Stroke.BezierCusps 属性

项目
11/04/2008

获取一个数组，该数组包含 Stroke 对象的贝塞尔曲线逼近的尖点的索引。

命名空间： Microsoft.Ink
程序集： Microsoft.Ink（在 Microsoft.Ink.dll 中）

语法

声明
Public ReadOnly Property BezierCusps As Integer()
用法
Dim instance As Stroke
Dim value As Integer()

value = instance.BezierCusps

public int[] BezierCusps { get; }

public:
property array<int>^ BezierCusps {
    array<int>^ get ();
}

/** @property */
public int[] get_BezierCusps()

public function get BezierCusps () : int[]

属性值

类型：array<System.Int32[]
点索引的 Array，这些点是 Stroke 对象的贝塞尔曲线逼近的尖点。

备注

BezierCusps 属性所返回的数组是 BezierPoints 属性所返回的数组的子集。BezierCusps 属性中的每个索引都对应于 BezierPoints 属性所返回的数组中的一个点，这些点是笔画的贝塞尔曲线控制点的尖点。

尖点是笔画的书写方向发生不连续更改的点。例如，如果笔画表示大写字母“L”，则此属性会返回三个尖点：其中两个尖点对应于笔画的第一个和最后一个控制点，第三个尖点表示“L”的拐点。

通过将贝塞尔曲线尖点用作 BezierPoints 属性所返回的数组的索引，可以确定该尖点的位置。

示例

此 C# 示例演示为每个 Stroke 对象记录的几种信息。调用程序使用菜单项切换每个笔画的点、折线尖点、贝塞尔曲线点、贝塞尔曲线尖点和自交点的显示。使用 Renderer 对象的 InkSpaceToPixel 方法转换要显示的点。使用 LocatePoint 方法内插自交点的位置。

Microsoft.Ink.InkCollector theInkCollector;

// Event handler for the form's load event.
private void Form1_Load(object sender, System.EventArgs e)
{
    // Create the InkCollector.
    theInkCollector = new InkCollector(this.Handle);

    // Attach an event handler for the Stroke event.
    theInkCollector.Stroke += new InkCollectorStrokeEventHandler(theInkCollector_Stroke);

    // Enable the InkCollector.
    theInkCollector.Enabled = true;
}

// Event handler for the InkCollector's Stroke event.
private void theInkCollector_Stroke(object sender, InkCollectorStrokeEventArgs e)
{
    // Force the form to repaint.
    Refresh();
}

// Event handler for the Clear menu's Click event.
private void menuClear_Click(object sender, System.EventArgs e)
{
    // Delete the strokes in the InkCollector.
    theInkCollector.Ink.DeleteStrokes();

    // Force the form to repaint.
    Refresh();
}

private void menuExit_Click(object sender, System.EventArgs e)
{
    this.Close();
}

// Event handler for the Click event for subitems of the Display menu.
private void menuDisplayItem_Click(object sender, System.EventArgs e)
{
    // Check each subitem to see if it was clicked.
    foreach (System.Windows.Forms.MenuItem menu in menuDisplay.MenuItems)
    {
        if (sender == menu)
        {
            // Toggle the menu item's checked property.
            menu.Checked = !menu.Checked;
        }
    }

    // Force the form to repaint.
    this.Refresh();
}

// Event handler for the form's Paint event.
private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{
    Graphics g = e.Graphics;

    // Highlight specific points or cusps of each stroke.
    Strokes theStrokes = theInkCollector.Ink.Strokes;
    foreach (Stroke theStroke in theStrokes)
    {
        // Convert the stroke's points and Bezier points from ink space to pixel coordinates.
        Point [] ptBezierPoints = theStroke.BezierPoints;
        Point [] ptStrokePoints = theStroke.GetPoints();
        theInkCollector.Renderer.InkSpaceToPixel(g, ref ptBezierPoints);
        theInkCollector.Renderer.InkSpaceToPixel(g, ref ptStrokePoints);

        // If all points is checked, highlight the points of the stroke.
        if (menuAllPoints.Checked)
        {
            foreach (Point pt in ptStrokePoints)
            {
                // draw a little diagonal line from each point
                g.DrawEllipse(Pens.Magenta, pt.X-2, pt.Y-2, 4, 4);
            }
        }

