feat: add matrix type stubs generation

Adds missing typing stubs:

- Matrix depths: `CV_8U`, `CV_8S` and etc.
- Matrix type constants: `CV_8UC1`, `CV_32FC3` and etc.
- Matrix type factory functions: `CV_*(channels) -> int` and `CV_MAKETYPE`

modules/python/src2/typing_stubs_generation/api_refinement.py

@@ -4,11 +4,13 @@ __all__ = [
 
 from typing import Sequence, Callable
 
-from .nodes import NamespaceNode, FunctionNode, OptionalTypeNode, ClassProperty, PrimitiveTypeNode
+from .nodes import (NamespaceNode, FunctionNode, OptionalTypeNode,
+                    ClassProperty, PrimitiveTypeNode)
 from .ast_utils import find_function_node, SymbolName
 
 
 def apply_manual_api_refinement(root: NamespaceNode) -> None:
+    export_matrix_type_constants(root)
     # Export OpenCV exception class
     builtin_exception = root.add_class("Exception")
     builtin_exception.is_exported = False
@@ -17,6 +19,33 @@ def apply_manual_api_refinement(root: NamespaceNode) -> None:
         refine_symbol(root, symbol_name)
 
 
+def export_matrix_type_constants(root: NamespaceNode) -> None:
+    MAX_PREDEFINED_CHANNELS = 4
+
+    depth_names = ("CV_8U", "CV_8S", "CV_16U", "CV_16S", "CV_32S",
+                   "CV_32F", "CV_64F", "CV_16F")
+    for depth_value, depth_name in enumerate(depth_names):
+        # Export depth constants
+        root.add_constant(depth_name, str(depth_value))
+        # Export predefined types
+        for c in range(MAX_PREDEFINED_CHANNELS):
+            root.add_constant(f"{depth_name}C{c + 1}",
+                              f"{depth_value + 8 * c}")
+        # Export type creation function
+        root.add_function(
+            f"{depth_name}C",
+            (FunctionNode.Arg("channels", PrimitiveTypeNode.int_()), ),
+            FunctionNode.RetType(PrimitiveTypeNode.int_())
+        )
+    # Export CV_MAKETYPE
+    root.add_function(
+        "CV_MAKETYPE",
+        (FunctionNode.Arg("depth", PrimitiveTypeNode.int_()),
+         FunctionNode.Arg("channels", PrimitiveTypeNode.int_())),
+        FunctionNode.RetType(PrimitiveTypeNode.int_())
+    )
+
+
 def make_optional_arg(arg_name: str) -> Callable[[NamespaceNode, SymbolName], None]:
     def _make_optional_arg(root_node: NamespaceNode,
                            function_symbol_name: SymbolName) -> None:

modules/python/src2/typing_stubs_generation/generation.py

@@ -103,9 +103,6 @@ def _generate_typing_stubs(root: NamespaceNode, output_path: Path) -> None:
 
     _write_reexported_symbols_section(root, output_stream)
 
-    # Write constants section, because constants don't impose any dependencies
-    _generate_section_stub(StubSection("# Constants", ConstantNode), root,
-                           output_stream, 0)
     # NOTE: Enumerations require special handling, because all enumeration
     # constants are exposed as module attributes
     has_enums = _generate_section_stub(StubSection("# Enumerations", EnumerationNode),