Various GUI & GUI API improvements.

* NEW: ActionGui: Added the GuiAction annotation.
* NEW: ConfirmDeleteMapGui: Updated to use the @GuiAction annotations.
* NEW: ExplorerGui: Added a default empty indicator.
* NEW: ExplorerGui: Updated to use the @GuiAction annotations.
* NEW: ExplorerGui: Added current page getters & setters.
* NEW: MapDetailGui: Updated to use the @GuiAction annotations.
* BUG: ActionGui: Fix event handler call if the method takes an 
  InventoryClickEvent as a parameter.
* BUG: ConfirmDeleteMapGui: Fix exception handling.
* BUG: ExplorerGui: Fix the hasData() method.
* BUG: ExplorerGui: Fix the empty indicator.
* BUG: ExplorerGui: Fix the keep*ScrollingSpace implementation.
* BUG: ExplorerGui: Fix item pickup when using coordinates.
* BUG: ExplorerGui: All callbacks can now take coordinates instead
  of data.
* OPT: ConfirmDeleteMapGui: Messages are now defined as constants.
* OPT: ConfirmDeleteMapGui: GUI's data is now final.
* OPT: MapDetailGui: Cleaned up GUI initialization a bit.
* OPT: MapListGui: Cleaned up ItemStack generation.
* OPT: MapDetailGui: Clarified UI tooltips.

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

@@ -272,14 +272,14 @@ abstract public class ActionGui extends Gui
 
         event.setCancelled(true);
         
-        callAction(actions.get(event.getRawSlot()));
+        callAction(actions.get(event.getRawSlot()), event);
     }
     
     /**
      * Triggers the given action's event handler.
      * @param action The action to trigger.
      */
-    private void callAction(Action action)
+    private void callAction(Action action, InventoryClickEvent event)
     {
         if(action == null) return;
 
@@ -291,7 +291,14 @@ abstract public class ActionGui extends Gui
         
         try
         {
-            action.callback.invoke(this);
+            if(action.callback.getParameterCount() == 1)
+            {
+                action.callback.invoke(this, event);
+            }
+            else
+            {
+                action.callback.invoke(this);
+            }
         }
         catch (IllegalAccessException | IllegalArgumentException ex)
         {
@@ -304,6 +311,30 @@ abstract public class ActionGui extends Gui
         }
     }
     
+    /**
+     * Returns if the given method is a valid action handler.
+     * An action handler is valid only if it is accessible and parameter types matches.
+     * @param method The method to test
+     * @return true if the given method is valid, false otherwise.
+     */
+    private boolean isActionHandlerValid(Method method)
+    {
+        if(method.getParameterCount() >= 2) return false;
+        if(method.getParameterCount() == 1)
+            if(method.getParameterTypes()[0] != InventoryClickEvent.class) 
+                return false;
+        
+        try
+        {
+            method.setAccessible(true);
+        }
+        catch(SecurityException ex)
+        {
+            return false;
+        }
+        return true;
+    }
+    
     /**
      * Retrieves the event handler matching the given name from a class (or any of its parents).
      *
@@ -313,32 +344,38 @@ abstract public class ActionGui extends Gui
      */
     private Method getActionHandler(Class<?> klass, String name)
     {
-        Method callback;
-
         do
         {
-            try
+            GuiAction actionAnnotation;
+            String methodName;
+            
+            for(Method method : klass.getDeclaredMethods())
             {
-                try
+                actionAnnotation = method.getDeclaredAnnotation(GuiAction.class);
+                if(actionAnnotation == null) continue;
+                if(!(actionAnnotation.value() == null || actionAnnotation.value().isEmpty()))
                 {
-                    callback = klass.getDeclaredMethod(ACTION_HANDLER_NAME + name, InventoryClickEvent.class);
+                    if(actionAnnotation.value().equals(name)) 
+                        if(isActionHandlerValid(method)) 
+                            return method;
                 }
-                catch(NoSuchMethodException e)
+                else
                 {
-                    callback = klass.getDeclaredMethod(ACTION_HANDLER_NAME + name);
+                    methodName = method.getName();
+                    if(methodName.equals(name)) 
+                        if(isActionHandlerValid(method)) 
+                            return method;
+                    
+                    if(methodName.startsWith(ACTION_HANDLER_NAME))
+                        if(methodName.substring(ACTION_HANDLER_NAME.length()).equals(name))
+                            if(isActionHandlerValid(method))
+                                return method;
                 }
-
-                callback.setAccessible(true);
-                break;
-            }
-            catch (Throwable ex)
-            {
-                callback = null;
-                klass = klass.getSuperclass();
             }
+            klass = klass.getSuperclass();
         } while (klass != null);
         
