试图绘制一个函数

Question

我试图在c＃中绘制图形，类似于

到目前为止，我已经能够使用DrawLine绘制简单的线条，但这是非常有限的，因为，不仅我被迫提供起点和终点，我也只限于直线。

正如你所看到的那样

我在表达的最后一个trech（倒置抛物线）上有一条曲线

有关如何在bmp绘图中执行此操作的任何提示？

我使用以下

绘图

   using (Graphics g = Graphics.FromImage(bmp))
           { //g.DrawLine and others
}

Answer 1

您可以使用Graphics类DrawCurve中的类似函数。它将一个点数组作为参数，然后通过它们绘制。根据您想要曲线的精确程度，您可以获得起点，终点和转折点。

https://msdn.microsoft.com/en-us/library/7ak09y3z%28v=vs.110%29.aspx?f=255&MSPPError=-2147217396

Answer 2

绘制函数的第一步是评估它并将其保存到Point数组：

        //Create a Point array to store the function's values
        Point[] functionValues = new Point[100];

        //Calculate the function for every Point in the Point array
        for (int x = 0; x < functionValues.Length; x++)
        {
            //Set the every point's X value to the current iteration of the loop. That means that we are evaluating the function in steps of 1
            functionValues[x].X = x;
            //Calculate the Y value of every point. In this exemple I am using the function x^2
            functionValues[x].Y = x * x;
        }

然后，当你绘制出函数时，像这样绘制它：

        //Iterate through every point in the array
        for (int i = 1; i < functionValues.Length; i++)
        {
            //Draw a line between every point and the one before it
            //Note that 'g' is your graphics object
            g.DrawLine(Pens.Black, functionValues[i-1], functionValues[i]);
        }

在绘图时，请在表单的Paint事件中执行此操作，并确保表单是双缓冲的：

    Point[] functionValues;

    public Form1()
    {
        InitializeComponent();
        this.DoubleBuffered = true;
        this.Paint += Form1_Paint; //Subscribe to the Paint Event

        //Create a Point array to store the function's values
        functionValues = new Point[100];

        //Calculate the function for every Point in the Point array
        for (int x = 0; x < functionValues.Length; x++)
        {
            //Set the every point's X value to the current iteration of the loop. That means that we are evaluating the function in steps of 1
            functionValues[x].X = x;
            //Calculate the Y value of every point. In this exemple I am using the function x^2
            functionValues[x].Y = x * x;
        }
    }

    void Form1_Paint(object sender, PaintEventArgs e)
    {
        Graphics g = e.Graphics;
        //Draw using 'g' or 'e.Graphics'.
        //For exemple:

        //Iterate through every point in the array
        for (int i = 1; i < functionValues.Length; i++)
        {
            //Draw a line between every point and the one before it
            g.DrawLine(Pens.Black, functionValues[i - 1], functionValues[i]);
        }

    }

并且，为了使表单更新并重新绘制自己，请调用表单的Invalidate方法：

this.Invalidate();