c# - 在 MSChart 控件上绘图

Question

我有一个简单的折线图，我想通过围绕该线绘制一个矩形来突出显示该图的某些部分（理想情况下是一个具有透明度的填充矩形......）。我不知道这是否可以通过 MS 图表控件实现？

Answer 1

我建议您从 MS 下载代码示例并查看注释部分。在那里，您将找到实现您所描述的内容所需的所有文档：

private void AddRectangleAnnotation()
{
RectangleAnnotation annotation = new RectangleAnnotation();
annotation.AnchorDataPoint = Chart1.Series[0].Points[2];
annotation.Text = "I am a\nRectangleAnnotation";
annotation.ForeColor = Color.Black;
annotation.Font = new Font("Arial", 12);;
annotation.LineWidth = 2;
annotation.BackColor = Color.PaleYellow;
annotation.LineDashStyle = ChartDashStyle.Dash;

Chart1.Annotations.Add(annotation);
}

Answer 2

你的意思是：

using (Graphics g = Graphics.FromImage(pictureBox1.Image))
{
    using(Brush brush = new SolidBrush(your_color))
    {
        g.FillRectangle(brush , x, y, width, height);
    }
}

或者你可以使用

Brush brush = new SolidBrush(Color.FromArgb(alpha, red, green, blue))

其中alpha从0到255，因此您的值为128将为您alpha提供50%的不透明度。

Answer 3

当您想在图表上绘图时，您可以添加 LineAnnotation 或 RectangleAnnotation。但是，如果您想要更多控制，您可以使用图表的 PrePaint 和 PostPaint 事件。如果你会画画，那么你可以画任何东西。同样使用它会使图表“打印”和“导出”看起来与您绘制的相同。当图表在屏幕上的位置改变时，在它上面画会看起来很有趣，所以一定要在上面画。

假设你有一个交易图表，你需要画一条线来说明你在哪里获利，或者画一条直线来说明你在哪里“做某事”，只需添加坐标，从哪里到你想去的地方和你去...

MS Chart 示例项目显示了如何使用以下代码执行此操作（vb.net 也可用）：

using System.Windows.Forms.DataVisualization.Charting;
...

private void chart1_PostPaint(object sender, System.Windows.Forms.DataVisualization.Charting.ChartPaintEventArgs e)
{
    if(sender is ChartArea)
    {

        ChartArea area = (ChartArea)sender;
        if(area.Name == "Default")
        {
            // If Connection line is not checked return
            if( !ConnectionLine.Checked )
                return;

            double max;
            double min;
            double xMax;
            double xMin;

            // Find Minimum and Maximum values
            FindMaxMin( out max, out min, out xMax, out xMin );

            // Get Graphics object from chart
            Graphics graph = e.ChartGraphics.Graphics;

            // Convert X and Y values to screen position
            float pixelYMax = (float)e.ChartGraphics.GetPositionFromAxis("Default",AxisName.Y,max);
            float pixelXMax = (float)e.ChartGraphics.GetPositionFromAxis("Default",AxisName.X,xMax);
            float pixelYMin = (float)e.ChartGraphics.GetPositionFromAxis("Default",AxisName.Y,min);
            float pixelXMin = (float)e.ChartGraphics.GetPositionFromAxis("Default",AxisName.X,xMin);

            PointF point1 = PointF.Empty;
            PointF point2 = PointF.Empty;

            // Set Maximum and minimum points
            point1.X = pixelXMax;
            point1.Y = pixelYMax;
            point2.X = pixelXMin;
            point2.Y = pixelYMin;

            // Convert relative coordinates to absolute coordinates.
            point1 = e.ChartGraphics.GetAbsolutePoint(point1);
            point2 = e.ChartGraphics.GetAbsolutePoint(point2);

            // Draw connection line
            graph.DrawLine(new Pen(Color.Yellow,3), point1,point2);
        }
    }
}

private void chart1_PrePaint(object sender, System.Windows.Forms.DataVisualization.Charting.ChartPaintEventArgs e)
{
    if(sender is ChartArea){

        ChartArea area = (ChartArea)sender;
        if(area.Name == "Default")
        {
            double max;
            double min;
            double xMax;
            double xMin;

            // Find Minimum and Maximum values
            FindMaxMin( out max, out min, out xMax, out xMin );

            // Get Graphics object from chart
            Graphics graph = e.ChartGraphics.Graphics;

            // Convert X and Y values to screen position
            float pixelYMax = (float)e.ChartGraphics.GetPositionFromAxis("Default",AxisName.Y,max);
            float pixelXMax = (float)e.ChartGraphics.GetPositionFromAxis("Default",AxisName.X,xMax);
            float pixelYMin = (float)e.ChartGraphics.GetPositionFromAxis("Default",AxisName.Y,min);
            float pixelXMin = (float)e.ChartGraphics.GetPositionFromAxis("Default",AxisName.X,xMin);

            // Specify width of triangle
            float width = 3;

            // Set Maximum points
            PointF [] points = new PointF[3];
            points[0].X = pixelXMax - width;
            points[0].Y = pixelYMax - width - 2;
            points[1].X = pixelXMax + width;
            points[1].Y = pixelYMax - width - 2;
            points[2].X = pixelXMax;
            points[2].Y = pixelYMax - 1;

            // Convert relative coordinates to absolute coordinates.
            points[0] = e.ChartGraphics.GetAbsolutePoint(points[0]);
            points[1] = e.ChartGraphics.GetAbsolutePoint(points[1]);
            points[2] = e.ChartGraphics.GetAbsolutePoint(points[2]);

            // Draw Maximum trangle
            graph.FillPolygon(new SolidBrush(Color.Red), points);

            // Set Minimum points
            points = new PointF[3];
            points[0].X = pixelXMin - width;
            points[0].Y = pixelYMin + width + 2;
            points[1].X = pixelXMin + width;
            points[1].Y = pixelYMin + width + 2;
            points[2].X = pixelXMin;
            points[2].Y = pixelYMin + 1;

            // Convert relative coordinates to absolute coordinates.
            points[0] = e.ChartGraphics.GetAbsolutePoint(points[0]);
            points[1] = e.ChartGraphics.GetAbsolutePoint(points[1]);
            points[2] = e.ChartGraphics.GetAbsolutePoint(points[2]);

            // Draw Minimum triangle
            graph.FillPolygon(new SolidBrush(Color.Blue), points);
        }
    }
}