-        return callback;
+        return null;
     }
     
     /**

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

@@ -100,6 +100,8 @@ abstract public class ExplorerGui<T> extends ActionGui
         this.data = data;
         if(dataWidth > 0)
             setDataShape(dataWidth, (int) Math.ceil((double) data.length / (double) dataWidth));
+        else
+            setDataShape(0, data.length);
     }
 
     /**
@@ -134,7 +136,10 @@ abstract public class ExplorerGui<T> extends ActionGui
      */
     protected boolean hasData()
     {
-        return (data == null || data.length == 0) && (dataWidth == 0 && dataHeight == 0);
+        if(isData2D)
+            return dataWidth > 0 && dataHeight > 0;
+        else
+            return data != null && data.length > 0;
     }
     
     @Override
@@ -161,7 +166,7 @@ abstract public class ExplorerGui<T> extends ActionGui
 
                 for (int i = 0; i < max; i++)
                 {
-                    inventory.setItem(i, getViewItem(i + start));
+                    inventory.setItem(i, getViewItem(getData(i + start)));
                 }
             }
             else
@@ -183,11 +188,7 @@ abstract public class ExplorerGui<T> extends ActionGui
         }
         else
         {
-            ItemStack emptyIndicator = getEmptyViewItem();
-            if(emptyIndicator != null)
-            {
-                action("", 22, emptyIndicator);
-            }
+            updateAction("__empty__", getEmptyViewItem());
         }
 
         if(hasActions()) super.populate(inventory);
@@ -297,23 +298,23 @@ abstract public class ExplorerGui<T> extends ActionGui
      */
     private void onActionPickup(InventoryClickEvent event)
     {
-        int dataIndex = getDataIndex(event.getSlot());
+        ExplorerGuiEvent eventSlot = new ExplorerGuiEvent(this, event);
         if(event.getClick().equals(ClickType.RIGHT))
         {
-            onRightClick(getData(dataIndex));
+            onRightClick(eventSlot);
             event.setCancelled(true);
             return;
         }
 
-        ItemStack pickedUpItem = getPickedUpItem(dataIndex);
+        ItemStack pickedUpItem = getPickedUpItem(eventSlot);
         if(pickedUpItem == null || mode.equals(Mode.READONLY))
         {
             event.setCancelled(true);
             return;
         }
-
+        
         event.setCurrentItem(pickedUpItem);
-        GuiUtils.setItemLater(this, event.getSlot(), getViewItem(dataIndex));
+        GuiUtils.setItemLater(this, event.getSlot(), getViewItem(eventSlot));
     }
 
     /**
@@ -363,8 +364,9 @@ abstract public class ExplorerGui<T> extends ActionGui
             viewHeight = Math.min((int)Math.ceil((double)dataLength / (double)viewWidth),
                                    MAX_INVENTORY_COLUMN_SIZE);
             
-            if(hasActions() || dataLength > MAX_INVENTORY_SIZE || keepHorizontalScrollingSpace)
-                viewHeight--;
+            if(viewHeight >= MAX_INVENTORY_COLUMN_SIZE)
+                if(hasActions() || dataLength > MAX_INVENTORY_SIZE || keepHorizontalScrollingSpace)
+                    viewHeight--;
 
             viewSize = viewWidth * viewHeight;
             
@@ -379,11 +381,13 @@ abstract public class ExplorerGui<T> extends ActionGui
             pageCountX = (int)Math.ceil((double)dataWidth / (double)viewWidth);
             pageCountY = (int)Math.ceil((double)dataHeight / (double)viewHeight);
             
