add output function callback, create context class

Author: NotAPenguin0

include/gl_layer/context.h

@@ -5,11 +5,14 @@
 extern "C" {
 #endif
 
-int gl_layer_init(int gl_version_major, int gl_version_minor);
+int gl_layer_init(unsigned int gl_version_major, unsigned int gl_version_minor);
 void gl_layer_terminate();
 
 void gl_layer_callback(const char* name, void* func_ptr, int num_args, ...);
 
+typedef void (*GLLayerOutputFun)(const char* text);
+void gl_layer_set_output_callback(GLLayerOutputFun callback);
+
 #ifdef __cplusplus
 };
 #endif

src/context.cpp

@@ -1 +1,62 @@
-#include <gl_layer/context.h>
+#include <gl_layer/context.h>
+
+#include <cstdio>
+
+namespace gl_layer {
+
+void default_output_func(const char* text) {
+    printf("%s", text);
+}
+
+struct Version {
+    unsigned int major = 0;
+    unsigned int minor = 0;
+};
+
+class Context {
+public:
+    explicit Context(Version gl_version) : gl_version(gl_version) {
+
+    }
+
+    void set_output_callback(GLLayerOutputFun callback) {
+        output_fun = callback;
+    }
+
+private:
+    Version gl_version;
+    GLLayerOutputFun output_fun = &default_output_func;
+};
+
+
+namespace {
+Context* g_context = nullptr;
+}
+
+} // namespace gl_layer
+
+int gl_layer_init(unsigned int gl_version_major, unsigned int gl_version_minor) {
+    gl_layer::g_context = new gl_layer::Context(gl_layer::Version{ gl_version_major, gl_version_minor });
+    if (gl_layer::g_context) return 0;
+
+    return -1;
+}
+
+void gl_layer_terminate() {
+    delete gl_layer::g_context;
+}
+
+void gl_layer_callback(const char* name, void* func_ptr, int num_args, ...) {
+    if (!gl_layer::g_context) {
+        // Report error: context not initialized.
+        return;
+    }
+}
+
+void gl_layer_set_output_callback(GLLayerOutputFun callback) {
+    if (!gl_layer::g_context) {
+        // Report error: context not initialized.
+        return;
+    }
+    gl_layer::g_context->set_output_callback(callback);
+}