perf(ui): memoize & otherwise optimize regional prompts ui

invokeai/frontend/web/src/features/regionalPrompts/components/AddLayerButton.tsx

@@ -1,10 +1,10 @@
 import { Button } from '@invoke-ai/ui-library';
 import { useAppDispatch } from 'app/store/storeHooks';
 import { layerAdded } from 'features/regionalPrompts/store/regionalPromptsSlice';
-import { useCallback } from 'react';
+import { memo, useCallback } from 'react';
 import { useTranslation } from 'react-i18next';
 
-export const AddLayerButton = () => {
+export const AddLayerButton = memo(() => {
   const { t } = useTranslation();
   const dispatch = useAppDispatch();
   const onClick = useCallback(() => {
@@ -12,4 +12,6 @@ export const AddLayerButton = () => {
   }, [dispatch]);
 
   return <Button onClick={onClick}>{t('regionalPrompts.addLayer')}</Button>;
-};
+});
+
+AddLayerButton.displayName = 'AddLayerButton';

invokeai/frontend/web/src/features/regionalPrompts/components/BrushPreview.tsx

@@ -1,49 +1,38 @@
 import { useStore } from '@nanostores/react';
 import { useAppSelector } from 'app/store/storeHooks';
-import { rgbColorToString } from 'features/canvas/util/colorToString';
+import { rgbaColorToString } from 'features/canvas/util/colorToString';
 import { $cursorPosition } from 'features/regionalPrompts/store/regionalPromptsSlice';
+import { memo } from 'react';
 import { Circle, Group } from 'react-konva';
 
-const useBrushData = () => {
+export const BrushPreviewOutline = memo(() => {
   const brushSize = useAppSelector((s) => s.regionalPrompts.brushSize);
   const tool = useAppSelector((s) => s.regionalPrompts.tool);
+  const a = useAppSelector((s) => s.regionalPrompts.promptLayerOpacity);
   const color = useAppSelector((s) => {
     const _color = s.regionalPrompts.layers.find((l) => l.id === s.regionalPrompts.selectedLayer)?.color;
     if (!_color) {
       return null;
     }
-    return rgbColorToString(_color);
+    return rgbaColorToString({ ..._color, a });
   });
+
   const pos = useStore($cursorPosition);
 
-  return { brushSize, tool, color, pos };
-};
-
-export const BrushPreviewFill = () => {
-  const { brushSize, tool, color, pos } = useBrushData();
   if (!brushSize || !color || !pos || tool === 'move') {
     return null;
   }
 
   return (
-    <Circle
+    <Group listening={false}>
-      x={pos.x}
+      <Circle
-      y={pos.y}
+        x={pos.x}
-      radius={brushSize / 2}
+        y={pos.y}
-      fill={color}
+        radius={brushSize / 2}
-      globalCompositeOperation={tool === 'brush' ? 'source-over' : 'destination-out'}
+        fill={color}
-    />
+        globalCompositeOperation={tool === 'brush' ? 'source-over' : 'destination-out'}
-  );
+        listening={false}
-};
+      />
-
-export const BrushPreviewOutline = () => {
-  const { brushSize, tool, color, pos } = useBrushData();
-  if (!brushSize || !color || !pos || tool === 'move') {
-    return null;
-  }
-
-  return (
-    <Group>
       <Circle
         x={pos.x}
         y={pos.y}
@@ -64,4 +53,6 @@ export const BrushPreviewOutline = () => {
       />
     </Group>
   );
-};
+});
+
+BrushPreviewOutline.displayName = 'BrushPreviewOutline';

invokeai/frontend/web/src/features/regionalPrompts/components/BrushSize.tsx

@@ -1,10 +1,10 @@
 import { CompositeNumberInput, CompositeSlider, FormControl, FormLabel } from '@invoke-ai/ui-library';
 import { useAppDispatch, useAppSelector } from 'app/store/storeHooks';
 import { brushSizeChanged } from 'features/regionalPrompts/store/regionalPromptsSlice';
-import { useCallback } from 'react';
+import { memo, useCallback } from 'react';
 import { useTranslation } from 'react-i18next';
 
