--- trunk/src/osm-gps-map-osd-classic.c	2009/09/08 10:24:11	100
+++ trunk/src/osm-gps-map-osd-classic.c	2009/09/08 19:08:37	102
@@ -736,6 +736,8 @@
     return g_strdup_printf("%u km", dist/1000);
 }
 
+#define OSD_SCALE_FONT_SIZE 12
+
 static void
 osd_render_scale(osm_gps_map_osd_t *osd) 
 {
@@ -752,56 +754,74 @@
 
     /* determine the size of the scale width in meters */
     float width = (OSD_SCALE_W-2) * m_per_pix;
-    printf("width = %f meters\n", width);
-
+    printf("%d pixels is %f m\n", OSD_SCALE_W-2, width);
+    
     /* scale this to useful values */
     int exp = logf(width)*M_LOG10E;
     int mant = width/pow(10,exp);
-    printf("mant = %d, exp = %d \n", mant, exp);
-
     int width_metric = mant * pow(10,exp);
     char *dist_str = dist_str_metric(width_metric);
     width_metric /= m_per_pix;
-    printf("metric scale width = %d pixels: %s\n", width_metric, dist_str);
 
-    int font_size = 12;
+    /* and now the hard part: scale for useful imperial values :-( */
+    /* try to convert to feet, 1ft == 0.3048 m */
+    width /= 0.3048;
+    float imp_scale = 0.3048;
+    char *dist_imp_unit = "ft";
+
+    if(width >= 100) {
+        /* 1yd == 3 feet */
+        width /= 3.0;
+        imp_scale *= 3.0;
+        dist_imp_unit = "yd";
+
+        if(width >= 1760.0) {
+            /* 1mi == 1760 yd */
+            width /= 1760.0;
+            imp_scale *= 1760.0;
+            dist_imp_unit = "mi";
+        }
+    }
+
+    printf("this is %f %s\n", width, dist_imp_unit);
+    printf("this is %f pixels\n", width * imp_scale / m_per_pix);
 
     cairo_select_font_face (cr, "Sans",
                             CAIRO_FONT_SLANT_NORMAL,
                             CAIRO_FONT_WEIGHT_BOLD);
-    cairo_set_font_size (cr, font_size);
+    cairo_set_font_size (cr, OSD_SCALE_FONT_SIZE);
     cairo_set_source_rgba(cr, 0.0, 0.0, 0.0, 1.0);
 
     cairo_text_extents_t extents;
     cairo_text_extents (cr, dist_str, &extents);
 
     cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);
-    cairo_move_to (cr, font_size/3, font_size);
+    cairo_move_to (cr, OSD_SCALE_FONT_SIZE/3, OSD_SCALE_FONT_SIZE);
     cairo_text_path (cr, dist_str);
     cairo_set_line_width (cr, 2);
     cairo_stroke (cr);
 
     cairo_set_source_rgb(cr, 0.0, 0.0, 0.0);
-    cairo_move_to (cr, font_size/3, font_size);
+    cairo_move_to (cr, OSD_SCALE_FONT_SIZE/3, OSD_SCALE_FONT_SIZE);
     cairo_show_text (cr, dist_str);
 
     /* draw white line */
     cairo_set_line_cap  (cr, CAIRO_LINE_CAP_ROUND);
     cairo_set_source_rgba(cr, 1.0, 1.0, 1.0, 1.0);
     cairo_set_line_width (cr, 4);
-    cairo_move_to (cr, 2, 2*font_size/3);
-    cairo_rel_line_to (cr, 0,  2*font_size/3);
+    cairo_move_to (cr, 2, 2*OSD_SCALE_FONT_SIZE/3);
+    cairo_rel_line_to (cr, 0,  2*OSD_SCALE_FONT_SIZE/3);
     cairo_rel_line_to (cr, width_metric, 0);
-    cairo_rel_line_to (cr, 0, -2*font_size/3);
+    cairo_rel_line_to (cr, 0, -2*OSD_SCALE_FONT_SIZE/3);
     cairo_stroke(cr);
 
     /* draw black line */
     cairo_set_source_rgba(cr, 0.0, 0.0, 0.0, 1.0);
     cairo_set_line_width (cr, 2);
-    cairo_move_to (cr, 2, 2*font_size/3);
-    cairo_rel_line_to (cr, 0,  2*font_size/3);
+    cairo_move_to (cr, 2, 2*OSD_SCALE_FONT_SIZE/3);
+    cairo_rel_line_to (cr, 0,  2*OSD_SCALE_FONT_SIZE/3);
     cairo_rel_line_to (cr, width_metric, 0);
-    cairo_rel_line_to (cr, 0, -2*font_size/3);
+    cairo_rel_line_to (cr, 0, -2*OSD_SCALE_FONT_SIZE/3);
     cairo_stroke(cr);
 
     /* xyz */