implement 'output.ansi' option (#2628)

docs/configuration.rst

@@ -2948,6 +2948,17 @@ Description
 .. __: `output.mode`_
 
 
+output.ansi
+-----------
+Type
+    ``bool``
+Default
+    ``false``
+Description
+    | On Windows, enable ANSI escape sequences and colored output
+    | by setting the ``ENABLE_VIRTUAL_TERMINAL_PROCESSING`` flag for stdout and stderr.
+
+
 output.skip
 -----------
 Type

docs/gallery-dl-example.conf

@@ -334,6 +334,9 @@
         "#": "while also considering wider East-Asian characters",
         "shorten": "eaw",
 
+        "#": "enable ANSI escape sequences on Windows",
+        "ansi": true,
+
         "#": "write logging messages to a separate file",
         "logfile": {
             "path": "~/gallery-dl/log.txt",

docs/gallery-dl.conf

@@ -355,6 +355,7 @@
         "mode": "auto",
         "progress": true,
         "shorten": true,
+        "ansi": false,
         "colors": {
             "success": "1;32",
             "skip"   : "2"

gallery_dl/__init__.py

@@ -154,6 +154,21 @@ def main():
                 else:
                     signal.signal(signal_num, signal.SIG_IGN)
 
+        # enable ANSI escape sequences on Windows
+        if util.WINDOWS and config.get(("output",), "ansi"):
+            from ctypes import windll, wintypes, byref
+            kernel32 = windll.kernel32
+            mode = wintypes.DWORD()
+
+            for handle_id in (-11, -12):  # stdout and stderr
+                handle = kernel32.GetStdHandle(handle_id)
+                kernel32.GetConsoleMode(handle, byref(mode))
+                if not mode.value & 0x4:
+                    mode.value |= 0x4
+                    kernel32.SetConsoleMode(handle, mode)
+
+            output.ANSI = True
+
         # extractor modules
         modules = config.get(("extractor",), "modules")
         if modules is not None: