input_gadgets: check polygon, too

1 files changed, 92 insertions, 2 deletions

diff --git a/input_gadgets.c b/input_gadgets.c
index 9076278..98f761f 100644
--- a/input_gadgets.c
+++ b/input_gadgets.c
@@ -36,6 +36,90 @@ WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp)
   return realsize;
 }
 
+int point_is_inside_polygon(double lat, double lon, char *text)
+{
+  char *input = malloc(strlen(text)+1);
+  if (input == NULL) {
+    fprintf(stderr, "malloc failed to allocate %d bytes\n", strlen(text)+1);
+    return -1;
+  }
+  strcpy(input, text);
+  double *lats = malloc(1);
+  if (lats == NULL) {
+    fprintf(stderr, "malloc failed to allocate 1 byte\n");
+    free(input);
+    return -1;
+  }
+  double *lons = malloc(1);
+  if (lons == NULL) {
+    fprintf(stderr, "malloc failed to allocate 1 byte\n");
+    free(lats);
+    free(input);
+    return -1;
+  }
+  int len = 0;
+  int alloc_len = 0;
+  char *q = NULL;
+  char *p = strtok_r(input, ",", &q);
+  while (p != NULL) {
+    if (alloc_len<=len) {
+      double *n;
+      alloc_len = len + 16;
+      n = realloc(lons, alloc_len*sizeof(lons[0]));
+      if (n == NULL) {
+        fprintf(stderr, "malloc failed to allocate %d byte\n", alloc_len*sizeof(lons[0]));
+        free(input);
+        free(lats);
+        free(lons);
+        return -1;
+      }
+      lons = n;
+      n = realloc(lats, alloc_len*sizeof(lats[0]));
+      if (n == NULL) {
+        fprintf(stderr, "malloc failed to allocate %d byte\n", alloc_len*sizeof(lats[0]));
+        free(input);
+        free(lats);
+        free(lons);
+        return -1;
+      }
+      lats = n;
+    }
+    lats[len] = atof(p);
+    p=strtok_r(NULL, " ", &q);
+    if (p == NULL) {
+      fprintf(stderr, "point_is_inside_polygon misses a space\n");
+      free(input);
+      free(lats);
+      free(lons);
+      return -1;
+    }
+    lons[len] = atof(p);
+    p=strtok_r(NULL, ",", &q);
+    len++;
+  }
+  free(input);
+  if ((lons[0] != lons[len-1]) || (lats[0] != lats[len-1])) {
+    fprintf(stderr, "point_is_inside_polygon was given a non-closed polygon border\n");
+    free(lats);
+    free(lons);
+    return -1;
+  }
+  int is_inside = 0;
+  for (int i=0; i<len-1; i++) {
+    if ((lat < lats[i]) && (lat <= lats[i+1]))
+      continue;
+    if ((lat > lats[i]) && (lat >= lats[i+1]))
+      continue;
+    if (lats[i] == lats[i+1])
+      continue;
+    if ((lat - lats[i]) / (lats[i+1] - lats[i]) * (lons[i+1] - lons[i]) + lons[i] < lon)
+      is_inside = 1 - is_inside;
+  }
+  free(lats);
+  free(lons);
+  return is_inside;
+}
+
 char *gadgets_retrieve_current_temperature(char *output, int max_len)
 {
   CURL *curl_handle;
@@ -653,8 +737,14 @@ char *gadgets_retrieve_weather_warnings(char *output, int max_len)
           xmlFreeDoc(doc);
           return NULL;
         }
-/*        if (point_is_inside_polygon(50.8830, 11.6223, text))  <<TODO>>
-          is_relevant = 1; */
+        int ret = point_is_inside_polygon(50.8830, 11.6223, (char *)text);
+        if (ret == 1)
+          is_relevant = 1;
+        else if (ret != 0) {
+          fprintf(stderr, "point_is_inside_polygon failed to parse '%s'\n", (char *)text);
+          xmlFree(text);
+          return NULL;
+        }
         xmlFree(text);
       }
     }