完善了README文件

重写了获得公交车位置的函数

src/busModel.cpp

@@ -29,6 +29,7 @@ void BusModel::ResetBus(rail_node_t *head)
 double BusModel::GetBusPosition(int remaining_time)
 {
     double result = 0;
+    double length = 0;
     rail_node_t *now_pos = rail_pos;
     rail_node_t *node = rail_head;
 
@@ -39,23 +40,43 @@ double BusModel::GetBusPosition(int remaining_time)
         node = node->next_node;
     } while (node != now_pos);
 
-    // 如果就在起始点，距离为0
-    if(now_pos == rail_head)
-    {
-        result = 0;
-    }
-
+    // 获得可能存在的偏移量
     if(remaining_time > 0)
     {
         if(direction == BUS_CLOCK_WISE)
         {
-            double length = now_pos->next_node_distance - (double)remaining_time / 1000.0 * velocity;
-            result = result + length;
+            length = now_pos->next_node_distance - (double)remaining_time / 1000.0 * velocity;
         }
         else if(direction == BUS_COUNTER_CLOCK_WISE)
         {
-            double length = now_pos->last_node_distance - (double)remaining_time / 1000.0 * velocity;
-            result = result - length;
+            length = now_pos->last_node_distance - (double)remaining_time / 1000.0 * velocity;
+            length = -length;
+        }
+    }
+
+    if(now_pos == rail_head)
+    {
+        // 在起点
+        if(length >= 0)
+        {
+            result = length;
+        }
+        else
+        {
+            result = result + length;
+        }
+    }
+    else
+    {
+        // 在其他点
+        if(now_pos == rail_head->last_node and length == -rail_head->last_node_distance)
+        {
+            // 恰好即将回到出发点的情况
+            result = 0;
+        }
+        else
+        {
+            result = result + length;
         }
     }
 

src/centralwidget.cpp

@@ -139,6 +139,26 @@ void CentralWidget::DeleteQueryList()
 
 void CentralWidget::AppendQueryItemSlot(int query_type, int node_id)
 {
+    // 判断是否存在相同的请求
+    // 如果存在就不再添加
+    bool is_exist = false;
+    auto first_item = query_items.begin();
+    first_item++;
+
+    for(auto itor = first_item; itor != query_items.end(); ++itor)
+    {
+        if((*itor)->query_type == query_type and (*itor)->target_node_id == node_id)
+        {
+            is_exist = true;
+            break;
+        }
+    }
+
+    if(is_exist)
+    {
+        return;
+    }
+
     QueryListItem *item = new QueryListItem(query_type, node_id);
 
     query_items.push_back(item);