Added composition mode to layer

TODO:

* Serialization in XML, JSON and Lua formats
* Decide which modes to support
* Consider what should happen when set on group layers

src/libtiled/layer.h

@@ -32,6 +32,7 @@
 #include "object.h"
 #include "tileset.h"
 
+#include <QPainter>
 #include <QPixmap>
 #include <QRect>
 #include <QSet>
@@ -192,6 +193,9 @@ class TILEDSHARED_EXPORT Layer : public Object
     QPointF parallaxFactor() const;
     QPointF effectiveParallaxFactor() const;
 
+    QPainter::CompositionMode compositionMode() const;
+    void setCompositionMode(QPainter::CompositionMode compositionMode);
+
     bool canMergeDown() const;
 
     virtual bool isEmpty() const = 0;
@@ -263,6 +267,7 @@ class TILEDSHARED_EXPORT Layer : public Object
     int mY = 0;
     QPointF mOffset;
     QPointF mParallaxFactor = { 1.0, 1.0 };
+    QPainter::CompositionMode mCompositionMode = QPainter::CompositionMode_SourceOver;
     qreal mOpacity = 1.0;
     QColor mTintColor;
     bool mVisible = true;
@@ -307,6 +312,16 @@ inline QPointF Layer::parallaxFactor() const
     return mParallaxFactor;
 }
 
+inline QPainter::CompositionMode Layer::compositionMode() const
+{
+    return mCompositionMode;
+}
+
+inline void Layer::setCompositionMode(QPainter::CompositionMode compositionMode)
+{
+    mCompositionMode = compositionMode;
+}
+
 
 /**
  * An iterator for iterating over the layers of a map, in the order in which

src/libtiled/mapwriter.cpp

@@ -677,6 +677,9 @@ void MapWriterPrivate::writeLayerAttributes(QXmlStreamWriter &w,
         w.writeAttribute(QStringLiteral("parallaxx"), QString::number(parallaxFactor.x()));
     if (parallaxFactor.y() != 1.0)
         w.writeAttribute(QStringLiteral("parallaxy"), QString::number(parallaxFactor.y()));
+
+    if (layer.compositionMode() != QPainter::CompositionMode_SourceOver)
+        w.writeAttribute(QStringLiteral("blend"), QStringLiteral("TODO: Convert composition mode to/from string"));
 }
 
 void MapWriterPrivate::writeObjectGroup(QXmlStreamWriter &w,

src/tiled/changeevents.h

@@ -128,7 +128,8 @@ class LayerChangeEvent : public ChangeEvent
         LockedProperty          = 1 << 3,
         OffsetProperty          = 1 << 4,
         ParallaxFactorProperty  = 1 << 5,
-        TintColorProperty       = 1 << 6,
+        CompositionModeProperty = 1 << 6,
+        TintColorProperty       = 1 << 7,
         PositionProperties      = OffsetProperty | ParallaxFactorProperty,
         AllProperties           = 0xFF
     };

src/tiled/changelayer.cpp

@@ -190,6 +190,28 @@ void SetLayerParallaxFactor::setValue(Layer *layer, const QPointF &value) const
 }
 
 
+SetLayerCompositionMode::SetLayerCompositionMode(Document *document,
+                                                 QList<Layer *> layers,
+                                                 QPainter::CompositionMode compositionMode,
+                                                 QUndoCommand *parent)
+    : ChangeValue<Layer, QPainter::CompositionMode>(document, std::move(layers), compositionMode, parent)
+{
+    setText(QCoreApplication::translate("Undo Commands",
+                                        "Change Layer Composition Mode"));
+}
+
+QPainter::CompositionMode SetLayerCompositionMode::getValue(const Layer *layer) const
+{
+    return layer->compositionMode();
+}
+
+void SetLayerCompositionMode::setValue(Layer *layer, const QPainter::CompositionMode &value) const
+{
+    layer->setCompositionMode(value);
+    emit document()->changed(LayerChangeEvent(layer, LayerChangeEvent::CompositionModeProperty));
+}
+
+
 SetTileLayerSize::SetTileLayerSize(Document *document,
                                    TileLayer *tileLayer,
                                    QSize size,

