Ink.NearestPoint 方法 (Point, Single%, Single%)

项目
10/28/2008

返回离指定点最近的 Stroke 对象，返回 Stroke 对象上离指定点最近的点，并返回指定点与 Ink 对象中 Stroke 对象上的最近点之间的距离。

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

语法

声明
Public Function NearestPoint ( _
    point As Point, _
    <OutAttribute> ByRef pointOnStroke As Single, _
    <OutAttribute> ByRef distanceFromPacket As Single _
) As Stroke
用法
Dim instance As Ink
Dim point As Point
Dim pointOnStroke As Single
Dim distanceFromPacket As Single
Dim returnValue As Stroke

returnValue = instance.NearestPoint(point, _
    pointOnStroke, distanceFromPacket)

public Stroke NearestPoint(
    Point point,
    out float pointOnStroke,
    out float distanceFromPacket
)

public:
Stroke^ NearestPoint(
    Point point, 
    [OutAttribute] float% pointOnStroke, 
    [OutAttribute] float% distanceFromPacket
)

public Stroke NearestPoint(
    Point point,
    /** @attribute OutAttribute */ /** @ref */float pointOnStroke,
    /** @attribute OutAttribute */ /** @ref */float distanceFromPacket
)

public function NearestPoint(
    point : Point, 
    pointOnStroke : float, 
    distanceFromPacket : float
) : Stroke

参数

point
类型：System.Drawing.Point
Ink 对象中的指定点，以墨迹空间坐标表示。

pointOnStroke
类型：System.Single%
Stroke 对象上离 Ink 对象中的指定点最近的点。

distanceFromPacket
类型：System.Single%
指定点与 Ink 对象中最近的 Stroke 对象之间的距离。

返回值

类型：Microsoft.Ink.Stroke
Stroke ，它包含离 Ink 对象中的指定点最近的 Point。如果多个笔画包含与已知 Point 距离相同的 Point，则此结果的值可以是任意的。

备注

distanceFromPacket 参数描述指定点与 Stroke 对象的包络之间的距离。这是两点之间距离减去 Stroke 对象的 DrawingAttributes 的 Width 属性的一半得出的值。

示例

在此示例中，如果 Stroke 对象包含与墨迹控件中心的距离在 500 HIMETRIC 单位以内的点，则 Stroke 对象的颜色将更改为红色。此外，将创建一个新的 Stroke 对象，该对象从发现的离墨迹控件中心最近的 Stroke 对象直到墨迹控件的中心。

Dim inkControl As Control = mInkOverlay.AttachedControl
' get the center of the ink control
Dim centerPt As Point = New Point(inkControl.Width / 2, inkControl.Height / 2)
Using g As Graphics = inkControl.CreateGraphics()
    ' convert center point to ink space coordinates
    mInkOverlay.Renderer.PixelToInkSpace(g, centerPt)
End Using
' get the nearest stroke
Dim pointOnStroke As Single
Dim distanceFromPacket As Single
Dim nStroke As Stroke = mInkOverlay.Ink.NearestPoint(centerPt, pointOnStroke, distanceFromPacket)
' nStroke will be null if there aren't any strokes
If Not IsNothing(nStroke) And distanceFromPacket <= 500.0 Then
    ' change the color of the nearest stroke to red
    nStroke.DrawingAttributes.Color = Color.Red
    'Dim ptIdx As Integer = DirectCast(Math.Round(pointOnStroke, MidpointRounding.ToEven), Integer)

    Dim ptIdx As Integer = CType(Math.Round(pointOnStroke, MidpointRounding.ToEven), Integer)

    ' create points from the center to the nearest point on the stroke
    Dim connectPts() As Point = _
            { _
                centerPt, _
                nStroke.GetPoint(ptIdx) _
            }
    ' create the stroke
    mInkOverlay.Ink.CreateStroke(connectPts)
    inkControl.Invalidate()
End If

Control inkControl = mInkOverlay.AttachedControl;
// get the center of the ink control
Point centerPt = new Point(inkControl.Width / 2, inkControl.Height / 2);
using (Graphics g = inkControl.CreateGraphics())
{
    // convert center point to ink space coordinates
    mInkOverlay.Renderer.PixelToInkSpace(g, ref centerPt);
}
// get the nearest stroke
float pointOnStroke;
float distanceFromPacket;
Stroke nStroke = mInkOverlay.Ink.NearestPoint(centerPt, out pointOnStroke, out distanceFromPacket);

// nStroke will be null if there aren't any strokes
if (nStroke != null && distanceFromPacket <= 500.0)
{
    // change the color of the nearest stroke to red
    nStroke.DrawingAttributes.Color = Color.Red;
    int ptIdx = (int)Math.Round(pointOnStroke, MidpointRounding.ToEven);
    // create points from the center to the nearest point on the stroke
    Point[] connectPts = new Point[2] 
    {
        centerPt, 
        nStroke.GetPoint(ptIdx)
    };
    // create the stroke
    mInkOverlay.Ink.CreateStroke(connectPts);
    inkControl.Invalidate();
}