Stacked Bar Chart and Marks

[Errol]

Lithology_Chart_Labels.png (12.22 KiB) Viewed 20757 times

I am using a Stacked Bar Chart to represent a lithology column from a well. As an alternative to drawing a legend, I want to be able to put labels directly on the bar chart. However, they always draw in the next lithology, and there does not appear to be a command akin to Marks | Arrows | Distance in the Chart Editor that I could set to a negative value and shift the labels to the centre of the strata. As a result, the labels end up as in the attachment. Any suggestions welcomed.

[Narcís]

Hi Errol,

Yes, you can do this:

Code: Select all

  Series1.Marks.ArrowLength:=-20;

However, there's new MarksOnBar property to achieve what you request:

Code: Select all

  Series1.MarksOnBar:=True;

[Errol]

Narcis

Thanks for your reply. I agree that Marks.ArrowLength can be set to a negative value (I had a code error before) but I am still unable to individually position each mark. The marks offset is always the same and in pixels so that when I zoom the label is no longer in the centre of the bar. The MarksOnBar command worked but put the marks just below each bar rather than in the centre of the bar. The code I use is shown below (Depth is the vertical length of each bar in the stack), and the results are in the attachment.

Clearly I am doing something wrong - what might it be?

Code: Select all

procedure TUnitBarSeries.DrawBar(BarIndex, StartPos, EndPos: Integer);

begin
  // go to dataset record for this index
  TkbmMemTable(self.DataSource).RecNo := BarIndex + 1;
  Brush.Style :=
    TBrushStyle(TkbmMemTable(self.DataSource).FieldByName('Pattern').asInteger); 
  Brush.Color :=
    TColor(TkbmMemTable(self.DataSource).FieldByName('Background').asInteger);
  Marks.Visible := True;
  Marks.ArrowLength :=
    -(TkbmMemTable(self.DataSource).FieldByName('Depth').asInteger) div 2;
  ShowInLegend := False;

  inherited DrawBar(BarIndex,StartPos,EndPos);

end;

Lithology_Chart_Labels002.png (6.82 KiB) Viewed 20717 times

[Narcís]

Hi Errol,

You can use custom marks position, something as the example Yeray Alonso made here.

[Yeray]

Hi Errol,

You can also try with:

Code: Select all

MarksLocation:=mlCenter;

[Errol]

Hi Yeray and Narcis

I am pleased to report that the following code places the marks in the center of each bar, and they remain in place when the chart is zoomed.

Many thanks

Errol

Code: Select all

procedure TQSCollection.InsertGeologicalSeries(aCodeFld,aFld:string);

begin

// code here to load data from dataset into kbmMemTable and calculate depth increments

  SeriesListB.AddObject(sTitle, TUnitBarSeries.Create(Owner));
  iIndex := SeriesListB.IndexOf(sTitle);
  with TUnitBarSeries(SeriesListB.Objects[iIndex]) do
  begin
    AutoMarkPosition := false;
    MultiBar := mbSelfStack;
    CustomBarWidth := 80;
    Marks.Visible := True;
    MarksLocation := mlCenter;
    MarksOnBar := True;

// additional code here

  end;
end;

[Errol]

I am able to place marks in the center of each bar on my stacked bar chart as required, and they stay in the correct place when I pan or zoom the chart. However, if I first drag one of the marks, this appears to lock the marks in the chart (see attachments). The only way to reset is to select another data set. How can I reset the marks to auto as I pan or zoom? I use an OnAfterDraw event to allow marks dragging (see code snippet).

Marks_Dragged_1.png (8.26 KiB) Viewed 20655 times

BarChart_Panned_2.png (7.57 KiB) Viewed 20666 times

Code: Select all

procedure TQSCollection.ChartAfterDraw(Sender: TObject);
var
  DragTool: TDragMarksTool;
begin
  self.Owner.Chart.Tools.Add(TDragMarksTool);
  DragTool.Active := true;
end;

[Yeray]

Hi Errol,

I am able to place marks in the center of each bar on my stacked bar chart as required, and they stay in the correct place when I pan or zoom the chart. However, if I first drag one of the marks, this appears to lock the marks in the chart (see attachments). The only way to reset is to select another data set. How can I reset the marks to auto as I pan or zoom?

Take a look at the answer here:
http://www.teechart.net/support/viewtop ... 033#p34033

I use an OnAfterDraw event to allow marks dragging (see code snippet).

Code: Select all

procedure TQSCollection.ChartAfterDraw(Sender: TObject);
var
  DragTool: TDragMarksTool;
begin
  self.Owner.Chart.Tools.Add(TDragMarksTool);
  DragTool.Active := true;
end;

Is this code working for you? Note the AfterDraw event is fired every time the chart is redrawn. This could be many times if you allow scroll or zoom. In that case, you could be creating more and more TDragMarksTool objects and adding to the chart list of tools. I'd strongly suggest you to move that code to the Form.Create or similar.
Even more, you are defining a variable (DragTool) and not initializing it. I guess the program doesn't crash because the compiler probably detects setting DragTool.Active:=true has little sense and skips it.
Sounds better to me like this:

Code: Select all

procedure TForm1.FormCreate(Sender: TObject);
var
  DragTool: TDragMarksTool;
begin
  Chart1.AddSeries(TBarSeries).FillSampleValues();

  DragTool:=Chart1.Tools.Add(TDragMarksTool) as TDragMarksTool;
  DragTool.Active := true;
end;

[Errol]

Yeray

Thanks for the suggestion regarding the OnAfterDraw event. I inherited this code and hadn't really thought about it, but zooming and panning now works much better since I adopted your suggestions.

