Added an emptiness representation in the explorer GUI.

It's an item displayed on the center of the GUI if there isn't any data to display.

 * NEW: added an item displayed if the explorer GUI is empty.
 * NEW: implementation of this empty item in the list GUI.
 * NEW: small adjustments on the statistics (removed the last empty line from the lore)
 * BUG: the old method was still used to remove the item attributes (the one from the `gui` package).

src/main/java/fr/moribus/imageonmap/guiproko/core/ExplorerGui.java

@@ -141,6 +141,8 @@ abstract public class ExplorerGui<T> extends ActionGui
             updateAction("down", getPageItem("down", canGoDown()));
         }
 
+        if(data != null && data.length > 0)
+        {
             if (!isData2D)
             {
                 int start = currentPageX * viewSize;
@@ -167,6 +169,15 @@ abstract public class ExplorerGui<T> extends ActionGui
                     }
                 }
             }
+        }
+        else
+        {
+            ItemStack emptyIndicator = getEmptyViewItem();
+            if(emptyIndicator != null)
+            {
+                action("", 22, emptyIndicator);
+            }
+        }
 
         if(hasActions()) super.populate(inventory);
     }
@@ -192,20 +203,32 @@ abstract public class ExplorerGui<T> extends ActionGui
             return;
         }
 
-        if(affectsGui(event)) // The user clicked in its own inventory
+        // The user clicked in the GUI
+        if(affectsGui(event))
+        {
+            if(data != null && data.length > 0)
             {
                 switch (event.getAction())
                 {
-                case PICKUP_ALL: case PICKUP_HALF: case PICKUP_ONE: case PICKUP_SOME:
+                    case PICKUP_ALL:
-                case HOTBAR_MOVE_AND_READD: case HOTBAR_SWAP:
+                    case PICKUP_HALF:
+                    case PICKUP_ONE:
+                    case PICKUP_SOME:
+                    case HOTBAR_MOVE_AND_READD:
+                    case HOTBAR_SWAP:
                     case MOVE_TO_OTHER_INVENTORY:
-                    onActionPickup(event); break;
+                        onActionPickup(event);
+                        break;
 
-                case PLACE_ALL: case PLACE_ONE: case PLACE_SOME:
+                    case PLACE_ALL:
+                    case PLACE_ONE:
+                    case PLACE_SOME:
                     case SWAP_WITH_CURSOR:
-                    onActionPut(event); break;
+                        onActionPut(event);
+                        break;
 
-                case DROP_ALL_CURSOR: case DROP_ONE_CURSOR: 
+                    case DROP_ALL_CURSOR:
+                    case DROP_ONE_CURSOR:
                         break;
 
                     default:
@@ -213,6 +236,11 @@ abstract public class ExplorerGui<T> extends ActionGui
                 }
             }
             else
+            {
+                event.setCancelled(true);
+            }
+        }
+        else
         {
             if(event.getAction().equals(InventoryAction.MOVE_TO_OTHER_INVENTORY))
                 onActionMove(event);
@@ -435,6 +463,13 @@ abstract public class ExplorerGui<T> extends ActionGui
      */
     protected ItemStack getViewItem(T data) { return null; }
 
+    /**
+     * Returns the stack displayed in the center of the GUI if it is empty.
+     *
+     * @return The stack.
+     */
+    protected ItemStack getEmptyViewItem() { return null; }
+
 
     private ItemStack getPickedUpItem(int dataIndex)
     {

src/main/java/fr/moribus/imageonmap/guiproko/list/MapListGui.java

@@ -47,6 +47,22 @@ public class MapListGui extends ExplorerGui<ImageMap>
                 "Poster map ("+map.getColumnCount()+"x"+map.getRowCount()+")", "#" + data.getId());
     }
 
+    @Override
+    protected ItemStack getEmptyViewItem()
+    {
+        ItemStack empty = new ItemStack(Material.BARRIER);
+        ItemMeta meta = empty.getItemMeta();
+
+        meta.setDisplayName(ChatColor.RED + "You don't have any map.");
+        meta.setLore(Arrays.asList(
+                ChatColor.GRAY + "Get started by creating a new one",
+                ChatColor.GRAY + "using " + ChatColor.WHITE + "/tomap <URL> [resize]" + ChatColor.GRAY + "!"
+        ));
+
+        empty.setItemMeta(meta);
+        return empty;
+    }
+
     @Override
     protected void onRightClick(ImageMap data)
     {
@@ -124,12 +140,11 @@ public class MapListGui extends ExplorerGui<ImageMap>
             lore.add("");
             lore.add(getStatisticText("Current consumption", ((int) Math.rint(percentageUsed)) + " %"));
             lore.add(getStatisticText("Maps left", mapPartLeft));
-            lore.add("");
 
             meta.setLore(lore);
         }
 
-        fr.moribus.imageonmap.gui.core.GuiUtils.removeVanillaInfos(meta);
+        GuiUtils.hideItemAttributes(meta);
 
         statistics.setItemMeta(meta);
         action("", getSize() - 5, statistics);