I have a custom Panel for laying out text. There is a DependancyProperty called “Text” and when that value changes, this piece of code runs:
if( !string.IsNullOrEmpty(Text))
{
Children.Clear();
foreach (char ch in Text)
{
TextBlock textBlock = new TextBlock();
textBlock.Text = ch.ToString();
textBlcok.Foreground = Foreground;
//The rest of these are DPs in the panel
textBlock.FontFamily = FontFamily;
textBlock.FontStyle = FontStyle;
textBlock.FontWeight = FontWeight;
textBlock.FontStretch = FontStretch;
textBlock.FontSize = FontSize;
Children.Add(textBlock);
}
}
}
Now, with font size of 15 and font Arial, these should be giving me a desired size of around 8 width and 10 height. However, when I do a Measure() and check the desired size, I get 40,18 every time!
So in trying to figure out what could’ve possibly changed the size, I put this code before and after the Children.Add in the code above:
textBlock.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
Console.WriteLine(ch.ToString() + ": " + textBlock.DesiredSize);
Children.Add(textBlock);
textBlock.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
Console.WriteLine(ch.ToString() + ": " + textBlock.DesiredSize);
What this gave me, was the proper desired size before it’s added to the children collection, and a size of 40,18 (regardless of letter) after it’s added to the collection.
What is causing this to happen?
Edit: You can find the full source for the control here:
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using IQ.Touch.Resources.Classes.Helpers;
/* TextOnAPath.cs
*
* A slightly modified version of the control found at
* http://www.codeproject.com/KB/WPF/TextOnAPath.aspx
*/
namespace IQ.Touch.Resources.Controls
{
public class TextOnAPath : Panel
{
// Fields
PathFigureHelper pathFigureHelper = new PathFigureHelper();
Size totalSize;
// Dependency properties
public static readonly DependencyProperty TextProperty =
DependencyProperty.Register("Text",
typeof(string),
typeof(TextOnAPath),
new PropertyMetadata(OnFontPropertyChanged));
public static readonly DependencyProperty FontFamilyProperty =
DependencyProperty.Register("FontFamily",
typeof(FontFamily),
typeof(TextOnAPath),
new PropertyMetadata(new FontFamily("Portable User Interface"), OnFontPropertyChanged));
public static readonly DependencyProperty FontStyleProperty =
DependencyProperty.Register("FontStyle",
typeof(FontStyle),
typeof(TextOnAPath),
new PropertyMetadata(FontStyles.Normal, OnFontPropertyChanged));
public static readonly DependencyProperty FontSizeProperty =
DependencyProperty.Register("FontSize",
typeof(double),
typeof(TextOnAPath),
new PropertyMetadata(12.0, OnFontPropertyChanged));
public static readonly DependencyProperty FontWeightProperty =
DependencyProperty.Register("FontWeight",
typeof(FontWeight),
typeof(TextOnAPath),
new PropertyMetadata(FontWeights.Normal, OnFontPropertyChanged));
public static readonly DependencyProperty FontStretchProperty =
DependencyProperty.Register("FontStretch",
typeof(FontStretch),
typeof(TextOnAPath),
new PropertyMetadata(FontStretches.Normal, OnFontPropertyChanged));
public static readonly DependencyProperty ForegroundProperty =
DependencyProperty.Register("Foreground",
typeof(Brush),
typeof(TextOnAPath),
new PropertyMetadata(new SolidColorBrush(Colors.Black), OnFontPropertyChanged));
public static readonly DependencyProperty PathFigureProperty =
DependencyProperty.Register("PathFigure",
typeof(PathFigure),
typeof(TextOnAPath),
new PropertyMetadata(OnPathFigureChanged));
// Properties
public string Text
{
set { SetValue(TextProperty, value); }
get { return (string)GetValue(TextProperty); }
}
public FontFamily FontFamily
{
set { SetValue(FontFamilyProperty, value); }
get { return (FontFamily)GetValue(FontFamilyProperty); }
}
public FontStyle FontStyle
{
set { SetValue(FontStyleProperty, value); }
get { return (FontStyle)GetValue(FontStyleProperty); }
}
public double FontSize
{
set { SetValue(FontSizeProperty, value); }
get { return (double)GetValue(FontSizeProperty); }
}
public FontWeight FontWeight
{
set { SetValue(FontWeightProperty, value); }
get { return (FontWeight)GetValue(FontWeightProperty); }
}
public FontStretch FontStretch
{
set { SetValue(FontStretchProperty, value); }
get { return (FontStretch)GetValue(FontStretchProperty); }
}
public Brush Foreground
{
set { SetValue(ForegroundProperty, value); }
get { return (Brush)GetValue(ForegroundProperty); }
}
public PathFigure PathFigure
{
set { SetValue(PathFigureProperty, value); }
