c# 使用GDI+画曲线图

效果如图所示：

 

以下是代码：

public class Curve
    {
        //picture
        Bitmap retbit = new Bitmap(800, 600);
        //
        Font _textFont;
        //x,y value in actual
        float[] x;
        float[] y;
        //x,y scale in the axies
        float[] scale_X;
        float[] scale_Y;

        float X_Max;
        float Y_Max;
        float X_Min;
        float Y_Min;
        //x,y与图标长度的换算值
        float ratio_X;
        float ratio_Y;
        //起始刻度
        float ScaleX_Min;
        float ScaleX_Max;
        float ScaleY_Min;
        float ScaleY_Max;
        //
        int stepes_X;
        int stepes_Y;
        //
        float stepSize_X;
        float stepSize_Y;

        float range_X;
        float range_Y;
        //
        PointF[] drawPts;

        //刻度文字
        string[] text_X;
        string[] text_Y;
        //
        SizeF lengthSizeText;

        //curve zone backcolor
        Color backColor_Curve;
        //
        float curvewidth;
        float curveheight;

        Pen arrowPen = new Pen(Color.Black, 1);

        //constructors
        public Curve()
        {
        }

        public Curve(PointF[] points)
        {
            x = new float[points.Length];
            y = new float[points.Length];


            for (int i = 0; i < x.Length; i++)
            {
                x[i] = points[i].X;
                y[i] = points[i].Y;

            }

            InitializePoints();

            DrawCurve();

        }
        public Curve(float[] x, float[] y)
        {
        }

        //
        private void InitializePoints()
        {
            scale_X = new float[x.Length];
            scale_Y = new float[x.Length];
            drawPts = new PointF[x.Length];
            //
            _textFont = new Font("宋体", 10);
            //
            ArrayList tempArray = new ArrayList();
            X_Max = x[0]; Y_Max = y[0];
            X_Min = x[0]; Y_Min = y[0];
            for (int i = 1; i < x.Length; i++)
            {
                X_Max = Math.Max(X_Max, x[i]);
                X_Min = Math.Min(X_Min, x[i]);
                Y_Max = Math.Max(Y_Max, y[i]);
                Y_Min = Math.Min(Y_Min, y[i]);
            }

            range_X = X_Max - X_Min;
            range_Y = Y_Max - Y_Min;
            backColor_Curve = Color.LightGray;
        }

        //
        protected void DrawCurve()
        {
            Graphics g = Graphics.FromImage(retbit);

            g.FillRectangle(Brushes.LightGray, new Rectangle(0, 0, retbit.Width, retbit.Height));


            arrowPen.EndCap = System.Drawing.Drawing2D.LineCap.ArrowAnchor;
            arrowPen.CustomEndCap = new System.Drawing.Drawing2D.AdjustableArrowCap(arrowPen.Width * 3, arrowPen.Width * 5);

            Pen pen = new Pen(Color.Red);

            //计算y的起始刻度值
            int tmpInt;
            stepSize_Y = (float)CalcStepSize(range_Y, 10);
                //y 最小刻度值
            tmpInt = (int)(Y_Min / stepSize_Y);
            if (tmpInt < 0)
                tmpInt = tmpInt - 1;
            ScaleY_Min = tmpInt * stepSize_Y;
                //y最大刻度值

            if (Y_Max % stepSize_Y == 0)
                tmpInt = (int)(Y_Max / stepSize_Y);
            else
                tmpInt = (int)(Y_Max / stepSize_Y + 1);
            ScaleY_Max = tmpInt * stepSize_Y;
            stepes_Y = (int)((ScaleY_Max - ScaleY_Min) / stepSize_Y)+1;


            //计算x的起始刻度值
            stepSize_X = (float)CalcStepSize(range_X, 10);
                //x最小刻度
            tmpInt = (int)(X_Min / stepSize_X);
            if (tmpInt < 0)
                tmpInt = tmpInt - 1;
            ScaleX_Min = tmpInt * stepSize_X;
                //x最大刻度
            if (X_Max % stepSize_X == 0)
                tmpInt = (int)(X_Max / stepSize_X);
            else tmpInt = (int)(X_Max / stepSize_X + 1);
            ScaleX_Max = tmpInt * stepSize_X;
            stepes_X = (int)((ScaleX_Max - ScaleX_Min) / stepSize_X)+1;

