Workaround for rendering issue with doji candles (candles with bodies so small, they are just represented by a line). It seems that WPF falsely renders these rectangles with their left coordinates adjusted to the left by the rectangles width (which effectively draws a line double it's intended size). In these edge cases, let's just draw a line (or two) instead of a polygon. Adresses issue oxyplot#1245 and possibly oxyplot#623.

Author: lauxjpn

CHANGELOG.md

@@ -47,6 +47,8 @@ All notable changes to this project will be documented in this file.
 - ScatterSeries with DateTimeAxis/TimeSpanAxis (#1132)
 - Exporting TextAnnotation with TextColor having 255 alpha to SVG produces opaque text (#1160)
 - Chart is not updated when top and bottom are not visible (#1219)
+- Candle overlap each candle (#623)
+- CandleStick is overlapped when item.open == item.close in the CandleStickAndVolumeSeries (#1245)
 
 ## [1.0.0] - 2016-09-11
 ### Added

CONTRIBUTORS

@@ -115,4 +115,5 @@ Vsevolod Kukol <sevo@sevo.org>
 Xavier <Xavier@xavier-PC.lsi>
 zur003 <Eric.Zurcher@csiro.au>
 Markus Ebner
-Duncan Robertson <duncanjacobrobertson@gmail.com>
+Duncan Robertson <duncanjacobrobertson@gmail.com>
+LauXjpn <laucomm@gmail.com>

Source/OxyPlot/Series/FinancialSeries/CandleStickAndVolumeSeries.cs

@@ -315,13 +315,22 @@ public override void Render(IRenderContext rc)
 
                 // Body
                 var openLeft = open + new ScreenVector(-candlewidth * 0.5, 0);
-                var rect = new OxyRect(openLeft.X, min.Y, candlewidth, max.Y - min.Y);
-                rc.DrawClippedRectangleAsPolygon(
-                    clippingBar,
-                    rect,
-                    fillColor,
-                    lineColor,
-                    this.StrokeThickness);
+
+                if (max.Y - min.Y < 1.0)
+                {
+                    var leftPoint = new ScreenPoint(openLeft.X - this.StrokeThickness, min.Y);
+                    var rightPoint = new ScreenPoint(openLeft.X + this.StrokeThickness + candlewidth, min.Y);
+                    rc.DrawClippedLine(clippingBar, new[] { leftPoint, rightPoint }, leftPoint.DistanceToSquared(rightPoint), lineColor, this.StrokeThickness, null, LineJoin.Miter, true);
+
+                    leftPoint = new ScreenPoint(openLeft.X - this.StrokeThickness, max.Y);
+                    rightPoint = new ScreenPoint(openLeft.X + this.StrokeThickness + candlewidth, max.Y);
+                    rc.DrawClippedLine(clippingBar, new[] { leftPoint, rightPoint }, leftPoint.DistanceToSquared(rightPoint), lineColor, this.StrokeThickness, null, LineJoin.Miter, true);
+                }
+                else
+                {
+                    var rect = new OxyRect(openLeft.X, min.Y, candlewidth, max.Y - min.Y);
+                    rc.DrawClippedRectangleAsPolygon(clippingBar, rect, fillColor, lineColor, this.StrokeThickness);
+                }
 
                 // Volume Part
                 if (this.VolumeAxis == null || this.VolumeStyle == VolumeStyle.None)
@@ -700,4 +709,4 @@ protected OxyRect GetSeparationClippingRect()
             return new OxyRect(minX, minY, maxX - minX, maxY - minY);
         }
     }
-}
+}

Source/OxyPlot/Series/FinancialSeries/CandleStickSeries.cs

@@ -159,8 +159,22 @@ public override void Render(IRenderContext rc)
 
                 // Body
                 var openLeft = open + new ScreenVector(-candlewidth * 0.5, 0);
-                var rect = new OxyRect(openLeft.X, min.Y, candlewidth, max.Y - min.Y);
-                rc.DrawClippedRectangleAsPolygon(clippingRect, rect, fillColor, lineColor, this.StrokeThickness);
+
+                if (max.Y - min.Y < 1.0)
+                {
+                    var leftPoint = new ScreenPoint(openLeft.X - this.StrokeThickness, min.Y);
+                    var rightPoint = new ScreenPoint(openLeft.X + this.StrokeThickness + candlewidth, min.Y);
+                    rc.DrawClippedLine(clippingRect, new[] { leftPoint, rightPoint }, leftPoint.DistanceToSquared(rightPoint), lineColor, this.StrokeThickness, null, LineJoin.Miter, true);
+
+                    leftPoint = new ScreenPoint(openLeft.X - this.StrokeThickness, max.Y);
+                    rightPoint = new ScreenPoint(openLeft.X + this.StrokeThickness + candlewidth, max.Y);
+                    rc.DrawClippedLine(clippingRect, new[] { leftPoint, rightPoint }, leftPoint.DistanceToSquared(rightPoint), lineColor, this.StrokeThickness, null, LineJoin.Miter, true);
+                }
+                else
+                {
+                    var rect = new OxyRect(openLeft.X, min.Y, candlewidth, max.Y - min.Y);
+                    rc.DrawClippedRectangleAsPolygon(clippingRect, rect, fillColor, lineColor, this.StrokeThickness);
+                }
             }
         }