phisi · phisi · Feb 26, 2017 · Feb 25, 2017
diff --git a/androidplot-core/src/main/java/com/androidplot/xy/StepMode.java b/androidplot-core/src/main/java/com/androidplot/xy/StepMode.java
@@ -20,9 +20,11 @@
  * INCREMENTAL_VALUE - (default) draw a tick every n values.
  * INCREMENTAL_PIXEL - draw a tick every n pixels.
  * SUBDIVIDE - draw n number of evenly spaced lines.
+ * INCREMENT_BY_FIT choose increment from a list of possible values
  */
 public enum StepMode {
     SUBDIVIDE,           // default
     INCREMENT_BY_VAL,
-    INCREMENT_BY_PIXELS
+    INCREMENT_BY_PIXELS,
+    INCREMENT_BY_FIT
 }
diff --git a/androidplot-core/src/main/java/com/androidplot/xy/StepModelFit.java b/androidplot-core/src/main/java/com/androidplot/xy/StepModelFit.java
@@ -0,0 +1,85 @@
+package com.androidplot.xy;
+
+import com.androidplot.Region;
+
+import java.util.Arrays;
+
+/**
+ * Subclass of StepModel that chooses from predefined step values. Depending on the currently
+ * displayed range (by value) choose increment so that the number of lines
+ * is closest to StepModel.value
+ */
+public class StepModelFit extends StepModel {
+
+    private double[] steps; // list of steps to choose from
+    private Region scale;   // axis region on display
+
+    public StepModelFit(Region axisRegion, double[] increments, double numLines) {
+        super(StepMode.INCREMENT_BY_FIT, numLines);
+
+        setSteps(increments);
+        setScale(axisRegion);
+    }
+
+    public double[] getSteps() {
+        return steps;
+    }
+
+    public void setSteps(double[] steps) {
+
+        // sanity checks: no null, 0 or negative
+        if (steps == null || steps.length == 0)
+            return;
+
+        for (double step : steps) {
+            if (step <= 0.0d)
+                return;
+        }
+
+        this.steps = steps;
+    }
+
+    public Region getScale() {
+        return scale;
+    }
+
+    public void setScale(Region scale) {
+        this.scale = scale;
+    }
+
+    // does not return StepModel.value instead calculates best fit
+    @Override
+    public double getValue() {
+
+        // no possible increments where supplied
+        // or no region defined
+        if (steps == null || scale == null || !scale.isDefined())
+            return super.getValue();
+
+        double curStep = steps[0];
+        double oldDistance = Math.abs((scale.length().doubleValue() / curStep)-super.getValue() );
+
+        // determine which step size comes closest to the desired number of steps
+        // since steps[] is a small array brute force search is ok
+        for (double step : steps) {
+
+            double newDistance = Math.abs((scale.length().doubleValue() / step)-super.getValue() );
+
+            // closer than previous stepping?
+            if (newDistance < oldDistance){
+                curStep = step;
+                oldDistance = newDistance;
+            }
+        }
+        return curStep;
+    }
+
+    @Override
+    public String toString() {
+        return "StepModelFit{" +
+                "steps=" + Arrays.toString(steps) +
+                ", scale=" + scale +
+                ", current stepping=" + getValue() +
+                '}';
+    }
+}
diff --git a/androidplot-core/src/main/java/com/androidplot/xy/XYGraphWidget.java b/androidplot-core/src/main/java/com/androidplot/xy/XYGraphWidget.java
@@ -546,7 +546,7 @@ protected void drawLineLabel(Canvas canvas, Edge edge, Number val, float x, floa
     }
 
