Windows/CLog: Support color logging on Win 10

Windows 10 supports V100 on all consoles given
you enable the ENABLE_VIRTUAL_TERMINAL_PROCESSING
flag for the console.

This patch enables color logging only on windows
10 and only if the log is not being redirected
to a file.

Differential Revision: https://developer.blender.org/D10546

1 files changed, 30 insertions, 9 deletions

diff --git a/intern/clog/clog.c b/intern/clog/clog.c
index 2bc3985c71f..af8bf38d84d 100644
--- a/intern/clog/clog.c
+++ b/intern/clog/clog.c
@@ -1,4 +1,4 @@
-/*
+/*
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version 2
@@ -38,8 +38,14 @@
 #endif
 
 #if defined(_MSC_VER)
+// clang-format off
+#  include <Windows.h>
+#  include <VersionHelpers.h> /* This needs to be included after Windows.h. */
 #  include <io.h>
-#  include <windows.h>
+// clang-format on
+#  if !defined(ENABLE_VIRTUAL_TERMINAL_PROCESSING)
+#    define ENABLE_VIRTUAL_TERMINAL_PROCESSING 0x0004
+#  endif
 #endif
 
 /* For printing timestamp. */
@@ -228,6 +234,9 @@ enum eCLogColor {
 #define COLOR_LEN (COLOR_RESET + 1)
 
 static const char *clg_color_table[COLOR_LEN] = {NULL};
+#ifdef _WIN32
+static DWORD clg_previous_console_mode = 0;
+#endif
 
 static void clg_color_table_init(bool use_color)
 {
@@ -548,13 +557,22 @@ static void CLG_ctx_output_set(CLogContext *ctx, void *file_handle)
 #if defined(__unix__) || defined(__APPLE__)
   ctx->use_color = isatty(ctx->output);
 #elif defined(WIN32)
-  /* Windows Terminal supports color like the Linux terminals do while the standard console does
-   * not, the way to tell the two apart is to look at the `WT_SESSION` environment variable which
-   * will only be defined for Windows Terminal. */
-
-  /* #getenv is used here rather than #BLI_getenv since it would be a bad level call
-   * and there are no benefits for using it in this context. */
-  ctx->use_color = isatty(ctx->output) && getenv("WT_SESSION");
+  /* As of Windows 10 build 18298 all the standard consoles supports color
+   * like the Linux Terminal do, but it needs to be turned on.
+   * To turn on colors we need to enable virtual terminal processing by passing the flag
+   * ENABLE_VIRTUAL_TERMINAL_PROCESSING into SetConsoleMode.
+   * If the system doesn't support virtual terminal processing it will fail silently and the flag
+   * will not be set. */
+
+  GetConsoleMode(GetStdHandle(STD_OUTPUT_HANDLE), &clg_previous_console_mode);
+
+  ctx->use_color = 0;
+  if (IsWindows10OrGreater() && isatty(ctx->output)) {
+    DWORD mode = clg_previous_console_mode | ENABLE_VIRTUAL_TERMINAL_PROCESSING;
+    if (SetConsoleMode(GetStdHandle(STD_OUTPUT_HANDLE), mode)) {
+      ctx->use_color = 1;
+    }
+  }
 #endif
 }
 
@@ -638,6 +656,9 @@ static CLogContext *CLG_ctx_init(void)
 
 static void CLG_ctx_free(CLogContext *ctx)
 {
+#if defined(WIN32)
+  SetConsoleMode(GetStdHandle(STD_OUTPUT_HANDLE), clg_previous_console_mode);
+#endif
   while (ctx->types != NULL) {
     CLG_LogType *item = ctx->types;
     ctx->types = item->next;