Add basic layer interface

modules/core/inc/tactile/core/map/layer/layer.hpp

@@ -0,0 +1,87 @@
+// Copyright (C) 2023 Albin Johansson (GNU General Public License v3.0)
+
+#pragma once
+
+#include "tactile/core/api.hpp"
+#include "tactile/core/container/smart_ptr.hpp"
+#include "tactile/core/context/meta_context.hpp"
+#include "tactile/core/functional/maybe.hpp"
+#include "tactile/core/prelude.hpp"
+
+namespace tactile {
+
+TACTILE_FWD(class ILayerVisitor)
+
+/**
+ * \interface ILayer
+ * \brief The common interface for all layer variants.
+ */
+class TACTILE_CORE_API ILayer : public IMetaContext {
+ public:
+  TACTILE_INTERFACE_CLASS(ILayer);
+
+  /**
+   * \brief Inspects the layer using the given visitor.
+   *
+   * \param visitor the visitor to use.
+   */
+  virtual void accept(ILayerVisitor& visitor) = 0;
+
+  /**
+   * \brief Sets the associated identifier used in save files.
+   *
+   * \param id the new persistent identifier, if any.
+   */
+  virtual void set_persistent_id(Maybe<int32> id) = 0;
+
+  /**
+   * \brief Sets the opacity of the layer content.
+   *
+   * \param opacity the opacity value, will be clamped to [0, 1].
+   */
+  virtual void set_opacity(float opacity) = 0;
+
+  /**
+   * \brief Sets the visibility of the layer content.
+   *
+   * \param visible true if the layer content should be rendered; false otherwise.
+   */
+  virtual void set_visible(bool visible) = 0;
+
+  /**
+   * \brief Returns the associated persistent identifier, if any.
+   *
+   * \return a layer identifier.
+   */
+  [[nodiscard]]
+  virtual auto get_persistent_id() const -> Maybe<int32> = 0;
+
+  /**
+   * \brief Returns the layer content opacity.
+   *
+   * \return an opacity value in the interval [0, 1].
+   */
+  [[nodiscard]]
+  virtual auto get_opacity() const -> float = 0;
+
+  /**
+   * \brief Indicates whether the layer content is rendered.
+   *
+   * \return true if the content is visible; false otherwise.
+   */
+  [[nodiscard]]
+  virtual auto is_visible() const -> bool = 0;
+
+  /**
+   * \brief Creates a clone of the layer.
+   *
+   * \note The layer clone may not be identical to the source layer, the only guarantee
+   *       is that the layer clone is logically equivalent.
+   *
+   * \return the new layer.
+   */
+  [[nodiscard]]
+  virtual auto clone() const -> Shared<ILayer> = 0;
+};
+
+}  // namespace tactile

modules/core/inc/tactile/core/map/layer/layer_visitor.hpp

@@ -0,0 +1,46 @@
+// Copyright (C) 2023 Albin Johansson (GNU General Public License v3.0)
+
+#pragma once
+
+#include "tactile/core/api.hpp"
+#include "tactile/core/prelude.hpp"
+
+namespace tactile {
+
+TACTILE_FWD(class TileLayer)
+TACTILE_FWD(class ObjectLayer)
+TACTILE_FWD(class GroupLayer)
+
+/**
+ * \brief Visitor type used to inspect non-const layers.
+ */
+class TACTILE_CORE_API ILayerVisitor {
+ public:
+  TACTILE_INTERFACE_CLASS(ILayerVisitor);
+
+  /**
+   * \brief Visits a tile layer.
+   *
+   * \param layer the visited layer.
+   */
+  virtual void visit([[maybe_unused]] TileLayer& layer)
+  {}
+
+  /**
+   * \brief Visits an object layer.
+   *
+   * \param layer the visited layer.
+   */
+  virtual void visit([[maybe_unused]] ObjectLayer& layer)
+  {}
+
+  /**
+   * \brief Visits a group layer.
+   *
+   * \param layer the visited layer.
+   */
+  virtual void visit([[maybe_unused]] GroupLayer& layer)
+  {}
+};
+
+}  // namespace tactile