src/tiled/changelayer.h

@@ -26,6 +26,7 @@
 #include <QPointF>
 #include <QSize>
 #include <QColor>
+#include <QPainter>
 
 namespace Tiled {
 
@@ -153,6 +154,24 @@ class SetLayerParallaxFactor : public ChangeValue<Layer, QPointF>
     void setValue(Layer *layer, const QPointF &value) const override;
 };
 
+/**
+ * Used for changing the layer parallax factor.
+ */
+class SetLayerCompositionMode : public ChangeValue<Layer, QPainter::CompositionMode>
+{
+public:
+    SetLayerCompositionMode(Document *document,
+                            QList<Layer *> layers,
+                            QPainter::CompositionMode compositionMode,
+                            QUndoCommand *parent = nullptr);
+
+    int id() const override { return Cmd_ChangeLayerCompositionMode; }
+
+private:
+    QPainter::CompositionMode getValue(const Layer *layer) const override;
+    void setValue(Layer *layer, const QPainter::CompositionMode &value) const override;
+};
+
 /**
  * Used for changing the tile layer size.
  *

src/tiled/imagelayeritem.cpp

@@ -55,5 +55,6 @@ void ImageLayerItem::paint(QPainter *painter,
 {
     // TODO: Display a border around the layer when selected
     MapRenderer *renderer = mMapDocument->renderer();
+    painter->setCompositionMode(layer()->compositionMode());
     renderer->drawImageLayer(painter, imageLayer(), option->exposedRect);
 }

src/tiled/mapitem.cpp

@@ -548,8 +548,10 @@ void MapItem::layerChanged(const LayerChangeEvent &change)
     QGraphicsItem *layerItem = mLayerItems.value(layer);
     Q_ASSERT(layerItem);
 
-    if (change.properties & LayerChangeEvent::TintColorProperty)
-        layerTintColorChanged(layer);
+    if (change.properties & (LayerChangeEvent::TintColorProperty |
+                             LayerChangeEvent::CompositionModeProperty)) {
+        updateLayerItems(layer);
+    }
 
     layerItem->setVisible(layer->isVisible());
 
@@ -584,7 +586,7 @@ void MapItem::layerChanged(const LayerChangeEvent &change)
     updateBoundingRect();   // possible layer offset change
 }
 
-void MapItem::layerTintColorChanged(Layer *layer)
+void MapItem::updateLayerItems(Layer *layer)
 {
     switch (layer->layerType()) {
     case Layer::TileLayerType:
@@ -600,7 +602,7 @@ void MapItem::layerTintColorChanged(Layer *layer)
     case Layer::GroupLayerType:
         // Recurse into group layers since tint color is inherited
         for (auto childLayer : static_cast<GroupLayer*>(layer)->layers())
-            layerTintColorChanged(childLayer);
+            updateLayerItems(childLayer);
         break;
     }
 }

src/tiled/mapitem.h

@@ -107,7 +107,7 @@ class MapItem : public QGraphicsObject
     void layerAboutToBeRemoved(GroupLayer *parentLayer, int index);
     void layerRemoved(Layer *layer);
     void layerChanged(const LayerChangeEvent &change);
-    void layerTintColorChanged(Layer *layer);
+    void updateLayerItems(Layer *layer);
 
     void imageLayerChanged(ImageLayer *imageLayer);
 

src/tiled/mapobjectitem.cpp

@@ -145,6 +145,8 @@ void MapObjectItem::paint(QPainter *painter,
     const QPointF pixelPos = renderer->pixelToScreenCoords(mObject->position());
 
     painter->translate(-pixelPos);
+    if (ObjectGroup *objectGroup = mObject->objectGroup())
+        painter->setCompositionMode(objectGroup->compositionMode());
     renderer->drawMapObject(painter, mObject, mColors);
     painter->translate(pixelPos);
 

src/tiled/propertieswidget.cpp

@@ -195,6 +195,38 @@ template<> EnumData enumData<WangSet::Type>()
     return { names, {}, icons };
 }
 