-            if((pageCountY > 1 && viewWidth == INVENTORY_ROW_SIZE) || keepVerticalScrollingSpace)
-                viewWidth--;
-
-            if((pageCountX > 1 && viewHeight == MAX_INVENTORY_COLUMN_SIZE) || keepHorizontalScrollingSpace)
-                viewHeight--;
+            if(viewWidth >= INVENTORY_ROW_SIZE)
+                if((pageCountY > 1 && viewWidth == INVENTORY_ROW_SIZE) || keepVerticalScrollingSpace)
+                    viewWidth--;
+            
+            if(viewHeight >= MAX_INVENTORY_COLUMN_SIZE)
+                if((pageCountX > 1 && viewHeight == MAX_INVENTORY_COLUMN_SIZE) || keepHorizontalScrollingSpace)
+                    viewHeight--;
             
             pageCountX = (int)Math.ceil((double)dataWidth / (double)viewWidth);
             pageCountY = (int)Math.ceil((double)dataHeight / (double)viewHeight);
@@ -399,39 +403,10 @@ abstract public class ExplorerGui<T> extends ActionGui
             action("up", INVENTORY_ROW_SIZE - 1);
             action("down", MAX_INVENTORY_SIZE - 1);
         }
-    }
-    
-    private void action_next()
-    {
-        next();
-    }
-    
-    private void action_previous()
-    {
-        previous();
-    }
-    
-    private void action_up()
-    {
-        up();
-    }
-    
-    private void action_down()
-    {
-        down();
-    }
-    
-    private int getDataIndex(int inventorySlot)
-    {
-        if(isData2D)
+        
+        if(!hasData())
         {
-            int column = currentPageX * viewWidth + inventorySlot % INVENTORY_ROW_SIZE;
-            int row = currentPageY * viewHeight + inventorySlot / INVENTORY_ROW_SIZE;
-            return row * dataWidth + column;
-        }
-        else
-        {
-            return currentPageX * viewSize + inventorySlot;
+            action("__empty__", 22);
         }
     }
     
@@ -442,18 +417,20 @@ abstract public class ExplorerGui<T> extends ActionGui
 
         return data[i];
     }
-
-    /**
-     * Returns the stack to display at the given index.
-     *
-     * @param i The index.
-     * @return The stack.
-     */
-    protected ItemStack getViewItem(int i)
+    
+    private ItemStack getViewItem(ExplorerGuiEvent event)
     {
-        return getViewItem(getData(i));
+        if(!event.isValid) return null;
+        if(isData2D)
+        {
+            return getViewItem(event.xData, event.yData);
+        }
+        else
+        {
+            return getViewItem(getData(event.posData));
+        }
     }
-
+    
     /**
      * Returns the stack to display at the given coordinates.
      *
@@ -463,7 +440,7 @@ abstract public class ExplorerGui<T> extends ActionGui
      */
     protected ItemStack getViewItem(int x, int y)
     {
-        return getViewItem(y * dataWidth + x);
+        return getViewItem(getData(y * dataWidth + x));
     }
 
     /**
@@ -475,12 +452,32 @@ 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.
+     * Returns the item displayed in the center of the GUI if it is empty.
      *
-     * @return The stack.
+     * @return The item.
      */
-    protected ItemStack getEmptyViewItem() { return null; }
-
+    protected ItemStack getEmptyViewItem() 
+    { 
+        return GuiUtils.makeItem(Material.BARRIER, "Empty", "There's nothing to see here"); 
+    }
+    
+    private ItemStack getPickedUpItem(ExplorerGuiEvent event)
+    {
+        if(!event.isValid) return null;
+        if(isData2D)
+        {
+            return getPickedUpItem(event.xData, event.yData);
+        }
+        else
+        {
+            return getPickedUpItem(event.posData);
+        }
+    }
+    
+    protected ItemStack getPickedUpItem(int x, int y)
+    {
+        return getViewItem(x,y);
+    }
 
     private ItemStack getPickedUpItem(int dataIndex)
     {
@@ -496,7 +493,7 @@ abstract public class ExplorerGui<T> extends ActionGui
      * mode.
      *
      * @param data The picked-up piece of data.
-     * @return The stack to pick-up ({@code null} to cancel the pick-up).
+     * @return The stack to pick-up (or {@code null} to cancel the pick-up).
      */
     protected ItemStack getPickedUpItem(T data) { return getViewItem(data); }
 