            //
            float offset_X = 0;
            float offset_Y = 0;
            lengthSizeText = SetText(g,ref offset_X,ref offset_Y);
            //图标距离顶部的高度，
            //预留的坐标轴箭头空间
            float curve_Top = lengthSizeText.Height/2;
            float curve_Right = lengthSizeText.Width / 2+1;
            offset_X = Math.Max(offset_X, lengthSizeText.Width / 2)+1;
            offset_Y = Math.Max(offset_Y, lengthSizeText.Height)+1;
            //图标区域实际的大小，用于计算坐标转换
            curvewidth = retbit.Width - offset_X - curve_Right;
            curveheight = retbit.Height - offset_Y - curve_Top;



            ////axies
            //PointF pt_center = new PointF(offset_X, retbit.Height - offset_Y);
            //g.DrawLine(arrowPen, pt_center, new PointF(pt_center.X, 0));//y
            //g.DrawLine(arrowPen, pt_center, new PointF(retbit.Width, pt_center.Y));//x

            //
            ratio_X = curvewidth / ((ScaleX_Max - ScaleX_Min) );
            ratio_Y = curveheight / ((ScaleY_Max - ScaleY_Min));            //
            //
            for (int i = 0; i < x.Length; i++)
            {
                drawPts[i] = new PointF(x[i] * ratio_X - ScaleX_Min * ratio_X, y[i] * ratio_Y - ScaleY_Min * ratio_Y);
                drawPts[i] = new PointF(drawPts[i].X, -drawPts[i].Y);
            }
            //
            g.TranslateTransform(offset_X, retbit.Height - offset_Y);
            //drawing
            g.FillRectangle(new SolidBrush(backColor_Curve), new RectangleF(0, -curveheight, curvewidth, curveheight));
            //scales :x,y
            DrawScale(g);
            //curve
            g.DrawCurve(pen, drawPts);
            //symbol 画点
            DrawSymbol(g);


        }
        //
        private SizeF SetText(Graphics g,ref float offset_X,ref float offset_Y)
        {
            //因为刻度值坐标轴移动的长度
            offset_X = 0;
            offset_Y = 0;
            //
            float lengthText_X_Max = 0;
            float lengthText_Y_Max = 0;

            //坐标值
            text_X = new string[stepes_X];
            text_Y = new string[stepes_Y];
            for (int i = 0; i < text_X.Length; i++)
            {
                text_X[i] = ScaleX_Min + i * stepSize_X + "f";
                SizeF tmpSize = g.MeasureString(text_X[i], _textFont);
                offset_Y = Math.Max(offset_Y, tmpSize.Height);
                lengthText_X_Max = Math.Max(lengthText_X_Max, tmpSize.Width);
            }
            for (int i = 0; i < text_Y.Length; i++)
            {
                text_Y[i] = ScaleY_Min + i * stepSize_Y + "";
                SizeF tmpSize = g.MeasureString(text_Y[i], _textFont);
                offset_X = Math.Max(offset_X, tmpSize.Width);
                lengthText_Y_Max = Math.Max(lengthText_Y_Max, tmpSize.Height);

            }
            return new SizeF(lengthText_X_Max, lengthText_Y_Max);
        }
        //画曲线的点
        private void DrawSymbol(Graphics g)
        {
            Pen pen=new Pen(Color.Blue);
            float r = 2;

