Stroke.GetRectangleIntersections 方法

项目
11/04/2008

返回 StrokeIntersection 结构的数组，这些结构指示 Stroke 对象与给定 Rectangle 的相交位置。

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

语法

声明
Public Function GetRectangleIntersections ( _
    intersectRectangle As Rectangle _
) As StrokeIntersection()
用法
Dim instance As Stroke
Dim intersectRectangle As Rectangle
Dim returnValue As StrokeIntersection()

returnValue = instance.GetRectangleIntersections(intersectRectangle)

public StrokeIntersection[] GetRectangleIntersections(
    Rectangle intersectRectangle
)

public:
array<StrokeIntersection>^ GetRectangleIntersections(
    Rectangle intersectRectangle
)

public StrokeIntersection[] GetRectangleIntersections(
    Rectangle intersectRectangle
)

public function GetRectangleIntersections(
    intersectRectangle : Rectangle
) : StrokeIntersection[]

参数

intersectRectangle
类型：System.Drawing.Rectangle
Rectangle 结构采用墨迹空间 坐标，用于描述命中测试区域。

返回值

类型：array<Microsoft.Ink.StrokeIntersection[]
返回 StrokeIntersection 结构的数组，这些结构指示 Stroke 对象与 intersectRectangle 参数的相交位置。

备注

此方法返回零个或多个索引集，这些索引集表示笔画与矩形相交的线段的开头和末尾。如果笔画直接穿过矩形，从而在两个位置与边界相交，则索引集由每个交点的浮点索引值组成。如果笔画在多个位置与矩形相交，则增加的索引数与交点数相同。

如果笔画从测试矩形内部开始，则第一个 StrokeIntersection 元素的 BeginIndex 属性设置为 -1。如果笔画在测试矩形内部终止，则最后一个 StrokeIntersection 元素的 EndIndex 属性设置为 -1。如果笔画完全包含在矩形中，则返回的数组将具有单个 StrokeIntersection 结构，其 BeginIndex 属性和 EndIndex 属性均设置为 -1。如果笔画完全位于测试矩形外部，则返回一个空 StrokeIntersection 数组。

例如，如果笔画从测试矩形内部开始，离开该矩形边界，然后返回内部，最后再离开，则 GetRectangleIntersections 方法可能返回 {{-1, 1.4}, {5.5, 10.1}} 来描述落在矩形中的两个笔画线段。

此方法返回的 StrokeIntersection 结构包含指示发生相交的位置的成对浮点索引值。浮点索引是一个浮点值，表示 Stroke 对象中两点之间的某个位置。例如，如果 0.0 是笔画中的第一个点，而 1.0 是笔画中的第二个点，则 0.5 位于第一个点和第二个点的正中间。与之类似，浮点索引值 37.25 表示位于笔画点 37 和 38 之间连线的 25% 的位置。

示例

此示例将删除传入的 Stroke 对象在指定 Rectangle 结构内的所有线段。此示例通过检查 StrokeIntersection 结构来确定对传入的 Stroke 对象进行拆分的位置以及要删除的线段，从而实现此操作。

Private Sub DeleteInsideRectangle(ByVal S As Stroke, ByVal R As Rectangle)
    ' get the StrokeIntersection array
    Dim SI() As StrokeIntersection = S.GetRectangleIntersections(R)
    ' examine each StrokeIntersection
    ' must work backwards through the array so that when splitting, 
    ' the remaining intersections are still valid for S
    For k As Integer = SI.Length - 1 To 0 Step -1

        Dim enterRect As Single = SI(k).BeginIndex
        Dim exitRect As Single = SI(k).EndIndex

        ' check if the whole stroke is inside the rectangle
        ' if so, delete the stroke
        If enterRect = -1 And exitRect = -1 Then
            S.Ink.DeleteStroke(S)
            Continue For
        End If

        ' check if a segment enters and exits the rectangle
        ' if so, split and delete the segment inside the rectangle
        If enterRect > 0 And exitRect > 0 Then
            ' the stroke resulting from split() is outside, keep it
            S.Split(exitRect)
            ' the stroke from this split() is inside, delete it
            Dim temp As Stroke = S.Split(enterRect)
            temp.Ink.DeleteStroke(temp)
            Continue For
        End If

        ' check if stroke starts inside the rectangle and goes outside
        ' if so, split and delete the segment inside the rectangle
        If enterRect = -1 And exitRect > 0 Then
            ' the stroke resulting from split() is outside, keep it
            S.Split(exitRect)
            ' delete the remaining segment of the stroke
            S.Ink.DeleteStroke(S)
            Continue For
        End If

        ' check if stroke starts outside the rectangle and ends inside
        ' if so, split and delete the segment inside the rectangle
        If enterRect > 0 And exitRect = -1 Then
            Dim temp2 As Stroke = S.Split(enterRect)
            temp2.Ink.DeleteStroke(temp2)
        End If
    Next
End Sub

private void DeleteInsideRectangle(Stroke S, Rectangle R)
{
    // get the StrokeIntersection array
    StrokeIntersection[] SI = S.GetRectangleIntersections(R);

    // examine each StrokeIntersection
    // must work backwards through the array so that when splitting, 
    // the remaining intersections are still valid for S
    for (int k = SI.Length - 1; k >= 0; k--)
    {
        float enterRect = SI[k].BeginIndex;
        float exitRect = SI[k].EndIndex;

        // check if the whole stroke is inside the rectangle
        // if so, delete the stroke
        if (enterRect == -1 && exitRect == -1)
        {
            S.Ink.DeleteStroke(S);
            continue;
        }

        // check if a segment enters and exits the rectangle
        // if so, split and delete the segment inside the rectangle
        if (enterRect > 0 && exitRect > 0)
        {
            // the stroke resulting from split() is outside, keep it
            S.Split(exitRect);
            // the stroke from this split() is inside, delete it
            Stroke temp = S.Split(enterRect);
            temp.Ink.DeleteStroke(temp);
            continue;
        }

        // check if stroke starts inside the rectangle and goes outside
        // if so, split and delete the segment inside the rectangle
        if (enterRect == -1 && exitRect > 0)
        {
            // the stroke resulting from split() is outside, keep it
            S.Split(exitRect);
            // delete the remaining segment of the stroke
            S.Ink.DeleteStroke(S);
            continue;
        }

        // check if stroke starts outside the rectangle and ends inside
        // if so, split and delete the segment inside the rectangle
        if (enterRect > 0 && exitRect == -1)
        {
            Stroke temp2 = S.Split(enterRect);
            temp2.Ink.DeleteStroke(temp2);
        }
    }
}