使用线条填充绘制的三角形

Question

我需要生成一个新方法来填充下面代码中的三角形并单独调用它有什么建议吗？

public void draw(Graphics g, Pen blackPen)
    {
        double xDiff, yDiff, xMid, yMid;

        xDiff = oppPt.X - keyPt.X;
        yDiff = oppPt.Y - keyPt.Y;
        xMid = (oppPt.X + keyPt.X) / 2;
        yMid = (oppPt.Y + keyPt.Y) / 2;

        // draw triangle
        g.DrawLine(blackPen, (int)keyPt.X, (int)keyPt.Y, (int)(xMid + yDiff / 2), (int)(yMid - xDiff / 2));
        g.DrawLine(blackPen, (int)(xMid + yDiff / 2), (int)(yMid - xDiff / 2), (int)oppPt.X, (int)oppPt.Y);
        g.DrawLine(blackPen, (int)keyPt.X, (int)keyPt.Y, oppPt.X, oppPt.Y);

    }

该方法应采用这两个参数

public void fillTriangle(Graphics g, Brush redBrush)
    {


    }

Answer 1

您只需要创建一个带点的数组，然后配置填充方式，然后绘制 FillPolygon 实体到 DrawPolygon 只是轮廓。

    public void draw(Pen blackPen)
    {
        Graphics draw = CreateGraphics();

        Point[] points = new Point[6];
        points[0].X = 0;
        points[0].Y = 0;
        points[1].X = 150;
        points[1].Y = 150;
        points[2].X = 0;
        points[2].Y = 150;

        using (SolidBrush fillvar = new SolidBrush(Color.FromArgb(100, Color.Yellow)))
        {
            draw.FillPolygon(fillvar, points.ToArray());
            draw.DrawPolygon(Pens.DarkBlue, points);
        }

    }

如果你想在某物内部绘制 FillPolygon，就像 PictureBox 一样，你只需将它分配给 Graphics draw。

    Graphics draw = picturebox.CreateGraphics();

以上只是其工作原理的实际说明，请查看您的代码。缺少只是实现它的 xDiff、yiff、xMid、yMid 坐标。

    public void draw(Graphics g, Pen blackPen)
    {
        double xDiff, yDiff, xMid, yMid;

        Point[] points = new Point[6];
        points[0].X = 50;
        points[0].Y = 50;
        points[1].X = 150;
        points[1].Y = 150;
        points[2].X = 0;
        points[2].Y = 150;

        SolidBrush varbrush = new SolidBrush(Color.FromArgb(100, Color.Yellow));

        fillTriangle(g, varbrush, points);
    }

您必须将点传递给 fillTriangle 并在此方法中绘制它们。

    public void fillTriangle(Graphics g, Brush varbrush, Point[] points)
    {
        g.FillPolygon(varbrush, points.ToArray());
        g.DrawPolygon(Pens.Red, points);
    }

Answer 2

为绘图使用单一函数，为了降低复杂性和一致性，使用 GraphicsPath 对象。

void DrawGraphics(Graphics g, Pen pen, Brush brush)
{
    float xDiff=oppPt.X-keyPt.X;
    float yDiff=oppPt.Y-keyPt.Y;
    float xMid=(oppPt.X+keyPt.X)/2;
    float yMid=(oppPt.Y+keyPt.Y)/2;

    // Define path with the geometry information only
    var path = new GraphicsPath();
    path.AddLines(new PointF[] {
        keyPt,
        new PointF(xMid + yDiff/2, yMid-xDiff/2),
        oppPt,
    });
    path.CloseFigure();

    // Fill Triangle
    g.FillPath(brush, path);

    // Draw Triangle
    g.DrawPath(pen, path);
}

结果如下：

使用线条填充绘制的三角形

Fill a drawn triangle using lines

c#

system.drawing

drawimage

draw