【发布时间】：2016-04-01 05:12:17
【问题描述】：
我想要一个文本框，您可以在其中从键盘输入文本，但显示为弧线。有可能吗？
【问题讨论】：
【发布时间】：2016-04-01 05:12:17
【问题描述】：
我在 codeproject 中找到了this solution。作者创建了可以显示弯曲文本的TextOnAPath控件。
源代码：
[ContentProperty("Text")]
public class TextOnAPath : Control
{
static TextOnAPath()
{
DefaultStyleKeyProperty.OverrideMetadata(typeof(TextOnAPath), new FrameworkPropertyMetadata(typeof(TextOnAPath)));
Control.FontSizeProperty.OverrideMetadata(typeof(TextOnAPath),
new FrameworkPropertyMetadata(
new PropertyChangedCallback(OnFontPropertyChanged)));
Control.FontFamilyProperty.OverrideMetadata(typeof(TextOnAPath),
new FrameworkPropertyMetadata(
new PropertyChangedCallback(OnFontPropertyChanged)));
Control.FontStretchProperty.OverrideMetadata(typeof(TextOnAPath),
new FrameworkPropertyMetadata(
new PropertyChangedCallback(OnFontPropertyChanged)));
Control.FontStyleProperty.OverrideMetadata(typeof(TextOnAPath),
new FrameworkPropertyMetadata(
new PropertyChangedCallback(OnFontPropertyChanged)));
Control.FontWeightProperty.OverrideMetadata(typeof(TextOnAPath),
new FrameworkPropertyMetadata(
new PropertyChangedCallback(OnFontPropertyChanged)));
}
static void OnFontPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
TextOnAPath textOnAPath = d as TextOnAPath;
if (textOnAPath == null)
return;
if (e.NewValue == null || e.NewValue == e.OldValue)
return;
textOnAPath.UpdateText();
textOnAPath.Update();
}
double[] _segmentLengths;
TextBlock[] _textBlocks;
Panel _layoutPanel;
bool _layoutHasValidSize = false;
#region Text DP
public String Text
{
get { return (String)GetValue(TextProperty); }
set { SetValue(TextProperty, value); }
}
// Using a DependencyProperty as the backing store for Text. This enables animation, styling, binding, etc...
public static readonly DependencyProperty TextProperty =
DependencyProperty.Register("Text", typeof(String), typeof(TextOnAPath),
new PropertyMetadata(null, new PropertyChangedCallback(OnStringPropertyChanged),
new CoerceValueCallback(CoerceTextValue)));
static void OnStringPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
TextOnAPath textOnAPath = d as TextOnAPath;
if (textOnAPath == null)
return;
if (e.NewValue == e.OldValue || e.NewValue == null)
{
if (textOnAPath._layoutPanel != null)
textOnAPath._layoutPanel.Children.Clear();
return;
}
textOnAPath.UpdateText();
textOnAPath.Update();
}
static object CoerceTextValue(DependencyObject d, object baseValue)
{
if ((String)baseValue == "")
return null;
return baseValue;
}
#endregion
#region TextPath DP
public Geometry TextPath
{
get { return (Geometry)GetValue(TextPathProperty); }
set { SetValue(TextPathProperty, value); }
}
public static readonly DependencyProperty TextPathProperty =
DependencyProperty.Register("TextPath", typeof(Geometry), typeof(TextOnAPath),
new FrameworkPropertyMetadata(null,
new PropertyChangedCallback(OnTextPathPropertyChanged)));
static void OnTextPathPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
TextOnAPath textOnAPath = d as TextOnAPath;
if (textOnAPath == null)
return;
if (e.NewValue == e.OldValue || e.NewValue == null)
return;
textOnAPath.TextPath.Transform = null;
textOnAPath.UpdateSize();
textOnAPath.Update();
}
#endregion
#region DrawPath DP
/// <summary>
/// Set this property to True to display the TextPath geometry in the control
/// </summary>
public bool DrawPath
{
get { return (bool)GetValue(DrawPathProperty); }
set { SetValue(DrawPathProperty, value); }
}
public static readonly DependencyProperty DrawPathProperty =
DependencyProperty.Register("DrawPath", typeof(bool), typeof(TextOnAPath),
new PropertyMetadata(false, new PropertyChangedCallback(OnDrawPathPropertyChanged)));
static void OnDrawPathPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
TextOnAPath textOnAPath = d as TextOnAPath;
if (textOnAPath == null)
return;
if (e.NewValue == e.OldValue || e.NewValue == null)
return;
textOnAPath.Update();
}
#endregion
#region DrawLinePath DP
/// <summary>
/// Set this property to True to display the line segments under the text (flattened path)
/// </summary>
public bool DrawLinePath
{
get { return (bool)GetValue(DrawLinePathProperty); }
set { SetValue(DrawLinePathProperty, value); }
}
// Using a DependencyProperty as the backing store for DrawFlattendPath. This enables animation, styling, binding, etc...
