Fix timeline scrolling when creating layer

Fix #4930

src/app/commands/cmd_new_layer.cpp

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019-2024  Igara Studio S.A.
+// Copyright (C) 2019-2025  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -268,11 +268,15 @@ void NewLayerCommand::onExecute(Context* context)
 
     switch (m_type) {
       case Type::Layer:
-        layer = api.newLayer(parent, name);
-        if (m_place == Place::BeforeActiveLayer)
+
+        if (m_place == Place::BeforeActiveLayer) {
+          layer = api.newLayer(parent, name);
           api.restackLayerBefore(layer, parent, activeLayer);
+        }
+        else
+          layer = api.newLayerAfter(parent, name, activeLayer);
         break;
-      case Type::Group: layer = api.newGroup(parent, name); break;
+      case Type::Group: layer = api.newGroupAfter(parent, name, activeLayer); break;
       case Type::ReferenceLayer:
         layer = api.newLayer(parent, name);
         if (layer)
@@ -296,9 +300,7 @@ void NewLayerCommand::onExecute(Context* context)
           tsi = tilesetInfo.tsi;
         }
 
-        layer = new LayerTilemap(sprite, tsi);
-        layer->setName(name);
-        api.addLayer(parent, layer, parent->lastLayer());
+        layer = api.newTilemapAfter(parent, name, tsi, activeLayer);
         break;
       }
     }
@@ -320,10 +322,6 @@ void NewLayerCommand::onExecute(Context* context)
           api.restackLayerBefore(layer, sprite->root(), first);
       }
     }
-    // Move the layer above the active one.
-    else if (activeLayer && m_place == Place::AfterActiveLayer) {
-      api.restackLayerAfter(layer, activeLayer->parent(), activeLayer);
-    }
 
     // Put all selected layers inside the group
     if (m_type == Type::Group && site.inTimeline()) {

src/app/doc_api.cpp

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019-2024  Igara Studio S.A.
+// Copyright (C) 2019-2025  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -52,6 +52,7 @@
 #include "doc/algorithm/flip_image.h"
 #include "doc/algorithm/shrink_bounds.h"
 #include "doc/cel.h"
+#include "doc/layer_tilemap.h"
 #include "doc/mask.h"
 #include "doc/palette.h"
 #include "doc/slice.h"
@@ -605,6 +606,18 @@ LayerImage* DocApi::newLayer(LayerGroup* parent, const std::string& name)
   return newLayer;
 }
 
+LayerImage* DocApi::newLayerAfter(LayerGroup* parent, const std::string& name, Layer* afterThis)
+{
+  LayerImage* newLayer = new LayerImage(parent->sprite());
+  newLayer->setName(name);
+
+  if (!afterThis)
+    afterThis = parent->lastLayer();
+
+  addLayer(parent, newLayer, afterThis);
+  return newLayer;
+}
+
 LayerGroup* DocApi::newGroup(LayerGroup* parent, const std::string& name)
 {
   LayerGroup* newLayerGroup = new LayerGroup(parent->sprite());
@@ -614,6 +627,33 @@ LayerGroup* DocApi::newGroup(LayerGroup* parent, const std::string& name)
   return newLayerGroup;
 }
 
+LayerGroup* DocApi::newGroupAfter(LayerGroup* parent, const std::string& name, Layer* afterThis)
+{
+  LayerGroup* newLayerGroup = new LayerGroup(parent->sprite());
+  newLayerGroup->setName(name);
+
+  if (!afterThis)
+    afterThis = parent->lastLayer();
+
+  addLayer(parent, newLayerGroup, afterThis);
+  return newLayerGroup;
+}
+
+LayerTilemap* DocApi::newTilemapAfter(LayerGroup* parent,
+                                      const std::string& name,
+                                      tileset_index tsi,
+                                      Layer* afterThis)
+{
+  LayerTilemap* newTilemap = new LayerTilemap(parent->sprite(), tsi);
+  newTilemap->setName(name);
+
+  if (!afterThis)
+    afterThis = parent->lastLayer();
+
+  addLayer(parent, newTilemap, afterThis);
+  return newTilemap;
+}
+
 void DocApi::addLayer(LayerGroup* parent, Layer* newLayer, Layer* afterThis)
 {
   m_transaction.execute(new cmd::AddLayer(parent, newLayer, afterThis));

src/app/doc_api.h

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019-2024  Igara Studio S.A.
+// Copyright (C) 2019-2025  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -15,6 +15,7 @@
 #include "doc/color.h"
 #include "doc/frame.h"
 #include "doc/image_ref.h"
+#include "doc/tile.h"
 #include "gfx/rect.h"
 
 #include <map>
@@ -26,6 +27,7 @@ class Image;
 class Layer;
 class LayerGroup;
 class LayerImage;
+class LayerTilemap;
 class Mask;
 class Palette;
 class Sprite;
@@ -104,7 +106,13 @@ public:
 
   // Layers API
   LayerImage* newLayer(LayerGroup* parent, const std::string& name);
+  LayerImage* newLayerAfter(LayerGroup* parent, const std::string& name, Layer* afterThis);
   LayerGroup* newGroup(LayerGroup* parent, const std::string& name);
+  LayerGroup* newGroupAfter(LayerGroup* parent, const std::string& name, Layer* afterThis);
+  LayerTilemap* newTilemapAfter(LayerGroup* parent,
+                                const std::string& name,
+                                tileset_index tsi,
+                                Layer* afterThis);
   void addLayer(LayerGroup* parent, Layer* newLayer, Layer* afterThis);
   void removeLayer(Layer* layer);
   void restackLayerAfter(Layer* layer, LayerGroup* parent, Layer* afterThis);