Tutorial on ColorMapSeries and Extent History
lazarus / 55-TAChart

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wp · 2012-10-27 22:19

Finally I managed to complete the new TAChart tutorial on
ColorMapSeries and zooming/panning/extent history. It was fun working
with the Mandelbrot set...

Here is the link: http://wiki.lazarus.freepascal.org/TAChart_Tutorial:
_ColorMapSeries,_Zooming

When you run the tutorial project you may notice that the extent
history does not work for panning. It should, and it is working in the
debugger, but I did not find a reason for it at runtime. Maybe
somebody has an idea...

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Ask · 2012-10-28 19:17

Quoteextent history does not work for panningThis is because you tried
to remember logical extent in mouse-up event.
However, since panning happens on mouse move, the extent has already
been changed several time by the moment of mouse-up.

So, you have to either use mouse-down event or prevent the tool from
working on mouse-move (via OnBeforeMouseMove event).

I have made this and a few other minor changes, and committed the
tutorial
source as tutorials\mandelbrot in r39179-39180.

The upside is that it is now easier to use, but the downside is that
it must be synchronized with wiki contents.
If you want, I'll try to require commit rights for you so that you
could
update tutorials yourself.

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wp · 2012-10-28 22:04

Quotesince panning happens on mouse move, the extent has already been
changed several time by the moment of mouse-up.Good explanation. I'll
update the tutorial text.

QuoteIf you want, I'll try to require commit rights for you so that
you could update tutorials yourself.That would be nice.