tchat point lables (Marks) making my bar charts look weird
lazarus / 39-Graphics

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drkppvch · 2013-12-06 02:45

Hello.
I am quite new to lazarus, 2 weeks.
I have created a charting application for my company database, It
works fine with the exception of one chart lables (Marks) seem to be
screwing the chart max and min val.

Some of the field data that need to be in the lables can be  a bit
long, some of my lables are being overlap with other lables and bars
making them hard to read.

I have change the orientation to be 900 and it works fine for a single
series, but when I have 2 series in the same chart (2 separate
datasources - one cound go from 0 to 20000 and the other series could
go from 0 to -20000) my bar graph goes all weird (it seems brack the
range of the chart and it seem to zoom in in the center of the chart.I
can't zoom out and can't find a way to format it properly.
Is there a way to restrict the lengh of the Marks and do some kind of
word wrap? so all my lables show without having to use 900
Orientation?

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wp · 2013-12-06 11:32

Could you upload a screenshot or, better, a short demo that shows the
issue?

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drkppvch · 2013-12-06 21:57

Hello WP,
Here are some screen soots.
When I chart my individual series they show up fine, as in Tab1 and
Tab2 Images.
When I combine the series I get Tab0 Image.

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wp · 2013-12-06 23:57

Thanks, I understand now. The problem seems to be related to the long
series marks, indeed.

There are several options:
As far as I know, TAChart does not provide automatic wrapping of too-
long labels. But inserted line breaks are respected. In the SysUtils
unit, there is a function WrapText which introduces linebreaks after
at given maximum count of characters. You should loop through your
ChartSource and apply this function to the texts of the ChartItems,
ie.Code: [Select]var i: Integer;
begin
  with Chart1BarSeries1 do
    for i:=0 to Source.Count-1 do
      Source.Item[i]^.Text := WrapText(Source.Item[i]^.Text, 30); 
      // 30 is the max width before a linebreak
...
Charts usually are in "landscape" orientation, therefore, there is
more space along the horizontal than the vertical direction. You could
rotate the bars by 90°, i.e. draw horizontal bars. You'll still need
the WrapText function, but the max width could be a bit longer. To
rotate the bar series, interchange the AxisIndexX and AxisIndexY of
the series, i.e. AxisIndexX gets the index of the chart's left axis,
AxisIndexY correspondingly that of the bottom axis. You could use axis
labels instead of marks labels. For this purpose, you assign the
source of the series to the source of the chart's bottom axis and set
that Style to smsLabel. Unfortunately, I could not find a working
solution with the rotated bars for this case.Don't show any series
marks labels at all, but use the ChartTools to display them as a
MouseOver effect. I have to admit, though, that this solution is not
good for printing... Anyway, you could use a TDatapointHintTool with
UseDefaultHintText = false and OnHint and OnHintPosition event
handlers as follows. You should set the DistanceMode to cdmOnlyX and
GrabRadius to something like the bar width in pixels otherwise the
hint would appear only if the mouse is in the center of the bar (you
could use the BarSeries method GetBarWidth(0) after population of the
series, to make sure if bar width changes when resizing the
chart).Code: [Select]procedure
TForm1.ChartToolset1DataPointHintTool1Hint(ATool: TDataPointHintTool;
  const APoint: TPoint; var AHint: String);
begin
  AHint :=
TChartSeries(ATool.Series).Source.Item[ATool.PointIndex]^.Text;
  // you could also use the WrapText function to introduce line breaks
if that string is too long
end; 

procedure TForm1.ChartToolset1DataPointHintTool1HintPosition(ATool:
TDataPointHintTool;
  var APoint: TPoint);
var
  src: TCustomChartSource;
  r: TRect;
  hintWnd: THintWindow;
  s: String;
  w, h: Integer;
begin
  src := TChartSeries(ATool.Series).Source;

  { Calculate size of hint window - borrowed from TATools }
  s := src.Item[ATool.PointIndex]^.Text;
    // if you used WrapText in the OnHint handler, use is here as
well.
  hintwnd := THintWindow.Create(nil);
  try
    r := hintwnd.CalcHintRect(Chart1.Width, s, nil);
    w := r.Right - r.Left;  // Hint width
    h := r.Bottom - r.Top;  // Hint height - not used here
  finally
    hintwnd.Free;
  end;

  // Center hint horizontally inside bar
  APoint.x := Chart1.XGraphToImage(src.Item[ATool.PointIndex]^.X) - w
div 2;

  // Show hint 30 pixels below bar top
  APoint.y := Chart1.YGraphToImage(src.Item[Atool.PointIndex]^.Y) +
30;