-export const BrushSize = () => {
+export const BrushSize = memo(() => {
   const dispatch = useAppDispatch();
   const { t } = useTranslation();
   const brushSize = useAppSelector((s) => s.regionalPrompts.brushSize);
@@ -21,4 +21,6 @@ export const BrushSize = () => {
       <CompositeNumberInput min={1} max={500} value={brushSize} onChange={onChange} />
     </FormControl>
   );
-};
+});
+
+BrushSize.displayName = 'BrushSize';

invokeai/frontend/web/src/features/regionalPrompts/components/LayerBoundingBox.tsx

@@ -1,14 +1,14 @@
-import { createSelector } from '@reduxjs/toolkit';
+import { createMemoizedSelector } from 'app/store/createMemoizedSelector';
 import { useAppDispatch, useAppSelector } from 'app/store/storeHooks';
 import { layerSelected, selectRegionalPromptsSlice } from 'features/regionalPrompts/store/regionalPromptsSlice';
-import { useCallback, useMemo } from 'react';
+import { memo, useCallback, useMemo } from 'react';
 import { Rect as KonvaRect } from 'react-konva';
 
 type Props = {
   layerId: string;
 };
 
-export const LayerBoundingBox = ({ layerId }: Props) => {
+export const LayerBoundingBox = memo(({ layerId }: Props) => {
   const dispatch = useAppDispatch();
   const tool = useAppSelector((s) => s.regionalPrompts.tool);
   const selectedLayer = useAppSelector((s) => s.regionalPrompts.selectedLayer);
@@ -19,7 +19,7 @@ export const LayerBoundingBox = ({ layerId }: Props) => {
 
   const selectBbox = useMemo(
     () =>
-      createSelector(
+      createMemoizedSelector(
         selectRegionalPromptsSlice,
         (regionalPrompts) => regionalPrompts.layers.find((layer) => layer.id === layerId)?.bbox ?? null
       ),
@@ -33,6 +33,7 @@ export const LayerBoundingBox = ({ layerId }: Props) => {
 
   return (
     <KonvaRect
+      name="layer bbox"
       onMouseDown={onMouseDown}
       stroke={selectedLayer === layerId ? 'rgba(153, 187, 189, 1)' : 'rgba(255, 255, 255, 0.149)'}
       strokeWidth={1}
@@ -43,4 +44,6 @@ export const LayerBoundingBox = ({ layerId }: Props) => {
       listening={tool === 'move'}
     />
   );
-};
+});
+
+LayerBoundingBox.displayName = 'LayerBoundingBox';

invokeai/frontend/web/src/features/regionalPrompts/components/LayerColorPicker.tsx

@@ -1,18 +1,31 @@
 import { IconButton, Popover, PopoverBody, PopoverContent, PopoverTrigger } from '@invoke-ai/ui-library';
-import { useAppDispatch } from 'app/store/storeHooks';
+import { createMemoizedSelector } from 'app/store/createMemoizedSelector';
+import { useAppDispatch, useAppSelector } from 'app/store/storeHooks';
 import RgbColorPicker from 'common/components/RgbColorPicker';
-import { useLayer } from 'features/regionalPrompts/hooks/layerStateHooks';
+import {
-import { promptRegionLayerColorChanged } from 'features/regionalPrompts/store/regionalPromptsSlice';
+  promptRegionLayerColorChanged,
-import { useCallback } from 'react';
+  selectRegionalPromptsSlice,
+} from 'features/regionalPrompts/store/regionalPromptsSlice';
+import { memo, useCallback, useMemo } from 'react';
 import type { RgbColor } from 'react-colorful';
 import { PiEyedropperBold } from 'react-icons/pi';
+import { assert } from 'tsafe';
 
 type Props = {
   id: string;
 };
 
-export const LayerColorPicker = ({ id }: Props) => {
+export const LayerColorPicker = memo(({ id }: Props) => {
-  const layer = useLayer(id);
+  const selectColor = useMemo(
+    () =>
+      createMemoizedSelector(selectRegionalPromptsSlice, (regionalPrompts) => {
+        const layer = regionalPrompts.layers.find((l) => l.id === id);
+        assert(layer);
+        return layer.color;
+      }),
+    [id]
+  );
+  const color = useAppSelector(selectColor);
   const dispatch = useAppDispatch();
   const onColorChange = useCallback(
     (color: RgbColor) => {
@@ -27,9 +40,11 @@ export const LayerColorPicker = ({ id }: Props) => {
       </PopoverTrigger>
       <PopoverContent>
         <PopoverBody minH={64}>
-          <RgbColorPicker color={layer.color} onChange={onColorChange} withNumberInput />
+          <RgbColorPicker color={color} onChange={onColorChange} withNumberInput />
         </PopoverBody>
       </PopoverContent>
     </Popover>
   );
-};
+});
+
+LayerColorPicker.displayName = 'LayerColorPicker';

