1 files changed, 56 insertions, 0 deletions
diff --git a/pkg/plot/hgpline.x b/pkg/plot/hgpline.x
new file mode 100644
index 00000000..50b3d9a8
--- /dev/null
+++ b/pkg/plot/hgpline.x
@@ -0,0 +1,56 @@
+include	<gset.h>
+
+
+# Any other type defaults to a connected line.
+define  PLOT_TYPES      "|line|lhist|bhist|"
+define	LINE		1		# Connected line
+define  LHIST		2		# Line histogram
+define  BHIST		3		# Box histogram
+
+procedure hgpline (gp, x, y, n, type)
+
+pointer	gp			#I GIO pointer
+real	x[ARB]			#I X coordinates
+real	y[ARB]			#I Y coordinates
+int	n			#I Number of coordinates
+char	type[ARB]		#I Plot type
+
+int	i
+real	x1, x2, bottom
+char	line[5]
+
+int	strdic()
+
+begin
+	# Draw lines.
+	switch (strdic (type, line, 5, PLOT_TYPES)) {
+	case LHIST:
+	    x1 = (3 * x[1] - x[2]) / 2
+	    call gamove (gp, x1, y[1])
+	    do i = 1, n-1 {
+		x2 = (x[i] + x[i+1]) / 2
+		call gadraw (gp, x2, y[i])
+		call gadraw (gp, x2, y[i+1])
+		x1 = x2
+	    }
+	    x2 = (3 * x[n] - x[n-1]) / 2
+	    call gadraw (gp, x2, y[n])
+	case BHIST:
+	    call ggwind (gp, x1, x2, bottom, x1)
+	    x1 = (3 * x[1] - x[2]) / 2
+	    call gamove (gp, x1, bottom)
+	    call gadraw (gp, x1, y[1])
+	    do i = 1, n-1 {
+		x2 = (x[i] + x[i+1]) / 2
+		call gadraw (gp, x2, y[i])
+		call gadraw (gp, x2, bottom)
+		call gadraw (gp, x2, y[i+1])
+		x1 = x2
+	    }
+	    x2 = (3 * x[n] - x[n-1]) / 2
+	    call gadraw (gp, x2, y[n])
+	    call gadraw (gp, x2, bottom)
+	default:
+	    call gpline (gp, x, y, n)
+	}
+end