[Lazarus] TAChart marks on mouseoverpoint

[Alexander Klenin]

On Tue, Sep 22, 2009 at 21:36, Andrea Mauri <andrea.mauri.75 at gmail.com> wrote:

> 1. If the point is on the border of the chart the mark is not fully visible.

You can increase Margins.Left and Margins.Right properties to avoid that.

> 2. I have charts with a lot of points, the marks are shown below the points,
> so often the marks are not fully visible.

Well, there is only so much pixels on the chart.
If you put enough marks, they will overlap sooner or later.
Do you have some concrete proposal to reduce overlapping?

> I have also another question. I need to draw a unitary circle on a chart.
> Here the function I use:

[skip]

> Anyway I don't know when/where I have to call this procedure in order to be
> sure that the unitary circle is drawn upon the chart. If I anchor the chart
> on the form and I put my procedure on the resizeform event I can see the
> circle for a while and then it immediately disappears.
> So how can I draw shapes on a chart?

Since r21827 you can use TUserDrawnSeries for that.
See demo/func/funcdemo project for an example.

> I have to put unitary circle but also
> other things, such as rays from the origin of the chart (0, 0) to all the
> points in a serie.

For this you need to create your own series class by inheriting
TCustomChartSeries, TChartSeries or TLineSeries and overriding Draw method.
Do you mean to create something like
http://www.steema.com/products/teechart/screenshots/infopoint3dpolaradar.htm ?
If so, you are very welcome to contribute your code back to the TAChart ;-)

-- 
Alexander S. Klenin