invokeai/frontend/web/src/features/regionalPrompts/components/LayerComponent.tsx

@@ -1,6 +1,5 @@
 import { useAppDispatch, useAppSelector } from 'app/store/storeHooks';
 import getScaledCursorPosition from 'features/canvas/util/getScaledCursorPosition';
-import { BrushPreviewFill } from 'features/regionalPrompts/components/BrushPreview';
 import { LayerBoundingBox } from 'features/regionalPrompts/components/LayerBoundingBox';
 import { LineComponent } from 'features/regionalPrompts/components/LineComponent';
 import { RectComponent } from 'features/regionalPrompts/components/RectComponent';
@@ -17,8 +16,7 @@ import type { Group as KonvaGroupType } from 'konva/lib/Group';
 import type { Layer as KonvaLayerType } from 'konva/lib/Layer';
 import type { KonvaEventObject, Node as KonvaNodeType, NodeConfig as KonvaNodeConfigType } from 'konva/lib/Node';
 import type { IRect, Vector2d } from 'konva/lib/types';
-import type React from 'react';
+import { memo, useCallback, useEffect, useRef } from 'react';
-import { useCallback, useEffect, useRef } from 'react';
 import { Group as KonvaGroup, Layer as KonvaLayer } from 'react-konva';
 
 type Props = {
@@ -28,15 +26,13 @@ type Props = {
 export const selectPromptLayerObjectGroup = (item: KonvaNodeType<KonvaNodeConfigType>) =>
   item.name() !== REGIONAL_PROMPT_LAYER_OBJECT_GROUP_NAME;
 
-export const LayerComponent: React.FC<Props> = ({ id }) => {
+export const LayerComponent = memo(({ id }: Props) => {
   const dispatch = useAppDispatch();
   const layer = useLayer(id);
-  const selectedLayer = useAppSelector((s) => s.regionalPrompts.selectedLayer);
   const promptLayerOpacity = useAppSelector((s) => s.regionalPrompts.promptLayerOpacity);
   const tool = useAppSelector((s) => s.regionalPrompts.tool);
   const layerRef = useRef<KonvaLayerType>(null);
   const groupRef = useRef<KonvaGroupType>(null);
-
   const onChangeBbox = useCallback(
     (bbox: IRect | null) => {
       dispatch(layerBboxChanged({ layerId: layer.id, bbox }));
@@ -94,39 +90,39 @@ export const LayerComponent: React.FC<Props> = ({ id }) => {
     }
     // Caching the group allows its opacity to apply to all shapes at once. We should cache only when the layer's
     // objects or attributes with a visual effect (e.g. color) change.
+    // TODO: Figure out a more efficient way to handle opacity - maybe a separate rect w/ globalCompositeOperation...
     groupRef.current.cache();
   }, [layer.objects, layer.color, layer.isVisible]);
 
