[SOLVED]Explanation of some TAGraph parameters
lazarus / 55-TAChart

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mtanner · 2015-10-31 22:17

I'm having trouble finding out what some of the TAGraph parameters
mean. I've searched a number of sources but cannot find any
straightforward explanation of some parameters. I find this a general
problem with TAGraph for anything beyond the most common parameters.
At the moment  I'm trying to use marks on a TBarSeries in a particular
way and wish to exercise detailed control over the marks.  Could
someone please tell me what the following parameters do. I'd really
like a complete list, but the following would be a good start. I don't
want or need a mini tutorial on using marks, I just want a simple
specific definition of the following.

For Marks.Arrow
  Baselength
  Length
  Width
For Marks
  Distance
  Frame
  Linkpen

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wp · 2015-10-31 23:38

TAGraph? I think you mean TAChart...

In this case: why don't you just play with it? Learning by doing is
much more efficient than learning by reading.

Maybe you did not make the step yet to see the marks at a barseries?
Open the folder "tutorials\barseries\vertical bars" and load the demo
project. Select the red bar series, for example, go to Marks.Style.
This shows smsNone - that's why you don't see any marks at the moment.
Pick smsValue. This adds marks to the bars showing the y value. To see
the arrow change the color of the linepen (white is barely visible on
the silver background) and set the arrow's Visible to true. Now you
can play with all the parameters which you don't understand - there is
immediate response in the object inspector.

Of course I could answer your question directly, but I want you to do
this experiment first.

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wp · 2015-11-01 11:59

I don't see why you don't want to change Marks.Arrow.Length in the
Object Inspector to see what happens in the chart.

But anyway, I don't want to argue on that.
Marks.LinkPen: a set of properties defining the connecting line
between the bar and the marks box (color, line style, visible or
not)Marks.Distance: distance between the top of the bar and the bottom
of the marks boxMarks.Frame: a set of properties defining the frame of
the marks box (color, visible or not etc.)Marks.Arrow: if Visible=true
an arrow is drawn at the end (bar side) of the marks connecting
line.Marks.Arrow.Width, .Length: what can I say? the width and length
of the arrow. Both define the opening angle of the arrow. Make width
smaller, or length larger, to get a narrower
arrow.Marks.Arrow.Baselength: hard to describe... (that's why I wanted
you to check it yourself, it much easier for you to see than for me to
describe...): Partly fills the arrow head if > 0. If equal to Length
then the beginning of the arrow is cut off at 90°, i.e. the arrow is a
filled triangle.See also the official documentation of Marks and
Arrows. I added an image demonstrating various arrow head types
created by different settings of Arrow.Baselength.