        // If polyline cusps is checked, highlight the cusps of the stroke.
        if (menuPolylineCusps.Checked)
        {
            int[] theCusps = theStroke.PolylineCusps;
            foreach (int i in theCusps)
            {
                // Draw a little rectangle around each polyline cusp.
                g.DrawEllipse(Pens.BlueViolet, ptStrokePoints[i].X - 3, ptStrokePoints[i].Y - 3, 6, 6);
            }
        }

        // If Bezier points is checked, highlight the Bezier points of the stroke.
        if (menuBezierPoints.Checked)
        {
            foreach (Point pt in ptBezierPoints)
            {
                // Draw a little diagonal line from each Bezier point.
                g.DrawEllipse(Pens.Goldenrod, pt.X-4, pt.Y-4, 8, 8);
            }
        }

        // If Bezier cusps is checked, highlight the Bezier cusps of the stroke.
        if (menuBezierCusps.Checked)
        {
            int [] theCusps = theStroke.BezierCusps;
            foreach (int i in theCusps)
            {
                // Draw a little rectangle around each Bezier cusp.
                g.DrawEllipse(Pens.Blue,
                    ptBezierPoints[i].X-5, ptBezierPoints[i].Y-5, 10, 10);
            }
        }

        // If self intersections is checked, highlight the self intersections of the stroke.
        if (menuSelfIntersections.Checked)
        {
            float [] theSelfIntersectionLocationsArray = theStroke.SelfIntersections;
            foreach (float f in theSelfIntersectionLocationsArray)
            {
                Point pt = LocatePoint(theStroke, f);
                theInkCollector.Renderer.InkSpaceToPixel(g, ref pt);
                // Draw a little circle around each intersection.
                g.DrawEllipse(Pens.Red, pt.X-7, pt.Y-7, 14, 14);
            }
        }
    }
}

// This function returns the approximate point along
// a stroke represented by a float, as a Point.
private Point LocatePoint(Stroke theStroke, float theFIndex)
{
    // Get the two nearest points to the point of interest.
    Point [] ptStrokePoints = theStroke.GetPoints((int)Math.Floor(theFIndex), 2);

    // Get fractional part to interpolate the distance between the points.
    float theFraction = theFIndex - (float)Math.Floor(theFIndex);
    int deltaX = (int)((ptStrokePoints[1].X - ptStrokePoints[0].X) * theFraction);
    int deltaY = (int)((ptStrokePoints[1].Y - ptStrokePoints[0].Y) * theFraction);

    // Return the interpolated point.
    return new Point(ptStrokePoints[0].X + deltaX, ptStrokePoints[0].Y + deltaY);
}

此 Microsoft Visual Basic .NET 示例演示为每个 Stroke 对象记录的几种信息。调用程序使用菜单项切换每个笔画的点、折线尖点、贝塞尔曲线点、贝塞尔曲线尖点和自交点的显示。使用 Renderer 对象的 InkSpaceToPixel 方法转换要显示的点。使用 LocatePoint 方法内插自交点的位置。

Dim WithEvents theInkCollector As Microsoft.Ink.InkCollector

' Event handler for the form's Load event.
Private Sub Form1_Load(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles MyBase.Load

    ' Create and enable the InkCollector
    theInkCollector = New Microsoft.Ink.InkCollector(Me.Handle)
    theInkCollector.Enabled = True

    ' Associate the Click event handler with subitems of the Display menu.
    AddHandler menuAllPoints.Click, AddressOf menuDisplayItem_Click
    AddHandler menuPolylineCusps.Click, AddressOf menuDisplayItem_Click
    AddHandler menuBezierPoints.Click, AddressOf menuDisplayItem_Click
    AddHandler menuBezierCusps.Click, AddressOf menuDisplayItem_Click
    AddHandler menuSelfIntersections.Click, AddressOf menuDisplayItem_Click
End Sub

' Event handler for the InkCollector's Stroke event.
Private Sub theInkCollector_Stroke(ByVal sender As Object, _
    ByVal e As Microsoft.Ink.InkCollectorStrokeEventArgs) Handles theInkCollector.Stroke

    ' Force the form to repaint.
    Me.Refresh()
End Sub

' Event handler for the Clear menu's Click event.
Private Sub menuClear_Click(ByVal sender As Object, _
    ByVal e As System.EventArgs) Handles menuClear.Click

    ' Delete the strokes in the InkCollector.
    theInkCollector.Ink.DeleteStrokes()