   return (
-    <>
+    <KonvaLayer
-      <KonvaLayer
+      ref={layerRef}
-        ref={layerRef}
+      id={layer.id}
-        id={layer.id}
+      name={REGIONAL_PROMPT_LAYER_NAME}
-        name={REGIONAL_PROMPT_LAYER_NAME}
+      onDragMove={onDragMove}
-        onDragMove={onDragMove}
+      dragBoundFunc={dragBoundFunc}
-        dragBoundFunc={dragBoundFunc}
+      visible={layer.isVisible}
-        visible={layer.isVisible}
+      draggable
-        draggable
+    >
+      <KonvaGroup
+        id={`layer-${layer.id}-group`}
+        name={REGIONAL_PROMPT_LAYER_OBJECT_GROUP_NAME}
+        ref={groupRef}
+        listening={false}
+        opacity={promptLayerOpacity}
       >
-        <KonvaGroup
+        {layer.objects.map((obj) => {
-          id={`layer-${layer.id}-group`}
+          if (obj.kind === 'line') {
-          name={REGIONAL_PROMPT_LAYER_OBJECT_GROUP_NAME}
+            return <LineComponent key={obj.id} line={obj} color={layer.color} layerId={layer.id} />;
-          ref={groupRef}
+          }
-          listening={false}
+          if (obj.kind === 'fillRect') {
-          opacity={promptLayerOpacity}
+            return <RectComponent key={obj.id} rect={obj} color={layer.color} />;
-        >
+          }
-          {layer.objects.map((obj) => {
+        })}
-            if (obj.kind === 'line') {
+      </KonvaGroup>
-              return <LineComponent key={obj.id} line={obj} color={layer.color} layerId={layer.id} />;
+      <LayerBoundingBox layerId={layer.id} />
-            }
+    </KonvaLayer>
-            if (obj.kind === 'fillRect') {
-              return <RectComponent key={obj.id} rect={obj} color={layer.color} />;
-            }
-          })}
-        </KonvaGroup>
-        <LayerBoundingBox layerId={layer.id} />
-      </KonvaLayer>
-      <KonvaLayer name="brushPreviewFill">{layer.id === selectedLayer && <BrushPreviewFill />}</KonvaLayer>
-    </>
   );
-};
+});
+
+LayerComponent.displayName = 'LayerComponent';

invokeai/frontend/web/src/features/regionalPrompts/components/LayerListItem.tsx

@@ -6,14 +6,14 @@ import { LayerMenu } from 'features/regionalPrompts/components/LayerMenu';
 import { LayerVisibilityToggle } from 'features/regionalPrompts/components/LayerVisibilityToggle';
 import { RegionalPromptsPrompt } from 'features/regionalPrompts/components/RegionalPromptsPrompt';
 import { layerSelected } from 'features/regionalPrompts/store/regionalPromptsSlice';
-import { useCallback } from 'react';
+import { memo, useCallback } from 'react';
 import { useTranslation } from 'react-i18next';
 
 type Props = {
   id: string;
 };
 
-export const LayerListItem = ({ id }: Props) => {
+export const LayerListItem = memo(({ id }: Props) => {
   const dispatch = useAppDispatch();
   const { t } = useTranslation();
   const selectedLayer = useAppSelector((s) => s.regionalPrompts.selectedLayer);
@@ -46,4 +46,6 @@ export const LayerListItem = ({ id }: Props) => {
       </Flex>
     </Flex>
   );
-};
+});
+
+LayerListItem.displayName = 'LayerListItem';

invokeai/frontend/web/src/features/regionalPrompts/components/LayerMenu.tsx

@@ -1,5 +1,5 @@
 import { IconButton, Menu, MenuButton, MenuDivider, MenuItem, MenuList } from '@invoke-ai/ui-library';
-import { createSelector } from '@reduxjs/toolkit';
+import { createMemoizedSelector } from 'app/store/createMemoizedSelector';
 import { useAppDispatch, useAppSelector } from 'app/store/storeHooks';
 import {
   layerDeleted,
@@ -10,8 +10,7 @@ import {
   layerReset,
   selectRegionalPromptsSlice,
 } from 'features/regionalPrompts/store/regionalPromptsSlice';
-import type React from 'react';
+import { memo, useCallback, useMemo } from 'react';
-import { useCallback, useMemo } from 'react';
 import { useTranslation } from 'react-i18next';
 import {
   PiArrowCounterClockwiseBold,
@@ -25,12 +24,12 @@ import {
 
 type Props = { id: string };
 
-export const LayerMenu: React.FC<Props> = ({ id }) => {
+export const LayerMenu = memo(({ id }: Props) => {
   const dispatch = useAppDispatch();
   const { t } = useTranslation();
   const selectValidActions = useMemo(
     () =>
-      createSelector(selectRegionalPromptsSlice, (regionalPrompts) => {
+      createMemoizedSelector(selectRegionalPromptsSlice, (regionalPrompts) => {
         const layerIndex = regionalPrompts.layers.findIndex((l) => l.id === id);
         const layerCount = regionalPrompts.layers.length;
         return {
@@ -87,4 +86,6 @@ export const LayerMenu: React.FC<Props> = ({ id }) => {
       </MenuList>
     </Menu>
   );
-};
+});
+
+LayerMenu.displayName = 'LayerMenu';

invokeai/frontend/web/src/features/regionalPrompts/components/LayerVisibilityToggle.tsx

