TAChart Bevel
lazarus / 55-TAChart

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fpcoder · 2013-09-22 20:57

For the Chart I would like to set:

BevelInner:= None
BevelOuter:= None

Is it possible somehow?

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wp · 2013-09-22 21:48

At first, I don't understand what you mean: Setting both the inner and
the outer bevels to none results in "no bevel" - and that's the
default. Anyway, let me explain here some possibilities to draw bevels
with TAChart.

Unlike Delphi's TeeChart there are no BevelInner and BevelOuter
properties. But you're not lost...

If you want a bevel around the outer chart border you could go the
easy way and put the chart client-aligned into a Panel where you have
access to these properties. Or you could use a separate TBevel
component around the chart.

Alternatively you could also modify the drawing procedure of the chart
itself which would have the advantage that if you would save the chart
to a file it would have the bevel also. And: you can also draw a bevel
instead of the axis lines.

There are two (or four) events you could consider:
Before/AfterDrawBackground is called before/after the background of
the entire control is painted. The BeforeDrawBackground event has a
parameter which allows you to turn off the default drawing by setting
ADoDefaultDrawing = false. You could even paint a background image or
gradient this way. For a simple "lowered" bevel you could use the
following procedure:

Code: [Select]procedure TForm1.Chart1AfterDrawBackground(ASender:
TChart; ACanvas: TCanvas;
  const ARect: TRect);
begin
  with ACanvas do begin
    Pen.Color := clBtnShadow;
    MoveTo(ARect.Left, ARect.Bottom - 1);
    LineTo(ARect.Left, ARect.Top);
    LineTo(ARect.Right - 1, ARect.Top);
    Pen.Color := clBtnHighlight;
    LineTo(ARect.Right - 1, ARect.Bottom - 1);
    LineTo(ARect.Left , ARect.Bottom - 1);
  end;
end;   

There is another pair of procedures, Before/AfterDrawBackWall which
gets called when painting the area enclosed by the axes. An example
for an "etched" bevel (like for a panel with BevelOuter=bvLowered and
BevelInner=bvRaised) is like this:

Code: [Select]procedure TForm1.Chart1BeforeDrawBackWall(ASender:
TChart; ACanvas: TCanvas;
  const ARect: TRect; var ADoDefaultDrawing: Boolean);
var
  R: TRect;
begin
  ADoDefaultDrawing := false;
  with ACanvas do begin
    Pen.Color := clBtnShadow;
    MoveTo(ARect.Left, ARect.Bottom - 1);
    LineTo(ARect.Left, ARect.Top);
    LineTo(ARect.Right - 1, ARect.Top);
    MoveTo(ARect.Right - 2, ARect.Top + 1);
    LineTo(ARect.Right - 2, ARect.Bottom - 2);
    LineTo(ARect.Left + 1, ARect.Bottom - 2);
    Pen.Color := clBtnHighlight;
    MoveTo(ARect.Left + 1, ARect.Bottom - 2);
    LineTo(ARect.Left + 1, ARect.Top + 1);
    LineTo(ARect.Right - 2, ARect.Top + 1);
    MoveTo(ARect.Right - 1, ARect.Top);
    LineTo(ARect.Right - 1, ARect.Bottom - 1);
    LineTo(ARect.Left, ARect.Bottom - 1);
  end;
end;

The code for these bevel drawing procedures is borrowed from the Paint
method of TBevel (unit ExtCtrls). See the attached screenshot for the
result.

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fpcoder · 2013-09-22 22:59

Interesting possibilities, might be handy in the future. At the moment
there should be no bevel. I had simply put the Chart on a TPanel and
forgotten about it. So it was this Panels bevel I tried to get rid of
from TACharts properties. 


Quote from: wp on September 22, 2013, 11:48:36 pmIf you want a bevel
around the outer chart border you could go the easy way and put the
chart client-aligned into a Panel where you have access to these
properties. Or you could use a separate TBevel component around the
chart.