WebguiScene.DownloadScreenshot()

To use it, you must pass an 'id' value to Draw().
This is because the scenes for screenshots need to be stored globally
and are not cleaned up automatically, so we don't want to store them all.

Author: mhochsteger

python/webgui.py

@@ -289,8 +289,16 @@ def GetData(self, set_minmax=True):
                         )
                     d["clipping_" + name] = val
 
-        if "js_code" in kwargs:
-            d["on_init"] = kwargs["js_code"]
+        id_ = kwargs.get("id", None)
+        js_code = kwargs.get("js_code", "")
+        if id_ is not None:
+            js_code += f"""
+                if(window._webgui_scenes === undefined)
+                    window._webgui_scenes = {{}};
+                window._webgui_scenes['{id_}'] = scene;
+            """
+        if js_code:
+            d["on_init"] = js_code
 
         if "min" in kwargs:
             d["funcmin"] = kwargs["min"]
@@ -351,6 +359,34 @@ def GetData(self, set_minmax=True):
 
         return d
 
+    def DownloadScreenshot(self, filename="image.jpg"):
+        from IPython.display import Javascript, display
+
+        if "id" not in self.kwargs:
+            raise Exception(
+                "To make a screenshot, please provide an id='some_unique_id' argument to Draw()"
+            )
+        format = filename.split(".")[-1].lower()
+        display(
+            Javascript(
+                f"""
+        {{
+            var scene = window._webgui_scenes['{self.kwargs['id']}'];
+            console.log("screenshot of scene", scene);
+            const toimage = () => {{
+                var link = document.createElement('a');
+                link.href = scene.renderer.domElement.toDataURL('image/{format}');
+                link.download = '{filename}';
+                link.click();
+                scene.event_handlers['afterrender'].pop(toimage);
+            }};
+            scene.on('afterrender', toimage);
+            scene.render();
+        }}
+        """
+            )
+        )
+
 
 bezier_trig_trafos = {}  # cache trafos for different orders