Cleanup following toga.Canvas audit

.github/workflows/ci.yml

@@ -44,12 +44,12 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12-dev"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
         include:
           - experimental: false
 
-          - python-version: "3.12-dev"
-            experimental: true
+          # - python-version: "3.13-dev"
+          #   experimental: true
 
     steps:
     - name: Checkout

.github/workflows/release.yml

@@ -9,9 +9,17 @@ jobs:
   ci:
     uses: ./.github/workflows/ci.yml
 
+  docs:
+    name: Verify Docs Build
+    uses: beeware/.github/.github/workflows/docs-build-verify.yml@main
+    secrets: inherit
+    with:
+      project-name: "toga-chart"
+      project-version: ${{ github.ref_name }}
+
   release:
     name: Create Release
-    needs: ci
+    needs: [ ci, docs ]
     runs-on: ubuntu-latest
     permissions:
       contents: write
@@ -54,4 +62,4 @@ jobs:
       - name: Publish release to Test PyPI
         uses: pypa/gh-action-pypi-publish@release/v1
         with:
-          repository_url: https://test.pypi.org/legacy/
+          repository-url: https://test.pypi.org/legacy/

changes/24.bugfix.rst

@@ -0,0 +1 @@
+The requirements of ``toga-chart`` were modified so that toga-chart is only dependent on ``toga-core``, rather than the ``toga`` meta-package. This makes it possible to install ``toga-chart`` on Android, as the meta-package no longer attempts to install the ``toga-gtk`` backend on Android; but it requires that end-users explicitly specify ``toga`` or an explicit backend in their own app requirements.

examples/chart/app.py

@@ -43,7 +43,7 @@ def startup(self):
         self.set_data()
 
         # Set up main window
-        self.main_window = toga.MainWindow(title=self.name)
+        self.main_window = toga.MainWindow()
 
         self.chart = toga_chart.Chart(style=Pack(flex=1), on_draw=self.draw_chart)
 

setup.cfg

@@ -25,7 +25,7 @@ classifiers =
 license = New BSD
 license_files =
     LICENSE
-description = "A Toga matplotlib backend."
+description = A Toga matplotlib backend.
 long_description = file: README.rst
 long_description_content_type = text/x-rst
 keywords=
@@ -41,7 +41,7 @@ include_package_data = True
 package_dir=
     = src
 install_requires =
-    toga >= 0.3.1
+    toga-core >= 0.4.0
     matplotlib >= 3.0.3
 
 [options.packages.find]
@@ -53,6 +53,7 @@ dev =
     pytest == 7.4.3
     setuptools_scm[toml] == 8.0.4
     tox == 4.11.3
+    toga-dummy >= 0.4.0
 docs =
     furo == 2023.9.10
     pyenchant == 3.2.2

src/toga_chart/chart.py

@@ -1,7 +1,7 @@
 import math
 import sys
 
-from matplotlib.backend_bases import FigureCanvasBase, RendererBase
+from matplotlib.backend_bases import RendererBase
 from matplotlib.figure import Figure
 from matplotlib.path import Path
 from matplotlib.transforms import Affine2D
@@ -12,36 +12,52 @@
 
 
 class Chart(Widget):
-    """Create new chart.
-
-    Args:
-        id (str):  An identifier for this widget.
-        style (:obj:`Style`): An optional style object. If no
-            style is provided then a new one will be created for the widget.
-        on_resize (:obj:`callable`): Handler to invoke when the chart is resized.
-            The default resize handler will draw the chart on every resize;
-            generally, you won't need to override this default behavior.
-        on_draw (:obj:`callable`): Handler to invoke when the chart needs to be
-            drawn.
-        factory (:obj:`module`): A python module that is capable to return a
-            implementation of this class with the same name. (optional &
-            normally not needed)
-    """
-
-    def __init__(self, id=None, style=None, on_resize=None, on_draw=None, factory=None):
+    def __init__(
+        self,
+        id: str = None,
+        style=None,
+        on_resize: callable = None,
+        on_draw: callable = None,
+    ):
+        """Create a new matplotlib chart.
+
+        :param id: An identifier for this widget.
+        :param style: An optional style object. If no style is provided then a new one
+            will be created for the widget.
+        :param on_resize: Handler to invoke when the chart is resized. The default
+            resize handler will draw the chart on every resize; generally, you won't
+            need to override this default behavior.
+        :param on_draw: Handler to invoke when the chart needs to be drawn. This
+            performs the matplotlib drawing operations that will be displayed on the
+            chart.
+        """
         self.on_draw = on_draw
         if on_resize is None:
             on_resize = self._on_resize
 
