IDWriteTextRenderer::DrawUnderline Method

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

Syntax

virtual HRESULT DrawUnderline(
  void * clientDrawingContext,
  FLOAT  baselineOriginX,
  FLOAT  baselineOriginY,
  [in]  const DWRITE_UNDERLINE * underline,
  IUnknown * clientDrawingEffect
) = 0;

Parameter

• 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 [in]
  Pointer to a structure containing underline logical information.

• clientDrawingEffect
  Application-defined effect to apply to the underline. Usually this argument represents effects such as the foreground brush filling the interior of a line.

Rückgabewert

Ist Methode erfolgreich, wird "S_OK" zurückgegeben. Andernfalls wird ein HRESULT-Fehlercode zurückgegeben.

Hinweise

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.

Anforderungen

Siehe auch

IDWriteTextRenderer