Resizable panes again

[kapibara]

I found the "dangling" divider happens only for panes added at the bottom, not top.

This divider appears to belong to the neighbor pane, which doesn't need divider anymore when the pane below is deleted. Hmm, how to best delete a divider that belongs to another pane than the deleted one?

[kapibara]

Turned out the Divider was not dangling. It just belonged to the pane above and seemed to be left over since the neighboring pane below was deleted.

I solved it in the new version by introducing a RemoveDivider procedure in TChartBox.
So thats some progress, but here's a situation I'd like to handle next:

Pane 1 is added topmost
Pane 2 is added bottommost
Pane 3 is added bottommost
Pane 4 is added topmost

But remove Pane 4 and Pane 3, and the party is over and panes misalign.
If possible, it should be solved in a way that allows for a pane between other panes to be selected and deleted.

[kapibara]

I think maybe I get it now, how it should work.

Except how to get a pane by clicking the chart.

[wp]

I think maybe I get it now, how it should work.

Except how to get a pane by clicking the chart.

Good that you found it yourself.

For finding the clicked pane, you could add a TUserDefinedTool to the ChartBox and implement a handler for the OnAfterMouseDown event. Here you get the X,Y coordinates of the clicked point in image coordinates. Convert it to graph coordinates (Chart.ImageToGraph) which is the unit system in which the pane borders are defined in the MinValue and MaxValue of the axis tranform. Then, iterate over all panes and check whether the clicked graph point is within the MinValue-to-MaxValue range of the pane's axis transform.

[kapibara]

Well, it's getting closer, but still the problem that panes get incorrect size after deleting one of them. I don't understand how to fix it.

I wrote the procedure AdjustPanesAfterDelete to see what happens if to keep the default min/max values for pane 0 and up. The adjustment is shown in the legend after deleting a pane. You can just comment it out.

[kapibara]

I changed TChartPane's destructor how to remove transformations from a pane. Hope its OK to remove them like this?

Code: Pascal  [Select][+][-]

1.   destructor TChartPane.Destroy;
2.   ..
3.     AxisTransform.Free;
4.     FAxis.Transformations.Free;
5.     FAxis.Transformations:= NIL;
6.  
7.     FAxis.Free;
8.   ..
9.   end;

[wp]

Yes.

Just added this to the wiki: https://wiki.lazarus.freepascal.org/TAChart_Runtime_FAQ#How_to_remove_an_axis_transformation.3F

[kapibara]

Thanks.
It seems that my problem with the axes is because when a pane is deleted an axis is removed, and then the axis indexes of the remaining panes dont match the AxisIndexY of the LineSeries. What to do?

I added some panels to view whats going on inside.

Edit: If the panes are added at the bottom, they can be deleted and axes still works. Only adding at the top causes a problem.

[wp]

It seems that my problem with the axes is because when a pane is deleted an axis is removed, and then the axis indexes of the remaining panes dont match the AxisIndexY of the LineSeries. What to do?

Good catch. The AxisIndex seems to be a bad concept for identification of an axis in such an application...

Anyway, so when you delete an axis why don't you iterate over all series and decrement their AxisIndexY if it is greater than the Index of the deleted axis? In fact, you already have it in TChartBox.RemovePane, but commented it out. Just store the axisindex before deleting the pane (--> pane_axisindex), remove the comment slashes and add an "if AxisIndexY > pane_axisindex":

Code: Pascal  [Select][+][-]

1. procedure TChartBox.RemovePane(APaneIndex: Integer);
2. var
3.   ...
4.   pane_axisindex: Integer;  
5. begin
6.   ...
7.   pane:= TChartPane(FPaneList[APaneIndex]);
8.   pane_axisindex := pane.Axis.Index;                             // <--- new
9.   //When deleting the bottom-most pane (has no divider),
10.   //the divider of its neighbor must be removed instead.
11.   if (APaneIndex = 0) and (PaneCount > 1) then
12.   begin
13.     divider_pane:= TChartPane(FPaneList[APaneIndex +1]);
14. //    divider_pane.axis.Visible:=false;
15.     divider_pane.RemoveDivider;
16.     pane.Free;  //Also removes series from chart
17.     FPaneList.Delete(APaneIndex);
18.     //AdjustPanesAfterDelete;
19.     for i:=0 to FChart.SeriesCount -1 do begin                  // <-- uncommented
20.       if FChart.Series[i] is TLineSeries then
21.       with FChart.Series[i] as TLineSeries do
22.         if AxisIndexY > pane_axisIndex then                    // <--- new
23.           AxisIndexY:= AxisIndexY -1;
24.     end;
25.   end
26.  

[kapibara]

That addition made it possible to remove panes both from the top and from the bottom with axes working as they should. Super!