matplotlib · QuLogic · Jul 14, 2021 · Jul 14, 2021 · Jul 15, 2021 · Jul 15, 2021
diff --git a/lib/matplotlib/artist.py b/lib/matplotlib/artist.py
@@ -924,13 +924,20 @@ def set_agg_filter(self, filter_func):
 
         Parameters
         ----------
-        filter_func : callable
-            A filter function, which takes a (m, n, 3) float array and a dpi
-            value, and returns a (m, n, 3) array.
+        filter_func : callable or str or None
+            A filter function, or the name of a builtin one.
 
-            .. ACCEPTS: a filter function, which takes a (m, n, 3) float array
-                and a dpi value, and returns a (m, n, 3) array
+            If passed a callable, then it should have the signature:
+
+            def filter_func(np.ndarray[(M, N, 3), float]) -> \
+                    np.ndarray[(M, N, 3), float]
+
+            If passed a string, it should be one of the names accepted by
+            `matplotlib.colors.get_color_filter`.
         """
+        if isinstance(filter_func, str):
+            from . import colors
+            filter_func = colors.get_color_filter(filter_func)
         self._agg_filter = filter_func
         self.stale = True
 

diff --git a/lib/matplotlib/backends/backend_gtk3.py b/lib/matplotlib/backends/backend_gtk3.py
@@ -503,6 +503,72 @@ def __init__(self, canvas, window):
                 'clicked', getattr(self, callback))
             tbutton.set_tooltip_text(tooltip_text)
 
+        # Add the CVD simulation button. The type of menu is progressively
+        # downgraded depending on GTK version.
+        toolitem = Gtk.SeparatorToolItem()
+        self.insert(toolitem, -1)
+
+        filters = ['None', 'Greyscale', 'Deuteranopia', 'Protanopia',
+                   'Tritanopia']
+        image = Gtk.Image.new_from_gicon(
+            Gio.Icon.new_for_string(
+                str(cbook._get_data_path('images', 'eye-symbolic.svg'))),
+            Gtk.IconSize.LARGE_TOOLBAR)
+
+        if Gtk.check_version(3, 6, 0) is None:
+            group = Gio.SimpleActionGroup.new()
+            action = Gio.SimpleAction.new_stateful('cvdsim',
+                                                   GLib.VariantType('s'),
+                                                   GLib.Variant('s', 'none'))
+            group.add_action(action)
+
+            @functools.partial(action.connect, 'activate')
+            def set_filter(action, parameter):
+                filter = parameter.get_string().lower()
+                if filter == 'none':
+                    filter = None
+
+                self.canvas.figure.set_agg_filter(filter)
+                self.canvas.draw_idle()
+                action.set_state(parameter)
+
+            menu = Gio.Menu()
+            for filt in filters:
+                menu.append(filt, f'local.cvdsim::{filt.lower()}')
+
+            button = Gtk.MenuButton.new()
+            button.add(image)
+            button.insert_action_group('local', group)
+            button.set_menu_model(menu)
+            button.get_style_context().add_class('flat')
+
+            item = Gtk.ToolItem()
+            item.add(button)
+            self.insert(item, -1)
+        else:
+            def set_filter(item):
+                filter = item.get_label().lower()
+                if filter == 'none':
+                    filter = None
+
+                self.canvas.figure.set_agg_filter(filter)
+                self.canvas.draw_idle()
+
+            menu = Gtk.Menu()
+            group = []
+            for filt in filters:
+                item = Gtk.RadioMenuItem.new_with_label(group, filt)
+                item.set_active(filt == 'None')
+                item.connect('activate', set_filter)
+                group.append(item)
+                menu.append(item)
+            menu.show_all()
+
+            tbutton = Gtk.MenuToolButton.new(image, "Filter")
+            tbutton.set_menu(menu)
+            self.insert(tbutton, -1)
+
+        # Fill the space in between to ensure message is at end.
         toolitem = Gtk.SeparatorToolItem()
         self.insert(toolitem, -1)
         toolitem.set_draw(False)

diff --git a/lib/matplotlib/backends/backend_qt5.py b/lib/matplotlib/backends/backend_qt5.py
@@ -621,6 +621,33 @@ def __init__(self, canvas, parent, coordinates=True):
                 if tooltip_text is not None:
                     a.setToolTip(tooltip_text)
 
