// Before placing a new label we need to see if the label overlaps over
// previously placed labels. This algorithm will be refactored a bit to try
// NE SE SW NW placements in the future.
void
try_and_insert_placement(simplet_lithograph_t *litho, PangoLayout *layout, double x, double y){
int width, height;
// Find the computed width and height of a layout in image pixels
pango_layout_get_pixel_size(layout, &width, &height);
simplet_bounds_t *bounds = simplet_bounds_new();
if(!bounds) return;
// Create a bounds to test for intersection
simplet_bounds_extend(bounds, floor(x - width / 2), floor(y - height / 2));
simplet_bounds_extend(bounds, floor(x + width / 2), floor(y + height / 2));
// Iterate through the list of already placed labels and check for overlaps.
simplet_listiter_t *iter = simplet_get_list_iter(litho->placements);
placement_t *placement;
while((placement = (placement_t *) simplet_list_next(iter))){
if(simplet_bounds_intersects(placement->bounds, bounds)){
simplet_bounds_free(bounds);
g_object_unref(layout);
simplet_list_iter_free(iter);
return;
}
}
// If we get here we can create and insert a new placement.
placement_t *plc = placement_new(layout, bounds);
if(!plc) {
simplet_bounds_free(bounds);
g_object_unref(layout);
return;
}
simplet_list_push(litho->placements, (void *)plc);
}
// Process a layer and add labels.
simplet_status_t
simplet_layer_process(simplet_layer_t *layer, simplet_map_t *map, simplet_lithograph_t *litho, cairo_t *ctx){
simplet_listiter_t *iter; OGRDataSourceH source;
if(!(source = OGROpenShared(layer->source, 0, NULL)))
return set_error(layer, SIMPLET_OGR_ERR, "error opening layer source");
// Retain the datasource because we want to cache open connections to a
// data source like postgres.
if(OGR_DS_GetRefCount(source) == 1) OGR_DS_Reference(source);
if(!(iter = simplet_get_list_iter(layer->filters))){
OGRReleaseDataSource(source);
return set_error(layer, SIMPLET_OOM, "out of memory getting list iterator");
}
// Loop through the layer's filters and process them.
simplet_filter_t *filter;
simplet_status_t status = SIMPLET_OK;
while((filter = simplet_list_next(iter))) {
status = simplet_filter_process(filter, map, source, litho, ctx);
if(status != SIMPLET_OK){
simplet_list_iter_free(iter);
OGRReleaseDataSource(source);
return status;
}
simplet_lithograph_apply(litho, filter->styles);
}
OGRReleaseDataSource(source);
return SIMPLET_OK;
}
// Apply the labels to the map.
void
simplet_lithograph_apply(simplet_lithograph_t *litho, simplet_list_t *styles){
simplet_listiter_t *iter = simplet_get_list_iter(litho->placements);
placement_t *placement;
cairo_save(litho->ctx);
while((placement = (placement_t *) simplet_list_next(iter))){
if(placement->placed == TRUE) continue;
cairo_move_to(litho->ctx, placement->bounds->nw.x, placement->bounds->se.y);
// Draw the placement
pango_cairo_layout_path(litho->ctx, placement->layout);
placement->placed = TRUE;
}
simplet_apply_styles(litho->ctx, styles, "text-stroke-weight", "text-stroke-color", "color", NULL);
// Apply and draw various outline options.
cairo_restore(litho->ctx);
}