@@ -2,14 +2,14 @@ import { IconButton } from '@invoke-ai/ui-library';
 import { useAppDispatch } from 'app/store/storeHooks';
 import { useLayerIsVisible } from 'features/regionalPrompts/hooks/layerStateHooks';
 import { layerIsVisibleToggled } from 'features/regionalPrompts/store/regionalPromptsSlice';
-import { useCallback } from 'react';
+import { memo, useCallback } from 'react';
 import { PiEyeBold, PiEyeClosedBold } from 'react-icons/pi';
 
 type Props = {
   id: string;
 };
 
-export const LayerVisibilityToggle = ({ id }: Props) => {
+export const LayerVisibilityToggle = memo(({ id }: Props) => {
   const dispatch = useAppDispatch();
   const isVisible = useLayerIsVisible(id);
   const onClick = useCallback(() => {
@@ -25,4 +25,6 @@ export const LayerVisibilityToggle = ({ id }: Props) => {
       onClick={onClick}
     />
   );
-};
+});
+
+LayerVisibilityToggle.displayName = 'LayerVisibilityToggle';

invokeai/frontend/web/src/features/regionalPrompts/components/LineComponent.tsx

@@ -1,5 +1,6 @@
 import { rgbColorToString } from 'features/canvas/util/colorToString';
 import type { LineObject } from 'features/regionalPrompts/store/regionalPromptsSlice';
+import { memo } from 'react';
 import type { RgbColor } from 'react-colorful';
 import { Line } from 'react-konva';
 
@@ -9,7 +10,7 @@ type Props = {
   color: RgbColor;
 };
 
-export const LineComponent = ({ layerId, line, color }: Props) => {
+export const LineComponent = memo(({ layerId, line, color }: Props) => {
   return (
     <Line
       id={`layer-${layerId}.line-${line.id}`}
@@ -25,4 +26,6 @@ export const LineComponent = ({ layerId, line, color }: Props) => {
       listening={false}
     />
   );
-};
+});
+
+LineComponent.displayName = 'LineComponent';

invokeai/frontend/web/src/features/regionalPrompts/components/PromptLayerOpacity.tsx

@@ -1,10 +1,10 @@
 import { CompositeSlider, FormControl, FormLabel } from '@invoke-ai/ui-library';
 import { useAppDispatch, useAppSelector } from 'app/store/storeHooks';
 import { promptLayerOpacityChanged } from 'features/regionalPrompts/store/regionalPromptsSlice';
-import { useCallback } from 'react';
+import { memo, useCallback } from 'react';
 import { useTranslation } from 'react-i18next';
 
-export const PromptLayerOpacity = () => {
+export const PromptLayerOpacity = memo(() => {
   const dispatch = useAppDispatch();
   const { t } = useTranslation();
   const promptLayerOpacity = useAppSelector((s) => s.regionalPrompts.promptLayerOpacity);
@@ -20,4 +20,6 @@ export const PromptLayerOpacity = () => {
       <CompositeSlider min={0.25} max={1} step={0.01} value={promptLayerOpacity} onChange={onChange} />
     </FormControl>
   );
-};
+});
+
+PromptLayerOpacity.displayName = 'PromptLayerOpacity';

invokeai/frontend/web/src/features/regionalPrompts/components/RectComponent.tsx

@@ -1,5 +1,6 @@
 import { rgbColorToString } from 'features/canvas/util/colorToString';
 import type { FillRectObject } from 'features/regionalPrompts/store/regionalPromptsSlice';
+import { memo } from 'react';
 import type { RgbColor } from 'react-colorful';
 import { Rect } from 'react-konva';
 
@@ -8,8 +9,18 @@ type Props = {
   color: RgbColor;
 };
 
-export const RectComponent = ({ rect, color }: Props) => {
+export const RectComponent = memo(({ rect, color }: Props) => {
   return (
-    <Rect key={rect.id} x={rect.x} y={rect.y} width={rect.width} height={rect.height} fill={rgbColorToString(color)} />
+    <Rect
+      key={rect.id}
+      x={rect.x}
+      y={rect.y}
+      width={rect.width}
+      height={rect.height}
+      fill={rgbColorToString(color)}
+      listening={false}
+    />
   );
-};
+});
+
+RectComponent.displayName = 'RectComponent';

invokeai/frontend/web/src/features/regionalPrompts/components/RegionalPromptsEditor.tsx

