String Widths and Heights
In addition to retrieving character-width data for individual characters,
applications also need to compute the width and height of entire strings. Two
functions retrieve string-width and height measurements:
GetTextExtentPoint32, and
GetTabbedTextExtent. If the string does not contain tab characters, an application can use the
GetTextExtentPoint32 function to retrieve the width and height of a specified string. If the
string contains tab characters, an application should call the
GetTabbedTextExtent function.
Windows also supports a special function, called
GetTextExtentExPoint, that applications can use for word-wrapping operations. This function
returns the number of characters from a specified string that fit within a given
space.
Font Ascenders and Descenders
Some applications determine the line spacing between text lines of different
sizes by using a font's maximum ascender and descender. An application can
retrieve these values by calling the
GetTextMetrics function and then checking the
tmAscent and
tmDescent members of the
TEXTMETRIC.
The maximum ascent and descent are different from the typographic ascent and
descent. In TrueType fonts, the typographic ascent and descent are typically the
top of the "f" glyph and bottom of the "g" glyph. An application can retrieve
the typographic ascender and descender for a TrueType font by calling the
GetOutlineTextMetrics function and checking the values in the
otmMacAscent and
otmMacDescent members of the
OUTLINETEXTMETRIC structure. It is important to note that TrueType font metrics do not
correspond exactly to the metrics for Windows raster fonts, because TrueType font
metrics have been designed by Apple Computer, Inc. for consistency across a variety
of display and output devices.
The following figure shows the difference between the vertical text metric
values returned in the
NEWTEXTMETRIC and
OUTLINETEXTMETRIC structures. (The names beginning with
otm are members of the
OUTLINETEXTMETRIC structure.)
Font Dimensions
An application can retrieve the physical dimensions of a TrueType font by
calling the
GetOutlineTextMetrics function. An application can retrieve the physical dimensions of any other
font by calling the
GetTextMetrics function. To determine the dimensions of an output device, an application can
call the
GetDeviceCaps function.
GetDeviceCaps returns both physical and logical dimensions.
A logical inch is a measure Windows uses to present legible fonts on the
screen and is approximately 30 to 40 percent larger than a physical inch. The use of
logical inches precludes an exact match between the output of the screen and
printer. Developers should be aware that the text on a screen is not simply a
scaled version of the text that will appear on the page, particularly if graphics
are incorporated into the text.
- Software for developers
-
Delphi Components
.Net Components
Software for Android Developers
- More information resources
-
MegaDetailed.Net
Unix Manual Pages
Delphi Examples
- Databases for Amazon shops developers
-
Amazon Categories Database
Browse Nodes Database
