Unify color export and handle rgba colors

Author: robertoffmoura

plotly/matplotlylib/mpltools.py

@@ -12,6 +12,8 @@
 
 from _plotly_utils.colors import hex_to_rgb
 
+from plotly.matplotlylib.mplexporter.utils import export_color
+
 
 def check_bar_match(old_bar, new_bar):
     """Check if two bars belong in the same collection (bar chart).
@@ -106,26 +108,6 @@ def convert_symbol(mpl_symbol):
         return "circle"  # default
 
 
-def merge_color_and_opacity(color, opacity):
-    """
-    Merge hex color with an alpha (opacity) to get an rgba tuple.
-
-    :param (str|unicode) color: A hex color string.
-    :param (float|int) opacity: A value [0, 1] for the 'a' in 'rgba'.
-    :return: (int, int, int, float) The rgba color and alpha tuple.
-
-    """
-    if color is None:  # None can be used as a placeholder, just bail.
-        return None
-
-    rgb_tup = hex_to_rgb(color)
-    if opacity is None:
-        return "rgb{}".format(rgb_tup)
-
-    rgba_tup = rgb_tup + (opacity,)
-    return "rgba{}".format(rgba_tup)
-
-
 def convert_va(mpl_va):
     """Convert mpl vertical alignment word to equivalent HTML word.
 
@@ -516,19 +498,29 @@ def prep_ticks(ax, index, ax_type, props):
     return axis_dict
 
 
-def _export_color(color):
+def _export_color(color, opacity=None):
     """Export a matplotlib color for use as a plotly color.
 
     matplotlib uses "none" for fully transparent colors, which plotly does not
-    accept, so transparent colors are exported as transparent black.
-    Colors already exported by the mplexporter (hex or rgba strings) are
-    passed through unchanged.
+    accept, so transparent colors are exported as transparent black. Colors
+    already exported by the mplexporter (hex or rgba strings) keep the alpha
+    they carry unless an explicit opacity overrides it.
     """
     if color is None:
         return None
-    if isinstance(color, str):
-        return color if color != "none" else "rgba(0,0,0,0)"
-    return [_export_color(c) for c in color]
+    if isinstance(color, (list, tuple)) and all(isinstance(c, str) for c in color):
+        return [_export_color(c, opacity) for c in color]
+    if not isinstance(color, str):
+        color = export_color(color)
+    if color == "none":
+        return "rgba(0,0,0,0)"
+    if color.startswith("#") and opacity is not None:
+        return "rgba{0}".format(hex_to_rgb(color) + (opacity,))
+    if color.startswith("rgb") and opacity not in (None, 1):
+        rgb = color[color.index("(") + 1 : color.rindex(")")].split(",")
+        r, g, b = (int(round(float(component))) for component in rgb[:3])
+        return "rgba({0}, {1}, {2}, {3})".format(r, g, b, opacity)
+    return color
 
 
 def prep_xy_axis(ax, props, x_bounds, y_bounds):

plotly/matplotlylib/renderer.py

@@ -388,13 +388,9 @@ def draw_marked_line(self, **props):
             self.msg += "... with just markers\n"
             mode = "markers"
         if props["linestyle"]:
-            if props["linestyle"]["color"] == "none":
-                # a fully transparent line; plotly rejects "none" as a color
-                color = "rgba(0,0,0,0)"
-            else:
-                color = mpltools.merge_color_and_opacity(
-                    props["linestyle"]["color"], props["linestyle"]["alpha"]
-                )
+            color = _export_color(
+                props["linestyle"]["color"], props["linestyle"]["alpha"]
+            )
 
