From c088be8840fc2d796ddba1ef15b428c9c1befbfb Mon Sep 17 00:00:00 2001
From: NyCode <nico@nycode.de>
Date: Thu, 29 Apr 2021 20:04:58 +0200
Subject: [PATCH] Add beforeChange and afterChange to GUIButtonPageChange

---
 .../kspigot/gui/elements/GUIButtonPageChange.kt | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/main/kotlin/net/axay/kspigot/gui/elements/GUIButtonPageChange.kt b/src/main/kotlin/net/axay/kspigot/gui/elements/GUIButtonPageChange.kt
index a21cf2f0..f7724e9f 100644
--- a/src/main/kotlin/net/axay/kspigot/gui/elements/GUIButtonPageChange.kt
+++ b/src/main/kotlin/net/axay/kspigot/gui/elements/GUIButtonPageChange.kt
@@ -6,7 +6,8 @@ import org.bukkit.inventory.ItemStack
 class GUIButtonPageChange<T : ForInventory>(
     icon: ItemStack,
     calculator: GUIPageChangeCalculator,
-    onChange: ((GUIClickEvent<T>) -> Unit)?
+    beforeChange: ((GUIClickEvent<T>) -> Boolean)?,
+    afterChange: ((GUIClickEvent<T>) -> Unit)?
 ) : GUIButton<T>(icon, {
 
     val currentPage = it.guiInstance.currentPage
@@ -18,13 +19,15 @@ class GUIButtonPageChange<T : ForInventory>(
     )
     if (newPage != null) {
 
-        val effect = (newPage.transitionTo ?: currentPage.transitionFrom)
-            ?: PageChangeEffect.INSTANT
+        val changePage = beforeChange?.invoke(it) ?: true
 
-        it.guiInstance.changePage(effect, currentPage, newPage)
-
-        onChange?.invoke(it)
+        if (changePage) {
+            val effect = (newPage.transitionTo ?: currentPage.transitionFrom)
+                ?: PageChangeEffect.INSTANT
 
+            it.guiInstance.changePage(effect, currentPage, newPage)
+            afterChange?.invoke(it)
+        }
     }
 
-})
\ No newline at end of file
+})