C# GraphicsPath的用法示例详解

graphicspath path = new graphicspath();

//添加矩形（正方形）
rectangle rect = new rectangle(50, 50, 100, 100);
path.addrectangle(rect);
//添加椭圆（圆形）
rectangle ellipserect = new rectangle(50, 50, 100, 100);
path.addellipse(ellipserect);
//添加多边形（三角形为例）
pointf[] trianglepoints = {
    new pointf(100, 50),
    new pointf(150, 150),
    new pointf(50, 150)
};
path.addpolygon(trianglepoints);
//添加线条（线段）
pointf start = new pointf(50, 50);
pointf end = new pointf(150, 150);
path.addline(start, end);
//添加闭合路径（例如箭头）
pointf[] arrowpoints = {
    new pointf(100, 50),
    new pointf(150, 100),
    new pointf(130, 100),
    new pointf(130, 150),
    new pointf(70, 150),
    new pointf(70, 100),
    new pointf(50, 100),
    new pointf(100, 50)
};
path.addpolygon(arrowpoints);
path.closefigure(); // 确保闭合

private void panel1_mousemove(object sender, mouseeventargs e)
{
    pointf mousepoint = new pointf(e.x, e.y);
    if (path.isvisible(mousepoint))
    {
        console.writeline("鼠标在图形内部");
    }
    if (path.isoutlinevisible(mousepoint, pen))
    {
        console.writeline("鼠标在图形轮廓线上");
    }
}

pen pen = new pen(color.black, 2); // 至少宽度为 2 才容易命中

protected override void onpaint(painteventargs e)
{
    base.onpaint(e);
    e.graphics.drawpath(pens.red, path); // 绘制路径轮廓
    e.graphics.fillpath(brushes.lightblue, path); // 填充路径
}

public bool ismousenearline(pointf p1, pointf p2, pointf mouse, float tolerance = 5f)
{
    float distance = distancefrompointtoline(p1, p2, mouse);
    return distance <= tolerance;
}
private float distancefrompointtoline(pointf a, pointf b, pointf p)
{
    float length = (float)math.sqrt((b.x - a.x) * (b.x - a.x) + (b.y - a.y) * (b.y - a.y));
    if (length == 0) return (float)math.sqrt((p.x - a.x) * (p.x - a.x) + (p.y - a.y) * (p.y - a.y));
    float t = ((p.x - a.x) * (b.x - a.x) + (p.y - a.y) * (b.y - a.y)) / (length * length);
    t = math.max(0, math.min(1, t));
    float projectionx = a.x + t * (b.x - a.x);
    float projectiony = a.y + t * (b.y - a.y);
    return (float)math.sqrt((p.x - projectionx) * (p.x - projectionx) + (p.y - projectiony) * (p.y - projectiony));
}

path.reset(); // 清空路径
path.dispose(); // 释放资源（记得在不再需要时调用）