Column data styles for Table and Tree widgets

android/src/toga_android/widgets/label.py

@@ -18,6 +18,18 @@ def set_textview_font(textview, font, default_typeface, default_size):
     textview.setTextSize(TypedValue.COMPLEX_UNIT_PX, font.size(default=default_size))
 
 
+def set_alignment(textview, value, vertical_gravity):
+    # Justified text wasn't added until API level 26.
+    # We only run the test suite on API 31, so we need to disable branch coverage.
+    if Build.VERSION.SDK_INT >= 26:  # pragma: no branch
+        textview.setJustificationMode(
+            Layout.JUSTIFICATION_MODE_INTER_WORD
+            if value == JUSTIFY
+            else Layout.JUSTIFICATION_MODE_NONE
+        )
+    textview.setGravity(vertical_gravity | android_text_align(value))
+
+
 class TextViewWidget(Widget):
     def cache_textview_defaults(self):
         self._default_text_color = self.native.getCurrentTextColor()
@@ -36,16 +48,7 @@ def set_color(self, value):
             self.native.setTextColor(native_color(value))
 
     def set_textview_alignment(self, value, vertical_gravity):
-        # Justified text wasn't added until API level 26.
-        # We only run the test suite on API 31, so we need to disable branch coverage.
-        if Build.VERSION.SDK_INT >= 26:  # pragma: no branch
-            self.native.setJustificationMode(
-                Layout.JUSTIFICATION_MODE_INTER_WORD
-                if value == JUSTIFY
-                else Layout.JUSTIFICATION_MODE_NONE
-            )
-
-        self.native.setGravity(vertical_gravity | android_text_align(value))
+        set_alignment(self.native, value, vertical_gravity)
 
 
 class Label(TextViewWidget):

android/src/toga_android/widgets/table.py

@@ -6,8 +6,9 @@
 from android.widget import LinearLayout, ScrollView, TableLayout, TableRow, TextView
 from java import dynamic_proxy
 
+from ..colors import native_color
 from .base import Widget
-from .label import set_textview_font
+from .label import set_alignment, set_textview_font
 
 
 class TogaOnClickListener(dynamic_proxy(View.OnClickListener)):
@@ -149,18 +150,35 @@ def create_table_row(self, row_index):
                 )
             text_view = TextView(self._native_activity)
             text_view.setText(toga_column.text(data_row, missing_value))
+            text_align = toga_column.text_align(data_row)
+            color = toga_column.color(data_row)
+            background_color = toga_column.background_color(data_row)
+            font = toga_column.font(data_row, self.interface.style.font)
+
+            if color is not None:
+                text_view.setTextColor(native_color(color))
+            if background_color is not None:
+                text_view.setBackgroundColor(native_color(background_color))
+            # font is only None if something is very wrong (eg. can't find system font)
+            # so can't test
+            if font is not None:
+                font_impl = font._impl
+            else:  # pragma: no cover
+                font_impl = self._font_impl
             set_textview_font(
                 text_view,
-                self._font_impl,
+                font_impl,
                 text_view.getTypeface(),
                 text_view.getTextSize(),
             )
             text_view_params = TableRow.LayoutParams(
                 TableRow.LayoutParams.MATCH_PARENT, TableRow.LayoutParams.WRAP_CONTENT
             )
             text_view_params.setMargins(10, 5, 10, 5)  # left, top, right, bottom
-            text_view_params.gravity = Gravity.START
+            text_view_params.gravity = Gravity.FILL_HORIZONTAL
             text_view.setLayoutParams(text_view_params)
+            if text_align is not None:
+                set_alignment(text_view, text_align, Gravity.CENTER_VERTICAL)
             table_row.addView(text_view)
         return table_row
 

android/tests_backend/widgets/table.py

@@ -1,6 +1,9 @@
 import pytest
 from android.widget import ScrollView, TableLayout, TextView
 
+from toga_android.colors import native_color
+from toga_android.widgets.base import android_text_align
+
 from .base import SimpleProbe
 
 HEADER = "HEADER"
@@ -11,6 +14,7 @@ class TableProbe(SimpleProbe):
     supports_icons = False
     supports_keyboard_shortcuts = False
     supports_widgets = False
+    supports_styles = True
     column_proportion_tolerance = 35
 
     def __init__(self, widget):
@@ -30,18 +34,63 @@ def row_count(self):
     def column_count(self):
         return self._row_view(HEADER).getChildCount()
 
