IV SV2Handle(SV *sv)
{
	if (SvGMAGICAL(sv))
		mg_get(sv);
	if (!sv_isobject(sv))
		croak("variable is not an object");
	SV *tsv = (SV*)SvRV(sv);
	if ((SvTYPE(tsv) != SVt_PVHV))
		croak("variable is not a hashref");
	if (!SvMAGICAL(tsv))
		croak("variable does not have magic");
	MAGIC *mg = mg_find(tsv,'P');
	if (!mg)
		croak("variable does not have right kind of magic");
	sv = mg->mg_obj;
	if (!sv_isobject(sv))
		croak("variable does not have really right kind of magic");
	return SvIV((SV*)SvRV(sv));
}

IV SV2Object(SV *sv, char *stash)
{
	if (!sv_isobject(sv)) {
		croak("variable is not an object");
		return 0;
	}
	sv = (SV*)SvRV(sv);
	if (strcmp(stash,HvNAME((HV*)SvSTASH(sv)))!=0) {
		croak("variable is not a %s",stash);
		return 0;
	}
	return SvIV(sv);
}

GDALColorEntry fetch_color(AV *a, int i)
{
	GDALColorEntry color;
	SV **s = av_fetch(a, i++, 0);
	color.c1 = s ? SvUV(*s) : 0;
	s = av_fetch(a, i++, 0);
	color.c2 = s ? SvUV(*s) : 0;
	s = av_fetch(a, i++, 0);
	color.c3 = s ? SvUV(*s) : 0;
	s = av_fetch(a, i++, 0);
	color.c4 = s ? SvUV(*s) : 0;
	return color;
}

#define RAL_FETCH(from, key, to, as)			\
    {SV **s = hv_fetch(from, key, strlen(key), 0);	\
	if (s) {					\
	    (to) = as(*s);				\
	}}

#define RAL_STORE(to, key, from, with) \
hv_store(to, key, strlen(key), with(from), 0);

int fetch2visual(HV *perl_layer, ral_visual *visual, OGRFeatureDefnH defn)
{
    /* these are mostly from the Geo::Layer object */
    SV **s = hv_fetch(perl_layer, "ALPHA", strlen("ALPHA"), 0);
    if (s && SvIOK(*s))
	visual->alpha = SvIV(*s);
    RAL_FETCH(perl_layer, "PALETTE_VALUE", visual->palette_type, SvIV);
    RAL_FETCH(perl_layer, "SYMBOL_VALUE", visual->symbol, SvIV);
    RAL_FETCH(perl_layer, "SYMBOL_SIZE", visual->symbol_pixel_size, SvIV);
    RAL_FETCH(perl_layer, "HUE_AT_MIN", visual->hue_at.min, SvIV);
    RAL_FETCH(perl_layer, "HUE_AT_MAX", visual->hue_at.max, SvIV);
    RAL_FETCH(perl_layer, "INVERT", visual->invert, SvIV);
    RAL_FETCH(perl_layer, "GRAYSCALE_SUBTYPE_VALUE", visual->scale, SvIV);
    s = hv_fetch(perl_layer, "SINGLE_COLOR", strlen("SINGLE_COLOR"), 0);
    if (s AND SvROK(*s)) {
	AV *a = (AV*)SvRV(*s);
	if (a)
	    visual->single_color = fetch_color(a, 0);
    }
    s = hv_fetch(perl_layer, "GRAYSCALE_COLOR", strlen("GRAYSCALE_COLOR"), 0);
    if (s AND SvROK(*s)) {
	AV *a = (AV*)SvRV(*s);
	if (a)
	    visual->grayscale_base_color = fetch_color(a, 0);
    }
    if (defn) {
	RAL_FETCH(perl_layer, "SYMBOL_FIELD_VALUE", visual->symbol_field, SvIV);
	if (visual->symbol_field >= 0) {
	    RAL_CHECK(ral_get_field_type(defn, visual->symbol_field, &(visual->symbol_field_type)));
	} else /* FID or fixed size */
	    visual->symbol_field_type = OFTInteger;
    } else
	visual->symbol_field = RAL_FIELD_UNDEFINED;
	
    switch (visual->symbol_field_type) {
    case OFTInteger:
	RAL_FETCH(perl_layer, "SYMBOL_SCALE_MIN", visual->symbol_size_scale_int.min, SvIV);
	RAL_FETCH(perl_layer, "SYMBOL_SCALE_MAX", visual->symbol_size_scale_int.max, SvIV);
	break;
    case OFTReal:
	RAL_FETCH(perl_layer, "SYMBOL_SCALE_MIN", visual->symbol_size_scale_double.min, SvNV);
	RAL_FETCH(perl_layer, "SYMBOL_SCALE_MAX", visual->symbol_size_scale_double.max, SvNV);
	break;
    default:
	RAL_CHECKM(0, ral_msg("Invalid field type for symbol scale: %s", OGR_GetFieldTypeName(visual->symbol_field_type)));
	break;
    }    
    
    if (defn) {
	RAL_FETCH(perl_layer, "COLOR_FIELD_VALUE", visual->color_field, SvIV);
	if (visual->color_field >= 0) {
	    RAL_CHECK(ral_get_field_type(defn, visual->color_field, &(visual->color_field_type)));
	} else /* FID */
	    visual->color_field_type = OFTInteger;
    } else
	visual->color_field = RAL_FIELD_UNDEFINED;
    
    switch (visual->color_field_type) {
    case OFTInteger:
	RAL_FETCH(perl_layer, "COLOR_SCALE_MIN", visual->color_scale_int.min, SvIV);
	RAL_FETCH(perl_layer, "COLOR_SCALE_MAX", visual->color_scale_int.max, SvIV);
	break;
    case OFTReal:
	RAL_FETCH(perl_layer, "COLOR_SCALE_MIN", visual->color_scale_double.min, SvNV);
	RAL_FETCH(perl_layer, "COLOR_SCALE_MAX", visual->color_scale_double.max, SvNV);
	break;
    case OFTString:
	break;
    default:
	RAL_CHECKM(0, ral_msg("Invalid field type for color scale: %s", OGR_GetFieldTypeName(visual->color_field_type)));
	break;
    }
	
