MS Chart (.Net 3.5): Line thickness in legend/key

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I'm using the MS Chart component for .Net 3.5, and I'm using it to construct a metafile. (We're embedding it in an RTF report.) In order to work around the issue with WMF coordinates being poor precision, my virtual chart area is large (6000×4000) pixels.

I am rescaling everything with the following method:

C#

public void UpdateScaledElements()
{
    float scaleFactor = Chart.Height / 400f;
    foreach (Series s in Chart.Series)
    {
        s.Font = new Font(FONT_NAME, 8 * scaleFactor);
        s.BorderWidth = (int)(1.6 * scaleFactor);
        s.MarkerSize = (int)(6 * scaleFactor);
    }
    foreach (Legend l in Chart.Legends) {
        l.Font = new Font(FONT_NAME, 8 * scaleFactor);
    }
    foreach (Axis a in Chart.ChartAreas[0].Axes)
    {
        a.TitleFont = new Font(FONT_NAME, 10 * scaleFactor);
        a.LabelStyle.Font = new Font(FONT_NAME, 8 * scaleFactor);
        a.LineWidth = (int)(2 * scaleFactor);
    }
}

It's working pretty well. However, I can't work out how to make the line thickness of the lines drawn in the legend/key to scale up. I expected them to come through from the series like the marker scale and colour do. I've searched but I can't find a solution.

I have tried changing l.BorderWidth (it actually does change the border of the key, not lines within it), rebuilding the key in this method, and using the CustomizeLegend event to set BorderWidth on individual items. None of those changed the default behaviour, which seems to be 1 unit – which will be a hairline when this is printed, not a nice bold line like the series.

Edit: I have 'solved' this by painting the line myself in a PostPaint handler. This is a hack so I'm still in the market for an elegant solution.

Posted 12-Apr-11 7:00am

BobJanova

Updated 12-Apr-11 23:14pm

v2

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wizardzz · Answer 1 · 2011-04-12T11:46:00

Solution 1

Can you possibly use an image for the legend value (I assume you want a colored box or line)?

Or could you try using a custom legend item like this, which is taken from the MSCharts sample program:

MIDL

legendItem = new LegendItem();
legendItem.Name = "Marker Style Item";
legendItem.Style = LegendImageStyle.Marker;
legendItem.ShadowOffset = 1;
legendItem.Color = Color.Yellow;
legendItem.MarkerStyle = MarkerStyle.Cross;
legendItem.MarkerSize = 10;
legendItem.MarkerBorderColor = Color.Black;
chart1.Legends["Default"].CustomItems.Add(legendItem);

Posted 12-Apr-11 11:46am

wizardzz

Comments

BobJanova 13-Apr-11 5:13am

Thanks but your code is for a marker style key item, not a line style one. Marker key entries are working correctly already.

wizardzz 13-Apr-11 10:08am

Do you have to use a line? Couldn't you just use a filled in box to represent the same thing?

BobJanova 13-Apr-11 10:53am

It's a line graph, the key entry should also be a line (as it is by default for a line series).

wizardzz 13-Apr-11 11:46am

Also, have you tried the MSCharts message boards as well?

wizardzz 13-Apr-11 11:44am

Hmm, so using an image is out of the question too?

BobJanova 14-Apr-11 6:01am

I would have to construct the image to look like a line. I think painting the line myself in PostPaint is less hacky than that ;).