-        self.canvas = Canvas(style=style, on_resize=on_resize, factory=factory)
+        # The Chart widget that the user interacts with is a subclass of Widget, not
+        # Canvas; this subclass acts as a facade over the underlying Canvas
+        # implementation (mostly so that the redraw() method of the Chart is independent
+        # of the Canvas redraw() method). The _impl of the Chart is set to the Canvas
+        # _impl so that functionally, the widget behaves as a Canvas.
+        self.canvas = Canvas(style=style, on_resize=on_resize)
+
+        super().__init__(id=id, style=style)
 
-        super().__init__(id=id, style=style, factory=factory)
         self._impl = self.canvas._impl
 
-    def _set_app(self, app):
+    @Widget.app.setter
+    def app(self, app):
+        # Invoke the superclass property setter
+        Widget.app.fset(self, app)
+        # Point the canvas to the same app
         self.canvas.app = app
 
-    def _set_window(self, window):
+    @Widget.window.setter
+    def window(self, window):
+        # Invoke the superclass property setter
+        Widget.window.fset(self, window)
+        # Point the canvas to the same window
         self.canvas.window = window
 
     @property
@@ -52,22 +68,19 @@ def layout(self):
     def layout(self, value):
         self.canvas.layout = value
 
-    def _draw(self, figure):
-        """Draws the matplotlib figure onto the canvas
+    def _draw(self, figure: Figure):
+        """Draw the matplotlib figure onto the canvas.
 
-        Args:
-            figure (figure):  matplotlib figure to draw
+        :param figure: The matplotlib figure to draw
         """
         l, b, w, h = figure.bbox.bounds
-        matplotlib_canvas = MatplotlibCanvasProxy(figure=figure, canvas=self.canvas)
-        renderer = ChartRenderer(matplotlib_canvas, w, h)
+        renderer = ChartRenderer(self.canvas, w, h)
 
-        # Invoke the on_draw handler (if present).
+        # Invoke the on_draw handler.
         # This is where the user adds the matplotlib draw instructions
         # to construct the chart, so it needs to happen before the
         # figure is rendered onto the canvas.
-        if self.on_draw:
-            self.on_draw(self, figure=figure)
+        self.on_draw(figure=figure)
 
         figure.draw(renderer)
 
@@ -79,66 +92,32 @@ def redraw(self):
         # 100 is the default DPI for figure at time of writing.
         dpi = 100
         figure = Figure(
-            figsize=(self.layout.content_width / dpi, self.layout.content_height / dpi)
+            figsize=(
+                self.layout.content_width / dpi,
+                self.layout.content_height / dpi,
+            ),
         )
         self._draw(figure)
 
     @property
-    def on_draw(self):
-        """The handler to invoke when the canvas needs to be drawn.
-
-        Returns:
-            The handler that is invoked on canvas draw.
-        """
+    def on_draw(self) -> callable:
+        """The handler to invoke when the canvas needs to be drawn."""
         return self._on_draw
 
     @on_draw.setter
-    def on_draw(self, handler):
-        """Set the handler to invoke when the canvas is drawn.
-
-        Args:
-            handler (:obj:`callable`): The handler to invoke when the canvas is drawn.
-        """
+    def on_draw(self, handler: callable):
         self._on_draw = wrapped_handler(self, handler)
 
 
-class MatplotlibCanvasProxy(FigureCanvasBase):
-    def __init__(self, figure, canvas: Canvas):
-        super().__init__(figure)
-        self.canvas = canvas
-
-    def fill(self, color):
-        return self.canvas.fill(color=color)
-
-    def stroke(self, color, line_width, line_dash):
-        return self.canvas.stroke(
-            color=color, line_width=line_width, line_dash=line_dash
-        )
-
-    def measure_text(self, text, font):
-        return self.canvas.measure_text(text=text, font=font)
-
-    def translate(self, tx, ty):
-        return self.canvas.translate(tx, ty)
-
-    def rotate(self, radians):
-        return self.canvas.rotate(radians)
-
-    def reset_transform(self):
-        return self.canvas.reset_transform()
-
-
 class ChartRenderer(RendererBase):
-    """
-    The renderer handles drawing/rendering operations.
-
-    Args:
-        canvas (:obj:`Canvas`):  canvas to render onto
-        width (int): width of canvas
-        height (int): height of canvas
-    """
+    def __init__(self, canvas: Canvas, width: int, height: int):
+        """
+        The matplotlib handler for drawing/rendering operations.
 
