Calculating size of a point

[Mike Jones]

I have a need to calculate the size of points in a Steema.TeeChart.Styles.Points series. I found that I can set the horizontal and verticle sizes and it will create an oval shaped point.

The points I am generating are evenly spaced. There is a horizontal spacing and a vertical spacing in the 2D chart that I am generating.

I want to calculate the horizontal and vertical sizes based on the following equation:

Width of point = ((width of chart)/(X max - X min)) * X increment

similarly with the vertical

Height of point = ((Height of chart)/(Y max - Y min)) * Y increment

I am setting Steema.TeeChart.Styles.Points.Pointer.HorizSize and Steema.TeeChart.Styles.Points.Pointer.VertSize

My questions are:

1. How do I get the Height and Width of the Chart in pixels?

2. Is there an event that is raised if the chart is zoomed? I will have to recalculate my point size if this occurs.

[Christopher]

Hello!

1. How do I get the Height and Width of the Chart in pixels?

tChart1.Chart.ChartRect will give you the rectangle which is bounded by the chart axes (the area in which the series is painted) and tChart1.Chart.ChartBounds will give you the rectangle within which the entire chart is painted.

2. Is there an event that is raised if the chart is zoomed? I will have to recalculate my point size if this occurs.

Yes, indeed, you can use the TChart.Zoomed event.

[Mike Jones]

Using the Zoomed event seems to work.

I need to recalculate the point sizes when the control is resized as well. Using the Resize event does not work for me, because while in the Resize event, the values in ChartRect are the old values before the resize. I need the sizes after it has resized.

Can you help me identify how to either get an event after the resize is complete, or find the new sizes while in the Resize event?

[Christopher]

Hello!

Have you tried moving your code into the TChart.BeforeDraw event?

[Mike Jones]

I tried BeforeDrawSeries and that did not work for me. I overlooked the BeforeDraw event. That seems to address my needs.


Thanks.

[Mike Jones]

In a simple example series of Steema.Styles.Points looks something like

0.0,1.0
2.0,1.0
4.0,1.0
6.0,1.0
8.0,1.0
10.0,1.0

When these points are shown in a chart the bottom axis goes from -0.8 to +10.8. The major tick marks are 2, 4, 6, 8, 10. When I do a quick watch on the Bottom axis, I can see the internal values being used and that is where I see the values -0.8 to +10.8.

I am trying to calculate programatically the width (and ultimately the height) of a point so that the edges of the point just touch.

I was doing the followng calculation

point width = (chart1.ChartRect.Width) * Increment / (XValues.Maximum - XValues.Minimum)

Where Increment = 2.0, which is the distance between my points along the Bottom Axis.

Using this calculation I am not getting the edges to touch. It seems to be significantly short. I am concerned that when I calculate my point width the the chart is autmatically adjusting the axis and this the value I get chart1.ChartRect.Width is not accurate for my calculations.

Do you have any suggestions?

[Mike Jones]

I never received a response to my previous question.

After further research it looks like I might be able to use the TChart Control's ability to autosize. I might have to calculate the sizing. I would like some feedback on my issues.

Thanks.

[Christopher]

Hello,

After further research it looks like I might be able to use the TChart Control's ability to autosize. I might have to calculate the sizing. I would like some feedback on my issues.

It would be greatly appreciated if you could upload a simple example which we can run "as-is" of the issues you have to:
http://www.steema.net/upload/

Please let us know when you've posted something.

[Mike Jones]

When you run the sample project, notice that the point sizes will change. The goal is to make them large enough so the vertical and horizonal edges just touch. Sometimes they willl overlap, other times there will be gaps.

Any suggestions to my calculations are welcome.

[Mike Jones]

I uploaded a VS2005.NET project a couple of days ago. Can you confirm that you received it and when I might expect a response?

Thanks

[Christopher]

Hello!

As you can see here:
http://www.steema.com/support/public_hols2007.html

yesterday was a public holiday for us at Steema which may explain the slight delay. We'll get back to you as soon as we have something for you!