Adds support for zoom level rules

include/mapcache.h

@@ -103,6 +103,8 @@ typedef struct mapcache_image mapcache_image;
 typedef struct mapcache_grid mapcache_grid;
 typedef struct mapcache_grid_level mapcache_grid_level;
 typedef struct mapcache_grid_link mapcache_grid_link;
+typedef struct mapcache_rule mapcache_rule;
+typedef struct mapcache_ruleset mapcache_ruleset;
 typedef struct mapcache_context mapcache_context;
 typedef struct mapcache_dimension mapcache_dimension;
 typedef struct mapcache_requested_dimension mapcache_requested_dimension;
@@ -834,6 +836,11 @@ struct mapcache_cfg {
    */
   apr_hash_t *grids;
 
+  /**
+   * hashtable containing (pre)defined rulesets
+   */
+  apr_hash_t *rulesets;
+
   /**
    * the format to use for some miscelaneaous operations:
    *  - creating an empty image
@@ -888,9 +895,11 @@ MS_DLL_EXPORT mapcache_cache* mapcache_configuration_get_cache(mapcache_cfg *con
 mapcache_grid *mapcache_configuration_get_grid(mapcache_cfg *config, const char *key);
 MS_DLL_EXPORT mapcache_tileset* mapcache_configuration_get_tileset(mapcache_cfg *config, const char *key);
 mapcache_image_format *mapcache_configuration_get_image_format(mapcache_cfg *config, const char *key);
+mapcache_ruleset *mapcache_configuration_get_ruleset(mapcache_cfg *config, const char *key);
 void mapcache_configuration_add_image_format(mapcache_cfg *config, mapcache_image_format *format, const char * key);
 void mapcache_configuration_add_source(mapcache_cfg *config, mapcache_source *source, const char * key);
 void mapcache_configuration_add_grid(mapcache_cfg *config, mapcache_grid *grid, const char * key);
+void mapcache_configuration_add_ruleset(mapcache_cfg *config, mapcache_ruleset *ruleset, const char * key);
 void mapcache_configuration_add_tileset(mapcache_cfg *config, mapcache_tileset *tileset, const char * key);
 void mapcache_configuration_add_cache(mapcache_cfg *config, mapcache_cache *cache, const char * key);
 
@@ -1040,6 +1049,12 @@ struct mapcache_grid_link {
   mapcache_extent_i *grid_limits;
   int minz,maxz;
 
+  /**
+   * rules (mapcache_rule) for each zoom level
+   * index in array = zoom level
+   */
+  apr_array_header_t *rules;
+
   /**
    * tiles above this zoom level will not be stored to the cache, but will be
    * dynamically generated (either by reconstructing from lower level tiles, or
@@ -1052,6 +1067,46 @@ struct mapcache_grid_link {
   apr_array_header_t *intermediate_grids;
 };
 
+/**\class mapcache_rule
+ * \brief a zoom level rule
+ */
+struct mapcache_rule {
+  /**
+   * rule for zoom level
+   */
+  int zoom_level;
+  /**
+   * color of tiles when outside visible extent, ARGB
+   */
+  unsigned int hidden_color;
+  /**
+   * tile to return when outside visible extent
+   */
+  mapcache_buffer *hidden_tile;
+  /**
+   * visible extents, array of mapcache_extent
+   */
+  apr_array_header_t *visible_extents;
+  /**
+   * visible limits, array of mapcache_extent_i
+   */
+  apr_array_header_t *visible_limits;
+};
+
+/**\class mapcache_ruleset
+ * \brief a set of rules
+ */
+struct mapcache_ruleset {
+  /**
+   * the name of this ruleset
+   */
+  char *name;
+  /**
+   * rules (mapcache_rule)
+   */
+  apr_array_header_t *rules;
+};
+
 /**\class mapcache_tileset
  * \brief a set of tiles that can be requested by a client, created from a mapcache_source
  *        stored by a mapcache_cache in a mapcache_format
@@ -1258,6 +1313,49 @@ MS_DLL_EXPORT mapcache_http_response* mapcache_core_proxy_request(mapcache_conte
 MS_DLL_EXPORT mapcache_http_response* mapcache_core_respond_to_error(mapcache_context *ctx);
 
 
+/* in ruleset.c */
+
+/**
+ * \brief allocate and initialize a new ruleset
+ * @param pool
+ */
+mapcache_ruleset* mapcache_ruleset_create(apr_pool_t *pool);
+
+/**
+ * \brief allocate and initialize a new rule
+ * @param pool
+ */
+mapcache_rule* mapcache_ruleset_rule_create(apr_pool_t *pool);
+
+/**
+ * \brief clone a rule
+ * @param pool
+ * @param rule
+ */
+mapcache_rule* mapcache_ruleset_rule_clone(apr_pool_t *pool, mapcache_rule *rule);
+
+/**
+ * \brief get rule for zoom level, or NULL if none exist
+ * @param ruleset
+ * @param zoom_level
+ */
+mapcache_rule* mapcache_ruleset_rule_find(apr_array_header_t *rules, int zoom_level);
+
+/**
+ * \brief get rule at index, or NULL if none exist
+ * @param rules
+ * @param idx
+ */
+mapcache_rule* mapcache_ruleset_rule_get(apr_array_header_t *rules, int idx);
+
+/**
+ * \brief check if tile is within visible extent
+ * @param rule
+ * @param tile
+ */
+int mapcache_ruleset_is_visible_tile(mapcache_rule* rule, mapcache_tile *tile);
+
+
 /* in grid.c */
 mapcache_grid* mapcache_grid_create(apr_pool_t *pool);
 
