1 files changed, 64 insertions, 0 deletions
diff --git a/src/prompt_toolkit/output/color_depth.py b/src/prompt_toolkit/output/color_depth.py
new file mode 100644
index 0000000..f66d2be
--- /dev/null
+++ b/src/prompt_toolkit/output/color_depth.py
@@ -0,0 +1,64 @@
+from __future__ import annotations
+
+import os
+from enum import Enum
+
+__all__ = [
+    "ColorDepth",
+]
+
+
+class ColorDepth(str, Enum):
+    """
+    Possible color depth values for the output.
+    """
+
+    value: str
+
+    #: One color only.
+    DEPTH_1_BIT = "DEPTH_1_BIT"
+
+    #: ANSI Colors.
+    DEPTH_4_BIT = "DEPTH_4_BIT"
+
+    #: The default.
+    DEPTH_8_BIT = "DEPTH_8_BIT"
+
+    #: 24 bit True color.
+    DEPTH_24_BIT = "DEPTH_24_BIT"
+
+    # Aliases.
+    MONOCHROME = DEPTH_1_BIT
+    ANSI_COLORS_ONLY = DEPTH_4_BIT
+    DEFAULT = DEPTH_8_BIT
+    TRUE_COLOR = DEPTH_24_BIT
+
+    @classmethod
+    def from_env(cls) -> ColorDepth | None:
+        """
+        Return the color depth if the $PROMPT_TOOLKIT_COLOR_DEPTH environment
+        variable has been set.
+
+        This is a way to enforce a certain color depth in all prompt_toolkit
+        applications.
+        """
+        # Disable color if a `NO_COLOR` environment variable is set.
+        # See: https://no-color.org/
+        if os.environ.get("NO_COLOR"):
+            return cls.DEPTH_1_BIT
+
+        # Check the `PROMPT_TOOLKIT_COLOR_DEPTH` environment variable.
+        all_values = [i.value for i in ColorDepth]
+        if os.environ.get("PROMPT_TOOLKIT_COLOR_DEPTH") in all_values:
+            return cls(os.environ["PROMPT_TOOLKIT_COLOR_DEPTH"])
+
+        return None
+
+    @classmethod
+    def default(cls) -> ColorDepth:
+        """
+        Return the default color depth for the default output.
+        """
+        from .defaults import create_output
+
+        return create_output().get_default_color_depth()