Update app.py

app.py

@@ -50,7 +50,7 @@ app_ui = ui.page_fluid(
 
 @module.ui
 def plot_ui():
-    opacity_slider = ui.input_slider("opacity", "Opacity", 0, 1.0, 0.5)
+    opacity_slider = ui.input_slider("opacity_slider", "Opacity", 0, 1.0, 0.5)
     return ui.row(
         ui.output_plot("plot_prediction"),
         opacity_slider
@@ -58,8 +58,15 @@ def plot_ui():
 
 @module.server
 def plot_server(input, output, session, r):
+    opacity = reactive.value(0.5)
+
+    @reactive.effect
+    @reactive.event(input.opacity_slider)
+    def _():
+        opacity.set(input.opacity_slider())
+    
     @render.plot
-    async def plot_prediction():
+    def plot_prediction():
         fig, ax = plt.subplots()
 
         # ax = plt.Axes(fig, [0., 0., 1., 1.])
@@ -80,9 +87,11 @@ def plot_server(input, output, session, r):
 
         out = v.overlay_instances(masks = r["instances"].pred_masks.to("cpu"),
                                   assigned_colors = colours, 
-                                  alpha = input.opacity())
+                                  alpha = opacity())
 
-        ax.imshow(cv2.cvtColor(out.get_image()[:, :, ::-1], cv2.COLOR_BGR2RGB))
+        annotations = ax.imshow(cv2.cvtColor(out.get_image()[:, :, ::-1], cv2.COLOR_BGR2RGB))
+        fig.canvas.draw()
+        fig.canvas.flush_events()
 
 def server(input, output, session: Session):
     analysis_results = reactive.Value([])