TeEngine.InternalDraw.ApplyMaxMinOffsets in conjuction with
Posted: Fri Apr 30, 2010 5:09 pm
In ApplyMaxMinOffsets, you calculate tmpR to see whether to adjust the axis.IMInimum and IMaximum.
In our case, tmpR is always (0,0,0,0). The problem with that is that you are calling Axis.AdjustMaxMinRect(0,0,0,0), probably assuming it will not do anything. But it does. In my case, before this method call, the Axis.MinimumValue is zero, as is the Axis.IMinimum.
However, when calling RecalcAdjustedMinMax, you recalculate IMinimum based on the the "adjusted" IStart value, which is the same as the regular IStart (in my case, pixel 37). However, due to rounding errors that occur when converting from pixel to double, the new IMinimum becomes ~0.002.... This would not be a problem, except that in OnGetNextAxisLabel, I use the Axis.MimimumValue as the basis for my calculations, and return 0 as my first label. When I return 0 as the next label value, DoCustomLabels stops drawing any more labels, because 0<0.002 and LabelInside=False;
see in DoCustomLabels
In short, I made the following changes. Please let me know if they are appropriate and I think you may want to consider them in your release.
In our case, tmpR is always (0,0,0,0). The problem with that is that you are calling Axis.AdjustMaxMinRect(0,0,0,0), probably assuming it will not do anything. But it does. In my case, before this method call, the Axis.MinimumValue is zero, as is the Axis.IMinimum.
However, when calling RecalcAdjustedMinMax, you recalculate IMinimum based on the the "adjusted" IStart value, which is the same as the regular IStart (in my case, pixel 37). However, due to rounding errors that occur when converting from pixel to double, the new IMinimum becomes ~0.002.... This would not be a problem, except that in OnGetNextAxisLabel, I use the Axis.MimimumValue as the basis for my calculations, and return 0 as my first label. When I return 0 as the next label value, DoCustomLabels stops drawing any more labels, because 0<0.002 and LabelInside=False;
see in DoCustomLabels
Code: Select all
LabelInside:=(tmpValue>=(IMinimum-DifFloat)) and
(tmpValue<=(IMaximum+DifFloat));
Code: Select all
procedure ApplyMaxMinOffsets;
var tmpHasOffsets : Boolean;
begin
tmpHasOffsets:=(Axis.MaximumOffset<>0) or (Axis.MinimumOffset<>0);
if tmpHasOffsets then
[b]begin // begin added by dns[/b]
if Axis.Horizontal then ApplyOffsets(tmpR.Left,tmpR.Right)
else ApplyOffsets(tmpR.Bottom,tmpR.Top);
Axis.AdjustMaxMinRect(tmpR);
Axis.CalcRoundScales;
if tmpHasOffsets then
with Axis do
FPosTitle:=InflateAxisPos(FPosLabels,SizeLabels);
[b] end;// end added by dns[/b]
end;Code: Select all
Procedure TChartAxis.AdjustMaxMinRect(Const Rect:TRect);
var tmpMin : Double;
tmpMax : Double;
Procedure RecalcAdjustedMinMax(Pos1,Pos2:Integer);
var OldStart : Integer;
OldEnd : Integer;
Begin
OldStart :=IStartPos;
OldEnd :=IEndPos;
Inc(IStartPos,Pos1);
Dec(IEndPos,Pos2);
IAxisSize:=IEndPos-IStartPos;
tmpMin:=CalcPosPoint(OldStart);
tmpMax:=CalcPosPoint(OldEnd);
end;
Begin
[b] // added by dns
if (rect.Left=0) and (rect.Top=0) and (rect.right=0) and (rect.Bottom=0) then
exit;[/b]
with Rect do
if Horizontal then ReCalcAdjustedMinMax(Left,Right)
else ReCalcAdjustedMinMax(Top,Bottom);
InternalCalcPositions;
IMaximum:=tmpMax;
IMinimum:=tmpMin;
if IMinimum>IMaximum then
SwapDouble(IMinimum,IMaximum);
InternalCalcRange;
end;
I am just wondering if that could cause other problems.
. Best I can do is what I have done, is walk you through the code path, so you can see that it is potentially possible if CalcPosPoint returns a slightly different value ....