get { return (PathFigure)GetValue(PathFigureProperty); }
}
// Property-changed handlers
static void OnFontPropertyChanged(DependencyObject obj,
DependencyPropertyChangedEventArgs args)
{
(obj as TextOnAPath).OnFontPropertyChanged(args);
}
void OnFontPropertyChanged(DependencyPropertyChangedEventArgs args)
{
Children.Clear();
if (String.IsNullOrEmpty(Text))
return;
foreach (char ch in Text)
{
TextBlock textBlock = new TextBlock();
textBlock.Text = ch.ToString();
textBlock.FontFamily = FontFamily;
textBlock.FontStyle = FontStyle;
textBlock.FontWeight = FontWeight;
textBlock.FontStretch = FontStretch;
textBlock.FontSize = FontSize;
textBlock.Foreground = Foreground;
textBlock.HorizontalAlignment = HorizontalAlignment.Center;
textBlock.VerticalAlignment = VerticalAlignment.Bottom;
textBlock.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
Console.WriteLine(ch.ToString() + ": " + textBlock.DesiredSize);
Children.Add(textBlock);
textBlock.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
Console.WriteLine(ch.ToString() + ": " + textBlock.DesiredSize);
}
CalculateTransforms();
InvalidateMeasure();
}
static void OnPathFigureChanged(DependencyObject obj,
DependencyPropertyChangedEventArgs args)
{
(obj as TextOnAPath).OnPathFigureChanged(args);
}
void OnPathFigureChanged(DependencyPropertyChangedEventArgs args)
{
pathFigureHelper.SetPathFigure(args.NewValue as PathFigure);
CalculateTransforms();
InvalidateMeasure();
}
void CalculateTransforms()
{
double pathLength = pathFigureHelper.Length;
double textLength = 0;
double textDesiredWidth = 9;
totalSize = new Size();
foreach (UIElement child in Children)
{
child.Measure(new Size(Double.PositiveInfinity,
Double.PositiveInfinity));
textLength += child.DesiredSize.Width;
}
//textLength = Children.Count * textDesiredWidth;
if (pathLength == 0 || textLength == 0)
return;
//double scalingFactor = pathLength / textLength;
double baseline = FontSize; // * FontFamily.Baseline;
double progress = 0;
if (textLength <= pathLength)
{
progress = ((pathLength - textLength) / 2) / pathLength;
}
foreach (UIElement child in Children)
{
double width = child.DesiredSize.Width;
//double width = textDesiredWidth;
progress += width / 2 / pathLength;
Point point, tangent;
pathFigureHelper.GetPointAtFractionLength(progress,
out point, out tangent);
TransformGroup transformGroup = new TransformGroup();
//ScaleTransform scaleTransform = new ScaleTransform();
//scaleTransform.ScaleX = scalingFactor;
//scaleTransform.ScaleY = scalingFactor;
//transformGroup.Children.Add(scaleTransform);
RotateTransform rotateTransform = new RotateTransform();
rotateTransform.Angle = Math.Atan2(tangent.Y, tangent.X) * 180 / Math.PI;
rotateTransform.CenterX = width / 2;
rotateTransform.CenterY = baseline;
transformGroup.Children.Add(rotateTransform);
TranslateTransform translateTransform = new TranslateTransform();
translateTransform.X = point.X - width / 2;
translateTransform.Y = point.Y - baseline;
transformGroup.Children.Add(translateTransform);
child.RenderTransform = transformGroup;
BumpUpTotalSize(transformGroup.Value, new Point(0, 0));
BumpUpTotalSize(transformGroup.Value, new Point(0, child.DesiredSize.Height));
BumpUpTotalSize(transformGroup.Value, new Point(child.DesiredSize.Width, 0));
BumpUpTotalSize(transformGroup.Value, new Point(child.DesiredSize.Width, child.DesiredSize.Height));
progress += width / 2 / pathLength;
}
Point endPoint, endTangent;
pathFigureHelper.GetPointAtFractionLength(1, out endPoint, out endTangent);
totalSize.Width = Math.Max(totalSize.Width, endPoint.X);
}
void BumpUpTotalSize(Matrix matrix, Point point)
{
point = matrix.Transform(point);
totalSize.Width = Math.Max(totalSize.Width, point.X);
totalSize.Height = Math.Max(totalSize.Height, point.Y);
}
protected override Size MeasureOverride(Size availableSize)
{
foreach (UIElement child in Children)
child.Measure(new Size(Double.PositiveInfinity, Double.PositiveInfinity));
// return the size calculated during CalculateTransforms
return totalSize;
}
protected override Size ArrangeOverride(Size finalSize)
{
foreach (UIElement child in Children)
child.Arrange(new Rect(new Point(0, 0), child.DesiredSize));
return finalSize;
}
}
}
I figured out the problem, it turns out that the problem was not related to the control at all, but somewhere in the code the default template for a textblock got changed, and MinWidth and MinHeight got set to 40,18 for some reason… Now to find the suspect and to yell at them.
Thanks guys