             if props["coordinates"] == "data":
                 line = go.scatter.Line(
@@ -722,7 +718,8 @@ def draw_text(self, **props):
                 yanchor=yanchor,
                 showarrow=False,  # change this later?
                 font=go.layout.annotation.Font(
-                    color=props["style"]["color"], size=props["style"]["fontsize"]
+                    color=_export_color(props["style"]["color"]),
+                    size=props["style"]["fontsize"],
                 ),
             )
             self.plotly_fig["layout"]["annotations"] += (annotation,)
@@ -762,7 +759,8 @@ def draw_title(self, **props):
             annotation = go.layout.Annotation(
                 text=props["text"],
                 font=go.layout.annotation.Font(
-                    color=props["style"]["color"], size=props["style"]["fontsize"]
+                    color=_export_color(props["style"]["color"]),
+                    size=props["style"]["fontsize"],
                 ),
                 xref="paper",
                 yref="paper",
@@ -777,7 +775,8 @@ def draw_title(self, **props):
             self.msg += "          Only one subplot found, adding as a plotly title\n"
             self.plotly_fig["layout"]["title"] = props["text"]
             title_font = dict(
-                size=props["style"]["fontsize"], color=props["style"]["color"]
+                size=props["style"]["fontsize"],
+                color=_export_color(props["style"]["color"]),
             )
             self.plotly_fig["layout"]["title_font"] = title_font
 
@@ -808,7 +807,8 @@ def draw_xlabel(self, **props):
         axis_key = "xaxis{0}".format(self.axis_ct)
         self.plotly_fig["layout"][axis_key]["title"] = str(props["text"])
         title_font = dict(
-            size=props["style"]["fontsize"], color=props["style"]["color"]
+            size=props["style"]["fontsize"],
+            color=_export_color(props["style"]["color"]),
         )
         self.plotly_fig["layout"][axis_key]["title_font"] = title_font
 
@@ -839,7 +839,8 @@ def draw_ylabel(self, **props):
         axis_key = "yaxis{0}".format(self.axis_ct)
         self.plotly_fig["layout"][axis_key]["title"] = props["text"]
         title_font = dict(
-            size=props["style"]["fontsize"], color=props["style"]["color"]
+            size=props["style"]["fontsize"],
+            color=_export_color(props["style"]["color"]),
         )
         self.plotly_fig["layout"][axis_key]["title_font"] = title_font
 

plotly/matplotlylib/tests/test_renderer.py

@@ -129,6 +129,46 @@ def test_line_with_none_color_converts():
     assert plotly_fig.data[0].line.color == "rgba(0,0,0,0)"
 
 
+def test_line_with_rgba_color_converts():
+    """Line colors that carry their own alpha (rgba tuple or 8-digit hex)
+    export as rgba strings."""
+    fig, ax = plt.subplots()
+    ax.plot([0, 1], [0, 1], color=(1.0, 0.0, 0.0, 0.5))
+    ax.plot([0, 1], [1, 0], color="#0000FF80")
+
+    plotly_fig = tls.mpl_to_plotly(fig)
+
+    assert plotly_fig.data[0].line.color == "rgba(255, 0, 0, 0.5)"
+    assert plotly_fig.data[1].line.color == "rgba(0, 0, 255, 0.5019607843137255)"
+
+
+def test_line_rgba_color_with_separate_alpha_converts():
+    """An explicit alpha overrides the alpha carried by the line color."""
+    fig, ax = plt.subplots()
+    ax.plot([0, 1], [0, 1], color=(1.0, 0.0, 0.0, 0.2), alpha=0.5)
+
+    plotly_fig = tls.mpl_to_plotly(fig)
+
+    assert plotly_fig.data[0].line.color == "rgba(255, 0, 0, 0.5)"
+
+
+def test_transparent_text_colors_export():
+    """Text, title, and axis labels with color 'none' export transparent
+    fonts."""
+    fig, ax = plt.subplots()
+    ax.text(0.5, 0.5, "text", color="none")
+    ax.set_title("title", color="none")
+    ax.set_xlabel("xlabel", color="none")
+    ax.set_ylabel("ylabel", color="none")
+
+    plotly_fig = tls.mpl_to_plotly(fig)
+
+    assert plotly_fig.layout.annotations[0].font.color == "rgba(0,0,0,0)"
+    assert plotly_fig.layout.title.font.color == "rgba(0,0,0,0)"
+    assert plotly_fig.layout.xaxis.title.font.color == "rgba(0,0,0,0)"
+    assert plotly_fig.layout.yaxis.title.font.color == "rgba(0,0,0,0)"
+
+
 def test_eventplot_segments_render():
     fig, ax = plt.subplots()
     ax.eventplot([np.random.randn(20) for _ in range(5)])