[WWcvs] pg: WWPlot: add arrowTo() method, support for width in lineTo()

[Gavin L. v. a. <we...@ma...>]

Log Message:
-----------
WWPlot: add arrowTo() method, support for width in lineTo()

Modified Files:
--------------
    pg/lib:
        WWPlot.pm

Revision Data
-------------
Index: WWPlot.pm
===================================================================
RCS file: /webwork/cvs/system/pg/lib/WWPlot.pm,v
retrieving revision 1.3
retrieving revision 1.4
diff -Llib/WWPlot.pm -Llib/WWPlot.pm -u -r1.3 -r1.4
--- lib/WWPlot.pm
+++ lib/WWPlot.pm
@@ -142,16 +142,19 @@
 to access methods defined in GD but not supported directly by WWPlot. (See the documentation
 for GD.)
 
-=item moveTo, lineTo
+=item moveTo, lineTo, arrowTo
 
 	$graph->moveTo($x,$y);
 	$graph->lineTo($x,$y,$color);
-
-Moves to the point ($x, $y) (defined in real world coordinates) or draws a line from the
-current position to the specified point ($x, $y) using the color $color.  $color is the
-name, e.g. 'white',  of the color, not an index value or RGB specification.  These are
-low level call back routines used by the function, label and stamp objects to draw themselves.
-
+	$graph->lineTo($x,$y,$color,$thickness);
+	$graph->arrowTo($x,$y,$color);
+	$graph->arrowTo($x,$y,$color,$thickness);
+
+Moves to the point ($x, $y) (defined in real world coordinates) or draws a line or arrow
+from the current position to the specified point ($x, $y) using the color $color.  $color 
+is the name, e.g. 'white',  of the color, not an index value or RGB specification.  
+$thickness gives the thickness of the line or arrow to draw.  These are low level call 
+back routines used by the function, label and stamp objects to draw themselves.
 
 =item ii, jj
 
@@ -363,12 +366,17 @@
 
 sub lineTo {
 	my $self = shift;
-	my ($x,$y,$color) = @_;
+	my ($x,$y,$color, $w) = @_;
+	$w = 1 if ! defined( $w );
+
 	$x=$self->ii($x);
 	$y=$self->jj($y);
 	$color = $self->{'colors'}{$color} if $color=~/[A-Za-z]+/ && defined($self->{'colors'}{$color}) ; # colors referenced by name works here.
 	$color = $self->{'colors'}{'default_color'} unless defined($color);
+
+	$self->im->setThickness( $w );
 	$self->im->line(@{$self->position},$x,$y,$color);
+	$self->im->setThickness( 1 );
 	 #warn "color is $color";
 	@{$self->position} = ($x,$y);
 }
@@ -383,6 +391,44 @@
 	@{$self->position} = ( $x,$y );
 }
 
+sub arrowTo {
+	my $self = shift;
+	my ( $x1, $y1, $color, $w ) = @_;
+	$w = 1 if ! defined( $w );
+	my $width = ( $w == 1 ) ? 2 : $w;
+
+	$x1 = $self->ii($x1);
+	$y1 = $self->jj($y1);
+	$color = $self->{'colors'}{$color} if $color=~/[A-Za-z]+/ && defined($self->{'colors'}{$color}) ;
+	$color = $self->{'colors'}{'default_color'} unless defined($color);
+
+	## set thickness
+	$self->im->setThickness($w);
+
+	my ($x0, $y0) = @{$self->position};
+	my $dx = $x1 - $x0;
+	my $dy = $y1 - $y0;
+	my $len = sqrt($dx*$dx + $dy*$dy);
+	my $ux = $dx/$len;  ## a unit vector in the direction of the arrow
+	my $uy = $dy/$len;
+	my $px = -1*$uy;    ## a unit vector perpendicular
+	my $py = $ux;
+	my $hbx = $x1 - 5*$width*$ux;  ## the base of the arrowhead
+	my $hby = $y1 - 5*$width*$uy;
+	my $head = new GD::Polygon;
+	$head->addPt($x1,$y1);
+	$head->addPt($hbx + 2*$width*$px, $hby + 2*$width*$py);
+	$head->addPt($hbx - 2*$width*$px, $hby - 2*$width*$py);
+	$self->im->filledPolygon( $head, $color );
+	$self->im->line( $x0,$y0,$x1,$y1,$color );
+
+	@{$self->position} = ( $x1, $y1 );
+
+	## reset thickness
+	$self->im->setThickness(1);
+}
+
+
 sub v_axis {
 	my $self = shift;
 	@{$self->{vaxis}}=@_; # y_value, color