I am working on allowing multiple axes in TAChart (issue 0013832). I am
working with the idea to have multiple x and multiple y axes for line
series.
At this moment the axes do not have minimum and maximum values (I've
submitted issue 0015371). As far as I know, the minimum and maximum
values moved to the chart (extent) recently. The axes have an offset and
scale. The offset and scale however are quite difficult to use.
To allow multiple axes, a line series should know to which axes
(vertical and horizontal) it must be drawn. The axis is then reponsible
for scaling a point allong its length. However, only the chart knows how
big the chart is on the screen and thus must be responsible for scaling
the point to the screen. So, the axis must know its minimum and maximum
values to allow scaling. The output of a scaling function in the axis
would be a value betwen 0 and 1, which would be the input for the
scaling function of the chart.
I don't know the impact of the above on the working of TAChart. Does it
have impact on other chart types, etc? When reasoning, I think it would
only have impact on vertical scaling of bar series and on the horizontal
and vertical scaling of line series. Before I continue solving my own
issues, I would like to know if I am on the right track. Why did the
minimum and maximum values move from the axis to the chart? Are my ideas
correct and should the scaling be distributed between axis and chart? Do
we seek compatibility with the Delphi chart component? How would that
compatibiltiy be guaranteed?
Regards,
Albert
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