From 5f5e7bef3e9a68efa5b3a8d5952d3d874ec3a15b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thorbj=C3=B8rn=20Lindeijer?= <bjorn@lindeijer.nl>
Date: Wed, 17 Jul 2019 11:08:22 +0200
Subject: [PATCH] Fixed layer IDs getting re-assigned when resizing the map

This happened as well when toggling infinite on/off, since that
effectively does a resize as well.

Closes #2160
---
 src/libtiled/layer.cpp      | 21 +++++++++++++++++++--
 src/libtiled/layer.h        |  1 +
 src/libtiled/map.cpp        |  1 -
 src/tiled/editablelayer.cpp |  1 +
 src/tiled/mapdocument.cpp   |  4 +---
 5 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/src/libtiled/layer.cpp b/src/libtiled/layer.cpp
index cb09ed6111..3cd50af22b 100644
--- a/src/libtiled/layer.cpp
+++ b/src/libtiled/layer.cpp
@@ -52,6 +52,23 @@ Layer::Layer(TypeFlag type, const QString &name, int x, int y) :
 {
 }
 
+void Layer::resetIds()
+{
+    mId = 0;        // reset out own ID
+
+    switch (layerType()) {
+    case ObjectGroupType:
+        static_cast<ObjectGroup*>(this)->resetObjectIds();
+        break;
+    case GroupLayerType:
+        for (Layer *layer : static_cast<GroupLayer*>(this)->layers())
+            layer->resetIds();
+        break;
+    default:
+        break;
+    }
+}
+
 /**
  * Returns the effective opacity, which is the opacity multiplied by the
  * opacity of any parent layers.
@@ -165,7 +182,7 @@ bool Layer::canMergeDown() const
  * A helper function for initializing the members of the given instance to
  * those of this layer. Used by subclasses when cloning.
  *
- * Layer name, position and size are not cloned, since they are assumed to have
+ * Layer name, position and size are not copied, since they are assumed to have
  * already been passed to the constructor. Also, map ownership is not cloned,
  * since the clone is not added to the map.
  *
@@ -174,7 +191,7 @@ bool Layer::canMergeDown() const
  */
 Layer *Layer::initializeClone(Layer *clone) const
 {
-    // mId is not copied, will be assigned when layer is added to a map
+    clone->mId = mId;
     clone->mOffset = mOffset;
     clone->mOpacity = mOpacity;
     clone->mVisible = mVisible;
diff --git a/src/libtiled/layer.h b/src/libtiled/layer.h
index a1147621ae..19981b711f 100644
--- a/src/libtiled/layer.h
+++ b/src/libtiled/layer.h
@@ -80,6 +80,7 @@ class TILEDSHARED_EXPORT Layer : public Object
      */
     int id() const { return mId; }
     void setId(int id) { mId = id; }
+    void resetIds();
 
     /**
      * Returns the type of this layer.
diff --git a/src/libtiled/map.cpp b/src/libtiled/map.cpp
index 989dcc7ae5..b73e7c161f 100644
--- a/src/libtiled/map.cpp
+++ b/src/libtiled/map.cpp
@@ -344,7 +344,6 @@ Map *Map::clone() const
     o->mDrawMarginsDirty = mDrawMarginsDirty;
     for (const Layer *layer : mLayers) {
         Layer *clone = layer->clone();
-        clone->setId(layer->id());
         clone->setMap(o);
         o->mLayers.append(clone);
     }
diff --git a/src/tiled/editablelayer.cpp b/src/tiled/editablelayer.cpp
index 9f278b6e35..5773664f5b 100644
--- a/src/tiled/editablelayer.cpp
+++ b/src/tiled/editablelayer.cpp
@@ -68,6 +68,7 @@ void EditableLayer::detach()
     setAsset(nullptr);
 
     mDetachedLayer.reset(layer()->clone());
+    mDetachedLayer->resetIds();
     setObject(mDetachedLayer.get());
     EditableManager::instance().mEditableLayers.insert(layer(), this);
 }
diff --git a/src/tiled/mapdocument.cpp b/src/tiled/mapdocument.cpp
index ad457cefe1..64a5dfd0a1 100644
--- a/src/tiled/mapdocument.cpp
+++ b/src/tiled/mapdocument.cpp
@@ -492,11 +492,9 @@ void MapDocument::duplicateLayers(const QList<Layer *> &layers)
         }
 
         Layer *duplicate = layer->clone();
+        duplicate->resetIds();
         duplicate->setName(tr("Copy of %1").arg(duplicate->name()));
 
-        if (duplicate->layerType() == Layer::ObjectGroupType)
-            static_cast<ObjectGroup*>(duplicate)->resetObjectIds();
-
         auto parentLayer = layer->parentLayer();
 
         int index = previousIndex;