Dynamically resizing ChartText Labels based on Column Width

405

Jeff posted over 16 years ago

Hoping for advice from the IG chart gurus...

Desired Result: I need to truncate ChartText labels (based on ITEM_LABEL) to fit within the column bounds of a 2d stacked column chart.

Progress so far: After searching the docs & boards, I've successfully implemented a custom class that implements IRenderLabel and I can truncate the labels based on a fixed size or number of characters.

Problem: How can I get a reference to the rectangle element that the label is being drawn within so that my custom IRenderLabel class can truncate the text to fit within the column. (The column width is subject to change as the form is resized, so a fixed width truncation would not allow long lables to to be displayed in their entirity once the chart is wide enough to display them.)

I appreciate your help and insight.

At your service,

Jeff

26458

Offline Max Rivlin [Infragistics] posted over 16 years ago in reply to Jeff

Silly me, I gave you a solution for the axis labels instead of chart text labels.
You can't use axis layout behaviors for this one, so it's a bit trickier. The chart needs to be re-invalidated because label renderer fires before FillSceneGraph has a chance to get the column width. Anyways, this should work:

public partial class Form1 : Form
{
public Form1()
{
   InitializeComponent();
}
LabelRenderer myLabelRenderer;
private void Form1_Load(object sender, EventArgs e)
{
   myLabelRenderer = new LabelRenderer();
   myLabelRenderer.ChartControl = chart;
   Hashtable labelHash = new Hashtable();
   labelHash.Add("MYLABEL", myLabelRenderer);
   chart.LabelHash = labelHash;
   ChartTextAppearance chartText = new ChartTextAppearance();
   chartText.Column = chartText.Row = -2;
   chartText.Visible = true;
   chartText.ItemFormatString = "<MYLABEL>";
   myLabelRenderer.Font = chartText.ChartTextFont;
   chart.ColumnChart.ChartText.Add(chartText);
   chart.Data.DataSource = new int[,] { { 1, 1, 1 }, { 2, 2, 2 }};
   chart.Data.SetColumnLabels(new string[ { "really really long column label that should be truncated" });
}
private void chart_FillSceneGraph(object sender, Infragistics.UltraChart.Shared.Events.FillSceneGraphEventArgs e)
{
   foreach (Primitive p in e.SceneGraph)
   {
      Box box = p as Box;
      if (box != null && box.Layer != null && box.Row != -1 && box.Column != -1)
      {
         myLabelRenderer.ColumnWidth = box.rect.Width;
        break;
      }
   }
}
}
class LabelRenderer : IRenderLabel
{
public double ColumnWidth { get; set; }
public Font Font { get; set; }
public UltraChart ChartControl { get; set; }
public string ToString(Hashtable context)
{
   if (ColumnWidth <= 0)
   {
      ChartControl.InvalidateLayers();
      return "";
   }

   string label = (string)context["ITEM_LABEL"];
   SizeF labelSize = Platform.GetStringSizePixels(label, this.Font);
   if (labelSize.Width > ColumnWidth)
   {
      return label.Substring(0, Convert.ToInt32(label.Length * ColumnWidth / labelSize.Width));
   }
   return label;
}
}
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405

Jeff posted over 16 years ago in reply to Max Rivlin [Infragistics]

Max:

The ClipTextAxisLabelLayoutBehavior behavior is exactly what I would like to accomplish, but I can't seem to apply it to the ChartTextAppearances of my stacked column chart. Any suggestions on how to make the ChartText comply with that behavoir restriction? (I've tried all the permutations I could think of.) In the meantime, I'll move forward with your FillSceneGraph suggestion.

Thanks, O Great Chart Guru!

At your service,

Jeff
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26458

Offline Max Rivlin [Infragistics] posted over 16 years ago

I think the simplest solution is to use a clip text behavior for x axis series labels. It will automatically determine if the series label needs to be trimmed.

ClipTextAxisLabelLayoutBehavior behavior = new ClipTextAxisLabelLayoutBehavior();
behavior.ClipText = true;
behavior.Enabled = true;
behavior.EnableRollback = false;
behavior.HideText = false;
behavior.Trimming = StringTrimming.EllipsisCharacter;
behavior.UseOnlyToPreventCollisions = false;
ultraChart1.Axis.X.Labels.SeriesLabels.Layout.Behavior = AxisLabelLayoutBehaviors.UseCollection;
ultraChart1.Axis.X.Labels.SeriesLabels.Layout.BehaviorCollection.Clear();
ultraChart1.Axis.X.Labels.SeriesLabels.Layout.BehaviorCollection.Add(behavior);

Of course, you can still use IRenderLabel instead, you'll just have to find the column width. If you handle FillSceneGraph event, use the axis.Map method to find it. You will also need to measure your strings in IRenderLabel.ToString using Infragistics.UltraChart.Core.Util.Platform.GetStringSizePixels() because the label's font will affect the its width.

IAdvanceAxis xAxis = (IAdvanceAxis)e.Grid["X"];
if (xAxis != null)
{
double width = xAxis.Map(1) - xAxis.Map(0);
}
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