public static readonly DependencyProperty DrawLinePathProperty =
DependencyProperty.Register("DrawLinePath", typeof(bool), typeof(TextOnAPath),
new PropertyMetadata(false, new PropertyChangedCallback(OnDrawLinePathPropertyChanged)));
static void OnDrawLinePathPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
TextOnAPath textOnAPath = d as TextOnAPath;
if (textOnAPath == null)
return;
if (e.NewValue == e.OldValue || e.NewValue == null)
return;
textOnAPath.Update();
}
#endregion
#region ScaleTextPath DP
/// <summary>
/// If set to True (default) then the geometry defined by TextPath automatically gets scaled to fit the width/height of the control
/// </summary>
public bool ScaleTextPath
{
get { return (bool)GetValue(ScaleTextPathProperty); }
set { SetValue(ScaleTextPathProperty, value); }
}
public static readonly DependencyProperty ScaleTextPathProperty =
DependencyProperty.Register("ScaleTextPath", typeof(bool), typeof(TextOnAPath),
new PropertyMetadata(false, new PropertyChangedCallback(OnScaleTextPathPropertyChanged)));
static void OnScaleTextPathPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
TextOnAPath textOnAPath = d as TextOnAPath;
if (textOnAPath == null)
return;
if (e.NewValue == e.OldValue)
return;
bool value = (Boolean)e.NewValue;
if (value == false && textOnAPath.TextPath != null)
textOnAPath.TextPath.Transform = null;
textOnAPath.UpdateSize();
textOnAPath.Update();
}
#endregion
void UpdateText()
{
if (Text == null || FontFamily == null || FontWeight == null || FontStyle == null)
return;
_textBlocks = new TextBlock[Text.Length];
_segmentLengths = new double[Text.Length];
for (int i = 0; i < Text.Length; i++)
{
TextBlock t = new TextBlock();
t.FontSize = this.FontSize;
t.FontFamily = this.FontFamily;
t.FontStretch = this.FontStretch;
t.FontWeight = this.FontWeight;
t.FontStyle = this.FontStyle;
t.Text = new String(Text[i], 1);
t.RenderTransformOrigin = new Point(0.0, 1.0);
t.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
_textBlocks[i] = t;
_segmentLengths[i] = t.DesiredSize.Width;
}
}
void Update()
{
if (Text == null || TextPath == null || _layoutPanel == null || !_layoutHasValidSize)
return;
List<Point> intersectionPoints;
intersectionPoints = GeometryHelper.GetIntersectionPoints(TextPath.GetFlattenedPathGeometry(), _segmentLengths);
_layoutPanel.Children.Clear();
_layoutPanel.Margin = new Thickness(FontSize);
for (int i = 0; i < intersectionPoints.Count - 1; i++)
{
double oppositeLen = Math.Sqrt(Math.Pow(intersectionPoints[i].X + _segmentLengths[i] - intersectionPoints[i + 1].X, 2.0) + Math.Pow(intersectionPoints[i].Y - intersectionPoints[i + 1].Y, 2.0)) / 2.0;
double hypLen = Math.Sqrt(Math.Pow(intersectionPoints[i].X - intersectionPoints[i + 1].X, 2.0) + Math.Pow(intersectionPoints[i].Y - intersectionPoints[i + 1].Y, 2.0));
double ratio = oppositeLen / hypLen;
if (ratio > 1.0)
ratio = 1.0;
else if (ratio < -1.0)
ratio = -1.0;
//double angle = 0.0;
double angle = 2.0 * Math.Asin(ratio) * 180.0 / Math.PI;
// adjust sign on angle
if ((intersectionPoints[i].X + _segmentLengths[i]) > intersectionPoints[i].X)
{
if (intersectionPoints[i + 1].Y < intersectionPoints[i].Y)
angle = -angle;
}
else
{
if (intersectionPoints[i + 1].Y > intersectionPoints[i].Y)
angle = -angle;
}
TextBlock currTextBlock = _textBlocks[i];
RotateTransform rotate = new RotateTransform(angle);
TranslateTransform translate = new TranslateTransform(intersectionPoints[i].X, intersectionPoints[i].Y - currTextBlock.DesiredSize.Height);
TransformGroup transformGrp = new TransformGroup();
transformGrp.Children.Add(rotate);
transformGrp.Children.Add(translate);
currTextBlock.RenderTransform = transformGrp;
_layoutPanel.Children.Add(currTextBlock);
if (DrawLinePath == true)
{
Line line = new Line();
