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LineDisplayBase Class

  • Article

2/27/2008

Contains most of the functionality required for support of Line Display devices, including drawing of text and graphics (glyphs and bitmaps), window management, and scrolling, marquee, and teletype functions.

Namespace: Microsoft.PointOfService.BaseServiceObjects
Assembly: Microsoft.PointOfService.ControlBase (in microsoft.pointofservice.controlbase.dll)

Syntax

'Declaration
Public MustInherit Class LineDisplayBase
    Inherits LineDisplayBasic

public abstract class LineDisplayBase : LineDisplayBasic

public ref class LineDisplayBase abstract : public LineDisplayBasic

public abstract class LineDisplayBase extends LineDisplayBasic

public abstract class LineDisplayBase extends LineDisplayBasic

Remarks

The LineDisplayBase class derives from the LineDisplayBasic class and contains most of the functionality required for support of Line Display devices, including drawing of text and graphics (glyphs and bitmaps), window management, and scrolling, marquee, and teletype functions.

When deriving from LineDisplayBase, service objects should implement the CheckHealth and DirectIO methods. In addition, they should, at a minimum,-implement the following:

  • The DisplayData method: LineDisplayBase class calls the service object's implementation of DisplayData when data needs to be displayed on the line display screen. LineDisplayBase passes in an array of Cell classes that describe the position and the data to be displayed.

  • The LineDisplayScreenModes property: The LineDisplayScreenModes property returns a list of LineDisplayScreenMode classes that describe the supported screen sizes. Service objects should update LineDisplayScreenModes with the screen sizes supported for the line display device.

By default, LineDisplayBase class fully supports ReadBack, InterCharacterWait, and both horizontal and vertical marquee functions. In addition, the LineDisplayBase class partially supports the following:

  • Bitmaps. The service object must set the CapBitmap property to true to enable the LineDisplayBase class support of bitmaps.

  • Custom glyphs. The service object must set the CapCustomGlyph property to true to enable the LineDisplayBase class support of custom glyphs. Be default, the CustomGlyphList property is set to a full range of characters; if necessary, the service object can change the list to more accurately reflect the capabilities of the line display device.

  • Descriptors. The service object must set the CapDescriptors property to true to enable the LineDisplayBase class support of descriptors. In addition, the service object must implement the ClearDescriptorImpl and SetDescriptorImpl methods.

Note: Cursors, Blinking, Brightness, Reverse Video, and Character Sets functionality must be implemented by the service object.

The LineDisplayBase class provides the core functionality for opening, claiming, and enabling line display devices. Typically, though, service objects will want to override these methods to add their own custom processing. (An example would be to update device statistics during the Open method, or to bring the device online when the application enables it.) When overriding these methods, the service object must call the base class implementation.

Inheritance Hierarchy

System.Object
   Microsoft.PointOfService.PosDevice
     Microsoft.PointOfService.PosCommon
       Microsoft.PointOfService.LineDisplay
         Microsoft.PointOfService.BasicServiceObjects.LineDisplayBasic
          Microsoft.PointOfService.BaseServiceObjects.LineDisplayBase

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread-safe. Any instance members are not guaranteed to be thread-safe.

See Also

Reference

LineDisplayBase Members
Microsoft.PointOfService.BaseServiceObjects Namespace

Other Resources

Using Impl Methods for Synchronous or Asynchronous Output