    RAL_FETCH(perl_layer, "RENDER_AS_VALUE", visual->render_as, SvIV);
    s = hv_fetch(perl_layer, "COLOR_TABLE", strlen("COLOR_TABLE"), 0);
    if (visual->palette_type == RAL_PALETTE_COLOR_TABLE AND s AND SvROK(*s)) {
	AV *a = (AV*)SvRV(*s);
	int i, n = a ? av_len(a)+1 : 0;
	if (n > 0) {
	    switch (visual->color_field_type) {
	    case OFTInteger:
		RAL_CHECK(visual->color_table = ral_color_table_create(n));
		for (i = 0; i < n; i++) {
		    SV **s = av_fetch(a, i, 0);
		    AV *c;
		    RAL_CHECKM(s AND SvROK(*s) AND (c = (AV*)SvRV(*s)), "Bad color table data");
		    s = av_fetch(c, 0, 0);
		    visual->color_table->keys[i] = s ? SvIV(*s) : 0;
		    visual->color_table->colors[i] = fetch_color(c, 1);
		}
		break;
	    case OFTString:
		RAL_CHECK(visual->string_color_table = ral_string_color_table_create(n));
		for (i = 0; i < n; i++) {
		    STRLEN len;
		    SV **s = av_fetch(a, i, 0);
		    AV *c;
		    RAL_CHECKM(s AND SvROK(*s) AND (c = (AV*)SvRV(*s)), "Bad color table data");
		    s = av_fetch(c, 0, 0);
		    if (s)
			ral_string_color_table_set(visual->string_color_table, SvPV(*s, len), i, fetch_color(c, 1));
		}
		break;
	    default:
		RAL_CHECKM(0, ral_msg("Invalid field type for color table: %s", OGR_GetFieldTypeName(visual->color_field_type)));
	    }
	}
    }
    s = hv_fetch(perl_layer, "COLOR_BINS", strlen("COLOR_BINS"), 0);
    if (visual->palette_type == RAL_PALETTE_COLOR_BINS AND s AND SvROK(*s)) {
	AV *a = (AV*)SvRV(*s);
	int i, n = a ? av_len(a)+1 : 0;
	if (n > 0) {
	    switch (visual->color_field_type) {
	    case OFTInteger:
		RAL_CHECK(visual->int_bins = ral_int_color_bins_create(n));
		for (i = 0; i < n; i++) {
		    SV **s = av_fetch(a, i, 0);
		    AV *c;
		    RAL_CHECKM(s AND SvROK(*s) AND (c = (AV*)SvRV(*s)), "Bad color bins data");
		    s = av_fetch(c, 0, 0);
		    if (i < n-1)
			visual->int_bins->bins[i] = s ? SvIV(*s) : 0;
		    visual->int_bins->colors[i] = fetch_color(c, 1);
		}
		break;
	    case OFTReal:
		RAL_CHECK(visual->double_bins = ral_double_color_bins_create(n));
		for (i = 0; i < n; i++) {
		    SV **s = av_fetch(a, i, 0);
		    AV *c;
		    RAL_CHECKM(s AND SvROK(*s) AND (c = (AV*)SvRV(*s)), "Bad color bins data");
		    s = av_fetch(c, 0, 0);
		    if (i < n-1)
			visual->double_bins->bins[i] = s ? SvNV(*s) : 0;
		    visual->double_bins->colors[i] = fetch_color(c, 1);
		}
		break;
	    default:
		RAL_CHECKM(0, ral_msg("Invalid field type for color bins: %s", OGR_GetFieldTypeName(visual->color_field_type)));
	    }
	}
    }
    return 1;
fail:
    return 0;
}

void gtk2_ex_geo_pixbuf_2_ral_pixbuf(gtk2_ex_geo_pixbuf *pb, ral_pixbuf *rpb)
{
    rpb->image = pb->image;
    rpb->image_rowstride = pb->image_rowstride;
    rpb->pixbuf = pb->pixbuf;
    rpb->destroy_fn = pb->destroy_fn;
    rpb->colorspace = pb->colorspace;
    rpb->has_alpha = pb->has_alpha;
    rpb->rowstride = pb->rowstride;
    rpb->bits_per_sample = pb->bits_per_sample;
    rpb->N = pb->width;
    rpb->M = pb->height;
    rpb->world.min.x = pb->world_min_x;
    rpb->world.min.y = pb->world_max_y-pb->height*pb->pixel_size;
    rpb->world.max.x = pb->world_min_x+pb->width*pb->pixel_size;
    rpb->world.max.y = pb->world_max_y;
    rpb->pixel_size = pb->pixel_size;
}