From edd774a031f68ca30ab9894dd4bfaf60d1db0d1e Mon Sep 17 00:00:00 2001
From: ask <ask@lazarus-ide.org>
Date: Sun, 8 Aug 2010 06:37:15 +0000
Subject: [PATCH] TAChart: Add TBarSeries.ZeroLevel property

git-svn-id: trunk@27031 -
---
 components/tachart/taseries.pas | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/components/tachart/taseries.pas b/components/tachart/taseries.pas
index 02b64780a1..46fec7957d 100644
--- a/components/tachart/taseries.pas
+++ b/components/tachart/taseries.pas
@@ -74,12 +74,15 @@ type
     FBarBrush: TBrush;
     FBarPen: TPen;
     FBarWidthPercent: Integer;
+    FZeroLevel: Double;
 
     function CalcBarWidth(AX: Double; AIndex: Integer): Double;
+    function IsZeroLevelStored: boolean;
     procedure SetBarBrush(Value: TBrush);
     procedure SetBarPen(Value: TPen);
     procedure SetBarWidthPercent(Value: Integer);
     procedure SetSeriesColor(AValue: TColor);
+    procedure SetZeroLevel(AValue: Double);
   protected
     procedure GetLegendItems(AItems: TChartLegendItems); override;
     function GetSeriesColor: TColor; override;
@@ -101,6 +104,8 @@ type
       read GetSeriesColor write SetSeriesColor default clTAColor;
     property Source;
     property UseReticule;
+    property ZeroLevel: Double
+      read FZeroLevel write SetZeroLevel stored IsZeroLevelStored;
   end;
 
   { TPieSeries }
@@ -890,9 +895,9 @@ begin
     p := FGraphPoints[i - FLoBound];
     w := CalcBarWidth(GetGraphPointX(i), i);
     if IsRotated then
-      graphBar := DoubleRect(AxisToGraphX(0), p.Y - w, p.X, p.Y + w)
+      graphBar := DoubleRect(AxisToGraphX(ZeroLevel), p.Y - w, p.X, p.Y + w)
     else
-      graphBar := DoubleRect(p.X - w, AxisToGraphY(0), p.X + w, p.Y);
+      graphBar := DoubleRect(p.X - w, AxisToGraphY(ZeroLevel), p.X + w, p.Y);
     if not RectIntersectsRect(graphBar, ext2) then continue;
 
     with imageBar do begin
@@ -917,7 +922,7 @@ var
 begin
   Result := inherited Extent;
   if IsEmpty then exit;
-  UpdateMinMax(0, Result.a.Y, Result.b.Y);
+  UpdateMinMax(ZeroLevel, Result.a.Y, Result.b.Y);
   // Show first and last bars fully.
   x := GetGraphPointX(0);
   Result.a.X := Min(Result.a.X, x - CalcBarWidth(x, 0));
@@ -935,6 +940,11 @@ begin
   Result := FBarBrush.Color;
 end;
 
+function TBarSeries.IsZeroLevelStored: boolean;
+begin
+  Result := ZeroLevel <> 0.0;
+end;
+
 procedure TBarSeries.SetBarBrush(Value: TBrush);
 begin
   FBarBrush.Assign(Value);
@@ -957,6 +967,13 @@ begin
   FBarBrush.Color := AValue;
 end;
 
+procedure TBarSeries.SetZeroLevel(AValue: Double);
+begin
+  if FZeroLevel = AValue then exit;
+  FZeroLevel := AValue;
+  UpdateParentChart;
+end;
+
 { TPieSeries }
 
 function TPieSeries.AddPie(Value: Double; Text: String; Color: TColor): Longint;