feat!(widgets/canvas): use spans for text of labels

examples/canvas.rs

@@ -7,7 +7,8 @@ use termion::{event::Key, input::MouseTerminal, raw::IntoRawMode, screen::Altern
 use tui::{
     backend::TermionBackend,
     layout::{Constraint, Direction, Layout, Rect},
-    style::Color,
+    style::{Color, Style},
+    text::Span,
     widgets::{
         canvas::{Canvas, Map, MapResolution, Rectangle},
         Block, Borders,
@@ -103,7 +104,11 @@ fn main() -> Result<(), Box<dyn Error>> {
                         color: Color::White,
                         resolution: MapResolution::High,
                     });
-                    ctx.print(app.x, -app.y, "You are here", Color::Yellow);
+                    ctx.print(
+                        app.x,
+                        -app.y,
+                        Span::styled("You are here", Style::default().fg(Color::Yellow)),
+                    );
                 })
                 .x_bounds([-180.0, 180.0])
                 .y_bounds([-90.0, 90.0]);

examples/demo/ui.rs

@@ -363,7 +363,11 @@ where
                 } else {
                     Color::Red
                 };
-                ctx.print(server.coords.1, server.coords.0, "X", color);
+                ctx.print(
+                    server.coords.1,
+                    server.coords.0,
+                    Span::styled("X", Style::default().fg(color)),
+                );
             }
         })
         .marker(if app.enhanced_graphics {

src/widgets/canvas/mod.rs

@@ -14,6 +14,7 @@ use crate::{
     layout::Rect,
     style::{Color, Style},
     symbols,
+    text::Spans,
     widgets::{Block, Widget},
 };
 use std::fmt::Debug;
@@ -26,10 +27,9 @@ pub trait Shape {
 /// Label to draw some text on the canvas
 #[derive(Debug, Clone)]
 pub struct Label<'a> {
-    pub x: f64,
-    pub y: f64,
-    pub text: &'a str,
-    pub color: Color,
+    x: f64,
+    y: f64,
+    spans: Spans<'a>,
 }
 
 #[derive(Debug, Clone)]
@@ -293,8 +293,15 @@ impl<'a> Context<'a> {
     }
 
     /// Print a string on the canvas at the given position
-    pub fn print(&mut self, x: f64, y: f64, text: &'a str, color: Color) {
-        self.labels.push(Label { x, y, text, color });
+    pub fn print<T>(&mut self, x: f64, y: f64, spans: T)
+    where
+        T: Into<Spans<'a>>,
+    {
+        self.labels.push(Label {
+            x,
+            y,
+            spans: spans.into(),
+        });
     }
 
     /// Push the last layer if necessary
@@ -433,6 +440,8 @@ where
             None => area,
         };
 
+        buf.set_style(canvas_area, Style::default().bg(self.background_color));
+
         let width = canvas_area.width as usize;
 
         let painter = match self.painter {
@@ -464,14 +473,12 @@ where
                     let (x, y) = (i % width, i / width);
                     buf.get_mut(x as u16 + canvas_area.left(), y as u16 + canvas_area.top())
                         .set_char(ch)
-                        .set_fg(color)
-                        .set_bg(self.background_color);
+                        .set_fg(color);
                 }
             }
         }
 
         // Finally draw the labels
-        let style = Style::default().bg(self.background_color);
         let left = self.x_bounds[0];
         let right = self.x_bounds[1];
         let top = self.y_bounds[1];
@@ -490,13 +497,7 @@ where
         {
             let x = ((label.x - left) * resolution.0 / width) as u16 + canvas_area.left();
             let y = ((top - label.y) * resolution.1 / height) as u16 + canvas_area.top();
-            buf.set_stringn(
-                x,
-                y,
-                label.text,
-                (canvas_area.right() - x) as usize,
-                style.fg(label.color),
-            );
+            buf.set_spans(x, y, &label.spans, canvas_area.right() - x);
         }
     }
 }

tests/widgets_canvas.rs

@@ -0,0 +1,42 @@
+use tui::{
+    backend::TestBackend,
+    buffer::Buffer,
+    style::{Color, Style},
+    text::Span,
+    widgets::canvas::Canvas,
+    Terminal,
+};
+
+#[test]
+fn widgets_canvas_draw_labels() {
+    let backend = TestBackend::new(5, 5);
+    let mut terminal = Terminal::new(backend).unwrap();
+    terminal
+        .draw(|f| {
+            let label = String::from("test");
+            let canvas = Canvas::default()
+                .background_color(Color::Yellow)
+                .x_bounds([0.0, 5.0])
+                .y_bounds([0.0, 5.0])
+                .paint(|ctx| {
+                    ctx.print(
+                        0.0,
+                        0.0,
+                        Span::styled(label.clone(), Style::default().fg(Color::Blue)),
+                    );
+                });
+            f.render_widget(canvas, f.size());
+        })
+        .unwrap();
+
+    let mut expected = Buffer::with_lines(vec!["    ", "    ", "     ", "     ", "test "]);
+    for row in 0..5 {
+        for col in 0..5 {
+            expected.get_mut(col, row).set_bg(Color::Yellow);
+        }
+    }
+    for col in 0..4 {
+        expected.get_mut(col, 4).set_fg(Color::Blue);
+    }
+    terminal.backend().assert_buffer(&expected)
+}