Locating ends of a DLine in Pixels.

[tirby]

Hi,

I've drawn a DrawLine on my graph, so now how do I find the ends in pixels?

I'm pretty sure this is easy, I'm just not seeing it...

Thanks!

[Yeray]

Hi,

Being ChartTool1 your TDrawLineTool, and being the line you want to check the one with index 0, the positions in axis values are:

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ChartTool1.Lines[0].StartPos.X
ChartTool1.Lines[0].StartPos.Y
ChartTool1.Lines[0].EndPos.X
ChartTool1.Lines[0].EndPos.Y

Then, you should use the axes CalcPosValue function to transform axis values to pixels. Ie:

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XStartPixel:=Chart1.Axes.Bottom.CalcPosValue(ChartTool1.Lines[0].StartPos.X);
YStartPixel:=Chart1.Axes.Left.CalcPosValue(ChartTool1.Lines[0].StartPos.Y);

[tirby]

Thanks Yeray!

[tirby]

Ok,

The above code does give me the info I need, however, it doesn't seem to give me the info I need when the Zoom function has been used.

When zooming in on an end of the DLine, the resulting view is expanded, but the CalcXPosValue(a) and CalcYPosValue(a) returns the same pixel value(s) as when the view is not Zoomed.

I can't figure out what parameter(s) are changed when the Zoom function is used.
Is there a "ZoomXFactor, ZoomYFactor" I can access?
Can you assist?

Thanks!

[Yeray]

Hi,

Try forcing a chart repaint:

Code: Select all

TChart1.Environment.InternalRepaint

at the beginning of the OnZoom event. After it, the chart should have updated its internal values and the Calc* functions should work fine then.

[tirby]

Thanks Yeray!
That solved the problem.