-    def assert_cell_content(self, row, col, value=None, icon=None, widget=None):
+    def assert_cell_content(
+        self,
+        row,
+        col,
+        value=None,
+        icon=None,
+        widget=None,
+        text_align=None,
+        color=None,
+        background_color=None,
+        font=None,
+    ):
         if widget:
             pytest.skip("This backend doesn't support widgets in Tables")
         else:
-            assert self._cell_text(row, col) == value
+            if value is not None:
+                assert self._cell_text(row, col) == value
             assert icon is None
+            if text_align is not None:
+                assert self._cell_gravity(row, col) & android_text_align(text_align)
+            if color is not None:
+                assert self._cell_color(row, col) == native_color(color)
+            if background_color is not None:
+                assert self._cell_background_color(row, col) == native_color(
+                    background_color
+                )
+            if font is not None:
+                assert self._cell_font(row, col) == (
+                    font._impl.typeface(),
+                    font._impl.size(),
+                )
 
     def _cell_text(self, row, col):
         tv = self._row_view(row).getChildAt(col)
         assert isinstance(tv, TextView)
         return str(tv.getText())
 
+    def _cell_color(self, row, col):
+        tv = self._row_view(row).getChildAt(col)
+        assert isinstance(tv, TextView)
+        return tv.getCurrentTextColor()
+
+    def _cell_background_color(self, row, col):
+        tv = self._row_view(row).getChildAt(col)
+        assert isinstance(tv, TextView)
+        return tv.getBackground().getColor()
+
+    def _cell_gravity(self, row, col):
+        tv = self._row_view(row).getChildAt(col)
+        assert isinstance(tv, TextView)
+        return tv.getGravity()
+
+    def _cell_font(self, row, col):
+        tv = self._row_view(row).getChildAt(col)
+        assert isinstance(tv, TextView)
+        return tv.getTypeface(), tv.getTextSize()
+
     def _row_view(self, row):
         if row == HEADER:
             row = 0

changes/4258.feature.md

@@ -0,0 +1 @@
+The `Table` and `Tree` widgets on Cocoa and Qt, and the `Table` widget on Android, can now specify colors, fonts and text alignment to use for individual cells based on the data contained in the cell by writing an appropriate `Column` subclass.

cocoa/src/toga_cocoa/widgets/table.py

@@ -10,8 +10,10 @@
     NSTableView,
     NSTableViewAnimation,
     NSTableViewColumnAutoresizingStyle,
+    NSTextAlignment,
 )
 
+from ..colors import native_color
 from .base import Widget
 from .internal.cells import TogaIconView
 
@@ -43,6 +45,10 @@ def tableView_viewForTableColumn_row_(self, table, column, row: int):
 
         icon = column.toga_column.icon(data_row)
         text = column.toga_column.text(data_row, self.interface.missing_value)
+        text_align = column.toga_column.text_align(data_row)
+        color = column.toga_column.color(data_row)
+        background_color = column.toga_column.background_color(data_row)
+        font = column.toga_column.font(data_row, self.interface.style.font)
 
         # creates a NSTableCellView from interface-builder template (does not exist)
         # or reuses an existing view which is currently not needed for painting
@@ -60,6 +66,26 @@ def tableView_viewForTableColumn_row_(self, table, column, row: int):
         else:
             tcv.setImage(None)
 
+        if text_align is not None:
+            tcv.textField.alignment = NSTextAlignment(text_align)
+        else:
+            tcv.textField.alignment = self.alignment
+
+        if color is not None:
+            tcv.textField.textColor = native_color(color)
+        else:
+            tcv.textField.textColor = None
+        if background_color is not None:
+            tcv.drawsBackground = True
+            tcv.backgroundColor = native_color(background_color)
+        else:
+            tcv.textField.drawsBackground = False
+
+        # font is only None if something is very wrong (eg. can't find system font)
+        # so can't test
+        if font is not None:  # pragma: no branch
+            tcv.textField.font = font._impl.native
+
         return tcv
 
     @objc_method

cocoa/src/toga_cocoa/widgets/tree.py

@@ -1,6 +1,7 @@
 from rubicon.objc import SEL, at, objc_method, objc_property
 from travertino.size import at_least
 
+from toga_cocoa.colors import native_color
 from toga_cocoa.libs import (
     NSBezelBorder,
     NSIndexSet,
@@ -9,6 +10,7 @@
     NSTableColumn,
     NSTableViewAnimation,
     NSTableViewColumnAutoresizingStyle,
+    NSTextAlignment,
 )
 from toga_cocoa.widgets.base import Widget
 from toga_cocoa.widgets.internal.cells import TogaIconView
@@ -64,6 +66,10 @@ def outlineView_viewForTableColumn_item_(self, tree, column, item):
             return widget._impl.native
         icon = column.toga_column.icon(node)
         text = column.toga_column.text(node, self.interface.missing_value)
+        text_align = column.toga_column.text_align(node)
+        color = column.toga_column.color(node)
+        background_color = column.toga_column.background_color(node)
+        font = column.toga_column.font(node, self.interface.style.font)
 
         # creates a NSTableCellView from interface-builder template (does not exist)
         # or reuses an existing view which is currently not needed for painting
@@ -84,6 +90,26 @@ def outlineView_viewForTableColumn_item_(self, tree, column, item):
         else:
             tcv.setImage(None)
 
