Add Delegate and --log-graphics-calls flag (#334)

This adds a Delegate which enables users of the amber library to
define some hook functions as they like. The first usage here is a
Delegate::Log() function to log graphics API calls.

In practice, a pointer to the delegate object is passed at engine
creation and the Vulkan engine eventually pass it to
LoadVulkanPointers() which calls the functions produced by
update_vk_wrappers.py. This enable to choose, when loading the Vulkan
functions, whether to load a straighforward wrapper to the API
command, or to load a lambda that surround the API command with calls
to the delegate methods.

The --log-graphics-calls flag in the samples sets the delegate to
produce a log of API calls.

1 files changed, 13 insertions, 0 deletions

diff --git a/include/amber/amber.h b/include/amber/amber.h
index b332129..5a89b88 100644
--- a/include/amber/amber.h
+++ b/include/amber/amber.h
@@ -52,6 +52,17 @@ struct BufferInfo {
   std::vector<Value> values;
 };
 
+/// Delegate class for various hook functions
+class Delegate {
+ public:
+  virtual ~Delegate();
+
+  /// Log the given message
+  virtual void Log(const std::string& message) = 0;
+  /// Tells whether to log the graphics API calls
+  virtual bool LogGraphicsCalls() const = 0;
+};
+
 struct Options {
   /// Sets the engine to be created. Default Vulkan.
   EngineType engine;
@@ -63,6 +74,8 @@ struct Options {
   std::vector<BufferInfo> extractions;
   /// Terminate after creating the pipelines.
   bool pipeline_create_only;
+  /// Delegate implementation
+  Delegate* delegate;
 };
 
 /// Main interface to the Amber environment.