时间：2019-03-17 标签：c#chartverticaltextannotation

我正在向 C# 折线图添加注释。我想更改文本方向，但看不到任何允许此操作的设置。

RectangleAnnotation annotation = new RectangleAnnotation();
annotation.AnchorDataPoint = chart1.Series[0].Points[x];
annotation.Text = "look an annotation";
annotation.ForeColor = Color.Black;
annotation.Font = new Font("Arial", 12); 
annotation.LineWidth = 2;   
chart1.Annotations.Add(annotation);

注释已正确添加到图表中，并且矩形和文本从左到右排列。我想将其定向为上下运行。关于如何实现这一目标有什么建议吗？

对我有用的解决方案。

首先，像往常一样添加注释。关键是使其不可见，然后在 Chart.PostPaint 事件中手动绘制它。

var text = new RectangleAnnotation();
text.ClipToChartArea = chart.ChartAreas[0].Name;
text.Text = "Title";
text.AxisX = chart.AxisX;
text.AxisY = chart.AxisY;
text.X = value;
text.Y = chart.AxisY.Maximum;
text.BackColor = chart.BaseSettings.ColorStorage["First"][1]; // Use your colors
text.LineColor = chart.BaseSettings.ColorStorage["First"][1];
text.ForeColor = Color.White;
text.Visible = false; // <- Hide the annotation.
chart.graph.Annotations.Add(text);
text.ResizeToContent();

其次，在Chart.PostPaint中手动绘制文本。

private static void ChartPostPaint(object sender, ChartPaintEventArgs e)
{    
    var chart = (Chart)sender;

    foreach (var annotation in chart.Annotations)
    {
        var text = annotation as RectangleAnnotation;
        if (text == null || text.Visible)
        {
            /* Skip all other irrelevant annotations and those which are visible. */
            continue;
        }

        var g = e.ChartGraphics.Graphics;
        var m = g.MeasureString(text.Text, text.Font);

        /* Convert the chart coordinates to the absolute values. */
        float x = (float)e.ChartGraphics.GetPositionFromAxis(text.ClipToChartArea, AxisName.X, text.X);
        float y = (float)e.ChartGraphics.GetPositionFromAxis(text.ClipToChartArea, AxisName.Y, text.Y);
        float w = m.Height;
        float h = m.Width;

        var p = e.ChartGraphics.GetAbsolutePoint(new PointF(x, y));

        using (var bg = new SolidBrush(text.BackColor))
        using (var fc = new SolidBrush(text.ForeColor))
        {
            g.FillRectangle(bg, p.X - m.Height, p.Y, w, h);

            /* Rotate the surface by 270 degrees around the text. */
            var dx = p.X - (m.Height / 2f);
            var dy = p.Y + (m.Height / 2f);
            g.TranslateTransform(dx, dy);
            g.RotateTransform(270);
            g.TranslateTransform(-dx, -dy);

            /* Draw the text as usual */
            g.DrawString(text.Text, text.Font, fc, p.X - m.Width, p.Y + 1);
            
            /* And rotate it back. */
            g.ResetTransform();
        }
    }
}