Merge pull request #3642 from pagrzybe/autoscale_restrictions

Option to set restrictions for Y axis autoscaling.

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

@@ -38,6 +38,16 @@ public class YAxis extends AxisBase {
      */
     protected boolean mDrawZeroLine = false;
 
+    /**
+     * flag indicating that auto scale min restriction should be used
+     */
+    private boolean mUseAutoScaleRestrictionMin = false;
+
+    /**
+     * flag indicating that auto scale max restriction should be used
+     */
+    private boolean mUseAutoScaleRestrictionMax = false;
+
     /**
      * Color of the zero line
      */
@@ -357,12 +367,57 @@ public class YAxis extends AxisBase {
             return false;
     }
 
+    /**
+     * Returns true if autoscale restriction for axis min value is enabled
+     */
+    public boolean isUseAutoScaleMinRestriction( ) {
+        return mUseAutoScaleRestrictionMin;
+    }
+
+    /**
+     * Sets autoscale restriction for axis min value as enabled/disabled
+     */
+    public void setUseAutoScaleMinRestriction( boolean isEnabled ) {
+        mUseAutoScaleRestrictionMin = isEnabled;
+    }
+
+    /**
+     * Returns true if autoscale restriction for axis max value is enabled
+     */
+    public boolean isUseAutoScaleMaxRestriction() {
+        return mUseAutoScaleRestrictionMax;
+    }
+
+    /**
+     * Sets autoscale restriction for axis max value as enabled/disabled
+     */
+    public void setUseAutoScaleMaxRestriction( boolean isEnabled ) {
+        mUseAutoScaleRestrictionMax = isEnabled;
+    }
+
+
     @Override
     public void calculate(float dataMin, float dataMax) {
 
+        float min = dataMin;
+        float max = dataMax;
+
         // if custom, use value as is, else use data value
-        float min = mCustomAxisMin ? mAxisMinimum : dataMin;
-        float max = mCustomAxisMax ? mAxisMaximum : dataMax;
+        if( mCustomAxisMin ) {
+            if( mUseAutoScaleRestrictionMin ) {
+                min = Math.min( dataMin, mAxisMinimum );
+            } else {
+                min = mAxisMinimum;
+            }
+        }
+
+        if( mCustomAxisMax ) {
+            if( mUseAutoScaleRestrictionMax ) {
+                max = Math.max( max, mAxisMaximum );
+            } else {
+                max = mAxisMaximum;
+            }
+        }
 
         // temporary range (before calculations)
         float range = Math.abs(max - min);