+        menu = QtWidgets.QMenu()
+        group = QtWidgets.QActionGroup(menu)
+
+        @group.triggered.connect
+        def set_filter(action):
+            filter = action.text().lower()
+            if filter == 'none':
+                filter = None
+            self.canvas.figure.set_agg_filter(filter)
+            self.canvas.draw_idle()
+
+        for filt in ['None', 'Greyscale', 'Deuteranopia', 'Protanopia',
+                     'Tritanopia']:
+            a = menu.addAction(filt)
+            a.setCheckable(True)
+            a.setActionGroup(group)
+            a.setChecked(filt == 'None')
+
+        self.addSeparator()
+        tb = QtWidgets.QToolButton()
+        tb.setIcon(self._icon('eye.png'))
+        tb.setText('Filter')
+        tb.setToolTip('Simulate color vision deficiencies')
+        tb.setPopupMode(QtWidgets.QToolButton.InstantPopup)
+        tb.setMenu(menu)
+        self.addWidget(tb)
+
         # Add the (x, y) location widget at the right side of the toolbar
         # The stretch factor is 1 which means any resizing of the toolbar
         # will resize this label instead of the buttons.

diff --git a/lib/matplotlib/colors.py b/lib/matplotlib/colors.py
@@ -2394,3 +2394,67 @@ def from_levels_and_colors(levels, colors, extend='neither'):
 
     norm = BoundaryNorm(levels, ncolors=n_data_colors)
     return cmap, norm
+
+
+def get_color_filter(name):
+    """
+    Given a color filter name, create a color filter function.
+
+    Parameters
+    ----------
+    name : str
+        The color filter name, one of the following:
+
+        - ``'greyscale'``: Convert the input to luminosity.
+        - ``'deuteranopia'``: Simulate the most common form of red-green
+          colorblindness.
+        - ``'protanopia'``: Simulate a rarer form of red-green colorblindness.
+        - ``'tritanopia'``: Simulate the rare form of blue-yellow
+          colorblindness.
+
+        Color conversions use `colorspacious`_.
+
+    Returns
+    -------
+    callable
+        A color filter function that has the form:
+
+        def filter(input: np.ndarray[M, N, D])-> np.ndarray[M, N, D]
+
+        where (M, N) are the image dimentions, and D is the color depth (3 for
+        RGB, 4 for RGBA). Alpha is passed through unchanged and otherwise
+        ignored.
+    """
+    from colorspacious import cspace_converter
+
+    filter = _api.check_getitem({
+        'greyscale': 'greyscale',
+        'deuteranopia': 'deuteranomaly',
+        'protanopia': 'protanomaly',
+        'tritanopia': 'tritanomaly',
+    }, name=name)
+
+    if filter == 'greyscale':
+        rgb_to_jch = cspace_converter('sRGB1', 'JCh')
+        jch_to_rgb = cspace_converter('JCh', 'sRGB1')
+
+        def filter(im):
+            greyscale_JCh = rgb_to_jch(im)
+            greyscale_JCh[..., 1] = 0
+            im = jch_to_rgb(greyscale_JCh)
+            return im
+    else:
+        cvd_space = {'name': 'sRGB1+CVD', 'cvd_type': filter,
+                     'severity': 100}
+        filter = cspace_converter(cvd_space, "sRGB1")
+
+    def filter_func(im, dpi):
+        alpha = None
+        if im.shape[-1] == 4:
+            im, alpha = im[..., :3], im[..., 3]
+        im = filter(im)
+        if alpha is not None:
+            im = np.dstack((im, alpha))
+        return np.clip(im, 0, 1), 0, 0
+
+    return filter_func
diff --git a/lib/matplotlib/mpl-data/images/eye-symbolic.svg b/lib/matplotlib/mpl-data/images/eye-symbolic.svg
@@ -0,0 +1 @@
+eye.svg
diff --git a/lib/matplotlib/mpl-data/images/eye.pdf b/lib/matplotlib/mpl-data/images/eye.pdf
diff --git a/lib/matplotlib/mpl-data/images/eye.png b/lib/matplotlib/mpl-data/images/eye.png
diff --git a/lib/matplotlib/mpl-data/images/eye.svg b/lib/matplotlib/mpl-data/images/eye.svg
diff --git a/lib/matplotlib/mpl-data/images/eye_large.png b/lib/matplotlib/mpl-data/images/eye_large.png
diff --git a/tools/make_icons.py b/tools/make_icons.py
@@ -88,6 +88,7 @@ def make_matplotlib_icon():
     ('subplots', 0xf1de),
     ('qt4_editor_options', 0xf201),
     ('help', 0xf128),
+    ('eye', 0xf06e),
 ]