Windows Store App - C# - TextBlock check if text is trimmed

Question

In the TextBlock class, there is a property to set the TextTrimming behaviour of the control, when the text exceeds the bounds of the control.

However, I can't seem to find a property that can inform my application if the TextBlock has been trimmed or not.

The problem I have is that I have a fixed sized TextBlock that can have text the exceeds the size. When this happens, I want to dynamically adjust the font size to fit the text into the block.

Any idea's how I can do this?

Pseudo Code

// Function added to TextBlock as SizeChanged event handler. 
private void textBlock_SizeChanged(object sender, SizeChangedEventArgs e)
{
    TextBlock textBlock = sender as TextBlock;
    if(textBlock.IsTrimmed && textBlock.FontSize > 10) // NOTE: IsTrimmed Property does not exist.
    {
        textBlock.FontSize -= 10;
    }
}

Then the UI thread will recursively shrink the text until it fits into the TextBlock

Answer 1

Here is a solution that works.

    private void textBlock_SizeChanged(object sender, SizeChangedEventArgs e)
    {
        TextBlock tb = sender as TextBlock;

        if (tb != null)
        {
            Grid parent = tb.Parent as Grid;
            if(parent != null)
            {
                if(parent.ActualWidth < tb.ActualWidth)
                {
                    tb.FontSize -= 10;
                }
            }
        }
    }

Though its not very efficient. If there was an algorithm that could be used to determine the font size, string length and pixel width, it could be improved.