static void scale_render(GpsdViewerOsd *self, OsmGpsMap *map)
{
GpsdViewerOsdScale *scale = self->priv->scale;
if(!scale->surface)
return;
/* this only needs to be rendered if the zoom or latitude has changed */
gint zoom;
gfloat lat;
g_object_get(G_OBJECT(map), "zoom", &zoom, "latitude", &lat, NULL);
if(zoom == scale->zoom && lat == scale->lat)
return;
scale->zoom = zoom;
scale->lat = lat;
float m_per_pix = osm_gps_map_get_scale(map);
/* first fill with transparency */
g_assert(scale->surface);
cairo_t *cr = cairo_create(scale->surface);
cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
cairo_set_source_rgba(cr, 1.0, 0.0, 0.0, 0.0);
// pink for testing: cairo_set_source_rgba(cr, 1.0, 0.0, 0.0, 0.2);
cairo_paint(cr);
cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
/* determine the size of the scale width in meters */
float width = (GPSD_VIEWER_OSD_SCALE_W-GPSD_VIEWER_OSD_SCALE_FONT_SIZE/6) * m_per_pix;
/* scale this to useful values */
int exp = logf(width)*M_LOG10E;
int mant = width/pow(10,exp);
int width_metric = mant * pow(10,exp);
char *dist_str = NULL;
if(width_metric<1000)
dist_str = g_strdup_printf("%u m", width_metric);
else
dist_str = g_strdup_printf("%u km", width_metric/1000);
width_metric /= m_per_pix;
/* 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";
}
}
/* also convert this to full tens/hundreds */
exp = logf(width)*M_LOG10E;
mant = width/pow(10,exp);
int width_imp = mant * pow(10,exp);
char *dist_str_imp = g_strdup_printf("%u %s", width_imp, dist_imp_unit);
/* convert back to pixels */
width_imp *= imp_scale;
width_imp /= m_per_pix;
cairo_select_font_face (cr, "Sans",
CAIRO_FONT_SLANT_NORMAL,
CAIRO_FONT_WEIGHT_BOLD);
cairo_set_font_size (cr, GPSD_VIEWER_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_set_line_width (cr, GPSD_VIEWER_OSD_SCALE_FONT_SIZE/6);
cairo_move_to (cr, 2*GPSD_VIEWER_OSD_SCALE_FD, GPSD_VIEWER_OSD_SCALE_H2-GPSD_VIEWER_OSD_SCALE_FD);
cairo_text_path (cr, dist_str);
cairo_stroke (cr);
cairo_move_to (cr, 2*GPSD_VIEWER_OSD_SCALE_FD,
GPSD_VIEWER_OSD_SCALE_H2+GPSD_VIEWER_OSD_SCALE_FD + extents.height);
cairo_text_path (cr, dist_str_imp);
cairo_stroke (cr);
cairo_set_source_rgb(cr, 0.0, 0.0, 0.0);
cairo_move_to (cr, 2*GPSD_VIEWER_OSD_SCALE_FD, GPSD_VIEWER_OSD_SCALE_H2-GPSD_VIEWER_OSD_SCALE_FD);
cairo_show_text (cr, dist_str);
cairo_move_to (cr, 2*GPSD_VIEWER_OSD_SCALE_FD,
GPSD_VIEWER_OSD_SCALE_H2+GPSD_VIEWER_OSD_SCALE_FD + extents.height);
cairo_show_text (cr, dist_str_imp);
g_free(dist_str);
g_free(dist_str_imp);
/* 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, GPSD_VIEWER_OSD_SCALE_FONT_SIZE/3);
cairo_move_to (cr, GPSD_VIEWER_OSD_SCALE_FONT_SIZE/6, GPSD_VIEWER_OSD_SCALE_M);
cairo_rel_line_to (cr, 0, GPSD_VIEWER_OSD_SCALE_TICK);
cairo_rel_line_to (cr, width_metric, 0);
cairo_rel_line_to (cr, 0, -GPSD_VIEWER_OSD_SCALE_TICK);
cairo_stroke(cr);
cairo_move_to (cr, GPSD_VIEWER_OSD_SCALE_FONT_SIZE/6, GPSD_VIEWER_OSD_SCALE_I);
cairo_rel_line_to (cr, 0, -GPSD_VIEWER_OSD_SCALE_TICK);
cairo_rel_line_to (cr, width_imp, 0);
cairo_rel_line_to (cr, 0, +GPSD_VIEWER_OSD_SCALE_TICK);
cairo_stroke(cr);
/* draw black line */
cairo_set_source_rgba(cr, 0.0, 0.0, 0.0, 1.0);
cairo_set_line_width (cr, GPSD_VIEWER_OSD_SCALE_FONT_SIZE/6);
cairo_move_to (cr, GPSD_VIEWER_OSD_SCALE_FONT_SIZE/6, GPSD_VIEWER_OSD_SCALE_M);
cairo_rel_line_to (cr, 0, GPSD_VIEWER_OSD_SCALE_TICK);
cairo_rel_line_to (cr, width_metric, 0);
cairo_rel_line_to (cr, 0, -GPSD_VIEWER_OSD_SCALE_TICK);
cairo_stroke(cr);
cairo_move_to (cr, GPSD_VIEWER_OSD_SCALE_FONT_SIZE/6, GPSD_VIEWER_OSD_SCALE_I);
cairo_rel_line_to (cr, 0, -GPSD_VIEWER_OSD_SCALE_TICK);
cairo_rel_line_to (cr, width_imp, 0);
cairo_rel_line_to (cr, 0, +GPSD_VIEWER_OSD_SCALE_TICK);
cairo_stroke(cr);
cairo_destroy(cr);
}
static int dist2pixel(OsmGpsMap *map, float km) {
return 1000.0*km/osm_gps_map_get_scale(map);
}
