From 5fb72b751ababdba6dd73b96e4b19d5ee4369ccb Mon Sep 17 00:00:00 2001
From: wp <wp.no-reply@lazarus-ide-org>
Date: Mon, 4 Mar 2019 17:34:41 +0000
Subject: [PATCH] TAChart: Fix TFitSeries extent calculation to include the
 fitted curve. Issue #35183, patch by Marcin Wiazowski.

git-svn-id: trunk@60585 -
---
 components/tachart/tafuncseries.pas | 25 +++++++++-
 components/tachart/tagraph.pas      | 71 ++++++++++++++++++++---------
 2 files changed, 73 insertions(+), 23 deletions(-)

diff --git a/components/tachart/tafuncseries.pas b/components/tachart/tafuncseries.pas
index b0379363ce..b503b6be2d 100644
--- a/components/tachart/tafuncseries.pas
+++ b/components/tachart/tafuncseries.pas
@@ -1601,7 +1601,7 @@ procedure TFitSeries.CalcXRange(out AXMin, AXMax: Double);
 var
   ext: TDoubleRect;
 begin
-  with Extent do begin
+  with Source.BasicExtent do begin
     ext.a := AxisToGraph(a);
     ext.b := AxisToGraph(b);
   end;
@@ -1793,8 +1793,31 @@ begin
 end;
 
 function TFitSeries.Extent: TDoubleRect;
+var
+  de : TIntervalList;
 begin
   Result := Source.BasicExtent;
+  if IsEmpty or (not Active) then exit;
+
+  if ParentChart = nil then exit;
+  ParentChart.ScaleNeedsSecondPass := True;
+  if not ParentChart.ScaleValid then exit;
+
+  if FAutoFit then ExecFit;
+
+  if (FState = fpsValid) and (FErrCode = fitOK) then begin
+    de := PrepareIntervals;
+    try
+      with TDrawFuncHelper.Create(Self, de, @Calculate, Step) do
+        try
+          CalcAxisExtentY(Result.a.X, Result.b.X, Result.a.Y, Result.b.Y);
+        finally
+          Free;
+        end;
+    finally
+      de.Free;
+    end;
+  end;
 end;
 
 function TFitSeries.FitParams: TDoubleDynArray;
diff --git a/components/tachart/tagraph.pas b/components/tachart/tagraph.pas
index 3c15013fbd..1e7e2dece4 100644
--- a/components/tachart/tagraph.pas
+++ b/components/tachart/tagraph.pas
@@ -1,4 +1,4 @@
-{
+{
  /***************************************************************************
                                TAGraph.pas
                                -----------
@@ -233,6 +233,8 @@ type
     FOnExtentChanging: TChartEvent;
     FPrevLogicalExtent: TDoubleRect;
     FScale: TDoublePoint;    // Coordinates transformation
+    FScaleValid: Boolean;
+    FScaleNeedsSecondPass: Boolean;
     FSavedClipRect: TRect;
     FClipRectLock: Integer;
 
@@ -359,6 +361,8 @@ type
     function XImageToGraph(AX: Integer): Double; inline;
     function YGraphToImage(AY: Double): Integer; inline;
     function YImageToGraph(AY: Integer): Double; inline;
+    property ScaleValid: Boolean read FScaleValid;
+    property ScaleNeedsSecondPass: Boolean read FScaleNeedsSecondPass write FScaleNeedsSecondPass;
 
   public
     procedure LockClipRect;
@@ -591,6 +595,7 @@ begin
   FOffset.Y := rY.CalcOffset(FScale.Y);
   rX.UpdateMinMax(@XImageToGraph);
   rY.UpdateMinMax(@YImageToGraph);
+  FScaleValid := True;
 end;
 
 procedure TChart.Clear(ADrawer: IChartDrawer; const ARect: TRect);
@@ -686,6 +691,8 @@ begin
   FGUIConnectorListener := TListener.Create(@FGUIConnector, @StyleChanged);
 
   FScale := DoublePoint(1, -1);
+  FScaleValid := False;
+  FScaleNeedsSecondPass := False;
 
   Width := DEFAULT_CHART_WIDTH;
   Height := DEFAULT_CHART_HEIGHT;
@@ -878,32 +885,49 @@ end;
 procedure TChart.Draw(ADrawer: IChartDrawer; const ARect: TRect);
 var
   ldd: TChartLegendDrawingData;
+  tmpExtent: TDoubleRect;
+  tries: Integer;
   s: TBasicChartSeries;
   ts: TBasicChartToolset;
 begin
-  Prepare;
-
-  ADrawer.SetRightToLeft(BiDiMode <> bdLeftToRight);
-
-  FClipRect := ARect;
-  with MarginsExternal do begin
-    FClipRect.Left += Left;
-    FClipRect.Top += Top;
-    FClipRect.Right -= Right;
-    FClipRect.Bottom -= Bottom;
-  end;
-
-  with ClipRect do begin
-    FTitle.Measure(ADrawer, 1, Left, Right, Top);
-    FFoot.Measure(ADrawer, -1, Left, Right, Bottom);
-  end;
-
   ldd.FItems := nil;
-  if Legend.Visible then
-    ldd := PrepareLegend(ADrawer, FClipRect);
-
   try
-    PrepareAxis(ADrawer);
+    Prepare;
+
+    ADrawer.SetRightToLeft(BiDiMode <> bdLeftToRight);
+
+    for tries := 1 to 2 do
+    begin
+      FClipRect := ARect;
+      with MarginsExternal do begin
+        FClipRect.Left += Left;
+        FClipRect.Top += Top;
+        FClipRect.Right -= Right;
+        FClipRect.Bottom -= Bottom;
+      end;
+
+      with ClipRect do begin
+        FTitle.Measure(ADrawer, 1, Left, Right, Top);
+        FFoot.Measure(ADrawer, -1, Left, Right, Bottom);
+      end;
+
+      if Legend.Visible then
+        ldd := PrepareLegend(ADrawer, FClipRect);
+
+      PrepareAxis(ADrawer);
+
+      if not FScaleNeedsSecondPass then break;
+
+      if FIsZoomed then break; // GetFullExtent() has not been called in this case,
+                               // in the Prepare() call above
+      tmpExtent := GetFullExtent; // perform second pass
+      if tmpExtent = FLogicalExtent then break; // second pass hasn't changed the extent
+
+      // as in the Prepare() call
+      FLogicalExtent := tmpExtent;
+      FCurrentExtent := FLogicalExtent;
+    end;
+
     if Legend.Visible and not Legend.UseSidebar then
       Legend.Prepare(ldd, FClipRect);
 
@@ -1470,6 +1494,9 @@ var
   a: TChartAxis;
   s: TBasicChartSeries;
 begin
+  FScaleValid := False;
+  FScaleNeedsSecondPass := False;
+
   for a in AxisList do
     if a.Transformations <> nil then
       a.Transformations.SetChart(Self);