Added TileLayerWangEdit.generate

Returns a bare tile layer for now. Example use in a custom tool:

    mouseMoved: function(x, y, modifiers) {
        let ws = tiled.mapEditor.currentWangSet
        let editor = tiled.activeAsset.currentLayer.wangEdit(ws)
        editor.correctionsEnabled = true
        editor.setCorner(this.tilePosition, tiled.mapEditor.currentWangColorIndex)
        let map = new TileMap()
        map.addLayer(editor.generate())
        this.preview = map
    },

src/tiled/editablelayer.cpp

@@ -24,7 +24,6 @@
 #include "editablegrouplayer.h"
 #include "editablemanager.h"
 #include "editablemap.h"
-#include "scriptmanager.h"
 
 namespace Tiled {
 

src/tiled/editabletilelayer.cpp

@@ -37,6 +37,11 @@ EditableTileLayer::EditableTileLayer(const QString &name, QSize size, QObject *p
 {
 }
 
+EditableTileLayer::EditableTileLayer(std::unique_ptr<TileLayer> tileLayer, QObject *parent)
+    : EditableLayer(std::move(tileLayer), parent)
+{
+}
+
 EditableTileLayer::EditableTileLayer(EditableMap *map,
                                      TileLayer *layer,
                                      QObject *parent)

src/tiled/editabletilelayer.h

@@ -44,6 +44,9 @@ class EditableTileLayer : public EditableLayer
                                            QSize size = QSize(0, 0),
                                            QObject *parent = nullptr);
 
+    explicit EditableTileLayer(std::unique_ptr<TileLayer> tileLayer,
+                               QObject *parent = nullptr);
+
     explicit EditableTileLayer(EditableMap *map,
                                TileLayer *layer,
                                QObject *parent = nullptr);

src/tiled/tilelayerwangedit.cpp

@@ -25,6 +25,7 @@
 #include "editabletilelayer.h"
 #include "maprenderer.h"
 #include "scriptmanager.h"
+#include "tilelayer.h"
 
 #include <QCoreApplication>
 
@@ -85,16 +86,32 @@ void TileLayerWangEdit::setEdge(QPoint pos, WangIndex::Value edge, int color)
     }
 }
 
-void TileLayerWangEdit::apply()
+EditableTileLayer *TileLayerWangEdit::generate()
 {
-    // apply terrain changes
-    mWangFiller->apply(mChanges, *mTargetLayer->tileLayer());
+    auto changes = std::make_unique<TileLayer>();
+    mWangFiller->apply(*changes, *mTargetLayer->tileLayer());
+
+    // Determine painted region and normalize the changes layer
+    auto paintedRegion = changes->region([] (const Cell &cell) { return cell.checked(); });
+    if (!paintedRegion.isEmpty()) {
+        auto rect = paintedRegion.boundingRect();
+        changes->resize(rect.size(), -rect.topLeft());
+        changes->setPosition(rect.topLeft());
+    }
+
+    return new EditableTileLayer(std::move(changes));
+}
 
+void TileLayerWangEdit::apply()
+{
     // Applying an edit automatically makes it mergeable, so that further
     // changes made through the same edit are merged by default.
-    bool mergeable = std::exchange(mMergeable, true);
-    mTargetLayer->applyChangesFrom(&mChanges, mergeable);
-    mChanges.clear();
+    const bool mergeable = std::exchange(mMergeable, true);
+
+    // Apply terrain changes
+    TileLayer changes;
+    mWangFiller->apply(changes, *mTargetLayer->tileLayer());
+    mTargetLayer->applyChangesFrom(&changes, mergeable);
 }
 
 } // namespace Tiled

src/tiled/tilelayerwangedit.h

@@ -23,7 +23,6 @@
 
 #include "editablewangset.h"
 #include "map.h"
-#include "tilelayer.h"
 #include "wangfiller.h"
 
 #include <QObject>
@@ -84,6 +83,8 @@ class TileLayerWangEdit : public QObject
 
     EditableTileLayer *target() const;
 
+    Q_INVOKABLE Tiled::EditableTileLayer *generate();
+
 public slots:
     void setWangIndex(int x, int y, Tiled::WangIndex::Value index, int color);
     void setWangIndex(QPoint pos, Tiled::WangIndex::Value index, int color);
@@ -96,7 +97,6 @@ public slots:
 
 private:
     EditableTileLayer *mTargetLayer;
-    TileLayer mChanges;
     bool mMergeable = false;
     const Map mMap;                             // Copy for the configuration
     std::unique_ptr<MapRenderer> mRenderer;