line.X1 = intersectionPoints[i].X;
line.Y1 = intersectionPoints[i].Y;
line.X2 = intersectionPoints[i + 1].X;
line.Y2 = intersectionPoints[i + 1].Y;
line.Stroke = Brushes.Black;
_layoutPanel.Children.Add(line);
}
}
// don't draw path if already drawing line path
if (DrawPath == true && DrawLinePath == false)
{
Path path = new Path();
path.Data = TextPath;
path.Stroke = Brushes.Black;
_layoutPanel.Children.Add(path);
}
}
public TextOnAPath()
{
}
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
_layoutPanel = GetTemplateChild("LayoutPanel") as Panel;
if (_layoutPanel == null)
throw new Exception("Could not find template part: LayoutPanel");
_layoutPanel.SizeChanged += new SizeChangedEventHandler(_layoutPanel_SizeChanged);
}
Size _newSize;
void _layoutPanel_SizeChanged(object sender, SizeChangedEventArgs e)
{
_newSize = e.NewSize;
UpdateSize();
Update();
}
void UpdateSize()
{
if (_newSize == null || TextPath == null)
return;
_layoutHasValidSize = true;
double xScale = _newSize.Width / TextPath.Bounds.Width;
double yScale = _newSize.Height / TextPath.Bounds.Height;
if (TextPath.Bounds.Width <= 0)
xScale = 1.0;
if (TextPath.Bounds.Height <= 0)
xScale = 1.0;
if (xScale <= 0 || yScale <= 0)
return;
if (TextPath.Transform is TransformGroup)
{
TransformGroup grp = TextPath.Transform as TransformGroup;
if (grp.Children[0] is ScaleTransform && grp.Children[1] is TranslateTransform)
{
if (ScaleTextPath)
{
ScaleTransform scale = grp.Children[0] as ScaleTransform;
scale.ScaleX *= xScale;
scale.ScaleY *= yScale;
}
TranslateTransform translate = grp.Children[1] as TranslateTransform;
translate.X += -TextPath.Bounds.X;
translate.Y += -TextPath.Bounds.Y;
}
}
else
{
ScaleTransform scale;
TranslateTransform translate;
if (ScaleTextPath)
{
scale = new ScaleTransform(xScale, yScale);
translate = new TranslateTransform(-TextPath.Bounds.X * xScale, -TextPath.Bounds.Y * yScale);
}
else
{
scale = new ScaleTransform(1.0, 1.0);
translate = new TranslateTransform(-TextPath.Bounds.X, -TextPath.Bounds.Y );
}
TransformGroup grp = new TransformGroup();
grp.Children.Add(scale);
grp.Children.Add(translate);
TextPath.Transform = grp;
}
}
}
public static class GeometryHelper
{
public static List<Point> GetIntersectionPoints(PathGeometry FlattenedPath, double[] SegmentLengths)
{
List<Point> intersectionPoints = new List<Point>();
List<Point> pointsOnFlattenedPath = GetPointsOnFlattenedPath(FlattenedPath);
if (pointsOnFlattenedPath == null || pointsOnFlattenedPath.Count < 2)
return intersectionPoints;
Point currPoint = pointsOnFlattenedPath[0];
intersectionPoints.Add(currPoint);
// find point on flattened path that is segment length away from current point
int flattedPathIndex = 0;
int segmentIndex = 1;
while (flattedPathIndex < pointsOnFlattenedPath.Count - 1 &&
segmentIndex < SegmentLengths.Length + 1)
{
Point? intersectionPoint = GetIntersectionOfSegmentAndCircle(
pointsOnFlattenedPath[flattedPathIndex],
pointsOnFlattenedPath[flattedPathIndex + 1], currPoint, SegmentLengths[segmentIndex - 1]);
if (intersectionPoint == null)
flattedPathIndex++;
else
{
intersectionPoints.Add((Point)intersectionPoint);
currPoint = (Point)intersectionPoint;
pointsOnFlattenedPath[flattedPathIndex] = currPoint;
segmentIndex++;
}
}
return intersectionPoints;
}
static List<Point> GetPointsOnFlattenedPath(PathGeometry FlattenedPath)
{
List<Point> flattenedPathPoints = new List<Point>();
// for flattened geometry there should be just one PathFigure in the Figures
if (FlattenedPath.Figures.Count != 1)
return null;
PathFigure pathFigure = FlattenedPath.Figures[0];
flattenedPathPoints.Add(pathFigure.StartPoint);
// SegmentsCollection should contain PolyLineSegment and LineSegment
foreach (PathSegment pathSegment in pathFigure.Segments)
{
if (pathSegment is PolyLineSegment)