+        if text_align is not None:
+            tcv.textField.alignment = NSTextAlignment(text_align)
+        else:
+            tcv.textField.alignment = self.alignment
+
+        if color is not None:
+            tcv.textField.textColor = native_color(color)
+        else:
+            tcv.textField.textColor = None
+        if background_color is not None:
+            tcv.drawsBackground = True
+            tcv.backgroundColor = native_color(background_color)
+        else:
+            tcv.textField.drawsBackground = False
+
+        # font is only None if something is very wrong (eg. can't find system font)
+        # so can't test
+        if font is not None:  # pragma: no branch
+            tcv.textField.font = font._impl.native
+
         return tcv
 
     # 2023-06-29: Commented out this method because it appears to be a

cocoa/tests_backend/widgets/table.py

@@ -1,8 +1,9 @@
 import pytest
 from rubicon.objc import NSPoint
 
+from toga_cocoa.colors import native_color
 from toga_cocoa.keys import NSEventModifierFlagCommand
-from toga_cocoa.libs import NSEventType, NSScrollView, NSTableView
+from toga_cocoa.libs import NSEventType, NSScrollView, NSTableView, NSTextAlignment
 
 from .base import SimpleProbe
 from .properties import toga_color
@@ -14,6 +15,7 @@ class TableProbe(SimpleProbe):
     supports_keyboard_shortcuts = True
     supports_keyboard_boundary_shortcuts = False
     supports_widgets = True
+    supports_styles = True
 
     def __init__(self, widget):
         super().__init__(widget)
@@ -22,7 +24,7 @@ def __init__(self, widget):
 
     @property
     def font(self):
-        pytest.skip("Font changes not implemented for Tree on macOS")
+        pytest.skip("Font changes not implemented for Table on macOS")
 
     @property
     def background_color(self):
@@ -43,7 +45,18 @@ def row_count(self):
     def column_count(self):
         return len(self.native_table.tableColumns)
 
-    def assert_cell_content(self, row, col, value=None, icon=None, widget=None):
+    def assert_cell_content(
+        self,
+        row,
+        col,
+        value=None,
+        icon=None,
+        widget=None,
+        color=None,
+        text_align=None,
+        background_color=None,
+        font=None,
+    ):
         view = self.native_table.tableView(
             self.native_table,
             viewForTableColumn=self.native_table.tableColumns[col],
@@ -59,6 +72,18 @@ def assert_cell_content(self, row, col, value=None, icon=None, widget=None):
             else:
                 assert view.imageView.image is None
 
+            if text_align:
+                assert view.textField.alignment == NSTextAlignment(text_align)
+
+            if color:
+                assert view.textField.textColor == native_color(color)
+
+            if background_color:
+                assert view.backgroundColor == native_color(background_color)
+
+            if font:
+                assert view.textField.font == font._impl.native
+
     @property
     def max_scroll_position(self):
         return int(self.native.documentView.bounds.size.height) - int(

cocoa/tests_backend/widgets/tree.py

@@ -3,8 +3,9 @@
 from pytest import skip
 from rubicon.objc import NSPoint
 
+from toga_cocoa.colors import native_color
 from toga_cocoa.keys import NSEventModifierFlagCommand
-from toga_cocoa.libs import NSEventType, NSOutlineView, NSScrollView
+from toga_cocoa.libs import NSEventType, NSOutlineView, NSScrollView, NSTextAlignment
 
 from .base import SimpleProbe
 from .properties import toga_color
@@ -14,6 +15,7 @@ class TreeProbe(SimpleProbe):
     native_class = NSScrollView
     supports_keyboard_shortcuts = True
     supports_widgets = True
+    supports_styles = True
 
     def __init__(self, widget):
         super().__init__(widget)
@@ -73,7 +75,18 @@ def child_count(self, row_path=None):
     def column_count(self):
         return len(self.native_tree.tableColumns)
 
-    def assert_cell_content(self, row_path, col, value=None, icon=None, widget=None):
+    def assert_cell_content(
+        self,
+        row_path,
+        col,
+        value=None,
+        icon=None,
+        widget=None,
+        text_align=None,
+        color=None,
+        background_color=None,
+        font=None,
+    ):
         view = self.native_tree.outlineView(
             self.native_tree,
             viewForTableColumn=self.native_tree.tableColumns[col],
@@ -89,6 +102,18 @@ def assert_cell_content(self, row_path, col, value=None, icon=None, widget=None)
             else:
                 assert view.imageView.image is None
 
+            if text_align:
+                assert view.textField.alignment == NSTextAlignment(text_align)
+
+            if color:
+                assert view.textField.textColor == native_color(color)
+
+            if background_color:
+                assert view.backgroundColor == native_color(background_color)
+
+            if font:
+                assert view.textField.font == font._impl.native
+
     @property
     def max_scroll_position(self):
         return int(self.native.documentView.bounds.size.height) - int(