@@ -1,6 +1,6 @@
 /* eslint-disable i18next/no-literal-string */
 import { Button, Flex } from '@invoke-ai/ui-library';
-import { createSelector } from '@reduxjs/toolkit';
+import { createMemoizedSelector } from 'app/store/createMemoizedSelector';
 import { useAppSelector } from 'app/store/storeHooks';
 import { AddLayerButton } from 'features/regionalPrompts/components/AddLayerButton';
 import { BrushSize } from 'features/regionalPrompts/components/BrushSize';
@@ -11,8 +11,9 @@ import { ToolChooser } from 'features/regionalPrompts/components/ToolChooser';
 import { selectRegionalPromptsSlice } from 'features/regionalPrompts/store/regionalPromptsSlice';
 import { getRegionalPromptLayerBlobs } from 'features/regionalPrompts/util/getLayerBlobs';
 import { ImageSizeLinear } from 'features/settingsAccordions/components/ImageSettingsAccordion/ImageSizeLinear';
+import { memo } from 'react';
 
-const selectLayerIdsReversed = createSelector(selectRegionalPromptsSlice, (regionalPrompts) =>
+const selectLayerIdsReversed = createMemoizedSelector(selectRegionalPromptsSlice, (regionalPrompts) =>
   regionalPrompts.layers.map((l) => l.id).reverse()
 );
 
@@ -20,7 +21,7 @@ const debugBlobs = () => {
   getRegionalPromptLayerBlobs(true);
 };
 
-export const RegionalPromptsEditor = () => {
+export const RegionalPromptsEditor = memo(() => {
   const layerIdsReversed = useAppSelector(selectLayerIdsReversed);
   return (
     <Flex gap={4}>
@@ -40,4 +41,6 @@ export const RegionalPromptsEditor = () => {
       </Flex>
     </Flex>
   );
-};
+});
+
+RegionalPromptsEditor.displayName = 'RegionalPromptsEditor';

invokeai/frontend/web/src/features/regionalPrompts/components/RegionalPromptsStage.tsx

@@ -1,5 +1,5 @@
 import { chakra } from '@invoke-ai/ui-library';
-import { createSelector } from '@reduxjs/toolkit';
+import { createMemoizedSelector } from 'app/store/createMemoizedSelector';
 import { useAppSelector } from 'app/store/storeHooks';
 import { BrushPreviewOutline } from 'features/regionalPrompts/components/BrushPreview';
 import { LayerComponent } from 'features/regionalPrompts/components/LayerComponent';
@@ -15,7 +15,7 @@ import type Konva from 'konva';
 import { memo, useCallback, useMemo, useRef } from 'react';
 import { Layer, Stage } from 'react-konva';
 
-const selectLayerIds = createSelector(selectRegionalPromptsSlice, (regionalPrompts) =>
+const selectLayerIds = createMemoizedSelector(selectRegionalPromptsSlice, (regionalPrompts) =>
   regionalPrompts.layers.map((l) => l.id)
 );
 

invokeai/frontend/web/src/features/regionalPrompts/store/regionalPromptsSlice.ts

@@ -2,7 +2,7 @@ import type { PayloadAction } from '@reduxjs/toolkit';
 import { createSlice } from '@reduxjs/toolkit';
 import type { PersistConfig, RootState } from 'app/store/store';
 import { moveBackward, moveForward, moveToBack, moveToFront } from 'common/util/arrayUtils';
-import type Konva from 'konva';
+import type { Stage } from 'konva/lib/Stage';
 import type { IRect, Vector2d } from 'konva/lib/types';
 import { atom } from 'nanostores';
 import type { RgbColor } from 'react-colorful';
@@ -270,8 +270,8 @@ export const regionalPromptsPersistConfig: PersistConfig<RegionalPromptsState> =
 export const $isMouseDown = atom(false);
 export const $isMouseOver = atom(false);
 export const $cursorPosition = atom<Vector2d | null>(null);
-export const $stage = atom<Konva.Stage | null>(null);
+export const $stage = atom<Stage | null>(null);
-export const getStage = (): Konva.Stage => {
+export const getStage = (): Stage => {
   const stage = $stage.get();
   assert(stage);
   return stage;