Add SetTraceLogCallback to enable users setting custom logging (#597)

examples/core/core_custom_logging.c

@@ -0,0 +1,90 @@
+/*******************************************************************************************
+*
+*   raylib [core] example - Custom logging
+*
+*   Welcome to raylib!
+*
+*   To test examples, just press F6 and execute raylib_compile_execute script
+*   Note that compiled executable is placed in the same folder as .c file
+*
+*   You can find all basic examples on C:\raylib\raylib\examples folder or
+*   raylib official webpage: www.raylib.com
+*
+*   Enjoy using raylib. :)
+*
+*   This example has been created using raylib 2.0 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   Copyright (c) 2018 Ramon Santamaria (@raysan5) and Pablo Marcos Oltra (@pamarcos)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+#include <stdio.h>                  // Required for: fopen(), fclose(), fputc(), fwrite(), printf(), fprintf(), funopen()
+#include <time.h>                   // Required for: time_t, tm, time(), localtime(), strftime()
+
+void logCustom(int msgType, const char *text, va_list args)
+{
+	char timeStr[64];
+	time_t now = time(NULL);
+	struct tm *tm_info = localtime(&now);
+
+	strftime(timeStr, sizeof(timeStr), "%Y-%m-%d %H:%M:%S", tm_info);
+	printf("[%s] ", timeStr);
+
+	switch (msgType)
+	{
+		case LOG_INFO: printf("[INFO] : "); break;
+		case LOG_ERROR: printf("[ERROR]: "); break;
+		case LOG_WARNING: printf("[WARN] : "); break;
+		case LOG_DEBUG: printf("[DEBUG]: "); break;
+		default: break;
+	}
+	vprintf(text, args);
+	printf("\n");
+}
+
+int main(int argc, char* argv[])
+{
+	// Initialization
+	//--------------------------------------------------------------------------------------
+	int screenWidth = 800;
+	int screenHeight = 450;
+
+	// First thing we do is setting our custom logger to ensure everything raylib logs
+	// will use our own logger instead of its internal one
+	SetTraceLogCallback(logCustom);
+
+	InitWindow(screenWidth, screenHeight, "raylib [core] example - custom logging");
+
+	SetTargetFPS(60);
+	//--------------------------------------------------------------------------------------
+
+	// Main game loop
+	while (!WindowShouldClose())    // Detect window close button or ESC key
+	{
+		// Update
+		//----------------------------------------------------------------------------------
+		// TODO: Update your variables here
+		//----------------------------------------------------------------------------------
+
+		// Draw
+		//----------------------------------------------------------------------------------
+		BeginDrawing();
+
+		ClearBackground(RAYWHITE);
+
+		DrawText("Check out the console output to see the custom logger in action!", 60, 200, 20, LIGHTGRAY);
+
+		EndDrawing();
+		//----------------------------------------------------------------------------------
+	}
+
+	// De-Initialization
+	//--------------------------------------------------------------------------------------
+	CloseWindow();        // Close window and OpenGL context
+	//--------------------------------------------------------------------------------------
+
+	return 0;
+}

src/raylib.h

@@ -71,6 +71,8 @@
 #ifndef RAYLIB_H
 #define RAYLIB_H
 
+#include <stdarg.h>                             // Required for va_list
+
 #if defined(_WIN32) && defined(BUILD_LIBTYPE_SHARED)
     #define RLAPI __declspec(dllexport)         // We are building raylib as a Win32 shared library (.dll)
 #elif defined(_WIN32) && defined(USE_LIBTYPE_SHARED)
@@ -727,6 +729,9 @@ typedef enum {
     HMD_SONY_PSVR
 } VrDeviceType;
 
+// Callbacks to be implemented by users
+typedef void (*TraceLogCallback)(int msgType, const char *text, va_list args);
+
 #ifdef __cplusplus
 extern "C" {            // Prevents name mangling of functions
 #endif
@@ -796,6 +801,7 @@ RLAPI Color Fade(Color color, float alpha);                       // Color fade-
 RLAPI void ShowLogo(void);                                        // Activate raylib logo at startup (can be done with flags)
 RLAPI void SetConfigFlags(unsigned char flags);                   // Setup window configuration flags (view FLAGS)
 RLAPI void SetTraceLog(unsigned char types);                      // Enable trace log message types (bit flags based)
+RLAPI void SetTraceLogCallback(TraceLogCallback callback);        // Set a trace log callback to enable custom logging bypassing raylib's one
 RLAPI void TraceLog(int logType, const char *text, ...);          // Show trace log messages (LOG_INFO, LOG_WARNING, LOG_ERROR, LOG_DEBUG)
 RLAPI void TakeScreenshot(const char *fileName);                  // Takes a screenshot of current screen (saved a .png)
 RLAPI int GetRandomValue(int min, int max);                       // Returns a random value between min and max (both included)

src/utils.c

@@ -74,6 +74,7 @@ FILE *funopen(const void *cookie, int (*readfn)(void *, char *, int),
 
 // Log types messages supported flags (bit based)
 static unsigned char logTypeFlags = LOG_INFO | LOG_WARNING | LOG_ERROR;
+static TraceLogCallback logCallback = NULL;
 
 #if defined(PLATFORM_ANDROID)
 AAssetManager *assetManager;
@@ -99,11 +100,26 @@ void SetTraceLog(unsigned char types)
     logTypeFlags = types;
 }
 
+// Set a trace log callback to enable custom logging bypassing raylib's one
+void SetTraceLogCallback(TraceLogCallback callback)
+{
+    logCallback = callback;
+}
+
 // Show trace log messages (LOG_INFO, LOG_WARNING, LOG_ERROR, LOG_DEBUG)
 void TraceLog(int msgType, const char *text, ...)
 {
 #if defined(SUPPORT_TRACELOG)
     static char buffer[128];
+    va_list args;
+    va_start(args, text);
+
+    if (logCallback)
+    {
+        logCallback(msgType, text, args);
+        va_end(args);
+        return;
+    }
 
     switch(msgType)
     {
@@ -117,9 +133,6 @@ void TraceLog(int msgType, const char *text, ...)
     strcat(buffer, text);
     strcat(buffer, "\n");
 
-    va_list args;
-    va_start(args, text);
-
 #if defined(PLATFORM_ANDROID)
     switch(msgType)
     {