具有 n 个部分的 FillPie 画笔颜色问题

Question

当尝试在我的图形对象上使用 FillPie 时，如果我实际上绘制了整个饼图，它全部显示为纯色（我使用的是打印预览对象）

我试过四处移动对象来查明问题，这是我现在所拥有的：

    //Each brush is made static, mostly because I wanted to make sure I wasn't mucking them up
    internal static SolidBrush Red = new SolidBrush(Color.Red);
    internal static SolidBrush Blue = new SolidBrush(Color.Blue);
    internal static SolidBrush Green = new SolidBrush(Color.Green);
    internal static SolidBrush Yellow = new SolidBrush(Color.Yellow);
    internal static SolidBrush Purple = new SolidBrush(Color.Purple);
    internal static SolidBrush Teal = new SolidBrush(Color.Teal);
    internal static SolidBrush Gold = new SolidBrush(Color.Gold);
    internal static SolidBrush Fuchsia = new SolidBrush(Color.Fuchsia);

    //Add each brush to an array for easier access
    SolidBrush[] brushes = new SolidBrush[] {
        Red,
        Blue,
        Green,
        Yellow,
        Purple,
        Teal,
        Gold,
        Fuchsia
    };

    //The outlining pen for our pie
    Pen BlackPen = new Pen(Color.Black, 10);

    private void printDocument1_PrintPage(object sender, PrintPageEventArgs e)
    {   
        //The bounding box of our Pie
        Rectangle FirstPie = new Rectangle(100, 100, 400, 400);

        //How many slices of pie?
        float maxParts = 7;

        //Get the angle for each slice
        float partSize = 360.00F / maxParts;

        for (int i = 0; i < maxParts; i++)
        {
            //Get the angles for this slice
            float AngleStart = (float)i * partSize;
            float AngleEnd = AngleStart + partSize;

            //Check that we aren't overflowing somehow (issue persists without these lines)
            if (AngleStart < 0F) AngleStart = 0F;
            if (AngleEnd > 360F) AngleEnd = 360F;

            //Figure out which brush we are using
            int brush = (int)(i % 8);

            //Output for Debug
            Console.WriteLine(AngleStart + " " + AngleEnd + " " + brush);

            //Draw the pie and overlay
            e.Graphics.FillPie(brushes[brush], FirstPie, AngleStart, AngleEnd);
            e.Graphics.DrawPie(BlackPen, FirstPie, AngleStart, AngleEnd);
        }
    }

我得到一个纯色派，从右上角到中心有一条线运行（来自 DrawPie）：

我可以通过注释掉 FillPie 行并仅使用 DrawPie 来验证角度是否正确：

如果您查看数组并推断正在发生的事情，整个饼图是由最后使用的颜色画笔金色绘制的。我将角度和正在使用的画笔输出到控制台，它在画笔阵列中正确循环：

如果我将饼图部分的数量更改为不同的数量，最终颜色仍会使用（有 11 个部分）：

以及此处使用的角度/每个笔刷索引

我做错了什么？

Answer 1

您不断增大 AngleEnd 值的大小。不要那样做：

//float AngleEnd = AngleStart + partSize;
float AngleEnd = partSize;

来自Graphics.FillPie Method

sweepAngle
Angle in degrees measured clockwise from the startAngle parameter to the second side of the pie section.

此外，请使用

e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;

摆脱那些粗糙的边缘。

具有 n 个部分的 FillPie 画笔颜色问题

FillPie with n sections Brush Color issue

c#

graphics

drawing

gdi

pie-chart