mm2gv hue2rgb: write output to an agxbuf instead of a raw string

This allows removing an `sprintf` call as well as a further temporary buffer.

Gitlab: #1950

diff --git a/cmd/tools/mm2gv.c b/cmd/tools/mm2gv.c
index 5c57d1b470252ca976b20e4cb921234b09854460..8ca3d370bd5800bb3f021ca85e80827b52e438ae 100644 (file)
--- a/cmd/tools/mm2gv.c
+++ b/cmd/tools/mm2gv.c
@@ -57,8 +57,7 @@ static double Hue2RGB(double v1, double v2, double H)
     return v1;
 }
 
-static char *hue2rgb(double hue, char *color)
-{
+static char *hue2rgb(double hue, agxbuf *xb) {
     double v1, v2, lightness = .5, saturation = 1;
     int red, blue, green;
 
@@ -72,8 +71,8 @@ static char *hue2rgb(double hue, char *color)
     red = (int) (255.0 * Hue2RGB(v1, v2, hue + 1.0 / 3.0) + 0.5);
     green = (int) (255.0 * Hue2RGB(v1, v2, hue) + 0.5);
     blue = (int) (255.0 * Hue2RGB(v1, v2, hue - 1.0 / 3.0) + 0.5);
-    sprintf(color, "#%02x%02x%02x", red, green, blue);
-    return color;
+    agxbprint(xb, "#%02x%02x%02x", red, green, blue);
+    return agxbuse(xb);
 }
 
 static Agraph_t *makeDotGraph(SparseMatrix A, char *name, int dim,
@@ -92,7 +91,6 @@ static Agraph_t *makeDotGraph(SparseMatrix A, char *name, int dim,
     double *val = A->a;
     Agnode_t **arr = gv_calloc(A->m, sizeof(Agnode_t*));
     double *color = NULL;
-    char cstring[8];
 
     name = strip_dir(name);
 
@@ -188,7 +186,7 @@ static Agraph_t *makeDotGraph(SparseMatrix A, char *name, int dim,
                agxset(e, sym, agxbuse(&xb));
            }
            if (with_color) {
-               agxset (e, sym2, hue2rgb(.65 * color[j], cstring));
+               agxset(e, sym2, hue2rgb(.65 * color[j], &xb));
                agxbprint(&xb, "%f", color[j]);
                agxset(e, sym3, agxbuse(&xb));
            }