Question 78838 in Flutter Question posted in
The official Flutter documentation can be found here.

The method 'toImage' isn't defined for the type 'RenderObject' – Flutter

How to fix this error message:

The method ‘toImage’ isn’t defined for the type ‘RenderObject’. Try
correcting the name to the name of an existing method, or defining a
method named ‘toImage’.

enter image description here

My Code:

  Future<void> saveImage() async {
    RenderObject? boundary = globalKey.currentContext!.findRenderObject() as RenderBox;
    ui.Image image = await boundary.toImage();
    ByteData? byteData = await image.toByteData(format: ui.ImageByteFormat.png);
    Uint8List pngBytes = byteData!.buffer.asUint8List();

    //Request permissions if not already granted
    if (!(await Permission.storage.status.isGranted))
      await Permission.storage.request();

    final result = await ImageGallerySaver.saveImage(
        Uint8List.fromList(pngBytes),
        quality: 60,
        name: "logo_image");
    print(result);
  }
Tags:

2

Answers


  1. 0

    You will have to wrap the widget you want to convert to image into RepaintBoundary widget with globalKey.

    Once that is done, you can change

    RenderObject? boundary = globalKey.currentContext!.findRenderObject() as RenderBox;

    to

    RenderRepaintBoundary? boundary = globalKey.currentContext!.findRenderObject() as RenderRepaintBoundary?;
if (boundary == null) {
    return;
}
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  2. 0

    That is because the RenderObject class (or even RenderBox) do not define toImage method. Instead you will have to cast to RenderRepaintBoundary.

    You are writing

    RenderObject? boundary = globalKey.currentContext!.findRenderObject() as RenderBox;
ui.Image image = await boundary.toImage();

    but in the docu they write

    final RenderRepaintBoundary boundary = globalKey.currentContext!.findRenderObject()! as RenderRepaintBoundary;
final ui.Image image = await boundary.toImage();

    try correcting that…

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