LineDisplayBase.DisplayText Method (String, DisplayTextMode)

2/27/2008

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

Syntax

'Declaration
Public Overrides Sub DisplayText ( _
    data As String, _
    attribute As DisplayTextMode _
)

public override void DisplayText (
    string data,
    DisplayTextMode attribute
)

public:
virtual void DisplayText (
    String^ data, 
    DisplayTextMode attribute
) override

public void DisplayText (
    String data, 
    DisplayTextMode attribute
)

public override function DisplayText (
    data : String, 
    attribute : DisplayTextMode
)

Parameters

• data
  The string of characters to display.

• attribute
  The display attribute for the text. Possible values are defined by the DisplayTextMode enumeration. Valid values are Normal or Blink.

Remarks

The characters in data are processed beginning at the location specified by the CursorRow and CursorColumn property settings, and continue in succeeding columns.

Character processing continues to the next row when the end of a window row is reached. If the end of the window is reached with additional characters to be processed, then the window is scrolled upward by one row and the bottom row is set to blanks. If the CursorUpdate property is set to true, then CursorRow and CursorColumn are updated to point to the character following the last character of data.

Note that scrolling will not occur when the last character of data is placed at the end of a row. In this case, when CursorUpdate is true, then CursorRow is set to the row containing the last character, and CursorColumn is set to the Columns setting (that is, to one more than the final character of the row). This stipulation ensures that the display does not scroll when a character is written into its last position. Instead, the window will not scroll until another character is written.

The operation of DisplayText (and DisplayTextAt) varies for each mode:

• Immediate mode (The MarqueeType property = None and the InterCharacterWait property = 0): Updates the window and viewport immediately.

• Teletype mode (MarqueeType = None and InterCharacterWait not = 0): The data is queued. Queued data requests are processed in order (typically by another thread within the service object), updating the window and viewport using a wait time in milliseconds of the InterCharacterWait property after each character is sent to the viewport.

• Marquee Init mode (MarqueeType = Init): Updates the window, but does not change the viewport.

• Marquee On mode (MarqueeType not = Init): Illegal.

If the service object has set the CapBlink property to NoBlink, then attribute is ignored. If it has been set to BlinkAll, then the entire display will blink when one or more characters have been set to blink. If it has been set to BlinkEach, then only those characters displayed with the blink attribute will blink.

Special character values within data are:

Value	Meaning
Carriage Return (13 Decimal)	Change the next character’s output position to the beginning of the current row.
Newline / Line Feed (10 Decimal)	Change the next character’s output position to the beginning of the next row. Scroll the window if the current row is the last row of the window.

The LineDisplayBase class ensures that the line display device has been opened, claimed, and enabled.

DisplayText may throw a PosControlException with the following ErrorCodes:

Value	Meaning
Illegal	One of the following conditions has occurred:The value specified for attribute wasn’t found in the DisplayTextMode enumeration; or DisplayText can’t be called when the device is in Marquee On Mode.

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 Class
LineDisplayBase Members
Microsoft.PointOfService.BaseServiceObjects Namespace
LineDisplay.DisplayText Method
DisplayTextMode Enumeration