@@ -1300,6 +1398,7 @@ int mapcache_grid_get_level(mapcache_context *ctx, mapcache_grid *grid, double *
  * \param tolerance the number of tiles around the given extent that can be requested without returning an error.
  */
 MS_DLL_EXPORT void mapcache_grid_compute_limits(const mapcache_grid *grid, const mapcache_extent *extent, mapcache_extent_i *limits, int tolerance);
+void mapcache_grid_compute_limits_at_level(const mapcache_grid *grid, const mapcache_extent *extent, mapcache_extent_i *limits_ptr, int tolerance, int zoom_level);
 
 /* in util.c */
 MS_DLL_EXPORT int mapcache_util_extract_int_list(mapcache_context *ctx, const char* args, const char *sep, int **numbers,

lib/cache.c

@@ -30,9 +30,18 @@
 
 int mapcache_cache_tile_get(mapcache_context *ctx, mapcache_cache *cache, mapcache_tile *tile) {
   int i,rv;
+  mapcache_rule *rule = mapcache_ruleset_rule_get(tile->grid_link->rules, tile->z);
 #ifdef DEBUG
   ctx->log(ctx,MAPCACHE_DEBUG,"calling tile_get on cache (%s): (tileset=%s, grid=%s, z=%d, x=%d, y=%d",cache->name,tile->tileset->name,tile->grid_link->grid->name,tile->z,tile->x, tile->y);
 #endif
+
+  /* if tile is outside visible limits, return a blank tile */
+  if (mapcache_ruleset_is_visible_tile(rule, tile) == MAPCACHE_FALSE) {
+    tile->encoded_data = mapcache_buffer_create(0, ctx->pool);
+    mapcache_buffer_append(tile->encoded_data, rule->hidden_tile->size, rule->hidden_tile->buf);
+    return MAPCACHE_SUCCESS;
+  }
+
   for(i=0;i<=cache->retry_count;i++) {
     if(i) {
       ctx->log(ctx,MAPCACHE_INFO,"cache (%s) get retry %d of %d. previous try returned error: %s",cache->name,i,cache->retry_count,ctx->get_error_message(ctx));
@@ -79,9 +88,17 @@ void mapcache_cache_tile_delete(mapcache_context *ctx, mapcache_cache *cache, ma
 
 int mapcache_cache_tile_exists(mapcache_context *ctx, mapcache_cache *cache, mapcache_tile *tile) {
   int i,rv;
+  mapcache_rule *rule = mapcache_ruleset_rule_get(tile->grid_link->rules, tile->z);
 #ifdef DEBUG
   ctx->log(ctx,MAPCACHE_DEBUG,"calling tile_exists on cache (%s): (tileset=%s, grid=%s, z=%d, x=%d, y=%d",cache->name,tile->tileset->name,tile->grid_link->grid->name,tile->z,tile->x, tile->y);
 #endif
+
+  /* if tile is outside visible limits return TRUE
+     a blank tile will be returned on subsequent get call on cache */
+  if (mapcache_ruleset_is_visible_tile(rule, tile) == MAPCACHE_FALSE) {
+    return MAPCACHE_TRUE;
+  }
+
   for(i=0;i<=cache->retry_count;i++) {
     if(i) {
       ctx->log(ctx,MAPCACHE_INFO,"cache (%s) exists retry %d of %d. previous try returned error: %s",cache->name,i,cache->retry_count,ctx->get_error_message(ctx));

lib/configuration.c

@@ -127,6 +127,7 @@ mapcache_cfg* mapcache_configuration_create(apr_pool_t *pool)
   cfg->grids = apr_hash_make(pool);
   cfg->image_formats = apr_hash_make(pool);
   cfg->metadata = apr_table_make(pool,3);
+  cfg->rulesets = apr_hash_make(pool);
 
   mapcache_configuration_add_image_format(cfg,
           mapcache_imageio_create_png_format(pool,"PNG",MAPCACHE_COMPRESSION_FAST),
@@ -241,6 +242,11 @@ mapcache_grid *mapcache_configuration_get_grid(mapcache_cfg *config, const char
   return (mapcache_grid*)apr_hash_get(config->grids, (void*)key, APR_HASH_KEY_STRING);
 }
 
+mapcache_ruleset *mapcache_configuration_get_ruleset(mapcache_cfg *config, const char *key)
+{
+  return (mapcache_ruleset*)apr_hash_get(config->rulesets, (void*)key, APR_HASH_KEY_STRING);
+}
+
 mapcache_tileset *mapcache_configuration_get_tileset(mapcache_cfg *config, const char *key)
 {
   if(config->mode == MAPCACHE_MODE_NORMAL) {
@@ -265,6 +271,11 @@ void mapcache_configuration_add_grid(mapcache_cfg *config, mapcache_grid *grid,
   apr_hash_set(config->grids, key, APR_HASH_KEY_STRING, (void*)grid);
 }
 
+void mapcache_configuration_add_ruleset(mapcache_cfg *config, mapcache_ruleset *ruleset, const char * key)
+{
+  apr_hash_set(config->rulesets, key, APR_HASH_KEY_STRING, (void*)ruleset);
+}
+
 void mapcache_configuration_add_tileset(mapcache_cfg *config, mapcache_tileset *tileset, const char * key)
 {
   tileset->config = config;