private void CalculateFontSize()
{
double fontSize = this.MaxFontSize;
List <TextBlock> tbs = VisualHelper.FindVisualChildren <TextBlock>(this.AssociatedObject);
// get grid height (if limited)
double gridHeight = double.MaxValue;
Grid parentGrid = VisualHelper.FindUpVisualTree <Grid>(this.AssociatedObject.Parent);
if (parentGrid != null)
{
RowDefinition row = parentGrid.RowDefinitions[Grid.GetRow(this.AssociatedObject)];
gridHeight = row.Height == GridLength.Auto ? double.MaxValue : this.AssociatedObject.ActualHeight;
}
foreach (var tb in tbs)
{
// get desired size with fontsize = MaxFontSize
System.Windows.Size desiredSize = MeasureText(tb);
double widthMargins = tb.Margin.Left + tb.Margin.Right;
double heightMargins = tb.Margin.Top + tb.Margin.Bottom;
double desiredHeight = desiredSize.Height + heightMargins;
double desiredWidth = desiredSize.Width + widthMargins;
// adjust fontsize if text would be clipped vertically
if (gridHeight < desiredHeight)
{
double factor = (desiredHeight - heightMargins) / (this.AssociatedObject.ActualHeight - heightMargins);
fontSize = Math.Min(fontSize, MaxFontSize / factor);
}
// get column width (if limited)
if (AssociatedObject.ColumnDefinitions.Count > 0)
{
ColumnDefinition col = this.AssociatedObject.ColumnDefinitions[Grid.GetColumn(tb)];
double colWidth = col.Width == GridLength.Auto ? double.MaxValue : col.ActualWidth;
// adjust fontsize if text would be clipped horizontally
if (colWidth < desiredWidth)
{
double factor = (desiredWidth - widthMargins) / (col.ActualWidth - widthMargins);
fontSize = Math.Min(fontSize, MaxFontSize / factor);
}
}
}
// apply fontsize (always equal fontsizes)
foreach (var tb in tbs)
{
tb.FontSize = fontSize;
}
}