[core] Rationalize naming for style-related code

1 files changed, 71 insertions, 0 deletions

diff --git a/include/mbgl/style/layers/custom_layer.hpp b/include/mbgl/style/layers/custom_layer.hpp
new file mode 100644
index 0000000000..d3867e2c4f
--- /dev/null
+++ b/include/mbgl/style/layers/custom_layer.hpp
@@ -0,0 +1,71 @@
+#pragma once
+
+#include <mbgl/style/layer.hpp>
+
+namespace mbgl {
+namespace style {
+
+/**
+ * Initialize any GL state needed by the custom layer. This method is called once, from the
+ * rendering thread, at a point when the GL context is active but before rendering for the
+ * first time.
+ *
+ * Resources that are acquired in this method must be released in the UninitializeFunction.
+ */
+using CustomLayerInitializeFunction = void (*)(void* context);
+
+/**
+ * Parameters that define the current camera position for a CustomLayerRenderFunction.
+ */
+struct CustomLayerRenderParameters {
+    double width;
+    double height;
+    double latitude;
+    double longitude;
+    double zoom;
+    double bearing;
+    double pitch;
+    double altitude;
+};
+
+/**
+ * Render the layer. This method is called once per frame. The implementation should not make
+ * any assumptions about the GL state (other than that the correct context is active). It may
+ * make changes to the state, and is not required to reset values such as the depth mask, stencil
+ * mask, and corresponding test flags to their original values.
+ */
+using CustomLayerRenderFunction = void (*)(void* context, const CustomLayerRenderParameters&);
+
+/**
+ * Destroy any GL state needed by the custom layer, and deallocate context, if necessary. This
+ * method is called once, from the rendering thread, at a point when the GL context is active.
+ *
+ * Note that it may be called even when the InitializeFunction has not been called.
+ */
+using CustomLayerDeinitializeFunction = void (*)(void* context);
+
+class CustomLayer : public Layer {
+public:
+    CustomLayer(const std::string& id,
+                CustomLayerInitializeFunction,
+                CustomLayerRenderFunction,
+                CustomLayerDeinitializeFunction,
+                void* context);
+    ~CustomLayer() final;
+
+    // Private implementation
+
+    class Impl;
+    Impl* impl;
+
+    CustomLayer(const Impl&);
+    CustomLayer(const CustomLayer&) = delete;
+};
+
+template <>
+inline bool Layer::is<CustomLayer>() const {
+    return type == Type::Custom;
+}
+
+} // namespace style
+} // namespace mbgl