From b776e24947fd8fda0c3a6735625d1c3d4506438a Mon Sep 17 00:00:00 2001 From: Stephen Adams Date: Fri, 12 Jul 1996 18:51:05 +0000 Subject: [PATCH] Added X-graphics documentation about DRAW-CIRCLE and FILL-CIRCLE. --- v7/doc/ref-manual/scheme.texinfo | 55 +++++++++++++++++++++++++++++++- 1 file changed, 54 insertions(+), 1 deletion(-) diff --git a/v7/doc/ref-manual/scheme.texinfo b/v7/doc/ref-manual/scheme.texinfo index 1117b2ef0..792dafd03 100644 --- a/v7/doc/ref-manual/scheme.texinfo +++ b/v7/doc/ref-manual/scheme.texinfo @@ -2,7 +2,7 @@ @iftex @finalout @end iftex -@comment $Id: scheme.texinfo,v 1.62 1996/04/16 20:29:18 cph Exp $ +@comment $Id: scheme.texinfo,v 1.63 1996/07/12 18:51:05 adams Exp $ @comment %**start of header (This is for running Texinfo on a region.) @setfilename scheme @settitle MIT Scheme Reference @@ -17396,6 +17396,59 @@ names, like @code{"red"}, and intensity names specified in the @code{"#@var{rrggbb}"} notation. @end defop +@defop {operation+} x-graphics-device draw-arc x y radius-x radius-y angle-start angle-sweep fill? +@cindex drawing arcs and circles, graphics +@cindex graphics, drawing arcs and circles +@cindex circles, drawing +@findex draw-arc + +Operation @code{draw-arc} draws or fills an arc. An arc is a segment of +a circle, which may have been stretched along the x- or y- axis to form +an ellipse. + +The parameters @var{X}, @var{Y}, @var{RADIUS-X} and @var{RADIUS-Y} +describe the circle and @var{ANGLE-START} and @var{ANGLE-SWEEP} choose +which part of the circle is drawn. The arc is drawn on the graphics +device with the center of the circle at the virtual coordinates given by +@var{X} and @var{Y}. @var{RADIUS-X} and @var{RADIUS-Y} determine the +size of the circle in virtual coordinate units. + +The parameter @var{ANGLE-START} determines where the arc starts. It is +measured in degrees in an anti-clockwise direction, starting at 3 +o'clock. @var{ANGLE-SWEEP} determines how much of the circle is drawn. +It too is measured anti-clockwise in degrees. A negative value means +the measurement is in a clockwise direction. + +Note that the angles are determined on a unit circle before it is +stretched into an ellipse, so the actual angles that you will see on the +computer screen depends on all of: @var{RADIUS-X} and @var{RADIUS-Y}, +the window size, and the virtual coordinates. + +If @var{fill?} is @code{#F} then just the segment of the circle is +drawn, otherwise the arc is filled in a pie-slice fashion. + +This draws a quarter circle pie slice, standing on its point, with point +at virtual coordinates (3,5): + +@example +(graphics-opereration g 'draw-arc 3 5 .5 .5 45 90 #T) +@end example + +@end defop + +@defop {operation+} x-graphics-device draw-circle x y radius +@defopx {operation+} x-graphics-device fill-circle x y radius +@cindex drawing arcs and circles, graphics +@cindex graphics, drawing arcs and circles +@cindex circles, drawing +@findex draw-circle +@findex fill-circle +These operations draw a circle (outline) or a filled circle (solid) at +on the graphics device at the virtual coordinates given by @var{X} and +@var{Y}. These operations could be implemented trivially interms of the +@code{draw-arc} operation. +@end defop + @defop {operation+} x-graphics-device set-border-width width @defopx {operation+} x-graphics-device set-internal-border-width width @findex graphics-clear -- 2.25.1