Add ProgressBar::force_draw (#689)

Author: jaheba

src/progress_bar.rs

@@ -423,6 +423,17 @@ impl ProgressBar {
         state.draw_target = target;
     }
 
+    /// Force a redraw of the progress bar to be in sync with its state
+    ///
+    /// For performance reasons the progress bar is not redrawn on each state update.
+    /// This is normally not an issue, since new updates will eventually trigger rendering.
+    ///
+    /// For slow running tasks it is recommended to rely on [`ProgressBar::enable_steady_tick()`]
+    /// to ensure continued rendering of the progress bar.
+    pub fn force_draw(&self) {
+        let _ = self.state().draw(true, Instant::now());
+    }
+
     /// Hide the progress bar temporarily, execute `f`, then redraw the progress bar
     ///
     /// Useful for external code that writes to the standard output.