Merge pull request #26 from guanghuispark/zgh/skia/log

output cpp log to c#

com.unity.uiwidgets/Runtime/engine2/UIWidgetsPanel.cs

                 JSONMessageCodec.instance.toJson(settings));
 
             Input_OnEnable();
+            NativeConsole.OnEnable();
         }
 
         protected virtual void main() {

engine/Build.bee.cs

                 "src/shell/platform/unity/unity_surface_manager.h",
                 "src/shell/platform/unity/win32_task_runner.cc",
                 "src/shell/platform/unity/win32_task_runner.h",
+                "src/shell/platform/unity/unity_console.cc",
+                "src/shell/platform/unity/unity_console.h",
 
                 "src/shell/version/version.cc",
                 "src/shell/version/version.h",

com.unity.uiwidgets/Runtime/engine2/native_console.cs

+using UnityEngine;
+using AOT;
+using System;
+using System.Runtime.InteropServices;
+using NativeBindings = Unity.UIWidgets.ui.NativeBindings;
+
+public static class NativeConsole {
+    internal delegate void LogDelegate(IntPtr message, int iSize);
+
+    [DllImport(NativeBindings.dllName)]
+    internal static extern void InitNativeConsoleDelegate(LogDelegate log);
+
+    [MonoPInvokeCallback(typeof(LogDelegate))]
+    internal static void LogMessageFromCpp(IntPtr message, int iSize) {
+        Debug.Log(Marshal.PtrToStringAnsi(message, iSize));
+    }
+
+    public static void OnEnable()
+    {
+        InitNativeConsoleDelegate(LogMessageFromCpp);
+    }
+}

engine/src/shell/platform/unity/unity_console.cc

+#include "unity_console.h"
+#include <stdarg.h>
+
+namespace uiwidgets {
+
+ void UnityConsole::WriteLine(const char* fmt, ...) {
+  char log_str[512] = { 0 };
+  va_list ap;
+  va_start(ap, fmt);
+  vsprintf(log_str, fmt, ap);
+  _log(log_str, strlen(log_str));
+  va_end(ap);
+}
+
+LogDelegate UnityConsole::_log;
+
+UIWIDGETS_API(void) 
+InitNativeConsoleDelegate(LogDelegate Log) { 
+  UnityConsole::_log = Log; 
+}
+
+}

engine/src/shell/platform/unity/unity_console.h

+#pragma once
+#include "runtime/mono_api.h"
+
+namespace uiwidgets {
+
+typedef void (*LogDelegate)(char* message, int iSize);
+
+
+class UnityConsole{
+ public:
+  static LogDelegate _log;
+
+   /**
+   output the log to unity editor console window
+    @param fmt   log format
+    @param ...   log args
+    @return      null
+
+    example: 
+      UnityConsole::WriteLine("output log without fmt param");
+      UnityConsole::WriteLine("%s: %d + %d = %d","output log with param", 1, 2, 3);
+   */
+  static void WriteLine(const char* fmt, ...);
+};
+
+} // namespace uiwidgets