@@ -563,7 +560,27 @@ abstract public class ExplorerGui<T> extends ActionGui
         icon.setItemMeta(meta);
         return icon;
     }
-
+    
+    private void onRightClick(ExplorerGuiEvent event)
+    {
+        if(!event.isValid) return;
+        if(isData2D)
+        {
+            onRightClick(event.xData, event.yData);
+        }
+        else
+        {
+            onRightClick(getData(event.posData));
+        }
+    }
+    
+    /**
+     * Triggered when the player right-clicks an item on the GUI.
+     * @param x The X position of the right-clicked data.
+     * @param y The Y position of the right-clicked data.
+     */
+    protected void onRightClick(int x, int y) {}
+    
     /**
      * Triggered when the player right-clicks an item on the GUI.
      *
@@ -572,7 +589,7 @@ abstract public class ExplorerGui<T> extends ActionGui
     protected void onRightClick(T data) {}
 
     /**
-     * Triggered when the player try to place an item inside the GUI.
+     * Triggered when the player tries to place an item inside the GUI.
      *
      * This will not place the item in the GUI, it's up to you to update the data and refresh
      * the GUI if you need so.
@@ -582,44 +599,69 @@ abstract public class ExplorerGui<T> extends ActionGui
      */
     protected boolean onPutItem(ItemStack item) { return true; }
 
+    static private final class ExplorerGuiEvent
+    {
+        //2D Explorer
+        public final int xData;
+        public final int yData;
+        
+        //1D Explorer
+        public final int posData;
+        
+        public final boolean isValid;
+        
+        public ExplorerGuiEvent(ExplorerGui gui, InventoryClickEvent event)
+        {
+            if(gui.isData2D)
+            {
+                xData = gui.currentPageX * gui.viewWidth + event.getSlot() % INVENTORY_ROW_SIZE;
+                yData = gui.currentPageY * gui.viewHeight + event.getSlot() / INVENTORY_ROW_SIZE;
+                posData = -1;
+                isValid = (xData < gui.dataWidth && xData >= 0 && yData < gui.dataHeight && yData >= 0);
+            }
+            else
+            {
+                xData = yData = -1;
+                posData = gui.currentPageX * gui.viewSize + event.getSlot();
+                isValid = (posData >= 0 && posData < gui.dataHeight);
+            }
+        }
+    }
+    
     /**
      * Displays the next horizontal page, if possible.
      */
+    @GuiAction
     public void next()
     {
-        if(!canGoNext()) return;
-        currentPageX++;
-        refresh();
+        setCurrentPageX(currentPageX - 1);
     }
 
     /**
      * Displays the previous horizontal page, if possible.
      */
+    @GuiAction
     public void previous()
     {
-        if(!canGoPrevious()) return;
-        currentPageX--;
-        refresh();
+        setCurrentPageX(currentPageX - 1);
     }
 
     /**
      * Displays the previous vertical page, if possible.
      */
+    @GuiAction
     public void up()
     {
-        if(!canGoUp()) return;
-        currentPageY--;
-        refresh();
+        setCurrentPageY(currentPageY - 1);
     }
 
     /**
      * Displays the next vertical page, if possible.
      */
+    @GuiAction
     public void down()
     {
-        if(!canGoDown()) return;
-        currentPageY++;
-        refresh();
+        setCurrentPageY(currentPageY + 1);
     }
     
     public boolean canGoNext()
@@ -641,6 +683,35 @@ abstract public class ExplorerGui<T> extends ActionGui
     {
         return currentPageY < pageCountY - 1;
     }
+    
+    public int getCurrentPageX()
+    {
+        return currentPageX;
+    }
+
+    public void setCurrentPageX(int currentPageX)
+    {
+        setCurrentPage(currentPageX, currentPageY);
+    }
+
+    public int getCurrentPageY()
+    {
+        return currentPageY;
+    }
+
+    public void setCurrentPageY(int currentPageY)
+    {
+        setCurrentPage(currentPageX, currentPageY);
+    }
+    
+    public void setCurrentPage(int currentPageX, int currentPageY)
+    {
+        if(currentPageX < 1 || currentPageX > pageCountX - 1) return;
+        if(currentPageY < 1 || currentPageY > pageCountY - 1) return;
+        this.currentPageX = currentPageX;
+        this.currentPageY = currentPageY;
+        refresh();
+    }
 
     /**
      * Returns the amount of horizontal pages.

