Switch from per-channel to global background color

Figure-global backgrounds are reasonably fast, while axes-specific
background color causes performance drop.

ovgenpy/channel.py

@@ -18,7 +18,6 @@ class ChannelConfig:
     render_width_ratio: int = 1
 
     ampl_ratio: float = 1.0     # TODO use amplification = None instead?
-    bg_color: Any = None
     line_color: Any = None
 
 

ovgenpy/renderer.py

@@ -18,12 +18,13 @@ if TYPE_CHECKING:
     from ovgenpy.channel import ChannelConfig
 
 
-@register_config(always_dump='init_bg_color init_line_color line_width')
+
+@register_config(always_dump='bg_color init_line_color line_width')
 class RendererConfig:
     width: int
     height: int
 
-    init_bg_color: Any = 'black'
+    bg_color: Any = 'black'
     init_line_color: Any = 'white'
     # line_width: Optional[float] = None  # TODO
 
@@ -63,7 +64,6 @@ class MatplotlibRenderer:
         self.axes: List['Axes'] = None        # set by set_layout()
         self.lines: List['Line2D'] = None     # set by render_frame() first call
 
-        self.bg_colors: List = [None] * nplots
         self.line_colors: List = [None] * nplots
 
         self._set_layout()   # mutates self
@@ -81,7 +81,7 @@ class MatplotlibRenderer:
         # https://matplotlib.org/api/_as_gen/matplotlib.pyplot.subplots.html
         if self.fig:
             raise Exception("I don't currently expect to call set_layout() twice")
-            plt.close(self.fig)
+            # plt.close(self.fig)
 
         axes2d: np.ndarray['Axes']
         self.fig, axes2d = plt.subplots(
@@ -93,7 +93,7 @@ class MatplotlibRenderer:
 
         # remove Axis from Axes
         for ax in axes2d.flatten():
-            ax.set_axis_off()   # FIXME ax.get_xaxis().set_visible(False)
+            ax.set_axis_off()
 
         # Generate arrangement (using nplots, cfg.orientation)
         self.axes = self.layout.arrange(lambda row, col: axes2d[row, col])
@@ -112,8 +112,6 @@ class MatplotlibRenderer:
             raise ValueError(
                 f"cannot assign {len(channel_cfgs)} colors to {self.nplots} plots"
             )
-        self.bg_colors = [coalesce(cfg.bg_color, self.cfg.init_bg_color)
-                          for cfg in channel_cfgs]
         self.line_colors = [coalesce(cfg.line_color, self.cfg.init_line_color)
                             for cfg in channel_cfgs]
 
@@ -125,17 +123,17 @@ class MatplotlibRenderer:
 
         # Initialize axes and draw waveform data
         if self.lines is None:
+            self.fig.set_facecolor(self.cfg.bg_color)
+
             self.lines = []
             for idx, data in enumerate(datas):
                 # Setup colors
-                bg_color = self.bg_colors[idx]
                 line_color = self.line_colors[idx]
 
                 # Setup axes
                 ax = self.axes[idx]
                 ax.set_xlim(0, len(data) - 1)
                 ax.set_ylim(-1, 1)
-                ax.set_facecolor(bg_color)
 
                 # Plot line
                 line = ax.plot(data, color=line_color)[0]