ComponentOne Bitmap for WinForms
C1.Win.C1DX.4.5.2 Assembly / C1.Util.DX.DirectWrite Namespace / TextRendererBase Class / DrawUnderline Method
The application-defined drawing context passed to IDWriteTextLayout::Draw.
The pixel location (X-coordinate) at the baseline origin of the run where underline applies.
The pixel location (Y-coordinate) at the baseline origin of the run where underline applies.
Pointer to a structure containing underline logical information.
Application-defined effect to apply to the underline. Usually this argument represents effects such as the foreground brush filling the interior of a line.

In This Topic
    DrawUnderline Method (TextRendererBase)
    In This Topic
    IDWriteTextLayout::Draw calls this function to instruct the client to draw an underline.
    Syntax
    '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.
    See Also