     /**
-     * Draws the drid and domain/range labels for the plot.
+     * Draws the grid and domain/range labels for the plot.
      *
      * @param canvas
      */

diff --git a/androidplot-core/src/main/java/com/androidplot/xy/XYStepCalculator.java b/androidplot-core/src/main/java/com/androidplot/xy/XYStepCalculator.java
@@ -59,6 +59,7 @@ public static Step getStep(StepMode typeXY, double stepValue, Region realBounds,
         double stepCount = 0;
         switch(typeXY) {
             case INCREMENT_BY_VAL:
+            case INCREMENT_BY_FIT:
                 stepVal = stepValue;
                 stepPix = stepValue / realBounds.ratio(pixelBounds).doubleValue();
                 stepCount = pixelBounds.length().doubleValue() / stepPix;

diff --git a/androidplot-core/src/test/java/com/androidplot/xy/StepModelFitTest.java b/androidplot-core/src/test/java/com/androidplot/xy/StepModelFitTest.java
@@ -0,0 +1,61 @@
+package com.androidplot.xy;
+
+import com.androidplot.Region;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class StepModelFitTest {
+
+    Region regionSmall = new Region(0,11);
+    Region regionBig = new Region(-111,420);
+    Region regionZero = new Region(0, 0);
+    Region regionUndef = new Region(0, null);
+
+    double[] stpSmall = {1,2,5}, stpBig = {1,10,100}, nonsense = {0};
+
+    @Before
+    public void setUp() throws Exception {
+
+    }
+
+    @After
+    public void tearDown() throws Exception {
+
+    }
+
+    @Test
+    public void getValue() throws Exception {
+
+        StepModelFit model = new StepModelFit(regionSmall,stpSmall,3);
+
+        assertEquals(5.0, model.getValue(), 0.0);
+        model.setValue(5.0);
+        assertEquals(2.0, model.getValue(), 0.0);
+        model.setValue(7.0);
+        assertEquals(2.0, model.getValue(), 0.0);
+
+        model.setSteps(stpBig);
+        assertEquals(1.0, model.getValue(), 0.0);
+
+        model.setScale(regionBig);
+        assertEquals(100.0, model.getValue(), 0.0);
+        model.setValue(1000.0);
+        assertEquals(1.0, model.getValue(), 0.0);
+
+        // bad parameters
+        model.setSteps(nonsense);
+        assertArrayEquals(stpBig,model.getSteps(), 0.0);
+
+        model.setScale(regionZero);
+        assertEquals(stpBig[0], model.getValue(), 0.0);
+
+        model.setScale(regionUndef);
+        model.setValue(1.1);
+        assertEquals(1.1, model.getValue(), 0.0);
+    }
+
+}
diff --git a/demoapp/src/main/java/com/androidplot/demos/TouchZoomExampleActivity.java b/demoapp/src/main/java/com/androidplot/demos/TouchZoomExampleActivity.java
@@ -31,6 +31,7 @@
 public class TouchZoomExampleActivity extends Activity {
     private static final int SERIES_SIZE = 3000;
     private static final int SERIES_ALPHA = 255;
+    private static final int NUM_GRIDLINES = 5;
     private XYPlot plot;
     private PanZoom panZoom;
     private Button resetButton;
@@ -53,8 +54,14 @@ public void onClick(View view) {
         // move dynamically with the data when the users pans or zooms:
         plot.setUserDomainOrigin(0);
         plot.setUserRangeOrigin(0);
-        plot.setDomainStep(StepMode.INCREMENT_BY_VAL, 500);
-        plot.setRangeStep(StepMode.INCREMENT_BY_VAL, 100);
+
+        // predefine the stepping of both axis
+        // increment will be chosen from list to best fit NUM_GRIDLINES grid lines
+        double[] inc_domain = new double[]{10,50,100,500};
+        double[] inc_range = new double[]{1,5,10,20,50,100};
+        plot.setDomainStepModel(new StepModelFit(plot.getBounds().getxRegion(),inc_domain,NUM_GRIDLINES));
+        plot.setRangeStepModel( new StepModelFit(plot.getBounds().getyRegion(),inc_range,NUM_GRIDLINES));
+
 
         panSpinner = (Spinner) findViewById(R.id.pan_spinner);
         zoomSpinner = (Spinner) findViewById(R.id.zoom_spinner);
-Original file line number
+Diff line change
@@ Expand Up @@
         }
         /**
-         * Draws the drid and domain/range labels for the plot.
+         * Draws the grid and domain/range labels for the plot.
          *
          * @param canvas
          */
@@ Expand Down @@