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

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2013 Moribus
+ * Copyright (C) 2015 ProkopyL <prokopylmc@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package fr.moribus.imageonmap.guiproko.core;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ElementType.METHOD})
+public @interface GuiAction
+{
+    String value() default "";
+}

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

@@ -36,34 +36,51 @@ public class ConfirmDeleteMapGui extends ActionGui
     static private final int FIRST_SLOT_DELETE_BUTTON = 27;
     static private final int SHIFT_CANCEL_BUTTON = 5;
 
+    /**
+     * The messages randomly displayed in the lore of the “delete” buttons.
+     */
+    static private final String[] DELETE_MESSAGES = new String[]{
+        "Please", "I'm still alive", "Don't do that", "I'm still loving you", "I want to live",
+        "Please please", "Please please please", "What are you doing?!", "Nooooo!",
+        "Click and I'll be dead", "Why?", "Please don't do that", "Think about my family",
+        "Click, I don't like you anymore.", "I don't hate you.", "Click, I'm ready.",
+        "I'm a green button.", "I'm different.", "Thanks anyway.", "Excuse me.", "Get mad.",
+        "Sorry!", "My fault!", "I don't blame you.", "No hard feelings.",
+        "But I need to protect the humans!", "Noooo!", "I'm scared!", "What are you doing?",
+        "It burns.", "This is not good.", "Can't breathe.", "Thanks anyway.", "These things happen.",
+        "That was nobody's fault.", "I probably deserved it.", "I blame myself."
+    };
 
+    /**
+     * The messages randomly displayed in the lore of the “cancel” buttons.
+     */
+    static private final String[] CANCEL_MESSAGES = new String[] {
+        "Yay!", "Still aliiiive!", "Click click click", "Yes do that", "I'm a red button.",
+        "Please click here", "The other button is ugly", "Save me", "This is the good choice",
+        "Click, I want to live!", "I'll be dead another day anyway", "Are you sure?",
+        "So you're still loving me?", "Please save me", "Take me with you.",
+        "Excuse me.", "Don't make lemonade.", "Sleep mode activated.", "Hybernating.",
+        "Your business is appreciated.", "Hey! It's me! Don't shoot!", "Wheee!", "Hurray!",
+        "You have excellent aim!", "Please please please"
+    };
+    
     /**
      * The map being deleted.
      */
-    private ImageMap mapToDelete;
+    private final ImageMap mapToDelete;
 
     /**
      * The previously-viewed page of the list GUI.
      * Used to be able to bring the user back to the same page.
      */
-    private int currentPage;
-
-    /**
-     * The messages randomly displayed in the lore of the “delete” buttons.
-     */
-    private String[] deleteMessages;
-
-    /**
-     * The messages randomly displayed in the lore of the “cancel” buttons.
-     */
-    private String[] cancelMessages;
+    private final int currentPage;
 
     /**
      * A source of randomness.
      *
      * Yes, this javadoc comment is REALLY useful. Trust me.
      */
-    private Random random = new Random();
+    private final Random random = new Random();
 
 
     /**
@@ -75,28 +92,6 @@ public class ConfirmDeleteMapGui extends ActionGui
     {
         this.mapToDelete = mapToDelete;
         this.currentPage = currentPage;
-
-        deleteMessages = new String[]{
-                "Please", "I'm still alive", "Don't do that", "I'm still loving you", "I want to live",
-                "Please please", "Please please please", "What are you doing?!", "Nooooo!",
-                "Click and I'll be dead", "Why?", "Please don't do that", "Think about my family",
-                "Click, I don't like you anymore.", "I don't hate you.", "Click, I'm ready.",
-                "I'm a green button.", "I'm different.", "Thanks anyway.", "Excuse me.", "Get mad.",
-                "Sorry!", "My fault!", "I don't blame you.", "No hard feelings.",
-                "But I need to protect the humans!", "Noooo!", "I'm scared!", "What are you doing?",
-                "It burns.", "This is not good.", "Can't breathe.", "Thanks anyway.", "These things happen.",
-                "That was nobody's fault.", "I probably deserved it.", "I blame myself."
-        };
-
-        cancelMessages = new String[] {
-                "Yay!", "Still aliiiive!", "Click click click", "Yes do that", "I'm a red button.",
-                "Please click here", "The other button is ugly", "Save me", "This is the good choice",
-                "Click, I want to live!", "I'll be dead another day anyway", "Are you sure?",
-                "So you're still loving me?", "Please save me", "Take me with you.",
-                "Excuse me.", "Don't make lemonade.", "Sleep mode activated.", "Hybernating.",
-                "Your business is appreciated.", "Hey! It's me! Don't shoot!", "Wheee!", "Hurray!",
-                "You have excellent aim!", "Please please please"
-        };
     }
 
