Layer scroll fix (#2196)

* fix scroll spacing

* fix and snapshot

* changelog

Author: willmcgugan

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## [0.17.3] - 2023-04-02
+
+### [Fixed]
+
+- Fixed scrollable area not taking in to account dock https://github.com/Textualize/textual/issues/2188
+
 ## [0.17.2] - 2023-04-02
 
 ### [Fixed]
@@ -693,6 +699,7 @@ https://textual.textualize.io/blog/2022/11/08/version-040/#version-040
 - New handler system for messages that doesn't require inheritance
 - Improved traceback handling
 
+[0.17.3]: https://github.com/Textualize/textual/compare/v0.17.2...v0.17.3
 [0.17.2]: https://github.com/Textualize/textual/compare/v0.17.1...v0.17.2
 [0.17.1]: https://github.com/Textualize/textual/compare/v0.17.0...v0.17.1
 [0.17.0]: https://github.com/Textualize/textual/compare/v0.16.0...v0.17.0

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "textual"
-version = "0.17.2"
+version = "0.17.3"
 homepage = "https://github.com/Textualize/textual"
 description = "Modern Text User Interface framework"
 authors = ["Will McGugan <[email protected]>"]

src/textual/_arrange.py

@@ -128,4 +128,4 @@ def arrange(
 
         placements.extend(layout_placements)
 
-    return DockArrangeResult(placements, arrange_widgets)
+    return DockArrangeResult(placements, arrange_widgets, scroll_spacing)

src/textual/_compositor.py

@@ -504,24 +504,25 @@ def add_widget(
                     }
                     get_layer_index = layers_to_index.get
 
+                    scroll_spacing = arrange_result.scroll_spacing
+
                     # Add all the widgets
                     for sub_region, margin, sub_widget, z, fixed in reversed(
                         placements
                     ):
+                        layer_index = get_layer_index(sub_widget.layer, 0)
                         # Combine regions with children to calculate the "virtual size"
                         if fixed:
                             widget_region = sub_region + placement_offset
                         else:
-                            total_region = total_region.union(sub_region.grow(margin))
+                            total_region = total_region.union(
+                                sub_region.grow(
+                                    margin if layer_index else margin + scroll_spacing
+                                )
+                            )
                             widget_region = sub_region + placement_scroll_offset
 
-                        widget_order = order + (
-                            (
-                                get_layer_index(sub_widget.layer, 0),
-                                z,
-                                layer_order,
-                            ),
-                        )
+                        widget_order = order + ((layer_index, z, layer_order),)
 
                         add_widget(
                             sub_widget,

src/textual/_layout.py

@@ -21,6 +21,8 @@ class DockArrangeResult:
     """A `WidgetPlacement` for every widget to describe it's location on screen."""
     widgets: set[Widget]
     """A set of widgets in the arrangement."""
+    scroll_spacing: Spacing
+    """Spacing to reduce scrollable area."""
 
     _spatial_map: SpatialMap[WidgetPlacement] | None = None
     """A Spatial map to query widget placements."""

tests/snapshot_tests/__snapshots__/test_snapshots.ambr

@@ -0,0 +1,31 @@
+from textual.app import App
+from textual.widgets import Header, Label, Footer
+
+
+class TestApp(App):
+    BINDINGS = [("ctrl+q", "app.quit", "Quit")]
+    CSS = """
+    
+    Label {
+        border: solid red;
+    }
+    Footer {
+        height: 4;
+    }
+    """
+
+    def compose(self):
+        text = (
+            "this is a sample sentence and here are some words".replace(" ", "\n") * 2
+        )
+        yield Header()
+        yield Label(text)
+        yield Footer()
+
+    def on_mount(self):
+        self.dark = False
+
+
+if __name__ == "__main__":
+    app = TestApp()
+    app.run()

tests/snapshot_tests/snapshot_apps/dock_scroll.py

@@ -381,3 +381,8 @@ def test_modal_dialog_bindings(snap_compare):
         SNAPSHOT_APPS_DIR / "modal_screen_bindings.py",
         press=["enter", "tab", "h", "i", "tab", "enter"],
     )
+
+
+def test_dock_scroll(snap_compare):
+    # https://github.com/Textualize/textual/issues/2188
+    assert snap_compare(SNAPSHOT_APPS_DIR / "dock_scroll.py", terminal_size=(80, 25))