fix(widgets/canvas): avoid panic on zero-width bounds

Author: fdehau

src/widgets/canvas/mod.rs

@@ -206,6 +206,9 @@ impl<'a, 'b> Painter<'a, 'b> {
         }
         let width = (self.context.x_bounds[1] - self.context.x_bounds[0]).abs();
         let height = (self.context.y_bounds[1] - self.context.y_bounds[0]).abs();
+        if width == 0.0 || height == 0.0 {
+            return None;
+        }
         let x = ((x - left) * self.resolution.0 / width) as usize;
         let y = ((top - y) * self.resolution.1 / height) as usize;
         Some((x, y))

tests/widgets_chart.rs

@@ -21,7 +21,7 @@ fn widgets_chart_can_have_axis_with_zero_length_bounds() {
             let chart = Chart::default()
                 .block(Block::default().title("Plot").borders(Borders::ALL))
                 .x_axis(Axis::default().bounds([0.0, 0.0]).labels(&["0.0", "1.0"]))
-                .y_axis(Axis::default().bounds([0.0, 1.0]).labels(&["0.0", "1.0"]))
+                .y_axis(Axis::default().bounds([0.0, 0.0]).labels(&["0.0", "1.0"]))
                 .datasets(&datasets);
             f.render_widget(
                 chart,