-    def __init__(self, canvas, width, height):
+        :param canvas: The canvas to render onto
+        :param width: Width of canvas
+        :param height: height of canvas
+        """
         self.width = width
         self.height = height
         self._canvas = canvas
@@ -157,25 +136,30 @@ def draw_path(self, gc, path, transform, rgbFace=None):
         color = parse_color(rgba(r * 255, g * 255, b * 255, a))
 
         if rgbFace is not None:
-            stroke_fill_context = self._canvas.fill(color=color)
+            stroke_fill_context = self._canvas.context.Fill(color=color)
         else:
             offset, sequence = gc.get_dashes()
-            stroke_fill_context = self._canvas.stroke(
-                color=color, line_width=gc.get_linewidth(), line_dash=sequence
+            stroke_fill_context = self._canvas.context.Stroke(
+                color=color,
+                line_width=gc.get_linewidth(),
+                line_dash=sequence,
             )
 
         transform = transform + Affine2D().scale(1.0, -1.0).translate(0.0, self.height)
 
         with stroke_fill_context as context:
-            with context.context() as path_segments:
+            with context.Context() as path_segments:
                 for points, code in path.iter_segments(transform):
                     if code == Path.MOVETO:
                         path_segments.move_to(points[0], points[1])
                     elif code == Path.LINETO:
                         path_segments.line_to(points[0], points[1])
                     elif code == Path.CURVE3:
                         path_segments.quadratic_curve_to(
-                            points[0], points[1], points[2], points[3]
+                            points[0],
+                            points[1],
+                            points[2],
+                            points[3],
                         )
                     elif code == Path.CURVE4:
                         path_segments.bezier_curve_to(
@@ -187,7 +171,7 @@ def draw_path(self, gc, path, transform, rgbFace=None):
                             points[5],
                         )
                     elif code == Path.CLOSEPOLY:
-                        path_segments.closed_path(points[0], points[1])
+                        path_segments.ClosedPath(points[0], points[1])
 
     def draw_image(self, gc, x, y, im):
         pass
@@ -217,12 +201,14 @@ def draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None):
             gc.set_linewidth(0.75)
             self.draw_path(gc, path, transform, rgbFace=color)
         else:
-            self._canvas.translate(x, y)
-            self._canvas.rotate(-math.radians(angle))
-            with self._canvas.fill(color=self.to_toga_color(*gc.get_rgb())) as fill:
+            self._canvas.context.translate(x, y)
+            self._canvas.context.rotate(-math.radians(angle))
+            with self._canvas.context.Fill(
+                color=self.to_toga_color(*gc.get_rgb())
+            ) as fill:
                 font = self.get_font(prop)
                 fill.write_text(s, x=0, y=0, font=font)
-            self._canvas.reset_transform()
+            self._canvas.context.reset_transform()
 
     def flipy(self):
         return True
@@ -231,23 +217,16 @@ def get_canvas_width_height(self):
         return self.width, self.height
 
     def get_text_width_height_descent(self, s, prop, ismath):
-        """
-        get the width and height in display coords of the string s
-        with FontPropertry prop
+        """Get the width and height in display coords of the string s
+        with FontProperty prop
         """
         font = self.get_font(prop)
         w, h = self._canvas.measure_text(s, font)
         return w, h, 1
 
     def get_font(self, prop):
-        if prop.get_family()[0] == SANS_SERIF:
-            font_family = SANS_SERIF
-        elif prop.get_family()[0] == CURSIVE:
-            font_family = CURSIVE
-        elif prop.get_family()[0] == FANTASY:
-            font_family = FANTASY
-        elif prop.get_family()[0] == MONOSPACE:
-            font_family = MONOSPACE
+        if prop.get_family()[0] in {SANS_SERIF, CURSIVE, FANTASY, MONOSPACE}:
+            font_family = prop.get_family()[0]
         else:
             font_family = SERIF