Merge pull request #2732 from ControlSystemStudio/FixLinearTicks

CSSTUDIO-1133 Change condition when selecting distance between major ticks in `LinearTicks.selectNiceStep()`.

Author: abrahamwolk

app/rtplot/src/main/java/org/csstudio/javafx/rtplot/internal/LinearTicks.java

@@ -254,27 +254,25 @@ public static int determinePrecision(final double number)
      *  A computed distance of 6.1 turns into 10.0, not 5.0.
      *  @see #selectNiceStep(double)
      */
-    final private static double[] NICE_STEPS = { 10.0, 5.0, 2.0, 1.0 },
-                             NICE_THRESHOLDS = {  6.0, 3.0, 1.2, 0.0 };
+    final private static double[] NICE_STEPS = { 1.0, 2.0, 5.0, 10.0 };
 
     /** To a human viewer, tick distances of 5.0 are easier to see
      *  than for example 7.
      *
      *  <p>This method tries to adjust a computed tick distance
      *  to one that is hopefully 'nicer'
      *
-     *  @param distance Original step distance
+     *  @param min_distance Original step distance
      *  @return
      */
-    public static double selectNiceStep(final double distance)
+    public static double selectNiceStep(final double min_distance)
     {
-        final double log = Math.log10(distance);
+        final double log = Math.log10(min_distance);
         final double order_of_magnitude = Math.pow(10, Math.floor(log));
-        final double step = distance / order_of_magnitude;
         for (int i=0; i<NICE_STEPS.length; ++i)
-            if (step >= NICE_THRESHOLDS[i])
+            if (NICE_STEPS[i] * order_of_magnitude >= min_distance)
                 return NICE_STEPS[i] * order_of_magnitude;
-        return step * order_of_magnitude;
+        return min_distance;
     }
 
     /** Create decimal format

app/rtplot/src/main/java/org/csstudio/javafx/rtplot/internal/Ticks.java

@@ -25,7 +25,7 @@ public abstract class Ticks<XTYPE>
     protected volatile List<MinorTick<XTYPE>> minor_ticks = Collections.emptyList();
 
     /** How many percent of the available space should be used for labels? */
-    final public static int FILL_PERCENTAGE = 60;
+    final public static int FILL_PERCENTAGE = 70;
 
     /** Used to adjust a range to a meaningful range for the chosen scale.
      *  @param low Desired low limit of the axis range.

app/rtplot/src/test/java/org/csstudio/javafx/rtplot/LogTicksTest.java

@@ -46,7 +46,7 @@ public void testLogTicks()
         System.out.println("Ticks for " + start + " .. " + end + ":");
         text = ticks2text(ticks);
         System.out.println(text);
-        assertThat(text, equalTo("'1.1E3' '1.2E3' "));
+        assertThat(text, equalTo("'1.05E3' '1.10E3' '1.15E3' '1.20E3' "));
 
     }
 }

app/rtplot/src/test/java/org/csstudio/javafx/rtplot/TicksTestBase.java

@@ -122,7 +122,7 @@ public void testNiceDistance()
             assertThat(LinearTicks.selectNiceStep(5.0*order_of_magnitude), equalTo(5.0*order_of_magnitude));
             assertThat(LinearTicks.selectNiceStep(4.0*order_of_magnitude), equalTo(5.0*order_of_magnitude));
             assertThat(LinearTicks.selectNiceStep(3.0*order_of_magnitude), equalTo(5.0*order_of_magnitude));
-            assertThat(LinearTicks.selectNiceStep(2.01*order_of_magnitude), equalTo(2.0*order_of_magnitude));
+            assertThat(LinearTicks.selectNiceStep(1.99*order_of_magnitude), equalTo(2.0*order_of_magnitude));
             assertThat(LinearTicks.selectNiceStep(1.5*order_of_magnitude), equalTo(2.0*order_of_magnitude));
         }
     }

app/rtplot/src/test/java/org/csstudio/javafx/rtplot/internal/LinearTicksTest.java

@@ -42,7 +42,7 @@ public void testNiceDistance()
             assertThat(LinearTicks.selectNiceStep(5.0*order_of_magnitude), equalTo(5.0*order_of_magnitude));
             assertThat(LinearTicks.selectNiceStep(4.0*order_of_magnitude), equalTo(5.0*order_of_magnitude));
             assertThat(LinearTicks.selectNiceStep(3.0*order_of_magnitude), equalTo(5.0*order_of_magnitude));
-            assertThat(LinearTicks.selectNiceStep(2.01*order_of_magnitude), equalTo(2.0*order_of_magnitude));
+            assertThat(LinearTicks.selectNiceStep(1.99*order_of_magnitude), equalTo(2.0*order_of_magnitude));
             assertThat(LinearTicks.selectNiceStep(1.5*order_of_magnitude), equalTo(2.0*order_of_magnitude));
         }
     }