{
PolyLineSegment seg = pathSegment as PolyLineSegment;
foreach (Point point in seg.Points)
flattenedPathPoints.Add(point);
}
else if (pathSegment is LineSegment)
{
LineSegment seg = pathSegment as LineSegment;
flattenedPathPoints.Add(seg.Point);
}
else
throw new Exception("GetIntersectionPoint - unexpected path segment type: " + pathSegment.ToString());
}
return (flattenedPathPoints);
}
static Point? GetIntersectionOfSegmentAndCircle(Point SegmentPoint1, Point SegmentPoint2,
Point CircleCenter, double CircleRadius)
{
// linear equation for segment: y = mx + b
double slope = (SegmentPoint2.Y - SegmentPoint1.Y) / (SegmentPoint2.X - SegmentPoint1.X);
double intercept = SegmentPoint1.Y - (slope * SegmentPoint1.X);
// special case when segment is vertically oriented
if (double.IsInfinity(slope))
{
double root = Math.Pow(CircleRadius, 2.0) - Math.Pow(SegmentPoint1.X - CircleCenter.X, 2.0);
if (root < 0)
return null;
// soln 1
double SolnX1 = SegmentPoint1.X;
double SolnY1 = CircleCenter.Y - Math.Sqrt(root);
Point Soln1 = new Point(SolnX1, SolnY1);
// have valid result if point is between two segment points
if (IsBetween(SolnX1, SegmentPoint1.X, SegmentPoint2.X) &&
IsBetween(SolnY1, SegmentPoint1.Y, SegmentPoint2.Y))
//if (ValidSoln(Soln1, SegmentPoint1, SegmentPoint2, CircleCenter))
{
// found solution
return (Soln1);
}
// soln 2
double SolnX2 = SegmentPoint1.X;
double SolnY2 = CircleCenter.Y + Math.Sqrt(root);
Point Soln2 = new Point(SolnX2, SolnY2);
// have valid result if point is between two segment points
if (IsBetween(SolnX2, SegmentPoint1.X, SegmentPoint2.X) &&
IsBetween(SolnY2, SegmentPoint1.Y, SegmentPoint2.Y))
//if (ValidSoln(Soln2, SegmentPoint1, SegmentPoint2, CircleCenter))
{
// found solution
return (Soln2);
}
}
else
{
// use soln to quadradratic equation to solve intersection of segment and circle:
// x = (-b +/ sqrt(b^2-4ac))/(2a)
double a = 1 + Math.Pow(slope, 2.0);
double b = (-2 * CircleCenter.X) + (2 * (intercept - CircleCenter.Y) * slope);
double c = Math.Pow(CircleCenter.X, 2.0) + Math.Pow(intercept - CircleCenter.Y, 2.0) - Math.Pow(CircleRadius, 2.0);
// check for no solutions, is sqrt negative?
double root = Math.Pow(b, 2.0) - (4 * a * c);
if (root < 0)
return null;
// we might have two solns...
// soln 1
double SolnX1 = (-b + Math.Sqrt(root)) / (2 * a);
double SolnY1 = slope * SolnX1 + intercept;
Point Soln1 = new Point(SolnX1, SolnY1);
// have valid result if point is between two segment points
if (IsBetween(SolnX1, SegmentPoint1.X, SegmentPoint2.X) &&
IsBetween(SolnY1, SegmentPoint1.Y, SegmentPoint2.Y))
//if (ValidSoln(Soln1, SegmentPoint1, SegmentPoint2, CircleCenter))
{
// found solution
return (Soln1);
}
// soln 2
double SolnX2 = (-b - Math.Sqrt(root)) / (2 * a);
double SolnY2 = slope * SolnX2 + intercept;
Point Soln2 = new Point(SolnX2, SolnY2);
// have valid result if point is between two segment points
if (IsBetween(SolnX2, SegmentPoint1.X, SegmentPoint2.X) &&
IsBetween(SolnY2, SegmentPoint1.Y, SegmentPoint2.Y))
//if (ValidSoln(Soln2, SegmentPoint1, SegmentPoint2, CircleCenter))
{
// found solution
return (Soln2);
}
}
// shouldn't get here...but in case
return null;
}
static bool IsBetween(double X, double X1, double X2)
{
if (X1 >= X2 && X <= X1 && X >= X2)
return true;
if (X1 <= X2 && X >= X1 && X <= X2)
return true;
return false;
}
}
用法：
<TextOnAPath:TextOnAPath FontSize="30" DrawPath="True"
Text="The quick brown fox jumped over the lazy hen.">
<TextOnAPath:TextOnAPath.TextPath>
<PathGeometry Figures="M0,0 C120,361 230.5,276.5 230.5,276.5
L308.5,237.50001 C308.5,237.50001 419.5,179.5002 367.5,265.49993
315.5,351.49966 238.50028,399.49924 238.50028,399.49924 L61.500017,
420.49911"/>
</TextOnAPath:TextOnAPath.TextPath>
</TextOnAPath:TextOnAPath>
</Grid>
【讨论】：