     @Override
@@ -140,13 +135,13 @@ public class ConfirmDeleteMapGui extends ActionGui
     private ItemStack createDeleteSubButton()
     {
         // Orange? Nooo. In the real world this is red. True story.
-        return createSubButton(DyeColor.ORANGE, ChatColor.RED + "Delete the map", deleteMessages);
+        return createSubButton(DyeColor.ORANGE, ChatColor.RED + "Delete the map", DELETE_MESSAGES);
     }
 
     private ItemStack createCancelSubButton()
     {
         // YES. Purple = lime. BECAUSE. Just accept it.
-        return createSubButton(DyeColor.PURPLE, ChatColor.GREEN + "Cancel", cancelMessages);
+        return createSubButton(DyeColor.PURPLE, ChatColor.GREEN + "Cancel", CANCEL_MESSAGES);
     }
 
     private ItemStack createSubButton(DyeColor color, String title, String[] messages)
@@ -167,11 +162,13 @@ public class ConfirmDeleteMapGui extends ActionGui
         return subButton;
     }
     
+    @GuiAction
     protected void action_cancel()
     {
-        Gui.open(getPlayer(), new MapDetailGui(null /*mapToDelete, currentPage */));
+        Gui.open(getPlayer(), new MapDetailGui(mapToDelete)).setCurrentPageX(currentPage);
     }
     
+    @GuiAction
     protected void action_delete()
     {
         MapManager.clear(getPlayer().getInventory(), mapToDelete);
@@ -183,8 +180,8 @@ public class ConfirmDeleteMapGui extends ActionGui
         }
         catch (MapManagerException ex)
         {
-            PluginLogger.warning("A non-existent map was requested to be deleted", ex);
-            getPlayer().sendMessage(ChatColor.RED + "This map does not exists.");
+            PluginLogger.warning("Error while deleting map", ex);
+            getPlayer().sendMessage(ChatColor.RED + ex.getMessage());
         }
 
         Gui.open(getPlayer(), new MapListGui(/* currentPage */));

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

@@ -42,7 +42,7 @@ public class MapDetailGui extends ExplorerGui<Void>
         Material partMaterial = Material.PAPER;
         if((y % 2 == 0 && x % 2 == 0) || (y % 2 == 1 && x % 2 == 1))
             partMaterial = Material.EMPTY_MAP;
-
+        
         ItemStack part = new ItemStack(partMaterial);
         ItemMeta meta = part.getItemMeta();
 
@@ -65,12 +65,20 @@ public class MapDetailGui extends ExplorerGui<Void>
         {
             return getViewItem(0, 0);
         }
-        else return null;
+        else return super.getEmptyViewItem();
+    }
+    
+    @GuiAction
+    private void delete()
+    {
+        Gui.open(getPlayer(), new ConfirmDeleteMapGui(map, getCurrentPageX()));
     }
 
     @Override
     protected void onUpdate()
     {
+        ItemStack back, rename, delete;
+        
         setTitle("Your maps » " + ChatColor.BLACK + map.getName());
         setKeepHorizontalScrollingSpace(true);
 
@@ -79,36 +87,21 @@ public class MapDetailGui extends ExplorerGui<Void>
         else
             setData(null); // Fallback to the empty view item.
 
