I can't get ActualSize of an UIElement

Question

I have an Image control, generated in runtime. It renders correct size when displaying. But I can't get size of that element. Width and Height is NaN. ActualWidth and ActualHeight is always 0.0 and control never fires SizeChanged event.

enter image description here

I'm also generating TextBoxes in the runtime and I can't get size of them too.

The code that generates image is bellow.

ExtendedImage image = new ExtendedImage();
image.Name = "element" + item.Id;
if (item.Text.ToUpperInvariant().EndsWith(".GIF"))
{
    var gif = BookReader.Imaging.GIFDecoder.Decode(Application.GetResourceStream(new Uri("Files/Books/" + item.BookId + "/" + item.Text, UriKind.Relative)).Stream);
    image.Source = gif.Frames[0].Image;
}
else
{
    var img = new BitmapImage(new Uri("/Files/Books/" + item.BookId + "/" + item.Text, UriKind.Relative));
    image.Source = img;
}

image.SetValue(Canvas.LeftProperty, (double)item.LocationX);
image.SetValue(Canvas.TopProperty, (double)(Application.Current.Host.Content.ActualHeight - item.LocationY));

image.SizeChanged += (o, e) =>
{
    var sender = o as ExtendedImage;
    image.SetValue(UIElement.RenderTransformOriginProperty, new Point(0.5, 0.5));
};

image.InvalidateMeasure();

if (!item.Visible)
{
    image.Visibility = System.Windows.Visibility.Collapsed;
}

ContentPanel.Children.Add(image);

score 3 · Answer 1 · edited Aug 21 '13 at 03:59

3

You can't access the size of the image before it's been rendered. And you can't render a item in a Canvas, without it having a explicit size.

So your problem is that you're attempting to get the size of the image before it's actually been rendered.

edited Aug 21 '13 at 03:59

Dave Clemmer

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answered Sep 18 '11 at 12:39

Claus Jørgensen

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score 1 · Accepted Answer · edited Aug 21 '13 at 03:59

1

If the container of the Image has Height and Width, the image should have it as well. Try to put your Image into a Grid or StackPanel and set the size explicitly.

edited Aug 21 '13 at 03:59

Dave Clemmer

3,741
12
49
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answered Sep 18 '11 at 12:22

Lukasz Madon

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It's contained in a Canvas and canvas has Height and Width. – Medeni Baykal Sep 18 '11 at 12:23
Thanks for your answer. Size of Canvas' container was NaN. When I'll fixes that, my problem is solved. – Medeni Baykal Sep 18 '11 at 13:59
Can you please tell me how you have fixed your problem, i am also having the same problem. – Animesh Sinha May 16 '12 at 11:30

I can't get ActualSize of an UIElement

2 Answers2