On 21/09/14 16:54, Werner Pamler wrote:
To convert image coordinates (pixels within the chart rectangle which
you, indeed, can obtain from the global mouse position converted to the
local chart pixels) to "graph" coordinates you call the chart methods
* "XImageToGraph(x:Integer): Double" for x coordinates,
* "YImageToGraph(y:Integer): Double" for y coordinates, or
* "ImageToGraph(P:TPoint): TDoublePoint" (for both).
(or XGraphToImage() etc for the other direction).
If you do not use axis transformations, then graph coordinates directly
refer to the units of your data. If, on the other hand, axis
transformations are involved (logarithmic axes, multiple axes etc) the
values on the axes may be different from the graph units used in an
internal coordinate system. In this case, you have to link the series to
the axis (by means of the AxisIndexX and AxisIndexY properties) and call
the GraphToAxis or AxisToGraph methods of the AxisTransformation which
is obtained from the method GetTransform of the axis. In your example of
y values the transformation chain would be
mouse point yi --> graph coords by yg := Chart.YImageToGraph(yi) -->
axis coords by ya := Chart.LeftAxis.GetTransform.GraphToAxis(yg).
Here, ya refers to your input data, yi to the pixel data.
But since you don't use transformations YImageToGraph is sufficient.
Great!, here's a screenshot.
Meanwhile I found a way to get the Y pixel value of a point, as you can
see, the "19.60" with yellow background refers to the last point in my
series, and is drawn exactly at the same position of the Close Y Point.
For this I used GetYImgValue( Index of last point ) of the series.
--
Leonardo M. Ramé
http://leonardorame.blogspot.com
--
_______________________________________________
Lazarus mailing list
Lazarus@lists.lazarus.freepascal.org
http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
