DrawUnderline Method (TextRendererBase)

IDWriteTextLayout::Draw calls this function to instruct the client to draw an underline.

Syntax

Visual Basic
C#

'Declaration
 
Public Overridable Function DrawUnderline( _
   ByVal clientDrawingContext As System.Object, _
   ByVal baselineOriginX As System.Single, _
   ByVal baselineOriginY As System.Single, _
   ByRef underline As Underline, _
   ByVal clientDrawingEffectPtr As System.IntPtr _
) As HResult

public virtual HResult DrawUnderline( 
   System.object clientDrawingContext,
   System.float baselineOriginX,
   System.float baselineOriginY,
   ref Underline underline,
   System.IntPtr clientDrawingEffectPtr
)

Parameters

clientDrawingContext: The application-defined drawing context passed to IDWriteTextLayout::Draw.
baselineOriginX: The pixel location (X-coordinate) at the baseline origin of the run where underline applies.
baselineOriginY: The pixel location (Y-coordinate) at the baseline origin of the run where underline applies.
underline: Pointer to a structure containing underline logical information.
clientDrawingEffectPtr: Application-defined effect to apply to the underline. Usually this argument represents effects such as the foreground brush filling the interior of a line.

Return Value

If the method succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

A single underline can be broken into multiple calls, depending on how the formatting changes attributes. If font sizes/styles change within an underline, the thickness and offset will be averaged weighted according to characters. To get an appropriate starting pixel position, add underline::offset to the baseline. Otherwise there will be no spacing between the text. The x coordinate will always be passed as the left side, regardless of text directionality. This simplifies drawing and reduces the problem of round-off that could potentially cause gaps or a double stamped alpha blend. To avoid alpha overlap, round the end points to the nearest device pixel.

Reference

TextRendererBase Class
TextRendererBase Members