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IDWriteTextRenderer1::DrawUnderline method (dwrite_2.h)

  • Article

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

Syntax

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

Parameters

clientDrawingContext

Type: void*

The application-defined drawing context passed to IDWriteTextLayout::Draw.

baselineOriginX

Type: FLOAT

The pixel location (X-coordinate) at the baseline origin of the run where underline applies.

baselineOriginY

Type: FLOAT

The pixel location (Y-coordinate) at the baseline origin of the run where underline applies.

orientationAngle

Type: DWRITE_GLYPH_ORIENTATION_ANGLE

Orientation of the underline.

[in] underline

Type: const DWRITE_UNDERLINE*

Pointer to a structure containing underline logical information.

clientDrawingEffect

Type: IUnknown*

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

Type: HRESULT

If this 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.

Requirements

Requirement Value
Minimum supported client Windows 7, Windows Vista with SP2 and Platform Update for Windows Vista [desktop apps | UWP apps]
Minimum supported server Windows Server 2008 R2, Windows Server 2008 with SP2 and Platform Update for Windows Server 2008 [desktop apps | UWP apps]
Target Platform Windows
Header dwrite_2.h
Library Dwrite.lib
DLL Dwrite.dll

See also

IDWriteTextRenderer1