suppress error on clear image

app.py

@@ -62,45 +62,53 @@ def subset_to_json_string(arr):
     return '[' + arr_str + ']'
 
 def estimate_body(source):
-    print("estimate_body")
     if source == None:
       return None
 
     candidate, subset = body_estimation(pil2cv(source))
-    print(candidate_to_json_string(candidate))
-    print(subset_to_json_string(subset))
     return "{ \"candidate\": " + candidate_to_json_string(candidate) + ", \"subset\": " + subset_to_json_string(subset) + " }"
     
 def image_changed(image):
   if (image == None):
-    return None
+    return {}, 512, 512
   json = estimate_body(image)
   return json, image.width, image.height
 
-def image_preprocess(image):
-  return image is not None
-
 html_text = f"""
     <canvas id="canvas" width="512" height="512"></canvas>
     <script type="text/javascript" defer>{file_contents}</script>
     """
 
 with gr.Blocks() as demo:
+  gr.Markdown("""### Usage
+
+Choose one of the following methods to edit the pose:
+
+| Style            | Description                                                                               |
+| -----------------| ----------------------------------------------------------------------------------------- |
+| Pose recognition | Upload an image and click "Start edit".                                               |
+| Input json       | Input json to "Json source" and click "Input Json", edit the width/height, then click "Start edit".    |
+| Free style       | Edit the width/height, then click "Start edit".                                        |
+
+To save the pose image, click "Save".  
+To export the pose data, click "Save" and "Copy to clipboard" of "Json" section.
+""")
   with gr.Row():
     with gr.Column(scale=1):
       source = gr.Image(type="pil")
       width = gr.Slider(label="Width", mininmum=512, maximum=1024, step=64, value=512, key="Width", interactive=True)
       height = gr.Slider(label="Height", mininmum=512, maximum=1024, step=64, value=512, key="Height", interactive=True)
       startBtn = gr.Button(value="Start edit")
-      json = gr.JSON(label="Body")
+      json = gr.JSON(label="Json", lines=10)
+      jsonInput = gr.Textbox(label="Json source", lines=10)
+      jsonInputBtn = gr.Button(value="Input Json")
     with gr.Column(scale=2):
-      gr.HTML("<ul><li>ctrl + drag to scale</li><li>alt + drag to translate</li><li>shift + drag to rotate(move right first, then up or down)</li></ul>")
       html = gr.HTML(html_text)
       saveBtn = gr.Button(value="Save")
+      gr.HTML("<ul><li>ctrl + drag to scale</li><li>alt + drag to translate</li><li>shift + drag to rotate(move right first, then up or down)</li></ul>")
 
   source.change(
     fn = image_changed,
-    preprocess = image_preprocess,
     inputs = [source],
     outputs = [json, width, height])
   startBtn.click(
@@ -112,5 +120,8 @@ with gr.Blocks() as demo:
     fn = None,
     inputs = [], outputs = [json],
     _js="() => { return [savePose()]; }")
-
+  jsonInputBtn.click(
+    fn = lambda x: x,
+    inputs = [jsonInput], outputs = [json])
+    
 gr.mount_gradio_app(app, demo, path="/")