File: TypeMetric.tex

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\section{Magick::TypeMetric}
\scriptsize{
\begin{verbatim}

The TypeMetric class provides the means to pass data from the Image class's
TypeMetric method to the user. It provides information regarding font
metrics such as ascent, descent, text width, text height, and maximum
horizontal advance. The units of these font metrics are in pixels, and that
the metrics are dependent on the current Image font (default Ghostscript's
"Helvetica"), pointsize (default 12 points), and x/y resolution (default 72
DPI) settings.

The pixel units may be converted to points (the standard
resolution-independent measure used by the typesetting industry) via the
following equation:

     size_points = (size_pixels * 72)/resolution

where resolution is in dots-per-inch (DPI). This means that at the default
image resolution, there is one pixel per point.

Note that a font's pointsize is only a first-order approximation of the font
height (ascender + descender) in points. The relationship between the
specified pointsize and the rendered font height is determined by the font
designer.

 See FreeType Glyph Conventions for a detailed description of font metrics
related issues.

The methods available in the TypeMetric class are shown in the following
table:

                             TypeMetric Methods

 Method               Returns  Units  Signature  Description

                                                 Returns the distance in
                                                 pixels from the text
                                                 baseline to the
 ascent               double   Pixels void       highest/upper grid
                                                 coordinate used to place
                                                 an outline point. Always a
                                                 positive value.

                                                 Returns the the distance
                                                 in pixels from the
 descent              double   Pixels void       baseline to the lowest
                                                 grid coordinate used to
                                                 place an outline point.
                                                 Always a negative value.


 textWidth            double   Pixels void       Returns text width in
                                                 pixels.


 textHeight           double   Pixels void       Returns text height in
                                                 pixels.

                                                 Returns the maximum
                                                 horizontal advance
 maxHorizontalAdvance double   Pixels void       (advance from the
                                                 beginning of a character
                                                 to the beginning of the
                                                 next character) in pixels.




\end{verbatim}
}