-
-        ItemStack back = new ItemStack(Material.EMERALD);
-        ItemMeta meta = back.getItemMeta();
-        meta.setDisplayName(ChatColor.GREEN + "« Back");
-        meta.setLore(Collections.singletonList(
-                ChatColor.GRAY + "Go back to the list."
-        ));
-        back.setItemMeta(meta);
-
-        ItemStack rename = new ItemStack(Material.BOOK_AND_QUILL);
-        meta = rename.getItemMeta();
-        meta.setDisplayName(ChatColor.BLUE + "Rename this image");
-        meta.setLore(Arrays.asList(
-                ChatColor.GRAY + "Click here to rename this image;",
-                ChatColor.GRAY + "this is used for your own organization."
-        ));
-        rename.setItemMeta(meta);
-
-        ItemStack delete = new ItemStack(Material.BARRIER);
-        meta = delete.getItemMeta();
-        meta.setDisplayName(ChatColor.RED + "Delete this image");
-        meta.setLore(Arrays.asList(
+        back = GuiUtils.makeItem(Material.EMERALD, 
+                ChatColor.GREEN + "« Back", 
+                
+                ChatColor.GRAY + "Go back to the list.");
+        
+        rename = GuiUtils.makeItem(Material.BOOK_AND_QUILL, 
+                ChatColor.BLUE + "Rename", 
+                
+                ChatColor.GRAY + "Renames this image");
+        
+        delete = GuiUtils.makeItem(Material.BARRIER, 
+                ChatColor.RED + "Delete", 
+                
                 ChatColor.GRAY + "Deletes this map " + ChatColor.WHITE + "forever" + ChatColor.GRAY + ".",
-                ChatColor.GRAY + "This action cannot be undone!",
-                "",
-                ChatColor.GRAY + "You will be asked to confirm your",
-                ChatColor.GRAY + "choice if you click here."
-        ));
-        delete.setItemMeta(meta);
-
+                ChatColor.GRAY + "This action cannot be undone!");
 
         action("rename", getSize() - 7, rename);
         action("delete", getSize() - 6, delete);

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

@@ -38,56 +38,38 @@ public class MapListGui extends ExplorerGui<ImageMap>
     @Override
     protected ItemStack getViewItem(ImageMap map)
     {
-        ItemStack icon = new ItemStack(Material.MAP);
-
-
-        ItemMeta meta = icon.getItemMeta();
-
-        meta.setDisplayName(ChatColor.GREEN + "" + ChatColor.BOLD + map.getName());
-
         String mapDescription;
+        
         if(map instanceof SingleMap)
             mapDescription = "Single map";
         else
             mapDescription = "Poster map (" + ((PosterMap) map).getColumnCount() + "×" + ((PosterMap) map).getRowCount() + ")";
-
-        meta.setLore(Arrays.asList(
+        
+        return GuiUtils.makeItem(Material.MAP, 
+                ChatColor.GREEN + "" + ChatColor.BOLD + map.getName(), 
+                
                 ChatColor.WHITE + mapDescription,
                 "",
                 ChatColor.GRAY + "Map ID: " + map.getId(),
                 "",
                 ChatColor.GRAY + "» Left-click to get this map",
-                ChatColor.GRAY + "» Right-click for details and options"
-        ));
-
-        GuiUtils.hideItemAttributes(meta);
-
-        icon.setItemMeta(meta);
-
-
-        return icon;
+                ChatColor.GRAY + "» Right-click for details and options");
     }
 
     @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(
+        return GuiUtils.makeItem(Material.BARRIER, 
+                ChatColor.RED + "You don't have any map.", 
+                
                 ChatColor.GRAY + "Get started by creating a new one",
-                ChatColor.GRAY + "using " + ChatColor.WHITE + "/tomap <URL> [resize]" + ChatColor.GRAY + "!"
-        ));
-
-        empty.setItemMeta(meta);
-        return empty;
+                ChatColor.GRAY + "using " + ChatColor.WHITE + "/tomap <URL>" + ChatColor.GRAY + "!");
     }
 
     @Override
-    protected void onRightClick(ImageMap data)
+    protected void onRightClick(ImageMap map)
     {
-        Gui.open(getPlayer(), new MapDetailGui(data));
+        Gui.open(getPlayer(), new MapDetailGui(map));
     }
     
     @Override
@@ -149,7 +131,7 @@ public class MapListGui extends ExplorerGui<ImageMap>
         if(mapPartLeft >= 0)
         {
             List<String> lore = meta.getLore();
-
+            
             lore.add("");
             lore.add(ChatColor.BLUE + "Minecraft maps limits");