Learn R Programming
RGtk2 (version 2.20.31)

pangoMacros: Pango Convenience Macros

Description

These macros and constants help you layout text with Pango.

Usage

pangoAscent(x)
pangoDescent(x)
pangoLbearing(x)
pangoRbearing(x)
PANGO_SCALE
pangoPixels(size)
PANGO_SCALE_LARGE
PANGO_SCALE_MEDIUM
PANGO_SCALE_SMALL
PANGO_SCALE_X_LARGE
PANGO_SCALE_X_SMALL
PANGO_SCALE_XX_LARGE
PANGO_SCALE_XX_SMALL

Arguments

x
A rectangle describing the glyph extents
size
A size on the Pango scale

Value

The requested quantity in the units of the provided rectangle.

Details

When positioning text, it is beneficial to know the extents of the glyphs being drawn. The macros pangoAscent, pangoDescent, pangoLbearing, and pangoRbearing perform simple math on the given rectangle (representing the glyph extents) to determine the corresponding properties. The "ascent" and "descent" are how high the glyph extends above and below the baseline, respectively. The "lbearing" and "rbearing" describe the left-most and right-most extents of the glyph.

The rest are merely constants for scaling. PANGO_SCALE is the factor by which device units are scaled to Pango units. To return to device units, use the pangoPixels. The rest are pre-fab factors for scaling by different degrees.