contained controls to inherit this property.	Yes
PictureBox	Not supported.	No
PrintDialog	Not affected; depends on the language of the operating system.	No
PrintDocument	The vertical scroll bar becomes left-aligned and the horizontal scroll bar starts from the left.	No
PrintPreview	Not affected by this property.	Yes
PrintPreviewDialog	Text displayed in the title bar of a form is right-aligned.	No
ProgressBar	Not affected by this property.	Yes
RadioButton	The radio button is displayed on the right side of the text.	No
RichTextBox	Control elements that include text are displayed from right to left with RTL reading order.	No
SaveFileDialog	Not affected; depends on the language of the operating system.	No
Splitter	Not supported.	No
StatusBar	The text in the panels aligned to right with RTL reading order.	Yes
TabControl	Not affected by this property.	Yes
TextBox	Displays text from right to left with RTL reading order.	No
Timer	Not required.	No
ToolBar	Not affected by this property.	Yes
ToolTip	Sets the RTL reading order.	No
TrackBar	The scroll bar or track bar starts from the right side of the screen.	No
TreeView	Sets the RTL reading order only.	Yes

Message Boxes

As its name suggests, the MessageBox class represents the message box; the Show method of this class displays a message box that can contain text, buttons, and symbols that inform and instruct the user. The MessageBox class fully supports RTL reading order and mirroring. The Show method of the MessageBox class takes constants defined in the MessageBoxOptions enumeration as parameters. These constants include RtlReading and RightAlign, both of which enable the message box to display bidirectional text. The following code illustrates how to display an Arabic message box:

 [Visual Basic ] MessageBox.Show("...", "",  MessageBoxButtons.OK,  MessageBoxIcon.Question,  MessageBoxDefaultButton.Button1,  MessageBoxOptions.RtlReading Or MessageBoxOptions.RightAlign)

RtlReading is responsible for ensuring that the text in the message box is displayed with RTL reading order, with mirroring applied. RightAlign allows the text to be right-aligned only, but does not enforce RTL reading order or mirroring in the message box.