I have overcome the "sticky" marks by simply calling Chart.RefreshData on Zoom, UndoZoom and Scroll. However, it would be nice to do this only if a mark has been dragged. Is there a Marks.HasBeenDragged boolean that I can interrogate to see if I need to refresh the chart?

Thanks and regards

Errol

[Yeray]

Hi Errol,

Thanks for the suggestion regarding the OnAfterDraw event. I inherited this code and hadn't really thought about it, but zooming and panning now works much better since I adopted your suggestions.

You're welcome!

I have overcome the "sticky" marks by simply calling Chart.RefreshData on Zoom, UndoZoom and Scroll. However, it would be nice to do this only if a mark has been dragged. Is there a Marks.HasBeenDragged boolean that I can interrogate to see if I need to refresh the chart?

No but you can create you own boolean, initialize it at OnCreate and change it at with the TDragMarksTool OnDraggedMark event. Ie:

Code: Select all

var HasBeenDragged: Boolean;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Chart1.Legend.Visible:=false;
  Chart1.View3D:=false;

  Chart1.AddSeries(TBarSeries).FillSampleValues;

  HasBeenDragged:=false;
  (Chart1.Tools.Add(TDragMarksTool) as TDragMarksTool).OnDraggedMark:=DraggedMark;
end;

procedure TForm1.DraggedMark(Sender:TDragMarksTool; Index:Integer; Button:TMouseButton; Shift: TShiftState; X,Y: Integer);
begin
  HasBeenDragged:=true;
end;

[Errol]

Good afternoon Yeray

Is there any way to left justify and offset marks on a (vertical) stacked bar chart. Properties such as MarksLocation and Marks.TextAlignment seem to control placement in the vertical direction, but I would like to control in the horizontal direction.

Regards

Errol

[Yeray]

Hi Errol,

Here you have an example of custom positioning for the Bar Marks:

Code: Select all

uses Series;

procedure TForm1.FormCreate(Sender: TObject);
var s, i: Integer;
begin
  Chart1.Legend.Visible:=false;
  Chart1.View3D:=false;

  for s:=0 to 4 do
    with Chart1.AddSeries(TBarSeries) as TBarSeries do
    begin
      for i:=0 to 4 do
        Add(25+random*75, 'S' + IntToStr(s) + ', I' + IntToStr(i));

      MultiBar:=mbStacked;
      MarksLocation:=mlCenter;
      MarksOnBar:=true;
    end;

  PlaceMarks;
end;

procedure TForm1.PlaceMarks;
var s, i, tmpSize: Integer;
begin
  Chart1.Draw;

  for s:=0 to Chart1.SeriesCount-1 do
    if Chart1[s] is TBarSeries then
      with Chart1[s] as TBarSeries do
      begin
        for i:=0 to Count-1 do
          with Marks.Positions[i] do
          begin
            Custom:=true;
            LeftTop.X:=CalcXPos(i);

            if MarksLocation=mlEnd then
              LeftTop.Y:=CalcYPos(i)
            else
            begin
              tmpSize:=CalcYSizeValue(YValue[i]);
              if MarksLocation=mlStart then
                LeftTop.Y:=CalcYPos(i)+tmpSize-Marks.Height
              else
                LeftTop.Y:=CalcYPos(i)+(tmpSize div 2)-(Marks.Height div 2);
            end;
          end;
      end;
end;

procedure TForm1.Chart1Scroll(Sender: TObject);
begin
  PlaceMarks;
end;

procedure TForm1.Chart1Zoom(Sender: TObject);
begin
  PlaceMarks;
end;

procedure TForm1.Chart1UndoZoom(Sender: TObject);
begin
  PlaceMarks;
end;

[Yeray]

Hi again Errol,

I added the possibility to have some property to horizontally align the marks in the Bars into the wish list so it can be considered for inclusion in future releases:
http://bugs.teechart.net/show_bug.cgi?id=645

[Errol]

Good morning Yeray

Thanks for all your help on this topic, and I look forward to tools to control basic marks positioning without having to go down the custom positioning route.

I have another problem which puzzles me - I am unable to hide the marks on my self-stacked bar chart. In the code snippet, the font size changes but the Marks.Visible setting is ignored, regardless of the value of the boolean ShowLabelText. Any ideas why this might be occurring?

Best regards

Errol

Code: Select all

  with TUnitBarSeries(SeriesListB.Objects[iIndex]) do
  begin
    MultiBar := mbSelfStack;
    CustomBarWidth := 80;
    MarksLocation := mlCenter;
    MarksOnBar := True;
    Marks.Visible := self.owner.ShowLabelText;
    Marks.Font.Size := self.owner.LabelFont;
    ShowInLegend := false;
    HorizAxis := aBottomAxis;
    VertAxis := aLeftAxis;
...
    active := true;
  end;

[Errol]

Hi Yeray

Can you please abandon my last request regarding hiding marks. I see that the program calls an override version of DrawBar that overrides the Marks visible setting. Sorry about this.

Regards

Errol