is _clear_rectangle working ?

funcs/rectangle.c

@@ -6,6 +6,8 @@
 #include  <stdio.h>
 #include  <stdlib.h>
 #include  <stdint.h>
+#include  <string.h>
+
 #include  <math.h>
 
 #include  "../floatimg.h"
@@ -23,7 +25,11 @@ fprintf(stderr, ">>> %s ( %p %p )\n", __func__, pi, coo);
 
 for (line=0; line<coo[3]; line++) {
 	off = (line+coo[1])*pi->width + coo[0];
-	fprintf(stderr, "line %d off %d\n", line, off);
+	// fprintf(stderr, "line %3d   off %8d\n", line, off);
+	/* Kaboum ! */
+	memset(pi->R + off, 0, coo[2]*sizeof(float));
+	memset(pi->G + off, 0, coo[2]*sizeof(float));
+	memset(pi->B + off, 0, coo[2]*sizeof(float));
 	}
 
 return -1;

funcs/t.c

@@ -24,7 +24,7 @@ enum nCmd { Equalize=1, Rotate, Sfx0, F3x3, MIRE, Wfits, Wpng, Wtiff,
 			Histo, Hsv, Classif, Ctr2x2, Qsortrgb,
 			Displace, ReadPNG, Plasmas, Hilight, OpenEXR,
 			Geometrie, FileType, Mirror, KillRGB,
-			Pixelize,SplitLevel,DecompRgbz  };
+			Pixelize,SplitLevel,DecompRgbz, Rectangle  };
 typedef struct {
 	char	*name;
 	int	Cmd;
@@ -56,6 +56,7 @@ Command commands[] = {
 	{ "pixelize",	Pixelize	},
 	{ "spltlvl",	SplitLevel	},
 	{ "decomprgbz",	DecompRgbz	},
+	{ "rectangle",  Rectangle	},
 	{ NULL,		0		}
 	} ;
 
@@ -233,6 +234,10 @@ switch(opt) {
 	case DecompRgbz:
 		foo = essai_decomprgb(filename, outfile);
 		break;
+	case Rectangle:
+		essai_rectangle(outfile, 0);
+		break;
+
 	default:
 		fprintf(stderr, "'%s' is a bad command\n", command);
 		exit(1);

funcs/tests.c

@@ -17,6 +17,31 @@
 
 extern int		verbosity;
 
+/* --------------------------------------------------------------------- */
+int essai_rectangle(char *outf, int k)
+{
+FloatImg	img;
+int		foo;
+int		rect[4];
+
+foo = fimg_create(&img, 320, 240, FIMG_TYPE_RGB);
+
+fimg_drand48(&img, 1.0);
+
+rect[0] = 100;		rect[1] = 100;
+rect[2] = 32;		rect[3] = 16;
+
+foo = fimg_clear_rectangle(&img, rect);
+
+foo = fimg_export_picture(&img, outf, 0);
+if (foo) {
+	fprintf(stderr, "%s : err %d saving result\n", __func__, foo);
+	return foo;
+	}
+
+fimg_destroy(&img);
+return 0;
+}
 /* --------------------------------------------------------------------- */
 int essai_killrgb(char *inf, char *outf)
 {