    ' Force the form to repaint.
    Me.Refresh()
End Sub

' Event handler for the Click event for subitems of the Display menu.
Private Sub menuDisplayItem_Click(ByVal sender As Object, _
    ByVal e As System.EventArgs)

    ' Check each subitem to see if it was clicked.
    For Each menu As System.Windows.Forms.MenuItem In menuDisplay.MenuItems
        If (sender Is menu) Then
            ' Toggle the menu item's checked property.
            menu.Checked = Not menu.Checked
        End If
    Next

    ' Force the form to repaint.
    Me.Refresh()
End Sub

' Event handler for the form's Paint event.
Private Sub Form1_Paint(ByVal sender As Object, _
    ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint

    Dim g As Graphics = e.Graphics

    ' Highlight specific points or cusps of each stroke.
    Dim theStrokes As Microsoft.Ink.Strokes = theInkCollector.Ink.Strokes
    For Each theStroke As Microsoft.Ink.Stroke In theStrokes

        ' Convert the stroke's points and Bezier points from ink space to pixel coordinates.
        Dim ptBezierPoints() As Point = theStroke.BezierPoints
        Dim ptStrokePoints() As Point = theStroke.GetPoints()
        theInkCollector.Renderer.InkSpaceToPixel(g, ptBezierPoints)
        theInkCollector.Renderer.InkSpaceToPixel(g, ptStrokePoints)

        ' If all points is checked, highlight the points of the stroke.
        If (menuAllPoints.Checked) Then
            For Each pt As Point In ptStrokePoints
                ' draw a little diagonal line from each point
                g.DrawEllipse(Pens.Magenta, pt.X - 2, pt.Y - 2, 4, 4)
            Next
        End If

        ' If polyline cusps is checked, highlight the cusps of the stroke.
        If (menuPolylineCusps.Checked) Then
            Dim theCusps() As Integer = theStroke.PolylineCusps
            For Each i As Integer In theCusps
                ' Draw a little rectangle around each polyline cusp.
                g.DrawEllipse(Pens.BlueViolet, ptStrokePoints(i).X - 3, ptStrokePoints(i).Y - 3, 6, 6)
            Next
        End If

        ' If Bezier points is checked, highlight the Bezier points of the stroke.
        If (menuBezierPoints.Checked) Then
            For Each pt As Point In ptBezierPoints
                ' Draw a little diagonal line from each Bezier point.
                g.DrawEllipse(Pens.Goldenrod, pt.X - 4, pt.Y - 4, 8, 8)
            Next
        End If

        ' If Bezier cusps is checked, highlight the Bezier cusps of the stroke.
        If (menuBezierCusps.Checked) Then
            Dim theCusps() As Integer = theStroke.BezierCusps
            For Each i As Integer In theCusps
                ' Draw a little rectangle around each Bezier cusp.
                g.DrawEllipse(Pens.Blue, ptBezierPoints(i).X - 5, ptBezierPoints(i).Y - 5, 10, 10)
            Next
        End If

        ' If self intersections is checked, highlight the self intersections of the stroke.
        If (menuSelfIntersections.Checked) Then
            Dim theSelfIntersectionLocationsArray() As Single = theStroke.SelfIntersections
            For Each f As Single In theSelfIntersectionLocationsArray
                Dim pt As Point = LocatePoint(theStroke, f)
                theInkCollector.Renderer.InkSpaceToPixel(g, pt)
                ' Draw a little circle around each intersection.
                g.DrawEllipse(Pens.Red, pt.X - 7, pt.Y - 7, 14, 14)
            Next
        End If
    Next
End Sub

' This function returns the approximate point along
' a stroke represented by a float, as a Point.
Private Function LocatePoint(ByVal theStroke As Microsoft.Ink.Stroke, _
    ByVal theFIndex As Single) As Point

    ' Get the two nearest points to the point of interest.
    Dim ptStrokePoints() As Point = theStroke.GetPoints(Math.Floor(theFIndex), 2)

    ' Get fractional part to interpolate the distance between the points.
    Dim theFraction As Single = theFIndex - Math.Floor(theFIndex)
    Dim deltaX As Integer = (ptStrokePoints(1).X - ptStrokePoints(0).X) * theFraction
    Dim deltaY As Integer = (ptStrokePoints(1).Y - ptStrokePoints(0).Y) * theFraction

    ' Return the interpolated point.
    LocatePoint = New Point(ptStrokePoints(0).X + deltaX, ptStrokePoints(0).Y + deltaY)
End Function