createImageFromWidget function

Future<Uint8List> createImageFromWidget(Widget widget, { Size? logicalSize, required Duration waitToRender, required FlutterView view, Size? imageSize, })

Creates an image from the given widget by first spinning up a element and render tree, wait waitToRender to render the widget that take time like network and asset images The final image will be of size imageSize and the the widget will be layout, ... with the given logicalSize. By default Value of imageSize and logicalSize will be calculate from the app main window

Implementation

/// The final image will be of size [imageSize] and the the widget will be layout, ... with the given [logicalSize].
/// By default Value of  [imageSize] and [logicalSize] will be calculate from the app main window

Future<Uint8List> createImageFromWidget(Widget widget,
    {Size? logicalSize,
    required Duration waitToRender,
    required ui.FlutterView view,
    Size? imageSize}) async {
  final RenderRepaintBoundary repaintBoundary = RenderRepaintBoundary();
  logicalSize ??= view.physicalSize / view.devicePixelRatio;
  imageSize ??= view.physicalSize;

  // assert(logicalSize.aspectRatio == imageSize.aspectRatio);

  final RenderView renderView = RenderView(
    view: view,
    child: RenderPositionedBox(
        alignment: Alignment.center, child: repaintBoundary),
    configuration: ViewConfiguration(
      physicalConstraints:
          BoxConstraints.tight(logicalSize) * view.devicePixelRatio,
      logicalConstraints: BoxConstraints.tight(logicalSize),
      devicePixelRatio: view.devicePixelRatio,
    ),
  );

  final PipelineOwner pipelineOwner = PipelineOwner();
  final BuildOwner buildOwner = BuildOwner(focusManager: FocusManager());

  pipelineOwner.rootNode = renderView;
  renderView.prepareInitialFrame();

  final RenderObjectToWidgetElement<RenderBox> rootElement =
      RenderObjectToWidgetAdapter<RenderBox>(
    container: repaintBoundary,
    child: widget,
  ).attachToRenderTree(buildOwner);

  buildOwner.buildScope(rootElement);

  await Future.delayed(waitToRender);

  buildOwner.buildScope(rootElement);
  buildOwner.finalizeTree();

  pipelineOwner.flushLayout();
  pipelineOwner.flushCompositingBits();
  pipelineOwner.flushPaint();

  final ui.Image image = await repaintBoundary.toImage(
      pixelRatio: imageSize.width / logicalSize.width);
  final ByteData? byteData =
      await image.toByteData(format: ui.ImageByteFormat.png);

  return byteData!.buffer.asUint8List();
}