具有虚线样式和大量数据点的MSChart折线图

Question

我正在尝试使用来自C#的MSChart以虚线样式渲染线图.我没有设置样式的问题,但我有大量的数据.这会导致虚线渲染出错,因为它似乎在绘制每个线段时重新启动"破折号"序列.因此,我得到一条看起来与实线相同的线.如果我向右缩放以使我的数据点密度减小,则虚线样式变为可见.

这对我没有好处,因为我真的需要它来保持任何缩放级别的冲刺.有没有人想过如何做到这一点？看起来像是这样让我这样渲染......这似乎很奇怪......

有什么想法吗？

Answer 1

好吧,这变成了一个比我期待的更多的faff.问题出现的原因是MSChart将每两个点之间的线作为单独的DrawLine调用绘制.如果使用一个DrawLines调用绘制整个事物,则问题将不存在.

因此,我想出了一种方法来处理它.

首先在PrePaint中我将所有"BorderWidth"存储在将它们设置为0之前.这意味着MSChart不会绘制我的线条.

最后在PostPaint中,我使用我想要的破折号样式绘制线条.这给出了完美渲染.

我确定有一些边缘情况,我的代码不能工作,但这应该让你知道如何做到这一点:

    private List< int > mBorderWidths   = null;
    private void LineChartPrePaint( object sender, System.Windows.Forms.DataVisualization.Charting.ChartPaintEventArgs e )
    {
        if ( e.ChartElement.GetType() == typeof( System.Windows.Forms.DataVisualization.Charting.ChartArea ) )
        {
            System.Windows.Forms.DataVisualization.Charting.Chart           c   = (System.Windows.Forms.DataVisualization.Charting.Chart)e.Chart;
            System.Windows.Forms.DataVisualization.Charting.ChartArea       ca  = (System.Windows.Forms.DataVisualization.Charting.ChartArea)e.ChartElement;

            mBorderWidths   = new List<int>();
            foreach( System.Windows.Forms.DataVisualization.Charting.Series s in c.Series )
            {
                mBorderWidths.Add( s.BorderWidth );
                s.BorderWidth   = 0;
                s.ShadowOffset  = 0;
            }

            RectangleF rectF    = ca.Position.ToRectangleF();
            rectF               = e.ChartGraphics.GetAbsoluteRectangle( rectF );

            e.ChartGraphics.Graphics.FillRectangle( new SolidBrush( ca.BackColor ), rectF );
        }
        if ( e.ChartElement.GetType() == typeof( System.Windows.Forms.DataVisualization.Charting.Chart ) )
        {
            RectangleF rectF    = e.Position.ToRectangleF();
            rectF               = e.ChartGraphics.GetAbsoluteRectangle( rectF );

            e.ChartGraphics.Graphics.FillRectangle( new SolidBrush( e.Chart.BackColor ), rectF );
        }
    }

    System.Drawing.Drawing2D.DashStyle ChartToDrawingDashStyle( System.Windows.Forms.DataVisualization.Charting.ChartDashStyle cds )
    {
        switch( cds )
        {
            case System.Windows.Forms.DataVisualization.Charting.ChartDashStyle.NotSet:
            case System.Windows.Forms.DataVisualization.Charting.ChartDashStyle.Solid:
                return System.Drawing.Drawing2D.DashStyle.Solid;
            case System.Windows.Forms.DataVisualization.Charting.ChartDashStyle.Dash:
                return System.Drawing.Drawing2D.DashStyle.Dash;
            case System.Windows.Forms.DataVisualization.Charting.ChartDashStyle.DashDot:
                return System.Drawing.Drawing2D.DashStyle.DashDot;
            case System.Windows.Forms.DataVisualization.Charting.ChartDashStyle.DashDotDot:
                return System.Drawing.Drawing2D.DashStyle.DashDotDot;
            case System.Windows.Forms.DataVisualization.Charting.ChartDashStyle.Dot:
                return System.Drawing.Drawing2D.DashStyle.Dot;
        }
        return System.Drawing.Drawing2D.DashStyle.Solid;
    }

    private void LineChartPostPaint( object sender, System.Windows.Forms.DataVisualization.Charting.ChartPaintEventArgs e )
    {
        if ( e.ChartElement.GetType() == typeof( System.Windows.Forms.DataVisualization.Charting.ChartArea ) )
        {
            System.Windows.Forms.DataVisualization.Charting.Chart       c   = (System.Windows.Forms.DataVisualization.Charting.Chart)e.Chart;
            System.Windows.Forms.DataVisualization.Charting.ChartArea   ca  = (System.Windows.Forms.DataVisualization.Charting.ChartArea)e.ChartElement;

            RectangleF clipRect = e.ChartGraphics.GetAbsoluteRectangle( e.Position.ToRectangleF() );
            RectangleF oldClip  = e.ChartGraphics.Graphics.ClipBounds;
            e.ChartGraphics.Graphics.SetClip( clipRect );

            int seriesIdx   = 0;
            foreach( System.Windows.Forms.DataVisualization.Charting.Series s in c.Series )
            {
                PointF  ptFLast         = new PointF( 0.0f, 0.0f );
                List< PointF > points   = new List<PointF>();
                foreach( System.Windows.Forms.DataVisualization.Charting.DataPoint dp in s.Points )
                {
                    double dx   = (double)dp.XValue;
                    double dy   = (double)dp.YValues[0];

                    // Log the value if its axis is logarithmic.
                    if ( ca.AxisX.IsLogarithmic )
                    {
                        dx  = Math.Log10( dx );
                    }
                    if ( ca.AxisY.IsLogarithmic )
                    {
                        dy  = Math.Log10( dy );
                    }

                    dx  = e.ChartGraphics.GetPositionFromAxis( ca.Name, System.Windows.Forms.DataVisualization.Charting.AxisName.X, dx );
                    dy  = e.ChartGraphics.GetPositionFromAxis( ca.Name, System.Windows.Forms.DataVisualization.Charting.AxisName.Y, dy );

                    PointF  ptFThis         = e.ChartGraphics.GetAbsolutePoint( new PointF( (float)dx, (float)dy ) );
                    points.Add( ptFThis );
                }


                if ( points.Count > 0 )
                {
                    Pen pen = new Pen( Color.FromArgb( 255, s.Color ) );
                    pen.Width       = mBorderWidths[seriesIdx];
                    pen.DashStyle   = ChartToDrawingDashStyle( s.BorderDashStyle );
                    //pen.DashStyle = System.Drawing.Drawing2D.DashStyle.Custom;
                    //pen.DashPattern   = new float[]{ 4.0f, 4.0f, 1.0f, 3.0f, 2.0f, 3.0f };
                    pen.DashCap     = System.Drawing.Drawing2D.DashCap.Round;

                    e.ChartGraphics.Graphics.SmoothingMode  = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                    e.ChartGraphics.Graphics.DrawLines( pen, points.ToArray() );

                }
                s.BorderWidth   = mBorderWidths[seriesIdx];
            }

            e.ChartGraphics.Graphics.SetClip( oldClip );
        }
    }

我真的希望拯救某人一些痛苦!