add a section on the XFT_DEBUG environment variable

Signed-off-by: Thomas E. Dickey <dickey@invisible-island.net>

1 files changed, 47 insertions, 2 deletions

diff --git a/man/Xft.man b/man/Xft.man
index 1b04e7b..04f040f 100644
--- a/man/Xft.man
+++ b/man/Xft.man
@@ -1372,7 +1372,7 @@ to render the data.
 	\fBint\fP	 \fIlen\fP);
 .PE
 Draw a list of glyphs associated with fonts at specified coordinates,
-passed as an array of 
+passed as an array of
 .I len
 .B XftGlyphFontSpec
 structures via the parameter
@@ -1450,7 +1450,7 @@ the X Render library.
 Finally,
 .BR XftGlyphFontSpecRender ()
 uses the X Render extension to draw the glyphs,
-with the appropriate 
+with the appropriate
 .BR XRenderCompositeText *()
 function according to the
 .IR width ,
@@ -1524,6 +1524,7 @@ copies the string and returns
 .BR FcTrue ,
 otherwise it returns
 .BR FcFalse .
+.\" *************************************************************************
 .SS Manipulating Font data
 .PS
 \fBvoid\fP \fBXftFontLoadGlyphs\fP (
@@ -1623,6 +1624,50 @@ and when cleaning up on failure in
 .BR XftFontInfoCreate ()
 and
 .BR XftFontOpenPattern ().
+.\" *************************************************************************
+.SH DEBUGGING
+.B Xft
+reads the environment variable
+.B XFT_DEBUG
+and converts that to an integer.
+Each bit in the resulting value tells
+.B Xft
+to print debugging information to the standard output:
+.TP 5
+1
+font-opening
+.TP 5
+2
+additional font-matching and opening (verbose)
+.TP 5
+4
+shows details about the
+.B XRenderPictFormat   
+which will be used.
+.TP 5
+8
+shows the string which 
+.BR XftDrawString8 ()
+will draw.
+.TP 5
+16
+shows which font-ids are matched.
+.TP 5
+32
+shows useful information about the glyphs which will be drawn
+.TP 5
+64
+shows an ASCII-art representation of the glyphs.
+.TP 5
+128
+shows details about the memory-cache management
+.TP 5
+256
+shows details about managing glyph cached-memory
+.TP 5
+512
+shows a report on memory-usage
+.\" *************************************************************************
 .SH COMPATIBILITY
 As of version 2 (May 2002),
 .B Xft