+template<> EnumData enumData<QPainter::CompositionMode>()
+{
+    const QStringList names {
+        QStringLiteral("SourceOver"),
+        QStringLiteral("DestinationOver"),
+        QStringLiteral("Clear"),
+        QStringLiteral("Source"),
+        QStringLiteral("Destination"),
+        QStringLiteral("SourceIn"),
+        QStringLiteral("DestinationIn"),
+        QStringLiteral("SourceOut"),
+        QStringLiteral("DestinationOut"),
+        QStringLiteral("SourceAtop"),
+        QStringLiteral("DestinationAtop"),
+        QStringLiteral("Xor"),
+        QStringLiteral("Plus"),
+        QStringLiteral("Multiply"),
+        QStringLiteral("Screen"),
+        QStringLiteral("Overlay"),
+        QStringLiteral("Darken"),
+        QStringLiteral("Lighten"),
+        QStringLiteral("ColorDodge"),
+        QStringLiteral("ColorBurn"),
+        QStringLiteral("HardLight"),
+        QStringLiteral("SoftLight"),
+        QStringLiteral("Difference"),
+        QStringLiteral("Exclusion"),
+    };
+
+    return { names };
+}
+
 
 class FlippingProperty : public IntProperty
 {
@@ -1037,6 +1069,15 @@ class LayerProperties : public ObjectProperties
                     });
         mParallaxFactorProperty->setSingleStep(0.1);
 
+        mCompositionModeProperty = new EnumProperty<QPainter::CompositionMode>(
+                    tr("Composition Mode"),
+                    [this] { return layer()->compositionMode(); },
+                    [this](QPainter::CompositionMode mode) {
+                        push(new SetLayerCompositionMode(mapDocument(),
+                                                         mapDocument()->selectedLayers(),
+                                                         mode));
+                    });
+
         mLayerProperties = new GroupProperty(tr("Layer"));
         mLayerProperties->addProperty(mIdProperty);
         mLayerProperties->addProperty(mNameProperty);
@@ -1048,6 +1089,7 @@ class LayerProperties : public ObjectProperties
         mLayerProperties->addProperty(mTintColorProperty);
         mLayerProperties->addProperty(mOffsetProperty);
         mLayerProperties->addProperty(mParallaxFactorProperty);
+        mLayerProperties->addProperty(mCompositionModeProperty);
 
         addProperty(mLayerProperties);
 
@@ -1114,6 +1156,7 @@ class LayerProperties : public ObjectProperties
     Property *mTintColorProperty;
     Property *mOffsetProperty;
     PointFProperty *mParallaxFactorProperty;
+    BaseEnumProperty *mCompositionModeProperty;
 };
 
 class ImageLayerProperties : public LayerProperties

src/tiled/tilelayeritem.cpp

@@ -68,5 +68,6 @@ void TileLayerItem::paint(QPainter *painter,
 {
     MapRenderer *renderer = mMapDocument->renderer();
     // TODO: Display a border around the layer when selected
+    painter->setCompositionMode(layer()->compositionMode());
     renderer->drawTileLayer(painter, tileLayer(), option->exposedRect);
 }

src/tiled/undocommands.h

@@ -32,6 +32,7 @@ enum UndoCommands {
     Cmd_ChangeClassName,
     Cmd_ChangeImageLayerRepeatX,
     Cmd_ChangeImageLayerRepeatY,
+    Cmd_ChangeLayerCompositionMode,
     Cmd_ChangeLayerLocked,
     Cmd_ChangeLayerName,
     Cmd_ChangeLayerOffset,