RenderingMode

0 = DWRITE_RENDERING_MODE_DEFAULT

 Specifies that the rendering mode is determined automatically based on the font and size.

1 = DWRITE_RENDERING_MODE_ALIASED

 Specifies that no antialiasing is performed. Each pixel is either set to the foreground 
 color of the text or retains the color of the background.

2 = DWRITE_RENDERING_MODE_GDI_CLASSIC

 Specifies that antialiasing is performed in the horizontal direction and the appearance
 of glyphs is layout-compatible with GDI using CLEARTYPE_QUALITY. Use DWRITE_MEASURING_MODE_GDI_CLASSIC 
 to get glyph advances. The antialiasing may be either ClearType or grayscale depending on
 the text antialiasing mode.

3 = DWRITE_RENDERING_MODE_GDI_NATURAL

 Specifies that antialiasing is performed in the horizontal direction and the appearance
 of glyphs is layout-compatible with GDI using CLEARTYPE_NATURAL_QUALITY. Glyph advances
 are close to the font design advances, but are still rounded to whole pixels. Use
 DWRITE_MEASURING_MODE_GDI_NATURAL to get glyph advances. The antialiasing may be either
 ClearType or grayscale depending on the text antialiasing mode.

4 = DWRITE_RENDERING_MODE_NATURAL

 Specifies that antialiasing is performed in the horizontal direction. This rendering
 mode allows glyphs to be positioned with subpixel precision and is therefore suitable
 for natural (i.e., resolution-independent) layout. The antialiasing may be either
 ClearType or grayscale depending on the text antialiasing mode.

5 = DWRITE_RENDERING_MODE_NATURAL_SYMMETRIC

 Similar to natural mode except that antialiasing is performed in both the horizontal
 and vertical directions. This is typically used at larger sizes to make curves and
 diagonal lines look smoother. The antialiasing may be either ClearType or grayscale
 depending on the text antialiasing mode.

6 = DWRITE_RENDERING_MODE_OUTLINE

 Specifies that rendering should bypass the rasterizer and use the outlines directly. 
 This is typically used at very large sizes.