何时建立伊斯兰大教堂UWP

Question

我必须设置IsLArgeArc，但我不能准确地做到这一点。

UserControl.xaml:

<UserControl
x:Class="Pointer_Answer_UWP.RadialSlider"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:Pointer_Answer_UWP"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="207"
d:DesignWidth="207">
<Grid>
<Grid x:Name="GridBase" Width="207" Height="207" Background="#FFD7B6B6">
<Ellipse Fill="#FFC7C7C7"/>
<Grid Height="207" Width="207" HorizontalAlignment="Center" VerticalAlignment="Center">
<Path Stroke="#FF34A1ED" StrokeThickness="7" x:Name="arcPath" StrokeEndLineCap="Round" StrokeStartLineCap="Round" RenderTransformOrigin="0.5,0.5">
<Path.RenderTransform>
<CompositeTransform TranslateX="3.5" TranslateY="3.5"/>
</Path.RenderTransform>
<Path.Data>
<PathGeometry>
<PathFigure x:Name="myArcStart" StartPoint="7.612,61.6317">
<ArcSegment x:Name="myArc" IsLargeArc="False" Point="78.3221,197.6221" Size="100,100"/>
</PathFigure>
</PathGeometry>
</Path.Data>
</Path>
</Grid>
<Canvas x:Name="CanvasVolume" Width="207" Height="207" RenderTransformOrigin="0.5,0.5">
<Canvas.RenderTransform>
<CompositeTransform x:Name="CompositePoint" Rotation="0"/>
</Canvas.RenderTransform>
<Ellipse x:Name="VolumePoint" Width="20" Height="20" Fill="#9923678A" PointerPressed="VolumePoint_PointerPressed" Canvas.Top="{x:Bind TopPosition, Mode=OneWay}" Canvas.Left="{x:Bind LeftPosition, Mode=OneWay}"/>
</Canvas>
</Grid>
</Grid>

UserControl.xaml.cs:

public sealed partial class RadialSlider : UserControl, INotifyPropertyChanged
{
private double topPosition = 55.2317;
public double TopPosition
{
get => topPosition;
set
{
topPosition = value;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(TopPosition)));
}
}
private double leftPosition = 1.112;
public double LeftPosition
{
get => leftPosition;
set
{
leftPosition = value;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(LeftPosition)));
}
}
public event PropertyChangedEventHandler PropertyChanged;
public RadialSlider()
{
this.InitializeComponent();
}

private void VolumePoint_PointerPressed(object sender, PointerRoutedEventArgs e)
{
RadialSlider radialSlider = this as RadialSlider;
Point puntopressd = e.GetCurrentPoint(CanvasVolume).Position;
PointerEventHandler moved = null;
moved = (s, args) =>
{
CanvasVolume.CapturePointer(e.Pointer);
Point puntomoved = e.GetCurrentPoint(CanvasVolume).Position;
double puntoX = puntomoved.X;
double puntoY = puntomoved.Y;
double raggio = 100;
double halfWidth = CanvasVolume.ActualHeight / 2;
double slashLength = Math.Sqrt((Math.Abs(puntoY - halfWidth) * Math.Abs(puntoY - halfWidth) + (Math.Abs(halfWidth - puntoX) * Math.Abs(halfWidth - puntoX))));
double coordinataX = CanvasVolume.ActualHeight / 2 + ((puntoX - halfWidth) * raggio / slashLength) - VolumePoint.Width / 2;
double coordinataY = puntoY - ((puntoY - halfWidth) * (slashLength - raggio) / slashLength) - VolumePoint.Width / 2;
double angolo = GetAngle(new Point((CanvasVolume.ActualHeight / 2 + ((puntoX - halfWidth) * raggio / slashLength)) - 3.5, (puntoY - ((puntoY - halfWidth) * (slashLength - raggio) / slashLength)) - 3.5), new Size(CanvasVolume.Width, CanvasVolume.Width));
LeftPosition = coordinataX;
TopPosition = coordinataY;
//myArc.IsLargeArc = angolo < 113 ? true : false;
myArc.Point = new Point((CanvasVolume.ActualHeight / 2 + ((puntoX - halfWidth) * raggio / slashLength)) -3.5, (puntoY - ((puntoY - halfWidth) * (slashLength - raggio) / slashLength)) - 3.5);
};
PointerEventHandler released = null;
released = (s, args) =>
{
Point puntoreleas = e.GetCurrentPoint(CanvasVolume).Position;
CanvasVolume.PointerMoved -= moved;
CanvasVolume.PointerReleased -= released;
};
CanvasVolume.PointerMoved += moved;
CanvasVolume.PointerReleased += released;
}
public enum Quadrants : int { nw = 2, ne = 1, sw = 4, se = 3 }
private double GetAngle(Point point, Size size)
{
var X = point.X - (size.Width / 2d);
var Y = size.Height - point.Y - (size.Height / 2d);
var Hypot = Math.Sqrt(X * X + Y * Y);
var Value = Math.Asin(Y / Hypot) * 180 / Math.PI;
var Quadrant = (X >= 0) ? (Y >= 0) ? Quadrants.ne : Quadrants.se : (Y >= 0) ? Quadrants.nw : Quadrants.sw;
switch (Quadrant)
{
case Quadrants.ne: Value = 090 - Value; break;
case Quadrants.nw: Value = 270 + Value; break;
case Quadrants.se: Value = 090 - Value; break;
case Quadrants.sw: Value = 270 + Value; break;
}
return Value;
}
}

如何准确计算何时设置IsLargeArc以获得正确的结果？当ArcSegment达到180°时，我尝试计算它的角度，但我无法得到正确的结果。

使用GetAngle，我可以获得角度，但无法正确使用数据。我该如何继续？

谢谢你的帮助。

Answer 1

考虑到360度的角度包裹，请尝试使用数学。Sin函数如下。顺便说一句，在这种情况下，要交给GetAngle的大小应该是size(raggio*2，raggio+2(。

double angolo = GetAngle(new Point(
(CanvasVolume.ActualHeight / 2 + ((puntoX - halfWidth) * raggio / slashLength)) - 3.5,
(puntoY - ((puntoY - halfWidth) * (slashLength - raggio) / slashLength)) - 3.5 
), new Size(raggio * 2, raggio * 2)
);
// BTW, it's also possible to calculate the angle at once with the handy Math.Atan2.
// double angolo = 180.0 - Math.Atan2(puntoX - halfWidth, puntoY - halfWidth) * 180.0 / Math.PI;
myArc.IsLargeArc = Math.Sin((angolo - 113) * Math.PI / 180.0) < 0.0;// ? true : false;