            for (int i = 0; i < drawPts.Length; i++)
            {
                PointF center = new PointF(drawPts[i].X - r, drawPts[i].Y - r);
                g.FillEllipse(new SolidBrush(backColor_Curve), center.X, center.Y, 2 * r, 2 * r);
                g.DrawEllipse(pen, center.X, center.Y, 2 * r, 2 * r);
            }
        }
        //画坐标轴
        private void DrawScale(Graphics g)
        {
            //x,y axis
            PointF pt_center = new PointF(0, 0);
            g.DrawLine(arrowPen, pt_center, new PointF(pt_center.X, -curveheight));//y
            g.DrawLine(arrowPen, pt_center, new PointF(curvewidth, pt_center.Y));//x
            //grid
            DrawGrid(g);
            //micro grid
            DrawMicroGrid(g);
            //draw text 刻度值
            DrawText(g);
        }
        private void DrawGrid(Graphics g)
        {
            Pen pen_Grid = new Pen(Color.Black);
            //x
            for (int i = 1; i < stepes_X; i++)
            {
                PointF pt1 = new PointF(i * stepSize_X * ratio_X, 0);
                PointF pt2 = new PointF(pt1.X, -curveheight);
                g.DrawLine(pen_Grid, pt1, pt2);
            }
            //y
            for (int i = 1; i < stepes_Y; i++)
            {
                PointF pt1 = new PointF(0, -i * stepSize_Y * ratio_Y);
                PointF pt2 = new PointF(curvewidth, pt1.Y);
                g.DrawLine(pen_Grid, pt1, pt2);
            }
        }
        private void DrawMicroGrid(Graphics g)
        {
            Pen pen_MGrid = new Pen(Color.Black);
            pen_MGrid.DashStyle = System.Drawing.Drawing2D.DashStyle.Dash;
            //x
            for (int i = 0; i < stepes_X-1; i++)
            {
                PointF pt1 = new PointF((i+0.5f) * stepSize_X * ratio_X, 0);
                PointF pt2 = new PointF(pt1.X, -curveheight);
                g.DrawLine(pen_MGrid, pt1, pt2);
            }
            //y
            for (int i = 0; i < stepes_Y-1; i++)
            {
                PointF pt1 = new PointF(0, -(i + 0.5f) * stepSize_Y * ratio_Y);
                PointF pt2 = new PointF(curvewidth, pt1.Y);
                g.DrawLine(pen_MGrid, pt1, pt2);
            }
        }
        private void DrawText(Graphics g)
        {
            Pen pen_Grid = new Pen(Color.Black);
            //

            int no_x = 1, no_y = 1;
            float tmp=stepSize_X * ratio_X;
            while (tmp <= lengthSizeText.Width)
            {
                tmp = tmp * 2;
                no_x *= 2;
            }
            tmp = stepSize_Y * ratio_Y;
            while (tmp < lengthSizeText.Height)
            {
                tmp *= 2;
                no_y *= 2;
            }

            //x
            for (int i = 0; i < stepes_X/no_x+1; i++)
            {
                if (i * no_x >= stepes_X)
                    continue;
                string text = text_X[i * no_x];
                SizeF textSize = g.MeasureString(text, _textFont);
                PointF pt1 = new PointF(i * no_x * stepSize_X * ratio_X - textSize.Width / 2, 5);
                g.DrawString(text, _textFont, Brushes.Black, pt1);
            }
            //y
            for (int i = 0; i < stepes_Y/no_y+1; i++)
            {
                if (i * no_y >= stepes_Y)
                    return;
                string text = text_Y[i * no_y];
                SizeF textSize = g.MeasureString(text, _textFont);
                PointF pt1 = new PointF(-textSize.Width-5, -i * no_y * stepSize_Y * ratio_Y-textSize.Height/2);
                g.DrawString(text, _textFont, Brushes.Black, pt1);
            }
        }
        //
        protected double CalcStepSize(double range, double targetSteps)
        {
            // Calculate an initial guess at step size
            double tempStep = range / targetSteps;

            // Get the magnitude of the step size
            double mag = Math.Floor(Math.Log10(tempStep));
            double magPow = Math.Pow((double)10.0, mag);

            // Calculate most significant digit of the new step size
            double magMsd = ((int)(tempStep / magPow + .5));

            // promote the MSD to either 1, 2, or 5
            if (magMsd > 5.0)
                magMsd = 10.0;
            else if (magMsd > 2.0)
                magMsd = 5.0;
            else if (magMsd > 1.0)
                magMsd = 2.0;

            return magMsd * magPow;
        }

        //properties

        public Bitmap CurveImage
        {
            get { return retbit; }
        }
    }

  

 

调用代码是：

 

 

//pts
            PointF[] pts = new PointF[]{
                //new PointF(-0.3f,-2.23f),
                new PointF(0.4f,3.191f),new PointF(0.5f,4.264f),new PointF(0.6f,5.525f),
                new PointF(0.7f,6.964f),new PointF(0.8f,8.436f),new PointF(0.9f,9.582f),
                new PointF(1.0f,10f),new PointF(1.1f,9.654f),new PointF(1.2f,8.878f),
                new PointF(1.3f,7.998f),new PointF(1.4f,7.179f),new PointF(1.5f,6.470f),
                new PointF(1.6f,5.871f)
            };
         Curve c = new  Curve(pts);

            g.DrawImage(c.CurveImage, new Point(10, 10));

