feat: spaceTop/spaceBottom for data sets

Author: farfromrefug

src/ui-chart/data/BaseDataSet.ts

@@ -123,6 +123,16 @@ export abstract class BaseDataSet<T extends Entry> implements IDataSet<T> {
      */
     visible = true;
 
+    /**
+     * data  space from the smallest value to the bottom in percent of the total axis range
+     */
+    spaceBottom = 0;
+
+    /**
+     * data  space from the highest value to the top in percent of the total axis range
+     */
+    spaceTop = 0;
+
     /**
      * Constructor with label.
      *

src/ui-chart/data/DataSet.ts

@@ -178,11 +178,11 @@ export abstract class DataSet<T extends Entry> extends BaseDataSet<T> {
     }
 
     public get yMin() {
-        return this.mYMin;
+        return this.mYMin - this.spaceBottom;
     }
 
     public get yMax() {
-        return this.mYMax;
+        return this.mYMax + this.spaceTop;
     }
 
     public get xMin() {