  // Hint coordinates are relative to screen
  APoint := Chart1.ClientToScreen(APoint);
end;

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drkppvch · 2013-12-07 00:50

Hi, Thank you for data.
I am not trying to be a pain, I have been working with lazarus for 2
weeks and I dont know much about coding.
I have added the code you showed me but is not making any difference
to the lables.
Can you please let me know if the way I implemented the code is wrong:
Code: [Select]procedure TForm1.ButtonChartData2Click(Sender: TObject);
var i: Integer;
    j: Integer;
  begin
     begin
  SQLQuery9.Close;
  SQLQuery10.Close;
  Chart2.visible:=False;
    SQLQuery9.Params.ParamByName('StartDate').AsDate :=DateEdit9.Date;
    SQLQuery9.Params.ParamByName('EndDate').AsDate :=DateEdit10.Date;
    SQLQuery9.Params.ParamByName('EnrDate1').AsDate :=DateEdit25.Date;
    SQLQuery9.Params.ParamByName('EnrDate2').AsDate :=DateEdit26.Date;
    SQLQuery9.Params.ParamByName('CourseType').AsString := Edit2.Text;
    SQLQuery10.Params.ParamByName('StartDate1').AsDate
:=DateEdit13.Date;
    SQLQuery10.Params.ParamByName('EndDate1').AsDate
:=DateEdit14.Date;
    SQLQuery10.Params.ParamByName('EnrDate3').AsDate
:=DateEdit15.Date;
    SQLQuery10.Params.ParamByName('EnrDate4').AsDate
:=DateEdit16.Date;
    SQLQuery10.Params.ParamByName('CourseType1').AsString :=
Edit2.Text;
  end;
  IBConnection1.Connected:= True;
  SQLTransaction1.Active:= True;
  SQLQuery9.Open;
  SQLQuery10.Open;
  DBChartSource3.FieldY := 'GP';
  DBChartSource4.FieldY := 'GP';
  Begin
     with Chart2BarSeries1 do
    for i:=0 to Source.Count-1 do
      Source.Item[i]^.Text := WrapText(Source.Item[i]^.Text, 30);
      // 30 is the max width before a linebreak
   Begin
     with Chart2BarSeries2 do
    for j:=0 to Source.Count-1 do
      Source.Item[j]^.Text := WrapText(Source.Item[j]^.Text, 30);
      // 30 is the max width before a linebreak
      Chart2.visible:=True;
  end;
end;
  end;
Thank you, Your help is very much appreciated.

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wp · 2013-12-07 15:36

You seem to be using a DBChartSource. Did not have so much experience
with that so far. But it could be that you cannot modify the items of
that source because they come from the Database. There are two
options:
Every Series has an event OnGetMark which allows you to taylor the
text displayed as series label. Just use the WrapText here:Code:
[Select]procedure TForm1.Chart1BarSeries1GetMark(out AFormattedMark:
String;
  AIndex: Integer);
begin
  AFormattedMark :=
WrapText(Chart1BarSeries1.Source.Item[AIndex]^.Text;
end;Or, if that does not work, add ListChartSources to the form and
copy the data from each DBChartSource to them. Then the data are
permanent, you can do with them whatever you want. You perform the
copy action after the queries are opened, i.e., in your code snippet,
before my code. Then, don't forget to assign the series' Source to the
corresponding ListChartSource (instead of the DBChartSource).
Code: [Select]...
  SQLQuery9.Open;
  SQLQuery10.Open;
  DBChartSource3.FieldY := 'GP';
  DBChartSource4.FieldY := 'GP';

  // These lines copy the data from DBChartSource3/4 to
ListChartSource1/2. Please update
  // to your situation...
  ListChartSource1.CopyFrom(DBChartSource3);
  ListChartSource2.CopyFrom(DBChartSource4);
...

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drkppvch · 2013-12-07 23:08

Thank you, That solved the problem.
Quote    Or, if that does not work, add ListChartSources to the form
and copy the data from each DBChartSource to them. Then the data are
permanent, you can do with them whatever you want. You perform the
copy action after the queries are opened, i.e., in your code snippet,
before my code. Then, don't forget to assign the series' Source to the
corresponding ListChartSource (instead of the DBChartSource).

Code: [Select]

...
  SQLQuery9.Open;
  SQLQuery10.Open;
  DBChartSource3.FieldY := 'GP';
  DBChartSource4.FieldY := 'GP';

  // These lines copy the data from DBChartSource3/4 to
ListChartSource1/2. Please update
  // to your situation...
  ListChartSource1.CopyFrom(DBChartSource3);
  ListChartSource2.CopyFrom(DBChartSource4);
...