  

 

由于最近没有时间，只能先把代码贴了上去。这是原稿还没怎么整理。

大家提提意见。准备后续开发一个图表控件。^.^

 

 

 

 

有一点bug，需要将curve.cs中的DrawCurve方法替换一下：

 

//
        public Bitmap DrawCurve(int width,int height)
        {
            retbit = new Bitmap(width, height);
            Graphics g = Graphics.FromImage(retbit);

            g.FillRectangle(Brushes.LightGray, new Rectangle(0, 0, retbit.Width, retbit.Height));


            arrowPen.EndCap = System.Drawing.Drawing2D.LineCap.ArrowAnchor;
            arrowPen.CustomEndCap = new System.Drawing.Drawing2D.AdjustableArrowCap(arrowPen.Width * 3, arrowPen.Width * 5);

            Pen pen = new Pen(Color.Red);

            //计算y的起始刻度值
            int tmpInt;
            stepSize_Y = (float)CalcStepSize(range_Y, 10);
                //y 最小刻度值
            tmpInt = Convert.ToInt32(Y_Min / stepSize_Y);
            if (tmpInt < 0)
                tmpInt = tmpInt - 1;
            ScaleY_Min = tmpInt * stepSize_Y;
                //y最大刻度值

            if (Convert.ToInt32( Convert.ToInt32(Y_Max / stepSize_Y) - Y_Max / stepSize_Y)==0 )
                tmpInt = Convert.ToInt32(Y_Max / stepSize_Y);
            else
                tmpInt = Convert.ToInt32(Y_Max / stepSize_Y + 1);
            ScaleY_Max = tmpInt * stepSize_Y;
            stepes_Y = Convert.ToInt32((ScaleY_Max - ScaleY_Min) / stepSize_Y)+1;


            //计算x的起始刻度值
            stepSize_X = (float)CalcStepSize(range_X, 10);
                //x最小刻度
            tmpInt = Convert.ToInt32(X_Min / stepSize_X);
            if (tmpInt < 0)
                tmpInt = tmpInt - 1;
            ScaleX_Min = tmpInt * stepSize_X;
                //x最大刻度
            if (Convert.ToInt32(Convert.ToInt32(X_Max / stepSize_X) - X_Max/stepSize_X)==0)
                tmpInt = Convert.ToInt32(X_Max / stepSize_X);
            else tmpInt = Convert.ToInt32(X_Max / stepSize_X + 1);
            ScaleX_Max = tmpInt * stepSize_X;
            stepes_X = Convert.ToInt32((ScaleX_Max - ScaleX_Min) / stepSize_X)+1;

            //
            float offset_X = 0;
            float offset_Y = 0;
            lengthSizeText = SetText(g,ref offset_X,ref offset_Y);
            //图标距离顶部的高度，
            //预留的坐标轴箭头空间
            float curve_Top = lengthSizeText.Height/2;
            float curve_Right = lengthSizeText.Width / 2+1;
            offset_X = Math.Max(offset_X, lengthSizeText.Width / 2)+1;
            offset_Y = Math.Max(offset_Y, lengthSizeText.Height)+1;
            //图标区域实际的大小，用于计算坐标转换
            curvewidth = retbit.Width - offset_X - curve_Right;
            curveheight = retbit.Height - offset_Y - curve_Top;

            //
            ratio_X = curvewidth / ((ScaleX_Max - ScaleX_Min) );
            ratio_Y = curveheight / ((ScaleY_Max - ScaleY_Min));            //
            //
            for (int i = 0; i < x.Length; i++)
            {
                drawPts[i] = new PointF(x[i] * ratio_X - ScaleX_Min * ratio_X, y[i] * ratio_Y - ScaleY_Min * ratio_Y);
                drawPts[i] = new PointF(drawPts[i].X, -drawPts[i].Y);
            }
            //
            g.TranslateTransform(offset_X, retbit.Height - offset_Y);
            //drawing
            g.FillRectangle(new SolidBrush(backColor_Curve), new RectangleF(0, -curveheight, curvewidth, curveheight));
            //scales :x,y
            DrawScale(g);
            //curve
            g.DrawCurve(pen, drawPts);
            //symbol 画点
            DrawSymbol(g);

            return retbit;
        }