Final fixes and improvements concerning zero line

MPChartExample/src/com/xxmassdeveloper/mpchartexample/BarChartPositiveNegative.java

@@ -67,6 +67,8 @@ public class BarChartPositiveNegative extends DemoBase {
         left.setDrawAxisLine(false);
         left.setDrawGridLines(false);
         left.setDrawZeroLine(true); // draw a zero line
+        left.setZeroLineColor(Color.GRAY);
+        left.setZeroLineWidth(0.7f);
         mChart.getAxisRight().setEnabled(false);
         mChart.getLegend().setEnabled(false);
 

MPChartExample/src/com/xxmassdeveloper/mpchartexample/LineChartActivity1.java

@@ -133,6 +133,7 @@ public class LineChartActivity1 extends DemoBase implements OnSeekBarChangeListe
         leftAxis.setStartAtZero(false);
         //leftAxis.setYOffset(20f);
         leftAxis.enableGridDashedLine(10f, 10f, 0f);
+        leftAxis.setDrawZeroLine(false);
 
         // limit lines are drawn behind data (and not on top)
         leftAxis.setDrawLimitLinesBehindData(true);

MPChartExample/src/com/xxmassdeveloper/mpchartexample/LineChartActivity2.java

@@ -123,6 +123,7 @@ public class LineChartActivity2 extends DemoBase implements OnSeekBarChangeListe
         rightAxis.setStartAtZero(false);
         rightAxis.setAxisMinValue(-200);
         rightAxis.setDrawGridLines(false);
+        rightAxis.setDrawZeroLine(false);
     }
 
     @Override

MPChartLib/src/com/github/mikephil/charting/components/YAxis.java

@@ -1,5 +1,6 @@
 package com.github.mikephil.charting.components;
 
+import android.graphics.Color;
 import android.graphics.Paint;
 
 import com.github.mikephil.charting.formatter.DefaultValueFormatter;
@@ -72,6 +73,16 @@ public class YAxis extends AxisBase {
      */
     protected boolean mDrawZeroLine = true;
 
+    /**
+     * Color of the zero line
+     */
+    protected int mZeroLineColor = Color.GRAY;
+
+    /**
+     * Width of the zero line in pixels
+     */
+    protected float mZeroLineWidth = 1f;
+
     /**
      * custom minimum value this axis represents
      */
@@ -365,6 +376,32 @@ public class YAxis extends AxisBase {
         this.mDrawZeroLine = mDrawZeroLine;
     }
 
+    public int getZeroLineColor() {
+        return mZeroLineColor;
+    }
+
+    /**
+     * Sets the color of the zero line
+     *
+     * @param color
+     */
+    public void setZeroLineColor(int color) {
+        mZeroLineColor = color;
+    }
+
+    public float getZeroLineWidth() {
+        return mZeroLineWidth;
+    }
+
+    /**
+     * Sets the width of the zero line in dp
+     *
+     * @param width
+     */
+    public void setZeroLineWidth(float width) {
+        this.mZeroLineWidth = Utils.convertDpToPixel(width);
+    }
+
     /**
      * This is for normal (not horizontal) charts horizontal spacing.
      *

MPChartLib/src/com/github/mikephil/charting/renderer/YAxisRenderer.java

@@ -21,6 +21,8 @@ public class YAxisRenderer extends AxisRenderer {
 
     protected YAxis mYAxis;
 
+    protected Paint mZeroLinePaint;
+
     public YAxisRenderer(ViewPortHandler viewPortHandler, YAxis yAxis, Transformer trans) {
         super(viewPortHandler, trans);
 
@@ -28,6 +30,11 @@ public class YAxisRenderer extends AxisRenderer {
 
         mAxisLabelPaint.setColor(Color.BLACK);
         mAxisLabelPaint.setTextSize(Utils.convertDpToPixel(10f));
+
+        mZeroLinePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
+        mZeroLinePaint.setColor(Color.GRAY);
+        mZeroLinePaint.setStrokeWidth(1f);
+        mZeroLinePaint.setStyle(Paint.Style.STROKE);
     }
 
     /**
@@ -283,7 +290,7 @@ public class YAxisRenderer extends AxisRenderer {
             position[1] = 0f;
             mTrans.pointValuesToPixel(position);
 
-            drawZeroLine(c, mViewPortHandler.offsetLeft(), mViewPortHandler.contentRight(), position[1], position[1]);
+            drawZeroLine(c, mViewPortHandler.offsetLeft(), mViewPortHandler.contentRight(), position[1]-1, position[1]-1);
         }
     }
 
@@ -298,13 +305,16 @@ public class YAxisRenderer extends AxisRenderer {
      */
     protected void drawZeroLine(Canvas c, float x1, float x2, float y1, float y2) {
 
+        mZeroLinePaint.setColor(mYAxis.getZeroLineColor());
+        mZeroLinePaint.setStrokeWidth(mYAxis.getZeroLineWidth());
+
         Path zeroLinePath = new Path();
 
         zeroLinePath.moveTo(x1, y1);
         zeroLinePath.lineTo(x2, y2);
 
         // draw a path because lines don't support dashing on lower android versions
-        c.drawPath(zeroLinePath, mGridPaint);
+        c.drawPath(zeroLinePath, mZeroLinePaint);
     }
 
     /**

MPChartLib/src/com/github/mikephil/charting/renderer/YAxisRendererHorizontalBarChart.java

@@ -185,7 +185,7 @@ public class YAxisRendererHorizontalBarChart extends YAxisRenderer {
             position[0] = 0f;
             mTrans.pointValuesToPixel(position);
 
-            drawZeroLine(c, position[0], position[0], mViewPortHandler.contentTop(), mViewPortHandler.contentBottom());
+            drawZeroLine(c, position[0]+1, position[0]+1, mViewPortHandler.contentTop(), mViewPortHandler.contentBottom());
         }
     }