ZedGraph点标签重叠

Question

I have line charts with multiple series data. points in series are little close to each other so due to that reason, label overlaps eachother. Is there any supportive lib which can handle point labels on its own.

Or Is there any smart logic that can identify closest points and set the location of label accordingly??

Answer 1

Maybe try the IsPreventLabelOverlap property to true. Unfortunately this usually just erases the labels that overlap and doesn't simply spread them out. So with that in mind, see below.

There is not a library which does what you asked, but there is the postpaint option. Zedgraph unfortunately does not fix overlapping labels (I tried for a long time and with no luck). However there is a work around but it is tedious and you have to put some real thought into where to place your graphic labels. See code below for a simple way to add a label:

protected void Chart1_PostPaint(object sender, ChartPaintEventArgs e)
{
  if (e.ChartElement is Chart)
{
// create text to draw
String TextToDraw;
TextToDraw = "Chart Label"

// get graphics tools
Graphics g = e.ChartGraphics.Graphics;
Font DrawFont = System.Drawing.SystemFonts.CaptionFont;
Brush DrawBrush = Brushes.Black;

// see how big the text will be
int TxtWidth = (int)g.MeasureString(TextToDraw, DrawFont).Width;
int TxtHeight = (int)g.MeasureString(TextToDraw, DrawFont).Height;

// where to draw
int x = 5;  // a few pixels from the left border

int y = (int)e.Chart.Height.Value;
y = y - TxtHeight - 5; // a few pixels off the bottom

// draw the string        
g.DrawString(TextToDraw, DrawFont, DrawBrush, x, y);
}

This will create a label for you and you can choose where to draw it. However that is the tricky part. You need to basically find out where your graph is on your screen and where the point is on that graph. Very cumbersome but if it is a static graph then it shouldn't be an issue. It's a hack, I know, but it works and it's all anyone has seemed to come up with.