ID Number: Q74298
3.00 3.10
WINDOWS
Summary:
The GetTextExtent function can be used to calculate the extent of a
string. The value returned may need to be adjusted, depending upon the
style of the font. When an italic or bold font is requested and none
are available, the graphics device interface (GDI) may simulate those
styles using an existing raster or vector font.
More Information:
GDI-simulated bold and italic fonts both include overhangs. The
overhang is specified in a TEXTMETRIC structure obtained by calling
the GetTextMetrics function. The proper method for calculating the
extent of a line of italic or bold text is shown below:
dwExtent = GetTextExtent(hDC, lpString, nCount);
GetTextMetrics(hDC, &tm);
xExtent = LOWORD(dwExtent) - tm.tmOverhang;
Listed below are examples of italic text alignment. If the next
character is not italic, the overhang should not be subtracted
from the extent returned from the GetTextExtent function. The
overhang needs to be subtracted only when the next character has the
same style.
GetTextExtent yields
this as the extent:
||
/ / \/
/ / / / / / / /| |
/---/ / / / / / / | |
/ / /---/ /---/ /---/ |---|
/ / / / / / / / | |
----- / / / / / / | |
^ /\ /\
Overhang || ||
Because the next Start the nonitalic H
character is italic, here because it does not
start the next slant and would partially
character within the overwrite the previous
overhang of the italic character.
current character
The overhang for bold characters synthesized by GDI is generally 1
because GDI synthesizes bold fonts by outputting the text twice,
offsetting the second output by one pixel, effectively increasing the
width of each character by one pixel. Calculating the extent of the
bold text is similar to the method for italic text. The
GetTextExtent function always returns the extent of the text plus 1
for bold text. Thus by subtracting the tmOverhang(1), the proper
extent is achieved.
|| ||
|| ||
||===||
|| ||
|| ||
---<= This line represents the "extra" overhang of 1.
/\
||
GetTextExtent yields
this as the extent of the
bold H.
Additional reference words: 3.00 3.10 3.x