TAChart: Extract TAxisCoeffHelper object

git-svn-id: trunk@27068 -

components/tachart/tachartaxis.pas

@@ -232,6 +232,23 @@ type
       read FOnVisitSources write FOnVisitSources;
   end;
 
+  TAxisConvFunc = function (AX: Integer): Double of object;
+
+  { TAxisCoeffHelper }
+
+  TAxisCoeffHelper = object
+    FAxis: TChartAxis;
+    FImageLo, FImageHi, FMarginLo, FMarginHi: Integer;
+    FLo, FHi: Integer;
+    FMin, FMax: PDouble;
+    constructor Init(
+      AAxis: TChartAxis; AImageLo, AImageHi, AMarginLo, AMarginHi: Integer;
+      AMin, AMax: PDouble);
+    function CalcScale(ASign: Integer): Double;
+    function CalcOffset(AScale: Double): Double;
+    procedure UpdateMinMax(AConv: TAxisConvFunc);
+  end;
+
   function SideByAlignment(
     var ARect: TRect; AAlignment: TChartAxisAlignment; ADelta: Integer): Integer;
   function TransformByAxis(
@@ -838,6 +855,44 @@ begin
   a.FAlignment := AXIS_INDEX[AIndex];
 end;
 
+{ TAxisCoeffHelper }
+
+constructor TAxisCoeffHelper.Init(
+  AAxis: TChartAxis; AImageLo, AImageHi, AMarginLo, AMarginHi: Integer;
+  AMin, AMax: PDouble);
+begin
+  FAxis := AAxis;
+  FImageLo := AImageLo;
+  FImageHi := AImageHi;
+  FMarginLo := AMarginLo;
+  FMarginHi := AMarginHi;
+  FMin := AMin;
+  FMax := AMax;
+  FLo := FImageLo + FMarginLo;
+  FHi := FImageHi + FMarginHi;
+end;
+
+function TAxisCoeffHelper.CalcScale(ASign: Integer): Double;
+begin
+  if (FMax^ = FMin^) or (Sign(FHi - FLo) <> ASign) then exit(1.0);
+  if (FAxis <> nil) and FAxis.Inverted then
+    Exchange(FLo, FHi);
+  Result := (FHi - FLo) / (FMax^ - FMin^);
+end;
+
+function TAxisCoeffHelper.CalcOffset(AScale: Double): Double;
+begin
+  Result := (FLo + FHi) / 2 - AScale * (FMin^ + FMax^) / 2;
+end;
+
+procedure TAxisCoeffHelper.UpdateMinMax(AConv: TAxisConvFunc);
+begin
+  FMin^ := AConv(FImageLo);
+  FMax^ := AConv(FImageHi);
+  if (FAxis <> nil) and FAxis.Inverted then
+    Exchange(FMin^, FMax^);
+end;
+
 procedure SkipObsoleteAxisProperties;
 const
   TRANSFORM_NOTE = 'Obsolete, use Transformations instead';

components/tachart/tagraph.pas

@@ -521,45 +521,21 @@ begin
 end;
 
 procedure TChart.CalculateTransformationCoeffs(const AMargin: TRect);
-type
+var
-  TConvFunc = function (AX: Integer): Double of object;
+  rX, rY: TAxisCoeffHelper;
-
-  procedure CalcOneCoord(
-    AAxis: TChartAxis; AConv: TConvFunc; var AGraphMin, AGraphMax: Double;
-    AImageLo, AImageHi, AMarginLo, AMarginHi, ASign: Integer;
-    out AScale, AOffset: Double);
-  var
-    lo, hi: Integer;
-  begin
-    lo := AImageLo + AMarginLo;
-    hi := AImageHi + AMarginHi;
-
-    if (AGraphMax = AGraphMin) or (Sign(hi - lo) <> ASign) then begin
-      AScale := 1;
-      AOffset := 0;
-      exit;
-    end;
-
-    if (AAxis <> nil) and AAxis.Inverted then
-      Exchange(lo, hi);
-
-    AScale := (hi - lo) / (AGraphMax - AGraphMin);
-    AOffset := hi - AScale * AGraphMax;
-    AGraphMin := AConv(AImageLo);
-    AGraphMax := AConv(AImageHi);;
-    if (AAxis <> nil) and AAxis.Inverted then
-      Exchange(AGraphMin, AGraphMax);
-  end;
-
 begin
-  CalcOneCoord(
+  rX.Init(
-    BottomAxis, @XImageToGraph, FCurrentExtent.a.X, FCurrentExtent.b.X,
+    BottomAxis, FClipRect.Left, FClipRect.Right, AMargin.Left, -AMargin.Right,
-    FClipRect.Left, FClipRect.Right, AMargin.Left, -AMargin.Right, 1,
+    @FCurrentExtent.a.X, @FCurrentExtent.b.X);
-    FScale.X, FOffset.X);
+  rY.Init(
-  CalcOneCoord(
+    LeftAxis, FClipRect.Bottom, FClipRect.Top, -AMargin.Bottom, AMargin.Top,
-    LeftAxis, @YImageToGraph, FCurrentExtent.a.Y, FCurrentExtent.b.Y,
+    @FCurrentExtent.a.Y, @FCurrentExtent.b.Y);
-    FClipRect.Bottom, FClipRect.Top, -AMargin.Bottom, AMargin.Top, -1,
+  FScale.X := rX.CalcScale(1);
-    FScale.Y, FOffset.Y);
+  FScale.Y := rY.CalcScale(-1);
+  FOffset.X := rX.CalcOffset(FScale.X);
+  FOffset.Y := rY.CalcOffset(FScale.Y);
+  rX.UpdateMinMax(@XImageToGraph);
+  rY.UpdateMinMax(@YImageToGraph);
 end;
 
 procedure TChart.Clean(ACanvas: TCanvas; ARect: TRect);
@@ -637,14 +613,14 @@ begin
   end;
 
   AxisList.PrepareGroups;
-  AxisList.Measure(ACanvas, FCurrentExtent, true, axisMargin);
+  AxisList.Measure(ACanvas, CurrentExtent, true, axisMargin);
   axisMargin[calLeft] := Max(axisMargin[calLeft], Depth);
   axisMargin[calBottom] := Max(axisMargin[calBottom], Depth);
   for a := Low(a) to High(a) do
     SideByAlignment(FClipRect, a, -axisMargin[a]);
 
   CalculateTransformationCoeffs(GetMargins(ACanvas));
-  AxisList.Measure(ACanvas, FCurrentExtent, false, axisMargin);
+  AxisList.Measure(ACanvas, CurrentExtent, false, axisMargin);
 
   // Background
   with ACanvas do begin
@@ -657,7 +633,7 @@ begin
       Rectangle(Left, Top, Right + 1, Bottom + 1);
   end;
 
-  AxisList.Draw(ACanvas, FCurrentExtent, Self, FClipRect);
+  AxisList.Draw(ACanvas, CurrentExtent, Self, FClipRect);
   // Z axis
   if Depth > 0 then
     with FClipRect do