BPY-like layout helper

bgui/__init__.py

@@ -10,3 +10,4 @@
 from .frame_button import *
 from .progress_bar import *
 from .list_box import *
+from .flow_layout import *

bgui/flow_layout.py

@@ -0,0 +1,115 @@
+from .frame import Frame
+from .widget import BGUI_DEFAULT, BGUI_FLOW_COLUMN, BGUI_FLOW_ROW
+
+from contextlib import contextmanager
+from inspect import signature
+
+BGUI_FLOW_ROW = 0
+BGUI_FLOW_COLUMN = 1
+
+
+class FlowLayout(Frame):
+    """Layout class with row() and column() support"""
+
+    theme_section = 'FlowLayout'
+
+    def __init__(self, parent, name=None, border=None, aspect=None, size=None, pos=None, sub_theme='',
+                 options=BGUI_DEFAULT, flow_type=BGUI_FLOW_COLUMN):
+        self._insert_at = [0.0, 1.0]
+        self._flow_type = flow_type
+
+        if pos is None:
+            pos = [0.0, 0.0]
+        else:
+            pos = pos[:]
+
+        if size is None:
+            size = [1.0, 1.0]
+
+        else:
+            size = size[:]
+
+        super().__init__(parent, name, border, aspect, size, pos, sub_theme, options, clip)
+
+    @contextmanager
+    def _insert_element(self, size, alternate_size=1.0, padding=0.0):
+        index = self._flow_type
+
+        if index == BGUI_FLOW_ROW:
+            direction_switch = 1
+
+        else:
+            direction_switch = -1
+
+        insert_size = [alternate_size, alternate_size]
+        padded_size = max(size - (2 * padding), 0.0)
+        insert_size[self._flow_type] = padded_size
+
+        delta_size = size - padded_size
+        adjusted_padding = delta_size / 2
+
+        self._insert_at[self._flow_type] += direction_switch * adjusted_padding
+
+        # Account for the fact we work downwards. Columns will make this permanent with the next insert position
+        insert_at = self._insert_at[:]
+        insert_at[BGUI_FLOW_COLUMN] -= insert_size[BGUI_FLOW_COLUMN]
+
+        yield insert_size[:], insert_at
+
+        self._insert_at[self._flow_type] += direction_switch * (adjusted_padding + insert_size[index])
+
+    def column(self, size, *, alternate_size=1.0, padding=0.0, **kwargs):
+        """Create a child column and follow internal direction information
+        :param width: width of row
+        :param height: height of row
+        :param name: name of added row
+        """
+        with self._insert_element(size, alternate_size, padding) as (size, pos):
+            column = UILayout(self, size=size, pos=pos, flow_type=BGUI_FLOW_COLUMN, **kwargs)
+
+        return column
+
+    def row(self, size, *, alternate_size=1.0, padding=0.0, **kwargs):
+        """Create a child row and follow internal direction information
+        :param height: height of row
+        :param width: width of row
+        :param name: name of added row
+        """
+        with self._insert_element(size, alternate_size, padding) as (size, pos):
+            row = UILayout(self, size=size, pos=pos, flow_type=BGUI_FLOW_ROW, **kwargs)
+
+        return row
+
+    def separator(self, size=0.0):
+        with self._insert_element(size):
+            pass
+
+    def widget(self, widget_cls, *, size=1.0, alternate_size=1.0, **kwargs):
+        """Create a child widget and follow internal direction information
+        :param widget_cls: widget class
+        :param size: size of widget in layout direction
+        :param name: name of added widget
+        """
+        if 'size' in signature(widget_cls).parameters:
+
+            if self._flow_type == BGUI_FLOW_ROW:
+                ordered_size = [size, alternate_size]
+
+            else:
+                ordered_size = [alternate_size, size]
+
+            kwargs['size'] = ordered_size
+
+        widget = widget_cls(self, **kwargs)
+
+        # Take into account widgets using aspect option (or without size argument)
+        if self._flow_type == BGUI_FLOW_ROW:
+            size, alternate_size = widget._base_size
+
+        else:
+            alternate_size, size = widget._base_size
+
+        with self._insert_element(size, alternate_size, 0.0) as (size_, pos):
+            widget._update_position(None, pos)
+
+        return widget

bgui/widget.py

@@ -52,6 +52,10 @@
 BGUI_OVERFLOW_REPLACE = 2
 BGUI_OVERFLOW_CALLBACK = 3
 
+# Layout flow
+BGUI_FLOW_ROW = 0
+BGUI_FLOW_COLUMN = 1
+
 # Mouse event states
 BGUI_MOUSE_NONE = 0
 BGUI_MOUSE_CLICK = 1