Doc: Usage added command for transparent pngs

Undocumented option to produce transparent png files
using lilypond command.

Even with @small example this line is too long (produces ugly black bars in PDF)
but lilypond command cannot be used with '/' for new lines.

So we have to list it on a single line.

diff --git a/Documentation/usage/external.itely b/Documentation/usage/external.itely
index 01e637bdc9726ccdc5fbe64caf6191a5b4060aeb..249e467a47eb7b1ac17c5cadf4c4799b05d7a5b9 100644 (file)
--- a/Documentation/usage/external.itely
+++ b/Documentation/usage/external.itely
@@ -546,15 +546,24 @@ the following options
 @{ c1 @}
 @end example
 
-To produce a useful @file{EPS} file, use
+To produce useful image files:
 
 @example
-lilypond -dbackend=eps -dno-gs-load-fonts -dinclude-eps-fonts   myfile.ly
+EPS
+
+lilypond -dbackend=eps -dno-gs-load-fonts -dinclude-eps-fonts myfile.ly
+
+PNG
 
-@file{PNG}:
 lilypond -dbackend=eps -dno-gs-load-fonts -dinclude-eps-fonts --png myfile.ly
+
+A transparent PNG
 @end example
 
+@smallexample
+lilypond -dbackend=eps -dno-gs-load-fonts -dinclude-eps-fonts -dpixmap-format=pngalpha --png myfile.ly
+@end smallexample
+
 
 @node Independent includes
 @section Independent @code{include}s